ES2265871T3 - LIGHTING CONTROL DEVICE. - Google Patents

Abstract

A lighting device and control means therefor is disclosed. The lighting device consists of a plurality of White LEDs (WLEDs) provided in separate chains all connected parallel. A small number of WLEDs is connected in series in each chain, and a number of such chains are wired together in parallel between a pair of voltage lines from which current is drawn. Current measurement and adjusting means is provided firstly between a high voltage line and all the parallely connected chains, and secondly in each chain. Each current measurement and adjusting means is controlled ideally by a microprocessor which monitors both the total current drawn by all the chains together and also the individual currents flowing in each chain. WLEDs have a tendency to fail when subjected to sudden current increases, and also when operating at extreme temperatures as temperature affects the operating characteristics of diodes in general. It cannot however accurately be predicted whether a particular WLED will fail in open or closed circuit and the invention provides a means of mitigating the effect of failure of one WLED on those which remain functioning in the circuit. The control means immediately increases or reduces the total current flow to all the chains depending on whether a WLEDs fails in short or open circuit. The control means also detects operating temperature and user light intensity requirement and adjusts various currents accordingly. <IMAGE>

Description

Lighting control device.

This invention relates to a device of control, and more specifically to a control device adapted for combined use in white light emitting diode assemblies, in hereinafter referred to as WLEDs. In particular, the invention that described below has particular application in the field of the lighting for airplane seats, since the WLEDs are starting to replace fiber optic lighting systems which are currently widely used.

Although the following invention is described making special reference to the lighting of seats individual aircraft, it should be noted that WLED groups can be used in any environment where lighting is needed a particular and discreet area, and where there is more a need for flexibility and versatility for the user, since the lighting arrangement must be able to adopt a number, and maybe an infinite number of positions and orientations, with Regarding its assembly. Such lighting arrangements are the more ideally suited to provide reading lighting to the occupant of a seat.

British Patent Application No. 2317421 describes a seat lighting arrangement comprising a plurality of fiber optic cables, whose terminations are grouped together in a so-called common end that is illuminated by a high intensity light source, being used alternating ends known as fiber optic shunts which are used to transfer light from the light source to a plurality of different sites. Individual fiber cables optics that connect the leads and common ends are to often bulky and difficult to handle, and are thus willing being an integral part in or under the seats for They are adapted to provide lighting.

This provision does not represent an advance significant about the seating lighting arrangement of airplane in which individual lights are personal lights that are incorporated in a serially produced console unit on each passenger seat on the plane, because the derivations fiber optic can be wrapped in an element of type flexible and stable, and thus the seat occupant can move the referral to some desired position. However, the provision of fiber optic seat lighting has several disadvantages because the device is bulky, and when it is considered that modern airplanes have seats arranged in rows of three and one lighting arrangement would generally be arranged inside or below each row of seats, it can be seen that the increase in the total weight of the plane is significant, especially in the longer routes and even larger planes that may have seats for more than 400 travelers.

An additional disadvantage of the provision of fiber optic lighting is your energy consumption, which is relatively high considering the power needs of high intensity lights that illuminate the common ends of the cables.

The recent introduction and acceptance by WLED consumers have boomed the development of systems of WLED lighting for airplanes, which is now believed to be the systems WLED will displace the fiber optic lighting equipment of your dominant position within the field of seating lighting in planes. However, the use of WLEDs so far has been prevented by its tendency to failures, which is greater than that of Conventional LEDs to fail. Additionally, the LEDs are either WLEDs or of another type and being essentially diodes can fail in a short circuit or in an open circuit, and therefore required any eventuality to be charged on any device that It depends on the correct operation of the LEDs or WLEDs for Provide light in a particular area. In addition, the odds Failure of WLEDs and LEDs are much greater than those of the high intensity light sources currently used in the fiber optic lighting arrangements, and therefore is crucial some eventuality.

Applicants have understood that a group layout of WLEDs that have a plurality of WLEDs in he would provide sufficient eventuality against a total failure of light because it would be very unlikely for all WLEDs of the group having a failure during a single use. In addition, they have also understood that at least some of the WLEDs within the group they must be connected in parallel because the fault of the open circuit of a single WLED if all were connected in series would result in a total failure of the light.

The use of WLEDs has also been previously prevented by the electronic and physical sensitivity of such components. For example, WLEDs are highly devices sensitive to temperature and current, and a slight increase in the operating temperature or electrical current that Happens can dramatically reduce device life. It should also be mentioned that diodes, being devices semiconductors, have a complex resistance that depends on the temperature, and also of the voltage characteristics and stream.

A subsequent difficulty associated with the Provision of light of uniform intensity with WLEDs is that the voltage supply on airplanes and inside vehicles often not It is uniform. The electrical sensitivity of the WLEDs and their increased probability of failure during occasional increases in power that can be experienced increases the need for some compensation form to ensure that the life of the WLEDs last as long as possible.

Examples of known lighting devices include DE9002812; WO9859015 and EP716
485. Document DE9002812 explains a lighting device that includes a plurality of non-white LEDs arranged in parallel strings between two voltage lines, each string including a plurality of LEDs in series. Each chain is provided with a transistor, a potentiometer and a resistor. The circuit also includes a resistor in series with a Zener diode to maintain a constant voltage along the voltage lines.

WO9859015 explains a method for produce highly white phosphorus emitting compounds for use in lighting arrangements. An example is given by which the method can be used to produce LEDs from blue LEDs.

EP716485 explains a source of diode current for use in lasers pumped with diode. A current source supplies current to drive a plurality of LED assemblies arranged in parallel. The current total for the parallel chains and the current in the chains is controlled by shunt switches. The switches in bypass are switched using a load factor controller and a current sensor, and a quasi-resonant controller is arranged to control the current flowing between the chains.

It is therefore an object of this invention provide a device to monitor and control the operation of a lighting device that includes a WLED group that guarantees safety and operation uninterrupted device and that can compensate for changes in the operating characteristics of the WLED group and the fault of one or more of them during device operation.

In accordance with the invention, a lighting device comprising a group of white LEDs chained in parallel between a couple of lines that apply a voltage in the chains of white LEDs, each having said at least one white LED strings on it; first means of change of the current that are able to adjust the total current drawn of the voltage lines for each individual string of white LEDs;  second means of changing the current arranged in each chain to adjust the particular current through each of said chains; means of measuring the current in each chain; characterized in that said control means provided are communicate with the current measurement means to allow the control of the first means of changing the current and at minus one of said second means of current change as response to variations in the current measured in the chains individual.

Preferably, the first measuring means of the current are also arranged between the lines of voltage and chains that measure the total current drawn by all the chains of WLEDs.

Preferably, each of the chains is provided with secondary means of measuring the current that communicate with a control means, preferably a microprocessor that works under the control of a program computer, said control means adjusting the flow of current through the WLEDs depending on a comparison between the current measured through each individual chain, and optionally through the first means of changing the current.

Preferably, three WLEDs are connected in series in each of said chains, and more preferably the number of strings is 6, so that the group of WLEDs has 18 WLEDs

Most preferable, than the measuring means of the current comprise a resistor connected in series with the WLEDs connected in series in each chain, and more preferably, that the first, second and second means of change of current Additional understand transistors.

It is still more preferable that the device is also provided with temperature measuring means that also communicate with the control means that adjust the stream accordingly through the chains of WLEDs.

Most preferably, the control means dynamically adjust the current flows through the WLED chains such that the flow of current through they are substantially uniform and devoid of discontinuities regardless of the temperature of operation and / or failure of one or more of the WLEDs.

Preferably, the control means, the voltage lines, and the WLEDs connected in string series are integrated into a single circuit.

Most preferably, the device is used to provide light for a seat, ideally an airplane seat, which often has energy sources built into it, and in this case the device would be ideally powered with energy from said built-in power source.

Preferably the control means is also communicate with means of indication that change the state of same when said control means recognize that one or more WLEDs it has failed.

Preferably the indication means they comprise light means that emit light other than white, said light means being arranged in series with means of barrier also in communication with the control means between lines, activating said barrier means thus allowing the current flow through the light means to illuminate the same only when one or more WLEDs have failed.

Preferably said light means are mounted in the vicinity of the WLEDs and are visible when viewed the set of WLEDs, one of which has failed.

Preferably, the WLEDs and the means of Optional indication are mounted next to each other in a hexagonal package arrangement closed in a circuit printed.

Preferably, the control means also are mounted on said printed circuit.

Preferably the WLEDs are connected within the circuit in groups of three, said group being connected  in series as a single string that is connected in parallel with others.

More preferably, the grouping of the WLEDs in three it is such that any WLED is contiguous to another WLED that is connected in series with him.

With such configuration, the circuit failure open or any of these WLEDs (which would necessarily give place to turn off the remaining two WLEDs connected in series between them in a certain chain) could be compensated automatically according to the invention without imbalance meaningful directional light emission from the device.

Most preferable is that the WLEDs and, the media Optional indication are mounted on a printed circuit integrated comprising the cables and in which said means of control are additionally mounted.

The integrated printed circuit board must be considered as an aspect of this independent invention and separately claimed.

Alternatively, the indication means can be arranged in a remote indicator panel and to which It supplies power from the control means.

Another alternative, the indicator means they can simply be one or more bits in a memory register at You can examine an engineer with the right equipment.

Thus, the control means are arranged to control the flow of current through a plurality of chains connected in parallel between a pair of voltage lines, each of these lines having at least one WLED connected to it, being connected means of change of current additionally to each of the chains and being the means of current measurement also provided in each of said chains that communicate with the control means, characterized because the flow of current through each of the chains is changes depending on a comparison made by the means of control of current flows through each of the plurality of chains, such that said current flows They remain substantially uniform.

Preferably, at least a single means of current change, and optionally current measurement means, are arranged between all the chains and one of the lines of voltage that are capable of changing and measuring respectively the Total current flow through all chains.

Preferably the control means also communicate with user-adjustable means to increase the intensity or attenuation of the light emitted by the WLEDs, and also to connect and disconnect the device.

Preferably the control means recognize when one or more of the WLEDs has failed and additionally causes a change of state of an additional component indicating that it has been Failed

The additional component may be a light of notice that can be seen instantly by an engineer, or a memory register in which a bit can be changed and stored for further analysis in connection with the control means of a lighting management system.

Experts in the field will warn instantly that the device according to the invention can be reliably and safely controlled and that WLEDs failures used in the device can be minimized due to this functioning. In addition, the constant and continuous monitoring of current flows through WLED chains also attenuate The falls.

An additional advantage of the proposed device here is the uniform and relatively low total energy consumption which can be achieved, for example, in an airplane.

The following will describe, by way of example, a specific embodiment of the invention with reference to following diagram in which:

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Figure 1 shows a possible sketch of a electronic circuit for device control according to the invention;

Figure 2 shows a perspective view of an exploded view of the various components that make up a lighting device according to the present invention; Y

Figure 3 shows a plan view of a integrated printed circuit on which a set of WLEDs hexagonal closed package.

Referring first to Figure 1, circuit 2 has been shown to provide controllable current  through a series of WLEDs chained according to the invention. The circuit comprises lines 4 and 6 of high and low voltage, among which a plurality of chains, three of which are show in 8, 10, 12, and of which 6 are ideally connected in parallel. Each of the chains is provided with three WLEDs 14, 16, 18 connected in series together with a transistor T_ {X}, where X is the number from left to right of the particular chain, and a resistance R_ {X} on which there is a fall in measurable potential within the particular chain.

Additionally a transistor of power 20 that is connected between high voltage line 4 and the chains 8, 10, 12 connected in parallel. Said transistor of power 20 provides a means to change the total amount of current that is fed from the high voltage line to all the chains. The high voltage line 4 ideally provides a potential drop across the circuit below 12 or 15 V of direct current, so that you will immediately notice that the Total system power consumption is relatively small, especially because WLEDs 14, 16, 18 usually work with low currents

The circuit shown ideally controls the light production of a single WLED group comprising only those connected in chains 8, 10, 12. Many more circuits similar will be in practice connected between the same two voltage lines 4, 6 and will provide light to a number of seats different within an airplane or similar vehicle.

The control of the currents flowing in the Different parts of the circuit are done as follows.

The potential drop across all R_ {X} resistors are measured by appropriate means and this information  it is fed to a microprocessor (not shown, but the connections to it are indicated by (M)) which can calculate the currents based on the value of the resistors. Saying microprocessor also communicates with and controls the transistor of power 20, and the transistors T_ {X} connected in parallel, and reduces or increases the current supplied to the bases of said transistors depending on the current flowing through the R_ {X} resistors.

The entire circuit is ideally integrated in a plate with a printed circuit (not shown) in which also has arranged a thermal resistance or similar component of temperature measurement (also not shown) that provides the microprocessor an indication of the operating temperature of the WLEDs. From here on, the current supplied to all WLEDs through power transistor 20, and through of each of the chains 8, 10, 12 can be dynamically adjusted by the microprocessor depending on the temperature of operation of the flow of current through each of the chains, of the total current flow, (although it could be deducted by the microprocessor from total currents individual string), and the instantaneous voltage of supply.

The provision of a microprocessor facilitates the following operations:

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total current control through of the WLEDs by setting the base input to the power transistor  20 which facilitates a cycle of attenuation and operation of light on / off;

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    reduction of total current and / or chain currents individual as the operating temperature increases from according to a previously programmed curve of reduction of capacity;

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    compensation of imperfections in the line voltage of supply maintaining a constant total current, known as regulation;

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    the automatic zeroing of a particular individual chain in if one of the WLEDs in that chain fails in short circuit and subsequent distribution of the total current to through all the other chains, known as failure of compensation, which may be additionally limited by compensation  Of temperature;

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    automatic compensation for failure of any particular WLED in open circuit in conjunction with the current distribution through of the remaining chains;

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    optional communication with a main controller about the status of operation of the WLEDs and of the total consumption of Energy.

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A flow chart of the possible cycle of operation of the microprocessor and the requirements of the program that controls it can be the following:

Set up the system

START

Measure the flow of current through each chain of WLEDs

Select the necessary current flow from the state press button / fader switch. The system can be preselected to have different switching sequences, that is, Connected-Disconnected, or Connected-Attenuator-Attenuator-Disconnected, o Ascending-Descending.

Measure the temperature of the WLEDs

Temperature compensation

At high temperatures apply an amount provided current limitation, thereby increasing the life of WLEDs at high temperature

WLED fault detection in circuit open

Check for a lack of current flow to through one or more chains and compensate for this failure allowing flow more current through the remaining chains to a safety limit

LED fault detection by short circuit

Check if there is a current flow disproportionately large across one or more chains and disconnect those chains; compensate for these failures allowing flow more current through the remaining chains, up to a safety limit

Current control

Using one more proportional algorithm integral plus deductive, set the current flowing in the WLED strings to meet certain requirements previously; flow control has the advantage that the unit is not voltage dependent and the system will maintain a stable production of light over a specified interval of voltage

Perform programming functions and surveillance; change the status indication means (ie LED  no blank, bit memory register, etc) if any fails WLED

Go back to START

Referring now to figures 2 and 3, an exploded view of some of the components that can be used in the manufacture of a device lighting according to the invention.

A lighting head is mounted between two shells 100, 102, the first shell 100 having an opening 104 which can receive a transparent insert 106 through which it emits light In use, the surface of the shell 100 on which it is arranged the opening 104 will normally be directed down on the lap of a user to project light on it, and by therefore this surface is often the lower surface of the device.

Within the two shells a usually black opaque plastic 107 insert that has a plurality of holes 108 that at least partially receive the tips of the 110 WLEDs mounted on an integrated printed circuit (IC) 112. The holes are arranged to insulate and soundproof each of the other WLEDs, to prevent them interfere with each other, and finally to arrange some support side for said WLEDs, since the terminals by which the LEDs are normally mounted on the ICs break easily. Be It should be noted that in the embodiment shown in Figure 2, a LED indicator 114 of conventional color (ie red) or color alternative (for example green) is arranged substantially centered form within the surrounding series of WLEDs and this particular LED is also received inside a hole substantially central 108 inside insert 107.

Said particular LED, when lit from according to a modified aspect of the invention to indicate when one or more WLEDs failed, can be seen through the insert transparent 106, despite the emission of light through said insert 106, for the WLEDs that remain illuminated. This does especially easy for an engineer or another person to inspect a large number of lighting installations determine if any particular WLED has failed and requires the replacement of the group sometime later. The programming of the replacement may depend on the maintenance plan applicable to a certain aircraft on which the device is installed.

The end 118 of a member 116 of type flexible and stable is fixed within the defined opening when  the two shells 100, 102 are carried together and a pair of power conveyor cables 120, 122 provide a power source to the corresponding contacts 124, 126 arranged at one end of the IC 112 board. It should be highlighted that the real way in which the WLED set is fed from Energy is not crucial to the invention, and experts in Matter may consider other methods.

Also mounted on said IC 112 board there are microprocessor devices 128, 130 that perform the control innovative of the current supplied to the various chains of WLED that constitute the set, and the specific means of LED indication that work when one or more WLEDs have failed. As required by the invention they can also be mounted on said IC 112 board other components such as thermal resistors to measure the ambient temperature.

Referring finally to figure 3, it shows the particular set 132 of "package-closed-hexagonal" of WLEDs mounted on said IC 112 board. This arrangement is the most desirable because it provides a uniform light emission and balanced from the bottom of said shell 100, and these features are not adversely affected when one fails of the WLEDs. Additionally, the particular indication of LED 114 it can be seen clearly in figure 3 located inside the set 132.

Claims (23)

1. A lighting device comprising a group of white LEDs (14, 16, 18) chained in parallel between a pair of lines (4, 6) that apply a voltage along the white LED strings (8, 10 , 12), each of these chains (8, 10, 12) having at least one white LED (14, 16, 18) in it; first means of changing the current capable of adjusting the total current drawn from the voltage lines (4, 6) for each individual string (8, 10, 12) of white LEDs; second means of changing the current arranged in each chain (8, 10, 12) to adjust the specific current through each of said chains (8, 10, 12); current measuring means in each chain (8, 10, 12); characterized in that the control means are arranged so that they communicate with the current measurement means to allow control of the first means of changing the current and at least one of the second means of changing the current in response to the variations in the measured current in the individual chains. 2. A lighting device according to claim 1, characterized in that primary means for measuring the current between the voltage lines (4, 6) and the chains (8, 10, 12) are provided which provides a representation of the Total current that is being taken out by all LED strings. 3. A lighting device according to claim 1, characterized in that the control means is a microprocessor (128, 130) that operates with the control of a computer program. 4. A lighting device according to claim 1, characterized in that three white LEDs (14, 16, 18) are connected in series in each of said chains. 5. A lighting device according to claim 1, characterized in that the number of strings (8, 10, 12) is 6. A lighting device according to some of claim 1, characterized in that the current measuring means comprise a resistor (R X) connected in series with the white LEDs (14, 16, 18) connected in series in each chain (8, 10, 12). 7. A lighting device according to claim 1, characterized in that the first and second means of current change comprise transistors (T X). A lighting device according to claim 1, characterized in that the device is provided with temperature measuring means that also communicate with the control means that adjust the flow of current through the white LED strings (8 , 10, 12) in response to temperature changes. A lighting device according to some of claim 1, characterized in that the control means dynamically adjust the current flows through the white LED strings (8, 10, 12), such that the flow of Current through them is substantially uniform and devoid of discontinuities regardless of the operating temperature and / or the failure of one or more of the white LEDs (14, 16, 18). 10. A lighting device according to any of claim 1, characterized in that the control means, voltage lines (4, 6), and white LEDs (14, 16, 18) connected in series are chained together, are integrated in a single circuit 11. A lighting device according to claim 1, characterized in that the device is used to provide light to a seat. 12. A lighting device according to some of claim 1, characterized in that the control means also communicate with indication means that change their status when said control means recognize that one or more white LEDs have failed. (14, 16, 18). 13. A lighting device according to claim 12, characterized in that the indicating means comprise light means (114) that emit a light other than white, said light means being arranged in series with barrier means also in communication with the control means between the lines, said control means activating said barrier means, thus allowing the current to flow through the light means to illuminate them only when one or more white LEDs has failed. 14. A lighting device according to claim 13, characterized in that said light means (114) are mounted next to the white LEDs (14, 16, 18) and are visible when the set of white LEDs is seen, one of which has failed. 15. A lighting device according to any preceding claim, characterized in that the white LEDs (14, 16, 18) and the indicating means are mounted close to each other in a hexagonal package arrangement (132) closed in a printed circuit ( 112). 16. A lighting device according to claim 15, characterized in that the control means are also mounted on said printed circuit (112). 17. A lighting device according to claim 16, characterized in that the white LEDs (14, 16, 18) are connected within the printed circuit (112) and arranged in groups of three, said groups being connected in series as a single string that is connected in parallel with the others. 18. A lighting device according to claim 17, characterized in that the grouping of the white LEDs (14, 16, 18) into three is such that any single white LED is adjacent to another white LED that is connected in series with it . 19. A lighting device according to claim 12, characterized in that the indication means can be arranged in a remote indicator panel and to which power is supplied from the control means. 20. A lighting device according to claim 12, characterized in that the indication means are manifested in one or more bits in a memory register that can be examined by a properly equipped engineer. 21. A lighting device according to claim 1, characterized in that said control means also communicate with user adjustable means to increase the intensity or attenuation of the light emitted by the white LEDs (14, 16, 18) and also to connect or disconnect the device. 22. A lighting device according to claim 1, characterized in that the control means recognize when one or more of the WLEDs (14, 16, 18) has failed and additionally causes a change of state of an additional component indicating that A fault has occurred. 23. A lighting device according to claim 22, characterized in that the additional component is a warning light (114) that can be instantly seen by an engineer.