WO2009095867A2

WO2009095867A2 - String of light modules

Info

Publication number: WO2009095867A2
Application number: PCT/IB2009/050344
Authority: WO
Inventors: Sebastiaan Constant Verhelst
Original assignee: Nxp B.V.
Priority date: 2008-01-30
Filing date: 2009-01-28
Publication date: 2009-08-06
Also published as: WO2009095867A3

Abstract

The present invention relates to a controlled lighting system (100) comprising a control system (10) and a string (40) of light modules (30). Each light module (30) consists of a light bar of LEDs (210, 211, 212) and each LED (210, 211, 212) is controlled by a shift register system (230) through a respective driver (220, 221, 222). The shift register system (230) receives an input data signal (TDI) and at least two control signals (TCK, TMS), while transmitting to the input of the next shift register system (230) an output data signal (TDO) and the same at least two control signals (TCK, TMS). In an embodiment, the shift register system (230) refers to a boundary scan test interface. Through the shift register system (230), each driver (220, 221, 222) is controlled by at least one 1-bit boundary scan cell implementing a boundary scan function. Thus, the intensity of each LED (210, 211, 212) in a string (40) of light modules (30) can be controllable, and the string (40) be effectively shortened using the bypass register (320) of the shift register system (230).

Description

String of light modules

FIELD OF THE INVENTION

The present invention relates to the field of lighting devices, and more particularly to a controlled lighting system including a string of light modules.

BACKGROUND OF THE INVENTION

LED-technology offers specific advantages for applications: robustness, low energy consumption, operating at low voltage, and a long life. Accordingly, LED products are more and more replacing conventional lighting devices, e.g. neon in a channel letter application. As LEDs become less costly, hundreds or thousands can be put in one application. However, reasonable solutions for individual control of each LED is still required.

When many LEDs are used in one application, the wiring of those LEDs becomes a problem, mainly if individual LED control is still required for pattern forming or for calibration or both. The wiring is costly, often requiring hand- work, and sensitive to manufacturing defects.

In many applications, three or more LEDs form one "pixel" that can assume many colors and intensities.

Due to the manufacturing process of LEDs, color and intensity can vary to an extent that is visible by the human eye, such that either better production techniques or calibration of pixels according to their specific properties are required. Such applications include LCD back-light and ambient lighting.

Another reason for requiring individual control is pattern forming, i.e. varying intensity or color. This is a requirement for light shows, moving light images, etc.

The straightforward conventional approach is to connect the LEDs to a limited number of wires, but with the disadvantage to have a limitation in the control.

CN 1725924 discloses a conventional shift register which is used to control the colored LEDs. In this application, an infinite length string of LEDs is individually controllable, but this technique offers only on-off control to LEDs, such that the control of color and/or intensity of an individual LED of the string is very limited. WO 2007/023454 Al discloses a LED backlight structure and technique for setting the voltages and currents for the LEDs. In this application, all LEDs of a single color, red, green or blue, are connected in series, thus forming a monochrome light bar of several LEDs for each color, and not a polychrome light bar of a combination of such LEDs. Hence, this configuration does not allow individual control of the color and brightness of a pixel formed by such a combination, and all attempt to overcome such a problem would lead to a complex configuration through the use of numerous hardware and signals.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide for an improved individual control in terms of intensity over each light emitting diode of a colored light bar inside a light module being part of a variable length string, while keeping costs low due to simple design and assembly technique.

This object is achieved by a light module as claimed in claim 1, a string of light modules as claimed in claim 20, a controlled lighting system as claimed in claim 22, a method of controlling a plurality of LEDs as claimed in claim 23, a method of shortening the effective length of a string of light modules as claimed in claim 27, a method of producing a string of light modules as claimed in claim 30, a method of producing an array of strings of light modules as claimed in claim 30, a computer program as claimed in claim 35 and a hybrid integrated circuit as claimed in claim 36.

In accordance with the present invention, there is provided a light module comprising at least: a light bar of at least one light emitting diode (LED); a plurality of drivers, each LED being respectively driven by one of the plurality of drivers; a shift register system, the shift register system controlling the light bar through the plurality of drivers, the shift register system receiving at least an input data signal at an input terminal, one or more control signals, and transmitting at least an output data signal from an output terminal and the one or more control signals. Thereby, each LED can be individually controlled depending on at least two signals, namely the input data signal and the one or more control signals.

The light module further comprises one or more light sensitive devices for monitoring an ambient light and/or a light generated by the at least one LED.

The shift register system further comprises: a first shift register, the first shift register being input at the input terminal and output at the output terminal, the first shift register consisting of a chain of a plurality of shift register cells, the first shift register being capable of providing control signals to the plurality of drivers. Thereby, the control of each LED through the shift register cells can be improved. - Each driver is coupled to at least one shift register cell. Thereby, each LED can be controlled through its respective driver by at least one bit.

The shift register system further comprises: a second shift register, the second shift register being input at the input terminal and output at the output terminal, the second shift register allowing to short-circuit the input and output terminals. Thereby, the effective length of a string of such light modules can be shortened and be hence made variable.

The second shift register is a 1-bit shift register. Thereby, the short-circuit can be achieved without affecting the operation of the shift register system.

The shift register system further comprises: - third shift register, the third shift register being input at the input terminal, output at the output terminal, and loaded with an instruction information, the third shift register determining, based on the instruction information, which amongst the first shift register and the second shift register is to drive the output terminal. Thereby, the shift register system operates either in short-circuit mode or in control mode. Thus, the effective length of a string of light modules can be controllable according to the instruction information.

Two or more amongst the first, second and third shift registers may be concatenated into one shift register.

The shift register system further comprises: a controller for controlling the first, second and third shift registers based on the one or more control signals. Thereby, the first, second and third shift registers are internally controlled inside the light module.

The controller may be a state machine.

The shift register system may be configured for electrical and/or optical test of the light module. - The instruction information may be user-defined.

If the shift register system is IEEE 1149.1 boundary scan standard compliant, the input data signal may be a serial test data input signal, one control signal may be a test clock input signal, another control signal may be a test mode select input signal, the output data signal may be a serial test data output signal, the controller may be a test access port (TAP) controller, the first shift register may be a boundary scan register and its shift register cells may be boundary scan cells, the second shift register may be a bypass register, and the third shift register may be an instruction register loaded with an instruction information that may be pre-defined according to the standard. - A pulse width modulated (PWM) controller or a digital-to-analog converter

(DAC) and/or a function generator may be placed between the shift register system and each one of the plurality of drivers. Thus, the intensity of each LED can be made variable and set to a specific brightness value.

The shift register system and the plurality of drivers may be either separate monolithic circuits or combined in a hybrid monolithic circuit.

The present invention extends to a string of light modules comprising: at least two light modules as previously specified, wherein the input data signal of each light module next to the first light module of the string corresponds to the output data signal of the preceding light module. Thereby, each light module can be individually controlled depending on at least three signals, the light module next to the first light module of the string being input by the output data signal and the first and second control signals of the preceding one.

The string may be electrically arranged as forming a two-dimensional matrix or array. Thereby, the string can be not only arranged in row, but also in a combination of rows and columns.

The present invention further extends to a controlled lighting system comprising:

- a string of light modules as previously specified; and

- a control system, the control system providing at least a power supply, the input data signal, and the one or more control signals to the first light module of the string.

In accordance with the present invention, there is provided a method comprising: controlling a plurality of light emitting diodes (LEDs) using a shift register system as previously specified. - The step of controlling further comprises implementing, in a plurality of scan cells, boundary scan functions associated with the plurality of LEDs.

In accordance with the present invention, there is also provided a method comprising: shortening an effective length of a string of light modules as previously specified, using the second shift register.

In accordance with the present invention, there is also provided a method comprising: - producing a string of light modules as previously specified, using a reel-to-reel lead frame, and wherein the lead frame forms the string.

In accordance with the present invention, there is also provided a method comprising: producing an array of strings of light modules as previously specified, using a strip lead frame, and wherein the lead frame forms the array.

The lead frame may also formed a heat sink for the LEDs.

The lead frame may also formed an electrical and mechanical connection between the light modules.

The lead frame may also be used to reflect a light emitted by the light module. - The steps of the previous methods can be carried out by a computer program including program code means, when the computer program is carried out on a computer.

The present invention further extends to a hybrid integrated circuit comprising the light module.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and advantages of the present invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. In the following drawings:

Fig. 1 shows a schematic diagram of a controlled lighting system according to an embodiment of the present invention;

Fig. 2 shows a schematic diagram of a light module of Fig. 1 according to an embodiment of the present invention;

Fig. 3 shows a plan view of a lead frame on top of which is bonded a hybrid integrated circuit including the light module 30 of Fig. 2 according to an embodiment of the present invention;

Fig. 4 shows a schematic diagram of a shift register system of Fig. 2 according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS Fig. 1 illustrates a schematic diagram of a controlled lighting system 100 according to an embodiment of the present invention. The system 100 comprises at least a control system 10 and a plurality of light modules 30, e.g. pixels. The light modules 30 are connected in series to each other through a set of electrical wires, thus forming a string 40 of light modules 30. The control system 10 supplies power (V+) to each light module 30, and transmits the input signals TDI, TCK and TMS to the first light module 30 of the string 40. The same TCK and TMS signals are also transmitted to each next light module 30 through the preceding one. Each next light module 30 is also input by an input signal that corresponds to the output signal TDO of the preceding one. As shown in the Figure, each light module 30 is further input by the same ground (GND) signal.

An identical string (not shown in the Figure) can also be concatenated to the string 40 in order to form a longer string.

It is to be noted that the string 40 of light modules 30 can be left open. Moreover, it will be apparent to those skilled in the art that the string 40 may also be electrically arranged in a combination of rows and columns, in order to form a matrix or array of regularly-spaced light modules 30.

Fig. 2 depicts a schematic diagram of a light module 30 of Fig. 1 according to an embodiment of the present invention. The light module 30 comprises a light bar of at least one light emitting diode (LED) 210, 211, 212, typically three LEDs of different primary colors: red (R), green (G) and blue (B). The anode of each LED 210, 211, 212 is connected to the electrical wire supplying the power V+, and the cathode of each LED 210, 211, 212 is connected to a respective driver 220, 221, 222, which drives the corresponding LED 210, 211, 212 by allowing current to flow through it. The drivers 220, 221, 222 are controlled by a shift register system 230. Fig. 3 shows a plan view of a lead frame on top of which is bonded a hybrid integrated circuit including the light module 30 of Fig. 2 according to an embodiment of the present invention. Different circuit configurations are possible according to whether the dies, i.e. the integrated circuit chips, of the LEDs 210, 211, 212 (depicted in Fig. 3 as small squares), drivers 220, 221, 222 (included in the block 50) and shift register system 230 (included in the block 50) are all separately mounted onto the lead frame, the dies of the drivers 220, 221, 222 are combined into a single die, or a hybrid monolithic solution including the shift register system 230 and the drivers 220, 221, 222 is chosen.

In an embodiment, the light modules 30 and the resulting string 40 can be made through a conventional reel-to-reel assembly process, wherein the dies are placed onto a flexible metal lead frame. The lead frame and integrated circuits are then rolled onto a reel that can be easily shipped and stored. In particular, the lead frame is endless, allowing manufacturing of endless strings 40, which can be then cut to the desired length. The lead frame has several bridges placed between the different lines, power-TDI/TDO, TDI/TDO- TMS, TMS-TCK, TCK-GND, in order to hold the TDI/TDO, TCK, and TMS lines physically connected between them until after molding. Then, these bridges can be cut away by trim/form tooling. Alternatively, they do not need to be removed if they are made of nonconducting material, e.g. plastic. The assembly process of such a hybrid integrated circuit is then standard, and consists of the steps of die bonding of the LEDs 210, 211, 212, die bonding of the ICs (shift register system 230 and drivers 220, 221, 222 or combination thereof), wire bonding, encapsulating the light module 30 in plastic molding, trim-form and testing. It is to be noted that the usual plating step between the molding and trim/form steps can be skipped.

Testing can then be performed in a string as a whole, by applying a string control through the control system 10 to the beginning of the string 40, sequentially shifting- in a pattern so that the light module 30 or pixel lights up, and proceeding so until the end of the string 40. If a light module 30 does not function, it can be cut out, and the two ends welded together.

The light module 30 can also test itself if all wires are double. In that case, the die of the shift register system 230 can test all connections, as defined in the IEEE 1149.1 boundary scan standard, such that the entire string 40 of light modules 30 can be tested in one go-

In another embodiment, the assembly process can be made on matrix lead frames, e.g. ultra-thin leadless package (UTLP), wherein the connections are already prepared on the lead frame.

It is to be noted that the string 40 of light modules 30 can be formed using the reel-to-reel lead frame, and an array of such strings 40 can also be formed using a strip lead frame. Additionally, the metal lead frame can act as a heat sink for the LEDs 210, 211, 212, form an electrical and mechanical connection between the light modules 30 of the string 40, and be used to reflect the light emitted by these light modules 30.

Fig. 4 shows a schematic diagram of the shift register system 230 of Fig. 2 according to an embodiment of the present invention. The shift register system 230 comprises at least a controller 340, e.g. a state machine, and three shift registers, i.e. a first shift register 310, a second shift register 320 and a third shift register 330. The basic operation of the shift register system 230 is controlled through the input data signal TDI and one or more control signals TCK, TMS. The TCK signal is an independent signal that provides the clock sequences to the controller 340, as well as to the shift registers 310, 320, 330. The TMS signal allows to control the state-to-state transitions of the controller 340. The TDI signal is a serial data input signal used for serial transmission of data or instruction bits, depending upon the state of the controller 340, to one of the shift registers 310, 320, 330. The TDO signal is a serial data output signal used for serial transmission of data or instruction bits, depending upon the state of the controller 340, to the data TDI terminal of the next light module 30. The basic function of the controller 340 is to generate clock and control signals required for the correct sequence of operations of the different shift registers 310, 320, 330. In particular, the controller 340 controls signals that facilitate loading of instructions into the third shift register 330, and shifting TDI data into and TDO data out of the first and second shift registers 310, 320. The third shift register 330 is serially loaded with specific instructions for the light module 30. These instructions may be user-defined, and an example could be a "stepwise fade-in to maximum intensity" instruction. The third shift register 330 drives the TDO terminal whenever it is chosen by the controller 340. When not chosen, the third shift register 330 must then determine, depending on the instruction loaded into it, which amongst the first shift register 310 and the second shift register 320 to drive the TDO terminal. The second shift register 320 allows serial data to be transferred through the shift register system 230 from the TDI terminal to the TDO terminal without affecting the operation of the controller 230. Thus, the second shift register 320 is typically a 1-bit shift register and can be used to shorten the effective length of the string 40 of light modules 30. The first shift register 310 is a data register consisting of a chain of a plurality of shift register cells, in which a single cell (bit) is linked to every digital pin of the corresponding drivers 220, 221, 222. Thus, the first shift register 310 provides control signals to these drivers 220, 221, 222. In particular, it controls the ON-OFF of each LED 210, 211, 212, and allows thanks to the chain or series of shift register cells to optimize the individual control of the intensity of each LED 210, 211, 212 through the respective drivers 220, 221, 222. For example, the first shift register 310 of Fig. 4 is a 12-bit shift register consisting of twelve (12) cells, i.e. four (4) per LED 210, 211, 212 through the respective drivers 220, 221, 222.

To adjust the color and the brightness of the light bar of light modules 30, the intensity of each LED 210, 211, 212 needs to be variable. This intensity variation can be achieved using, for each LED 210, 211, 212, either a digital-to-analog converter (not shown in the Figure) to provide a variable analog voltage control signal, or a pulse width modulated (PWM) controller (not shown in the Figure) operating with an adjustable duty cycle, and/or a function generator, connected between the first shift register 310 and the respective driver 220, 221, 222.

It is to be noted that two or more amongst the individual first, second and third shift registers 310, 320, 330 may be concatenated into one shift register.

In another embodiment, the shift register system 230 may be IEEE 1149.1 boundary scan standard compliant. In this case, the controller 340 can be a test access port (TAP) controller, the first shift register 310 can be a boundary scan register and its shift register cells can be boundary scan cells, the second shift register 320 can be a bypass register, the third shift register 330 can be an instruction register loaded with an instruction information that can be pre-defined according to the standard, the TDI signal can be a serial test data input signal, the TDO output signal can be a serial test data output signal, the TCK signal can be a test clock input signal, and the TMS signal can be a test mode select input signal. The light module 30 can also comprise one or more light sensitive devices for monitoring an ambient light and/or a light generated by the LEDs 210, 211, 212.

Applications contemplated for such controlled lighting system 100 include, but are not limited to, decorative and entertainment-oriented lighting applications, e.g. LCD back-lights, display lights, ambient lighting, etc., and also professional applications, e.g. LED screens, special effects lighting for shop windows, etc.

In summary, a controlled lighting system 100 comprising a control system 10 and a string 40 of light modules 30 has been described. Each light module 30 consists of a light bar of LEDs 210, 211, 212 and each LED 210, 211, 212 is controlled by a shift register system 230 through a respective driver 220, 221, 222. The shift register system 230 receives an input data signal TDI and at least two control signals TCK, TMS, while transmitting to the input of the next shift register system 230 an output data signal TDO and the same at least two control signals TCK, TMS. In an embodiment, the shift register system 230 refers to a boundary scan test interface. Through the shift register system 230, each driver 220, 221, 222 is controlled by at least one 1-bit boundary scan cell implementing a boundary scan function. Thus, the intensity o f each LED 210, 211, 212 in a string 40 of light modules 30 can be controllable, and the string 40 be effectively shortened using the bypass register 320 of the shift register system 230. While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single ... or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A light module comprising at least: a light bar of at least one light emitting diode (LED) (210, 211, 212); a plurality of drivers (220, 221 , 222), each LED (210, 211, 212) being respectively driven by one of said plurality of drivers (220, 221, 222); - a shift register system (230), said shift register system (230) controlling said light bar through said plurality of drivers (220, 221, 222), said shift register system (230) receiving at least an input data signal (TDI) at an input terminal, one or more control signals (TCK, TMS), and transmitting at least an output data signal (TDO) from an output terminal and said one or more control signals (TCK, TMS).

2. The light module according to claim 1, said light module (30) comprising one or more light sensitive devices for monitoring an ambient light and/or a light generated by said at least one LED (210, 211, 212).

3. The light module according to claim 1 or 2, wherein said shift register system

(230) comprises: a first shift register (310), said first shift register (310) being input at said input terminal and output at said output terminal, said first shift register (310) consisting of a chain of a plurality of shift register cells, said first shift register (310) being capable of providing control signals to said plurality of drivers (220, 221 , 222).

4. The light module according to claim 3, wherein said each driver (220, 221,

222) is coupled to at least one of said plurality of shift register cells.

5. The light module according to any one of the preceding claims, wherein said shift register system (230) comprises: a second shift register (320), said second shift register (320) being input at said input terminal and output at said output terminal, said second shift register (320) allowing to short-circuit said input and output terminals.

6. The light module according to claim 5, wherein said second shift register (320) is a 1-bit shift register.

7. The light module according to any one of the preceding claims, wherein said shift register system (230) comprises: a third shift register (330), said third shift register (330) being input at said input terminal, output at said output terminal, and loaded with an instruction information, said third shift register (330) determining, based on said instruction information, which amongst said first shift register (310) or said second shift register (320) is to drive said output terminal.

8. The light module according to claim 7, wherein two or more amongst said first, second and third shift registers (310, 320, 330) are concatenated into one shift register.

9. The light module according to claim 7 or 8, wherein said shift register system (230) comprises: a controller (340) for controlling said first, second and third shift registers (310, 320, 330) based on said one or more control signals (TCK, TMS).

10. The light module according to claim 9, wherein said controller (340) is a state machine.

11. The light module according to any one of the preceding claims, wherein said shift register system (230) is configured for electrical and/or optical test of said light module

(30).

12. The light module according to claim 7, wherein said instruction information is user-defined.

13. The light module according to any one of claims 1 to 11, wherein said shift register system (230) is IEEE 1149.1 boundary scan standard compliant.

14. The light module according to claim 13, wherein said input data signal (TDI) is a serial test data input signal, said one or more control signals (TCK, TMS) include at least a test clock input signal and a test mode select input signal, and said output data signal (TDO) is a serial test data output signal.

15. The light module according to claim 13 or 14, wherein said controller (340) as claimed in claim 9 is a test access port (TAP) controller.

16. The light module according to any one of claims 13 to 15, wherein said first shift register 310 as claimed in claim 3 is a boundary scan register, said shift register cells as claimed in claim 3 are boundary scan cells, said second shift register 320 as claimed in claim 5 is a bypass register, said third shift register 330 as claimed in claim 7 is an instruction register, and said instruction information is pre-defined according to said IEEE 1149.1 boundary scan standard.

17. The light module according to any one of the preceding claims, wherein a pulse width modulated (PWM) controller or a digital-to-analog converter (DAC) and/or a function generator is placed between said shift register system (230) and each one of said plurality of drivers (220, 221, 222).

18. The light module according to any one of the preceding claims, wherein said shift register system (230) and said plurality of drivers (220, 221, 222) are combined in a hybrid monolithic circuit.

19. The light module according to any one of the preceding claims, wherein said shift register system (230) and said plurality of drivers (220, 221, 222) are separate monolithic circuits.

20. A string of light modules comprising: - at least two light modules (30) according to any one of the preceding claims, wherein said input data signal (TDI) of each light module (30) next to the first light module (30) of said string (40) corresponds to said output data signal (TDO) of the preceding light module (30).

21. The string of light modules according to claim 20, wherein said string (40) is electrically arranged as forming a two-dimensional matrix.

22. A controlled lighting system comprising: - a string (40) of light modules (30) as claimed in claim 20 or 21; and a control system (10), said control system (10) providing at least a power supply (V+), the input data signal (TDI), and the one or more control signals (TCK, TMS) to the first light module (30) of said string (40).

23. A method comprising: controlling a plurality of light emitting diodes (LEDs) (210, 211, 212) using a shift register system (230) as claimed in any one of claims 1 to 19.

24. The method according to claim 23, wherein the step of controlling comprises implementing, in a plurality of scan cells, boundary scan functions associated with said plurality of LEDs (210, 211, 212).

25. The method according to claim 24, wherein each LED (210, 211, 212) is controlled through a respective driver (220, 221, 222).

26. The method according to claim 25, wherein a pulse width modulated (PWM) controller or a digital-to-analog converter (DAC) and/or a function generator is placed between said shift register system (230) and said respective driver (220, 221, 222).

27 ^'. A method comprising: shortening an effective length of a string (40) of light modules (30) as claimed in any one of claims 1 to 19, using the second shift register (320) as claimed in any one of claims 5 to 10.

28. The method according to any one of claims 23 to 27, wherein the shift register system (230) is configured for electrical and/or optical test of said light module (30).

29. The method according to any one of claims 23 to 28, wherein the shift register system (230) is IEEE 1149.1 boundary scan standard compliant.

30. A method comprising: producing a string (40) of light modules (30) as claimed in claim 20 or 21, using a reel-to-reel lead frame, and wherein said lead frame forms said string (40).

31. A method comprising: producing an array of strings (40) of light modules (30) as claimed in claim 20 or 21, using a strip lead frame, and wherein said lead frame forms said array.

32. The method according to claim 30 or 31, wherein said lead frame forms a heat sink for the LEDs (210, 211, 212).

33. The method according to claim 30 or 32, wherein said lead frame forms an electrical and mechanical connection between said light modules (30).

34. The method according to any one of claims 30 to 33, wherein said lead frame is used to reflect a light emitted by said light module (30).

35. Computer program comprising program code means for causing a computer to carry out the steps of the method as claimed in any one of claims 23 to 34 when said computer program is carried out on a computer.

36. A hybrid integrated circuit comprising a light module as claimed in claim 18 or 19.