GB2402821A

GB2402821A - Lamp driver for decorative lighting

Info

Publication number: GB2402821A
Application number: GB0323025A
Authority: GB
Inventors: Simon Bibby; Bernard Ward
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-06-09
Filing date: 2003-10-01
Publication date: 2004-12-15
Anticipated expiration: 2023-10-01
Also published as: GB0323025D0; GB2402821B; GB0313199D0; GB0320700D0

Abstract

A lamp driver system for decorative lighting such as festoon lighting comprises a sender unit 3 and a plurality of reciever units 5 connected to the sender unit 3 by at least one supply line 1. Each lamp receiver unit 5 has an associated lamp 7 and the sender unit 3 uses or produces a DC supply on the at least one supply line 1 to power the lamps 7. A data control stream is created on the at least one supply line 1 by the sender unit 3 to control operation of the lamps 7 individually in response to the data control stream. The data control stream is created by inverting the power supply on the at least one supply line 1.

Description

240282 1 TITLE: Lamp Driver System

DESCRIPTION

The present invention relates to a system for driving lamp loads, especially low voltage 'baton' type units, but without limitation to same.

Festoon lighting systems are in a wide spread use for decorative lighting systems and comprise a plurality of lamps. The lamps may be of one colour or a variety of different colours. In the simplest examples the lamps are wired m parallel and may be low voltage or extra low voltage. With parallel wiring, lighting effects are limited to switching all the lamps on and off simultaneously, and in order to be able to produce more elaborate lighting sequences, it has become common to use multiple circuits, usually with a plurality of lamps in each circuit. However, such an arrangement necessarily increases the bulk of the wiring loom which can be disadvantageous aesthetically as well as increasing the wiring cost compared with a single circuit system. Simple time based sequencers are also used. However the range of effects is limited.

It is an aim of the present invention to provide a lamp driver system that facilitates a wide variety of decorative lighting effects and yet overcomes the above mentioned difficulties.

Accordingly, the present invention provides a lamp driver system comprising a sender unit and a plurality of lamp receiver units connected to the sender unit by at least one supply line, each lamp receiver unit having an associated lamp; and wherein the sender unit uses or produces a D.C. supply on the at least one supply line to power the lamps, and in which a data control stream is created on the at least one supply line by the sender unit to control operation of the lamps individually in response to the data control stream, and wherein the data control stream is created by inverting the power supply on the at least one supply line.

A plurality of the lamp receiver units are preferably connected in parallel to the sender unit sing a common supply line. There may be a number of supply lines extending from the sender unit and each having a plurality of lamp receiver units connected thereto.

Means to control inverting of the power supply to generate the data control stream is preferably part of the sender unit and conveniently comprises a polarity switching circuit controlled by a logic circuitry, which may be for example a micro processor, a logic device, a microcontroller, a programmable integrated circuit (PIC) or a single-board PC.

The lamp receiver units decode the supply polarity inversions as data and control the state of the lamp depending on the signals received. The LED's could be used instead of lamps. The system avoids the need for separate data wires. Usually the D.C. supply is an extra low voltage D.C. supply in the range 12v to 48v, but the principle could be utilised with higher D.C. voltages.

To operate each lamp a voltage must be applied across it. However, the polarity of this voltage is not relevant. Conveniently each lamp unit incorporates a full wave bridge rectifier in order to produce a steady D. C. supply even when the line polarity is reversing. The signal on one or both of the lamp power lines are fed to a micro-controller or logic system, conveniently via a voltage attenuator, and will be seen (at one of those lines) as high or low depending on line polarity. The high or low signals can then be interpreted as logic level 1 or logic level 0 and be used for control purposes. The micro-controller or logic device of each lamp receiver unit incorporates on address memory unit which is programmed with the desired address code for that unit. An EEPROM memory chip is conveniently used. A programmer may be plugged into the lamp unit lamp socket temporarily instead of the lamp, or via a special connection, to program the unit address.

The present invention will now be described further hereinafter, by way of example only, with reference to the accompanying drawings; in which: Figure 1 is a schematic diagram of a festoon lighting system embodying the present invention.

Figures 2 and 3 are circuit diagrams of a lamp receiver unit used in the present invention and illustrate the effects of polarity reversal; Figure 4 illustrates part of the circuit diagram of Figure 1 in conjunction with a programmer unit; and Figure 5 is a circuit diagram of a sender unit and associated control circuitry used in the present invention.

The present invention is described by way of example only with reference to its application to a festoon type lighting system. Figure 1 illustrates a common cable constituting a supply line and shown generally at 1 and comprises a pair of wires I a, lb. The wires extend from a sender unit 3, described further hereinafter, and connect to a plurality of lamp receiver units 5, each having a lamp 7 and described further hereinafter. The lamp receiver units are disposed in parallel. In the example the system is mains operated and incorporates a transformer/rectifier and smoothing unit 6 to provide a 1 KVA, 24V D.C. supply to drive the polarity inverting data/power lines la, lb of the common cable. The supply is configured to drive up to 200, 5W 24V lamps.

The D.C. supply is fed to a polarity switching circuit 8 formmg part of the sender unit 3. The circuit can switch either output line la, lb to the positive or negative supply. Logic circuitry (output protection device 7) ensures that a given line cannot simultaneously be connected to positive and negative. The polarity of the supply is switched by a microcontroller 9. The micro-controller is programmed to control polarity reversal in a desired manner to control illumination of lamps 7 in a desired manner. Figure 5 illustrates further details of the sender unit and the associated control circuitry. The transformer is shown at 6 and feeding a rectifier with smoothing capacitor shown at 6a. Four electronic switches 52 are provided to switch the polarity appearing as lines 1 a, lb and controlled by output switch timing and control device 54. A logic supply circuit 56 powered from the rectified D.C.

voltage connects with the device 54 as with a memory card 58 associated with the micro-controller 9, and programming interfaces. In the illustrated example a DMX interface and an RS232 interface (59,60) are provided and which facilitate programming of the micro-controller 9 from a separate source when connected via the appropriate data input line. The programming is stored in the memory card 58.

The provision of two interfaces is optional.

Each lamp receiver unit, as well as having a socket connection for lamp 7, also comprises a small full wave bridge rectifier 11. A micro-controller or logic device 12 and an electronic switch 14. The bridge AC input connects across the incoming lines I a, I b. The bridge output provides a D.C. supply which is smoothed with capacitor 13 to prevent power supply dip during polarity changes. The D.C.

supply is supplied to a voltage regulator 15 to provide a stable supply for the micro- controller 12. One of the incoming feed lines 19 feeds into a voltage attentuator and a filter. The attenuated signal connects to a micro- controller input 23. This is effectively a serial data input to the micro- controller. Figures 2 and 3 show how line 23 goes high or low when the polarity at the input la, lb is reversed.

The operation of the sender unit and the lamp receiver units in the system of the invention will now be described further hereinafter.

The lines la, lb are switched by the sender unit 3 in a manner that ensures that, apart from a 15pS transition period, the full DC voltage is present across the output lines however the polarity reverses in accordance with instructions from the micro-controller.

A data protocol chosen for the system operates as follows. Initially a unique period corresponding to 35 data bits is sent as a system address lock synchronizing pulse. Following this a high start bit is sent followed by 16 data bits. One low bit is sent to complete the frame. Each lamp receiver unit actually only receives two bits of data so the first 16 bit frame pertains to lamp addresses 1-8. The next start bit follows immediately after the last stop bit so frame timing remains constant. Each subsequent frame pertains to the next batch of 8 lamps so the second frame is address 9-16 and so on. The two data bits perform two functions. The first bit commands a given damp on or off. The next bit sets the lamp mto a fade mode where the on/off commands from the first bit cause the lamp to fade on and off over a set period. The system uses a data rate of I OK bits/St The rise and fall times of the output switches is set at 15, uS and the output drivers are bandwidth limited to switch over the 151ls period. The comparatively long rise and fall times reduce EMC emissions to a point where for the longest line length likely to be encountered the bandwidth is still sufficiently low to prevent significant radiation. The fact that the signals are switching in anti phase also helps cancel radiated noise.

The organisation of data within the sender unit relating to creating desired patterns and lighting effects is not described in further detail because this is just standard software and any number of approaches could be adopted. It would, for instance, be possible for the sender unit to translate the lighting industry DMX protocol into data suitable for the baton lamps.

In relation to operation of the lamp receiver units 5, the microcontroller 12 first needs to establish the sense of the data because the lamp unit connectors are not polarised and can be connected to the line I a, lb either way round. Polarity can be determined by detecting the polarity of the unique length synchronising pulse. Once this is established the correct Input routine is selected to read the data. The micro- controller 12 in a given damp unit locks onto the synchronising pulse and then counts frames. When the frame/bit count equals the micro-controllers own address, data will be received.

The address of a given lamp is set in EEPROM memory within the microcontroller 12. The address EEPROM memory is loaded using a special programmer plugged into the lamp unit lamp socket temporarily instead of the lamp. The programmer communicates to the micro-controller in the lamp unit using simple serial data through the lamp connector into an input of the micro-controller. The programmer also powers the micro-controller in the lamp unit see figure 4.

The programmer 20 powers the lamp unit 5 by forward biasing the diode D1 and back feeding the 24V rectified supply. To send data the signal must be switched. A special protocol is implemented which maintains the supply by using very short low periods between long on periods. Using this method the average charge in C1 is kept sufficiently high to maintain the regulated supply. The micro- controller reads the low pulses using an attenuated input similar to the one used to read the data line but on a different input. To start programming a series of 5 short low pulses are sent with a space of exactly lmS in between. The lamp unit then enters programming mode. The next low pulse acts as a start bit and the following 8 bits provide the lamps address. Once a lamp has been programmed it can communicate with the sender.

By means of the present invention, each of the plurality of lamps of the festoon lighting systems can be given an address and thereafter the reversals of polarity generated by the sender unit will generate a data stream on the supply line that is Interpreted by the lamp receiver unit to cause each lamp unit to power on or off at the prescribed time to give the desired lighting effect. It will be understood that each lamp unit could have a unique address to permit individual control of each lamp, or some lamp units may share the same address so that the lamp units sharing the same address operate simultaneously in response to the receipt of the appropriate control data.

Claims

1. A lamp driver system comprising a sender unit and a plurality of lamp receiver units connected to the sender unit by at least one supply line, each lamp receiver unit having an associated lamp, and wherein the sender unit uses or produces a D.C.

supply on the at least one supply line to power the lamps, and in which a data control stream is created on the at least one supply line by the sender unit to control operation of the lamps individually in response to the data control stream, and wherein the data control stream is created by inverting the power supply on the at least one supply line.

2. A lamp driver system as claimed in claim 1 in which the means to control inverting of the power supply comprises a polarity switching circuit controlled by logy circuitry.

A lamp driver system as claimed in claim 2 in which the logic circuitry is programmable and selected from a micro processor, micro-controller, programmable integrated circuit, sngle-board PC, or other logic device.

4. A lamp driver system as claimed in claim 2 or 3 in which said means is part of the sender unit.

5. A lamp driver system as claimed in any one of the preceding claims in which each lamp receiver unit incorporates a full wave bridge rectifier.

6. A lamp driver system as claimed in any one of the preceding claims in which the lamp receiving unit incorporates a mcro-controller or logic unit that detects the change in polarity as logic level 1 or O that is used for control purposes.

7. A lamp driver system as claimed in any one of the preceding claims to which each lamp receiver unit incorporates an address memory unit.

8. A lamp driver system as claimed in claim 7 in which each address memory is individually programmable.

9. A lamp driver system as deemed in any one of the preceding claims and comprising a memory for controlling the illumination sequence for the plurality of lamps.

10. A lamp driver system constructed and arranged or adapted to generate substantially as hereinbefore described with reference to and as illustrated in the I accompanying drawings.