WO2003065201A1

WO2003065201A1 - Simple display system especially adapted to display complex patterns

Info

Publication number: WO2003065201A1
Application number: PCT/GB2003/000380
Authority: WO
Inventors: Nigel John Halse
Original assignee: Nigel John Halse
Priority date: 2002-02-01
Filing date: 2003-01-30
Publication date: 2003-08-07
Also published as: GB0202426D0

Abstract

A display system comprises a controller (20), a plurality of processors (46) controlled by the controller and a display element (48,50,52) such as one or more LED associated with each processor (46). Power and control signals are sent to the processors via a common bus (22) allowing complex displays to be achieved using the distributed computing power of the processors (46).

Description

SIMPLE DISPLAY SYSTEM ESPECIALLY ADAPTED TO DISPLAY COMPLEX PATTERNS

The invention relates to a display system, to an illumination device and to a method of controlling a display.

One well-known display system comprises the "fairy lights" used to decorate Christmas trees. These lights generally comprise a strand of several tens of bulbs powered by a common source. In the simplest form, the bulbs are powered in series along a length of wire that can be draped or suspended as appropriate for display purposes. More sophisticated versions are known allowing more complex display patterns. In particular flashing displays are available. This is either by insertion of a modified bulb into the series connection including a bi-metallic strip that makes and breaks an electrical contact as it heats and cools. This breaks the connection across the entire series strand so that all of the lights flash with the modified bulb. Alternatively, a more sophisticated version comprises a centralised controller that controls the supply of power to a strand of bulbs. In one known arrangement the controller independently controls two or more separate strands allowing more complex display patterns to be achieved.

A problem with these known arrangements is that only very simple display configurations are available and that a bulky and complex controller is required, as displays become more complex.

According to the invention there is provided a display system comprising a display controller, a plurality of processors in communication with the controller via a common communication path and at least one display element in communication with each processor, in which the controller is arranged to control the display elements via the processor. As a result processing power is distributed along the communication path whilst allowing more complex displays.

The invention further provides a display system comprising a display controller, a plurality of processors connected with the display controller and receiving power and control information via the connection and at least one display element in communication with each processor.

The invention further comprises a method of controlling a display comprising a plurality of processors each in communication with at least one display element comprising the steps of sending display control information from a controller to the processors via a common communication path.

In yet another aspect, the invention provides an illumination device comprising a plurality of illumination elements and a display system described above in which the illumination elements comprise said display elements.

Further aspects of embodiments of the invention are set out in the claims.

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

Fig. 1 is a block diagram of a system embodying the present invention;

Fig. 2 is a block diagram of a node of the system of Figure 1;

Fig. 3 shows a data structure for the system of Figure 1 ; and Fig. 4 shows a control switching arrangement for the system of Figure 1.

In the various figures like reference numerals refer to like parts. Fig. 1 shows an embodiment of a basic system exemplifying the present invention. A power adapter 10 receives power from a mains supply (not shown) and powers a control unit 20. The control unit sends power and a data signal down a 2- wire bus 22. For example this can be a simple twisted pair. A plurality of nodes 24, 26, 28 take the power/data signal off the bus 22. The nodes are discussed in more detail below but include means for separating the power and data signals, means for processing the data signal and at least one display element, typically an LED, controlled according to the data signal. This arrangement allows complex displays to be achieved limited only by the number of nodes/display elements per node, with processing power distributed across the system rather than residing at the control unit 20.

The system also includes a remote or other user control 30 arranged to communicate and control the control unit 20. As shown this is via a wired connection but a wireless connection is also envisaged. Such wireless connections may include a radio frequency, optical, infrared or acoustic link.

The various components shown in Fig. 1 are, individually, available off the shelf and will be well known to the skilled person. The power adapter 10 can be any appropriate power adapter that can be country specific. In one embodiment the adapter provides a + 6v supply to the controller 20 which is appropriate to drive the nodes 24, 26, 28 where the display elements comprise LEDs. In another, the power adapter provides +6v and Ov. The controller 20 can be any appropriate microprocessor, for example processor number PIC16F628 manufactured by Microchip Pic of Arizona, U.S.A.

Turning now to Fig. 2, the node structure can be seen in more detail with reference to a node designated generally 24. A power separator comprises a bridge rectifier and smoothing capacitor 42 arranged to smooth out power derived from the bus. A signal separator 40 includes a resistor 44 and a capacitor 45 arranged to extract the data signal that is then passed to processor 46. The resistor 44 and capacitor 45 form a transient-suppressing filter to avoid spikes from the bus 22 from reaching the processor 46. The processor controls a red green and blue LED 48, 50, 52 respectively via a respective series resistor 54. The use of the three LEDs 48, 50, 52 allows a very wide range of colours and effects to be achieved under the control of the processor 46 as is generally well known. For example at least 32,000 colours are achievable using an LED configuration of this type.

As a result of the node configuration, the number of control lines from the controller is reduced to a single twisted pair bus linking all the nodes. A larger proportion of computational work is done locally to the nodes including decoding the control signals, generating the amplitude and frequency signals for the lamps and for example calculating blend and random switching functions. This local processing helps to keep radio frequency interference (RFI)/electro-magnetic-compatibility (EMC) problems to a minimum.

The data/signal extractor 40 can be the simple circuitry shown in fig 2 or any appropriate data/signal extractor. It will be understood that the use of an RC filter provides an inexpensive solution to the problem of spikes and other transients on the bus, but that this solution may not be appropriate in all applications. For example, in environments where noise or bus spikes are more critical, a zener diode or like voltage dependent switch could be substituted for the capacitor. The processor 46 can be any appropriate processor for example the Microchip Pic range processor number PIC12CE674 manufactured by Microchip Pic of Arizona, U.S.A. Similarly the LEDs can be any appropriate red/green blue LED such as Farnell 621.419 manufactured by Multicomp. The processor 46 is arranged to control the LEDs 48, 50, 52 either based on programme instructions received from the controller 20 or instructions hard wired or coded into the processor and triggered by a data signal from the controller. In one embodiment the controller 20 loads instructions into the processors 46 at the outset or prior to operation according to those instructions being required, and then triggers the operation subsequently with a data signal.

In one possible configuration the controller 20 can send instructions to each node 24, 26, 28 to commence operation according to a pre-determined programme and then the controller can lie dormant. In that case the controller 20 may poll the nodes at pre-determined intervals - for example every thirty minutes - to check on synchronisation or can issue synchronisation signals at pre-determined intervals.

An example of an appropriate data structure is shown in Fig. 3. The data structure is a 2-byte structure. The first byte 60 of the pair is an address byte. The second byte 62 either carries an instruction (where the first three most significant bits are Is and the remaining bits carry the instruction data) to be carried out by the processor or 8 bits of data to trigger the processor to operate previously coded instructions. Examples of instructions might be:

Possible data structures, where the top three bits are not 111 and n is 0...31 might be:

In addition, one 1-byte instruction is available indicating reset and having a value of 00 (hex) and a byte value of 255 signifies data or an instruction to all lamps. In this scheme the system can accommodate 254 individual nodes on a single bus 22, each being individually addressed. The actual manner in which the instructions are decoded and enacted is a matter of conventional choice for the skilled person and is not explored in detail here.

Turning now to the controller 20, a simple bipolar modulation scheme is applied to the power signal to impress the data signal thereon. This modulation scheme is preferred, as polarity switching is extremely robust. Fig. 4 shows a simple H-bridge configuration in which power signal modulation is achieved by switches 70 controlled by the controller 20. Preferably the switches comprise MOSFETs. According to this arrangement data transmission can be modulated over the power signal at a frequency of up to 10⁶ bps; in the embodiment discussed a bit rate of 9600 bps is adopted. Accidental reversing of polarity may be accommodated by incorporating appropriate sensors at the respective processors 46, which detects initial polarity and operates accordingly. Alternatively, as described above bridge rectifiers may be used to ensure correct polarity to the processors 46.

Control of the display can be achieved in various manners. The controller itself can simply be pre-programmed to run a sequence of display schemes by the way of simple data instructions to the respective nodes or by triggering instructions coded or loaded to the nodes. However the versatility of the system allows a greater level of control to the user. For example by entering user commands to the controller 20 or to control device 30, display schemes can be defined or selected from a range of pre-defined options using an appropriate user interface. Instead of command based control, ambient conditions can be used to determine the display schemes adopted. For example ambient sound such as music can comprise the input via a suitable transducer allowing synchronised or atmospheric display lighting. It will be appreciated that any appropriate controller, processor and LED components can be used to implement the invention as discussed above. The controller can run multiple strings via separate H-bridges or other command interfaces allowing the user to purchase additional strings as desired.

Nor are the display elements limited to red, green and blue LEDs. Any other available colours of LEDs, for example white LEDs - can be incorporated and alternative illumination sources can be used instead. Further still the display elements can extend to mechanical devices such as articulated elements.

The modulation scheme can be selected as appropriate and can, for example, comprise frequency shift keying (FSK) modulation, phase shift keying (PSK) modulation or a modulated wave signal imposed on the power signal. Similarly any appropriate data structure and command language can be adopted and can be transmitted to the nodes via any appropriate physical data or power carrier.

It will further be appreciated that the invention can be implemented in a range of alternative applications. For example the nodes can be laid out in a grid forming a display board allowing the display of text or graphical elements.

Such a display would have a range of uses and could for example be used as a simple illumination device transferable to a display device when required - for example in emergency situation it could be used to indicate emergency exits and so forth. A system such as this could be used domestically, in shops, hospitals, aircraft, car dashboards or any other appropriate environment.

The controller may in another family of embodiments communicate control signals wirelessly with the nodes, which can in such embodiments either be separately connected to receive power from the mains, or can be self-powered, e.g. from batteries or accumulators. Such accumulators can be associated with solar cells, wind power generators or the like.

Several embodiments of the invention have now been described. It will be understood however that the invention is not limited to details of the embodiments but instead extends to the full scope of the appended claims.

Claims

1. A display system comprising a display controller, a plurality of processors in communication with the controller via a common communication path and at least one display element in communication with each processor, in which the controller is arranged to control the display elements via the processor.

2. A system as claimed in claim 1, in which the common communication path carries power and data to each processor.

3. A system as claimed in claim 2, in which the data is modulated on the power signal.

4. A system as claimed in any preceding claim, in which the processor stores display control information triggered by communication of command information from the controller.

5. A system as claimed in any preceding claim, in which the processor receives display control information from the controller.

6. A system as claimed in any preceding claim, in which the display element comprises an illumination device.

7. A system as claimed in claim 6, in which the illumination device comprises at least one LED.

8. A display system comprising a display controller, a plurality of processors connected with the display controller for receiving power and control information via the connection and at least one display element in communication with each processor.

9. A method of controlling a display comprising a plurality of processors each in communication with at least one display element, the method comprising the steps of sending display control information from a controller to the processors via a common communication path.

10. A method as claimed in claim 9, in which display control information is communicated from a controller to each processor at a first interval and the display element to be controlled is triggered at a subsequent interval via subsequent command information from the controller.

11. A method as claimed in claim 9 or claim 10, in which each processor stores control information triggered by command information from the controller.

12. An illumination device comprising a plurality of illumination elements and a display system as claimed in any of claims 1 to 7 in which the illumination elements comprise said display elements.