Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/40—Details of LED load circuits
  • H05B45/44—Details of LED load circuits with an active control inside an LED matrix
  • H05B45/46—Details of LED load circuits with an active control inside an LED matrix having LEDs disposed in parallel lines
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/30—Driver circuits
  • H05B45/37—Converter circuits
  • H05B45/3725—Switched mode power supply [SMPS]
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/30—Driver circuits
  • H05B45/37—Converter circuits
  • H05B45/3725—Switched mode power supply [SMPS]
  • H05B45/375—Switched mode power supply [SMPS] using buck topology
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
  • H05B45/30—Driver circuits
  • H05B45/37—Converter circuits
  • H05B45/3725—Switched mode power supply [SMPS]
  • H05B45/38—Switched mode power supply [SMPS] using boost topology
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
  • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
  • Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Definitions

• the invention relates to a driver circuit arrangement.
• the invention relates to a driver circuit arrangement, comprising a connection to a source of electrical energy, and a plurality of individually switchable electrical subsystems, each subsystem comprising a switch for controlling a flow of energy from the source of electrical energy to said subsystem, an electrical device, and an energy storage device for storing energy.
• Such electrical devices may e.g. be connected in series, in parallel or in combinations thereof.
• 2004/0066154 Al discloses a lighting circuit for lighting a vehicular lamp that includes a plurality of light-emitting diodes (LEDs).
• the lighting circuit includes an output voltage regulator, a light source selecting unit and an output controlling unit. Furthermore, each LED or group of LEDs has a capacitor connected in parallel that is charged during a period in which the light source is selected. During a period in which the light source is not selected, the capacitor supplies a current to the light source.
• a problem of the known circuit is that control over the energy flow to the devices, and thus over the circuit as a whole, is lost in the OFF-period of the time- sequential driving. In many cases, this is undesirable, since this limits the control over the performance of the total device. For example, in the case of the vehicular lamp of US 2004/0066154 Al, control over the brightness of the individual LEDs is lost.
• each subsystem comprises a subswitch, constructed and arranged to control a flow of stored energy from the energy storage device to the electrical device.
• a subswitch constructed and arranged to control a flow of stored energy from the energy storage device to the electrical device.
• the driver circuit arrangement further comprises a power converter.
• the circuit arrangement thus comprises a converter for driving the subsystems.
• a converter for driving the subsystems.
• Having a low number of power converters has a relatively large influence on said component count, or at least on the complexity and costs of the total circuit arrangement.
• Examples of power converters are buck converters and boost converters, both of which are known in the art per se.
• a power source in the circuit arrangement.
• An example could be a battery, such as is used in motor vehicles or the like.
• the driver circuit arrangement further comprises a switch controller for controlling the switches.
• a switch controller may comprise any known type of switch controller, in particular various types of transistor based switch controllers, although other types are not excluded.
• the switch controller establishes time-sequential driving of the various subsystems. This may comprise simple subsequent switching between the various subsystems according to a clock frequency, i.e. in a regular fashion. In particular, it relates to time-sequential driving with a pulse width manipulation (PWM), or corresponding types of driving each subsystem with its own specific power demand.
• PWM pulse width manipulation
• the driver circuit arrangement further comprises a subswitch controller for controlling the subswitches.
• a subswitch controller for controlling the subswitches.
• the subswitch controller may control the subswitches in a similar fashion as the switch controller controls the switches. I.e., the subswitch controller may switch the electrical device on and off according to a clock frequency or according to some external control instruction. In particular, such external control instruction may be based on a feedback signal that results e.g. from a measured effect of the electrical devices. This will be further elucidated below.
• the energy storage device comprises a capacitor.
• the invention is not limited as to the type of energy storage device, the use of a simple device such as a capacitor offers advantages with respect to the relatively simple layout of the driver circuit arrangement. However, other energy storage devices, such as batteries, are not excluded.
• At least one subsystem comprises a plurality of electrical devices connected in parallel and/or in series.
• the driver circuit arrangement of the present invention allows optimum control over the electrical devices even during times when those devices do not obtain energy from the main source of electrical energy.
• more than one electrical device is present in a subsystem. This may be useful if driving that number of electrical devices in said subsystem is easily performed by the source of electrical energy and an optional power converter in the circuit arrangement. Examples are circuit arrangements with large numbers of electrical devices, that are grouped in a number of subsystems, such as light sources in lighting systems.
• each electrical device is individually switchable and individually energizable.
• Each electrical device being individually switchable and energizable means that, if the subsystem comprises N electrical devices, there are at least N separate switch conditions for the subswitch as well as for the energy storage device. This may be achieved by providing the subsystem with a separate subswitch for each electrical device, in other words with N subswitches and similarly by providing N separate energy storage devices. Alternatively or additionally, it is possible to make the subswitch able to select each of the electrical devices separately, e.g. time-sequentially, and also to select an energy flow from a single energy storage device to a selected electrical device. However, it is advantageous to provide each electrical device with its own subswitch and its own energy storage device, since this allows maximum freedom in control over each electrical device, and a maximum total duty cycle.
• control of the subswitches of said other subsystems allows control over the balance of the performance of said other subsystems not only with respect to said some subsystem, but also with respect to each other. This will be elucidated below.
• At least one electrical device comprises a LED.
• substantially all electrical devices are LEDs.
• any electrical device may be used, such as lamps, sensors, etc., in particular LEDs are very useful in the driver circuit arrangement according to the present invention, since they not only occur very frequently in large groups, but it is also very important for lighting to be controlled to a very high degree.
• the color of some individual LEDs may be varied within certain boundaries.
• the light of various LEDs may be combined, in order to form other colors. This principle may be used for general illumination, LCD backlights, etc. Since the human eye is very sensitive to variations in the observed color of the light, optimum control is desirable in such applications.
• red, green, blue, RGB red, green, blue, RGB
• the groups of LEDs for each color will often be driven time- sequentially.
• the emission of the red and greed LEDs may be adapted to maintain a certain total color by controlling the energy flow from the energy storage devices to the red and green LEDs by appropriate switching of the subswitches.
• OLEDs organic LEDs
• the electrical devices may be driven individually and independently of each other, while still allowing a flow of energy during the OFF period of a time-sequential driving by a main source of energy.
• Figure 1 shows a prior art driver circuit arrangement.
• Figure 2 schematically shows a driver circuit arrangement according to the present invention.
• Figure 3 diagrammatically shows a driver circuit arrangement 100 according to another embodiment of the present invention.
• Fig. 1 shows a prior art driver circuit arrangement.
• the driver circuit arrangement 1 comprises a connecting switch 3, which connects a power converter, schematically indicated by reference numeral 5, to an external source of energy 7.
• the arrangement 1 further comprises three subsystems A, B and C, each of which comprises an electrical device 9, an energy storage device 10 and a switch 11.
• the prior art driver circuit arrangement as shown in Fig. 1 is connectable to a source of electrical energy 7, such as a voltage source, e.g. a battery.
• the circuit arrangement 1 comprises three subsystems A, B and C.
• Each subsystem A, B, C comprises an electrical device, an energy storage device and a switch. Taking a look at the first subsystem A, this would work as follows:
• this subsystem A could be supplied with electrical energy from the source 7, and switch H-A will be in a closed position. If desired, switches H-B and 11-C may be in an open position, although this is not necessary.
• the device 9- A will now be supplied with energy from the energy source 7, while also energy source device 10-A will be supplied with energy.
• the device 9- A may, in principle, be any desired electrical device, but is preferably a simple device such as an LED, including an organic LED, and so on. For the present embodiment, the devices are taken to be LEDs.
• the energy storage device 10-A may for example be a capacitor. Subsequently, the control device (not shown) may deselect the first subsystem
• the capacitor 10-A will start supplying the electrical device 9-A with electrical energy.
• the electrical device 9-A will be supplied with electrical energy even after disconnecting the device 9-A from the main source 7 of electrical energy. This reduces control over the functioning of the device 9-A. Similar considerations of course hold for the other subsystems B and C.
• Fig. 2 schematically shows a driver circuit arrangement according to the present invention. Similar parts are denoted by the same reference numerals.
• the driver circuit arrangement 1' again comprises a connecting switch 3 that connects a power converter 5 to a source 7 of electrical energy.
• the driver circuit arrangement 1 ' again comprises 3 subsystems A', B' and C. Of course, any other plural number of subsystems, such as 2, or 4, 5, etc., is also possible. Note that in particular very large numbers of electrical subsystems are contemplated, such as large numbers of LEDs or pixels in a display.
• Each subsystem, e.g. subsystem A' comprises an electrical device, an energy storage device, a switch and a subswitch, for example 9-A, 10-A, H-A and 13-A, respectively.
• the connecting switch 3 may also be some other means of connecting the driver circuit arrangement 1 to the source of energy 7, such as an electrical plug etc.
• the power converter 5 has only been indicated schematically. It may comprise a buck converter, a boost converter, and a combination thereof, etc. It is also possible to provide such a power converter 5 as an external device, such as being a part of the source of electrical energy 7.
• the driver circuit arrangement 1' may e.g. function as follows.
• An external control unit (not shown), which may also be comprised in the driver circuit arrangement, in the form of an IC, may e.g. select the first subsystem A' to be supplied with energy from the source 7.
• the control unit may for example close the switch H-A, while the other switches, H-B and 11-C, may either be open or closed.
• the control unit may further control the subswitch 13-A, for example to be in a closed position.
• the device 9-A will be supplied with energy from the source 7, while also the energy storage device 10- A will be supplied with energy.
• the control unit deselects the first subsystem A', e.g.
• the energy storage device 10- A may still provide energy to the electrical device 9-A if the subswitch 13-A is closed.
• the control unit (not shown) may still control energy flow to the electrical device 9-A by controlling the position of the subswitch 13-A. This may be performed in e.g. the pulse width modulation mode, or by simply keeping the subswitch 13-A closed until a certain amount of energy has flown from the energy storage device 10-A.
• a subsystem A' After deselecting the first subsystem A', another subsystem, B' or C, may be selected. Alternatively, the selection of A, B' and C may be completely independent of each other.
• a big advantage of the driver circuit arrangement 1' according to the present invention is that the control unit may still control the energy flow to the electrical devices, even when the main flow of energy from the source 7 of electrical energy to the electrical devices 9-A has been interrupted by the switch H-A.
• the present invention has particular advantages when the electrical device 9-A, B, C, is a more complex device then the simple devices shown in Fig. 2. All this will be discussed in the following embodiment.
• Fig. 3 diagrammatically shows a driver circuit arrangement 100 according to another embodiment of the present invention.
• the arrangement 100 comprises a subsystem A" comprising a large number of LEDs 9-A, an energy storage device 10-A, a switch H-A and a large number of subswitches 13-A.
• the circuit arrangement 100 comprises more subsystems B", , which have not been indicated any further.
• the subsystem A" comprises a single capacitor 10-A and five LEDs, each with a separate subswitch 13-A.
• each of the electrical "subdevices" or LEDs 9-A may be controlled separately, by a control unit (not shown here). This allows optimum control over the total performance of the circuit arrangement 100. It is even possible to provide each electrical device 9- A with its own energy storage device 10-A. It is furthermore possible to make the circuit arrangement of the subsystem A" even more complex by providing a combination of series and parallel connections of electrical devices, or even more complexly connected devices 9-A.
• the electrical devices 9-A may for example be LEDs, although any other electrical device, such as lamps, LCD pixels, traffic lights, etc., are also possible.
• each subsystem A", B", etc. may form a single light emitting element of a display or the like.
• each light emitting element, or subsystem may be controlled subsequently, by correspondingly switching the switches H-A, H-B etc.
• a setting changes such as a desired overall brightness of the display
• the setting of the devices 9-A in the subsystem A" may still be changed by accordingly controlling the subswitches 13-A.
• control unit may decrease the pulse width with which the subswitches 30- A are closed, or may alternatively open those subswitches 13-A. It goes without saying that a similar control is exerted over the corresponding subswitches etc. in subsystem B", etc.

Landscapes

• Led Devices (AREA)
• Control Of Indicators Other Than Cathode Ray Tubes (AREA)
• Electronic Switches (AREA)
• Dc-Dc Converters (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (2)

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ID=37816578

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Country Status (7)

Cited By (4)

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Citations (1)

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• 2006
  • 2006-10-02 AT AT06809462T patent/ATE551769T1/de active
  • 2006-10-02 EP EP06809462A patent/EP1935085B1/en active Active
  • 2006-10-02 CN CN2006800369378A patent/CN101278469B/zh active Active
  • 2006-10-02 US US12/089,236 patent/US7893661B2/en active Active
  • 2006-10-02 WO PCT/IB2006/053581 patent/WO2007039862A2/en not_active Ceased
  • 2006-10-02 ES ES06809462T patent/ES2384886T3/es active Active
  • 2006-10-02 JP JP2008534125A patent/JP4971338B2/ja active Active

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