Graphics engine, and display driver IC and display module incorporating the graphics engine

Abstract

The invention provides a display driver integrated circuit, for connection to a small-area display, the integrated circuit including a hardware-implemented graphics engine for receiving vector graphics commands and rendering image data for display pixels in dependence upon the received commands, and also including display driver circuitry for driving the connected display in accordance with the image data rendered by the graphics engine. In another aspect the graphics engine is held within the display module, but not embedded in the display driver IC. The invention provides graphics acceleration that increases display performance, but does not significantly increase cost of manufacture. Power consumption in comparison to non-accelerated CPU graphics processing is lowered.

Description

FIELD OF THE INVENTION The present invention relates to a graphics engine, and a display driver IC and display module incorporating the graphics engine. BACKGROUND OF THE INVENTION The invention finds application notably in small-area displays found on portable or console electrical devices. Numerous such devices exist, such as PDAs, cordless, mobile and desk telephones, in-car information consoles, hand-held electronic games sets, multifunction watches etc. In the prior art, there is typically a main CPU, which has the task of receiving display commands, processing them and sending the results to the display module in a pixel-data form describing the properties of each display pixel. The amount of data sent to the display module is proportional to the display resolution and the colour depth. For example, a small monochrome display of 96×96 pixels with a four level grey scale requires a fairly small amount of data to be transferred to the display module. Such a screen does not, h...

AI Technical Summary

Benefits of technology

For the first time, the inventors have realised that a graphics engine need not be provided in the CPU part of a device, but may be held in the display module. They have been able to design a hardware graphics engine that is sufficiently simple that it can be embedded in a display driver IC for a small-area display or in a display module for a portable electrical device. Since the graphics engine is in the display module, high-level graphics commands travel between the CPU and the display part of the mobile device, rather than pixel data. Use of graphics engines as opposed to non-accelerated CPU processing reduces power consumption. Use of the graphics engine in the display module allows considerable savings in power in a device of almost identical size and weight.

If a software (or a hardware) graphics engine is held in CPU (or a processing unit), it does not benefit from the advantage of decreased traffic between the CPU and display module. However, the specific advantages of the logical construction of the graphics engine remain. In this aspect, one advantage is that it does not require memory to hold a polygon edge or fill command once it has been read into the engine. Considerable memory savings are achievable, making the graphics engine particularly suitable for use with portable electrical devices, but also useful for larger electrical devices, which are not necessarily portable.

Problems solved by technology

Such a screen does not, however, meet user demand for increasingly attractive and informative displays.

More complex graphics processing places a heavy strain on the CPU and slows the device, so that display reaction and refresh rate may become unacceptable.

This is especially problematic for games applications.

Another problem is the power drain caused by increased graphics processing, which can substantially shorten the intervals between recharging of battery-powered devices.

Known graphics engines used in PCs are specially conceived for large-area displays and are thus highly complex systems requiring separate silicon dies for the high number of gates used.

It is impractical to incorporate these engines into portable devices, which have small-area displays and in which size and weight are strictly limited, and which have limited power resources.

The size of the master list that can be processed is limited by the amount of memory available in the software.

The known software algorithms thus suffer from the disadvantage that they require a large amount of memory to store all the commands for complex polygons before rendering.

This may prejudice manufacturers against incorporating vector graphics processing in mobile devices.

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