Driver device for a light emitting device - Patents.com

Abstract

The present invention provides a driver apparatus for a light emitting device. The driver apparatus comprises two driver circuits. The power output by each driver circuit is controlled by a respective control loop. The control system comprises a single manual switch device that is switchable between a plurality of switch positions. Switching between the different positions simultaneously changes which, if any, of one or more setting components form part of each control loop. Changing which setting components form part of the control loop changes or controls the power output by the respective driver circuit.

Description

[Technical field]

[0001] The present invention relates to the field of driver devices, and in particular to a driver device for outputting two power supplies. [Background technology]

[0002] In the field of lighting devices, there is a desire to provide a color temperature adjustable lamp that can output light of various color temperatures.

[0003] Some existing three-stage color temperature adjustable light emitting devices have one constant current converter and two output channels, i.e., two LED devices. One of these LED devices outputs a high color temperature, and the other outputs a low color temperature. The three-stage color temperature change is realized by a DIP switch, which can be operated in four different modes, so that the current through the LED device can be controlled in four different states, i.e., no current flows, all current flows through the LED device with the high color temperature, all current flows through the LED device with the low color temperature, or the current is split between the two LED devices. This kind of control mechanism is only suitable for three-stage color temperature adjustment, and should not be used for five-stage or more color temperature adjustment techniques, because more control would require additional LED devices, which would greatly increase the cost and size of the entire light emitting device.

[0004] Another way to adjust the color temperature is to change the number of resistors connected in series with each LED device by controlling a DIP switch. The change in the number of resistors results in a change in the current through each LED device, thereby adjusting the color temperature accordingly. However, this method is not power efficient due to the power loss caused by connecting additional resistors in series. Furthermore, due to the diode characteristics of LEDs, the accuracy of the color temperature is low, which means that a small difference in forward voltage (VF) (e.g. due to natural manufacturing variations and / or aging of diodes, resulting in moisture ingress or thermal shock) can result in a large current difference and therefore a large variation in color temperature. Therefore, it is a complex task to ensure accurate color temperature adjustment in five steps using this approach.

[0005] An alternative approach proposed by, for example, US20150338268A1 is to use two or more LED drivers, each driving an LED string with different LEDs, and using a DIP switch to control each LED driver. This approach employs digital control, using a microcontroller unit (MCU) to detect the position of the DIP switch and control the output current of each driver according to a mapping table. This control method is complex, expensive, and more resource-intensive, since an MCU is required. Summary of the Invention [Problem to be solved by the invention]

[0006] There is therefore a desire to provide new techniques that facilitate accurate, precise and resource-efficient control of the operation of light emitting devices. [Means for solving the problem]

[0007] The invention is defined by the claims.

[0008] The embodiment proposes a technique whereby a single manual switch device simultaneously controls the power supplied by two driver circuits of a driver device. Moreover, the control is performed in an analog manner by directly adjusting the control loops of the driver circuits via setting components instead of using detection, mapping and control involving digital components. More specifically, the single manual switch device controls which (if any) of a set of one or more setting components / elements, such as resistors, form part of the control loop of each driver circuit. The proposed technique is particularly advantageous for light emitting devices having LED devices with different color temperatures powered by respective driver circuits. In particular, compared to the prior art where each of the two driver circuits has its own adjustment interface and the user needs to adjust two interfaces to set the respective output of each of the two driver circuits, the proposed mechanism provides an intuitive and cost-effective mechanism where the user only needs to operate a single switch to set the respective output of each of the two driver circuits, thereby facilitating the control of the output of the driver circuits to provide consistent and resource-efficient color temperature adjustment. From a user's point of view, the present invention as a whole provides one-click settings for both driver circuits, which is quite different from having to set settings for both driver circuits separately.

[0009] According to an example according to an aspect of the present invention, a driver apparatus for a light emitting device includes a first driver circuit and a second driver circuit, each configured to supply power to a respective load; a first control loop configured to control the power supplied by the first driver circuit and a second control loop configured to control the power supplied by the second driver circuit; a control system including one or more setting components that, when connected to a selected one of the control loops, sets an amplitude of the power supplied by the driver circuit as controlled by the selected one of the control loops; and a single manual switch device configured to control an electrical connection between the one or more setting components and each control loop, at least and a control system including a single manual switch device configured to be switchable between at least a first switch position and a second switch position, wherein switching between the first and second switch positions simultaneously changes the setting components connected to the first and second control loops such that when the single manual switch device is in the first switch position, the first driver circuit provides a first output and the second driver circuit provides a second output, and when the single manual switch device is in the second switch position, the first driver circuit provides a third output different from the first output, and the second driver circuit provides a fourth output different from the second output.

[0010] The proposed mechanism utilizes a single manual switch device to control the number and / or characteristics of any setting components connected to a control loop for each of two or more driver circuits in the driver apparatus. The single manual switch device thereby facilitates a mechanism for controlling the amount of power output by each driver circuit. It should be understood that in many applications, it is not necessary to provide the user with all possible combinations of settings of two driver circuits, and a set of some suggested selected combinations will suffice. More specifically, the first / second output combination and the third / fourth output combination are two selected combinations (that may prove useful to the user), whereas the first / fourth output combination or the third / second output combination may be excessive to the user and can be discarded (e.g., the mechanism may not facilitate such combinations). Further examples below provide further details.

[0011] This approach provides a resource-efficient mechanism for controlling the power output by each driver circuit, and thereby the power drawn by the loads connected to each driver circuit, which can be used to appropriately control the power drawn by each LED device (e.g., acting as a load).

[0012] Optionally, when the single switch device is in the first switch position, it connects a first set of the one or more setting components to the first control loop and a second set of the one or more setting components to the second control loop, and when the single switch device is in the second switch position, it connects a third set of the one or more setting components, different from the first set, to the first control loop and connects a fourth set of the one or more setting components, different from the second set, to the second control loop.

[0013] Each of these sets of configuration components may be different or may overlap. For example, the second set and the third set may be the same, the first set and the fourth set may be the same, etc. In another example, components may be shared between the different sets of configuration components.

[0014] In some examples, the first output is greater than the third output and the second output is less than the fourth output, such that the output of the first driver circuit and the output of the second driver circuit are complementary.

[0015] This example facilitates user operation. In the prior art using respective interfaces for two driver circuits, if complementary outputs are required, the user must turn one driver circuit up through one interface and turn the other driver circuit down through the other interface. By using this example, the user can make these settings in one go through operating the single manual switch from the first position to the second position.

[0016] In some examples, each setting component has a sensing component adapted to sense a value of an output of the driver associated with the control loop to which the sensing component is connected, and switching the position of the single manual switch device causes a simultaneous change in the total impedance of each of the sensing components connected to each control loop.

[0017] By changing the resistance of the sensing component, the effective output as seen by the control loop is altered and the control loop can be set to a different output. This example is easy to implement.

[0018] In some embodiments, each setting component has a biasing component to the dimming terminal of the control loop to which it is connected, and switching the position of the single manual switch device causes a change in the total impedance of the respective biasing component connected to each control loop. Furthermore, the total impedance of any biasing component connected to a control loop can be adapted to set a reference value for the output of the driver circuit associated with the control loop.

[0019] This embodiment provides an alternative to setting the output by changing the reference value of the control loop, and in the case of an IC with a dimming terminal, adjusting the dimming terminal to adjust the output is relatively stable for the control loop.

[0020] Optionally, the one or more setting components include one or more resistors, and switching the position of the single manual switch device changes which resistors, if any, are connected to each control loop.

[0021] Using resistors as the setting components is low cost. Resistors are also easier to switch.

[0022] In some embodiments, the one or more setting components have a common setting resistor, and the single manual switch device is adapted to connect the common setting resistor to the first control loop and isolate the common setting resistor from the second control loop when in the first switch position, and to connect the common setting resistor to the second control loop and isolate the common setting resistor from the first control loop when in the second switch position.

[0023] In this embodiment, setting components are selectively coupled to either the first driver circuit or the second driver circuit, which therefore uses fewer setting components to achieve complementary outputs of the first driver circuit and the second driver circuit.

[0024] In at least one embodiment, the one or more setting components have two series resistor configurations, and the single manual switch is adapted to switch where each control loop taps a respective one of the two series resistor configurations.

[0025] This embodiment uses respective / independent setting components for the two driver circuits. An advantage is that the value of the setting components for each driver circuit can be set independently, and therefore the absolute value of the output of each driver circuit can be set independently from the other driver circuit.

[0026] In some examples, the one or more setting components have a plurality of different setting resistors, and the single manual switch device is adapted to, when in the first switch position, connect a first group of one or more of the different setting resistors to the first control loop and isolate a second, different group of one or more of the different setting resistors from the second control loop, and to, when in the second switch position, isolate the first group of one or more different setting resistors from the first control loop and connect the second group of one or more different setting resistors to the second control loop.

[0027] This example shows a particular way to switch the configuration components for the two control loops.

[0028] In some embodiments, the one or more setting components have, for each control loop, a fixed section that is fixed to the respective control loop and is not switchable by the single manual switch device, and a variable section that is adapted to be switchable to the respective control loop by the single manual switch device.

[0029] This embodiment makes the fixed setting component portion non-switchable, so that the two control loops have at least the fixed portion to make their output continuous during switching, and the driver circuit does not enter protection or shutdown operation during switching of the setting component.

[0030] Optionally, the first control loop has a first protection terminal and the second control loop has a second protection terminal, the single manual switch device being further adapted to, in the second switch position, control an impedance at the first protection terminal to a level at which the control loop of the first driver enters a protection mode thereby adapted to supply substantially zero of the third output to its respective load, and to, in the first switch position, control an impedance at the second protection terminal to a level at which the control loop of the second driver enters a protection mode thereby adapted to supply substantially zero of the second output to its respective load.

[0031] To obtain a single output from one driver circuit, the other driver circuits need to be turned off. However, for some driver circuits that do not have a standby control terminal, it is not easy to turn it off. Many control loops, especially ICs, have a protection terminal that is originally designed to be triggered by an abnormal condition such as overheating, and the driver circuit enters a protection mode / shutdown operation. This optional embodiment operates the protection terminal and causes the control loop to enter a protection mode, thereby effectively turning off the driver circuit.

[0032] Optionally, each driver circuit is configured to convert power from a mains power supply into a DC current for driving a respective LED device, the first control loop being configured to control the current supplied by the first driver circuit and the second control loop being configured to control the current supplied by the second driver circuit.

[0033] This option controls the current which directly determines the LED output lumen, therefore this option is more suitable for driving LEDs for general lighting purposes.

[0034] There is also proposed a light emitting device comprising a driver device as described above, a first LED device arranged to be powered by the first driver circuit, and a second LED device arranged to be powered by the second driver circuit.

[0035] In some embodiments, the first LED device is configured to output light of a first color temperature and the second LED device is configured to output light of a second, different color temperature.

[0036] For a lighting device with adjustable color temperature, in many applications, users prefer to simply select one of a few typical color points, rather than having the complexity of selecting one among all possible color points. Therefore, this embodiment can facilitate the design of the switching of the setting components to provide respective outputs at a few color points, and users can switch the lighting device to one of the few typical color points. This saves users troublesome operations.

[0037] These and other aspects of the invention will be elucidated and elucidated with reference to the following embodiments. [Brief description of the drawings]

[0038] For a better understanding of the present invention, and to show more clearly how the same may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which: [Figure 1] 1 illustrates a light emitting device according to an embodiment. [Diagram 2] 1 illustrates a control system for use in an embodiment. [Diagram 3] 1 illustrates a control system for use in another embodiment. [Figure 4] 1 illustrates a control system for use in another embodiment. [Diagram 5] 1 illustrates a control system for use in another embodiment. [Figure 6] 1 illustrates a control system for use in another embodiment. [Figure 7] 1 illustrates a control system for use in another embodiment. [Figure 8] 1 illustrates a control system for use in another embodiment. [Figure 9] 1 illustrates a control system for use in another embodiment. [Figure 10] 1 illustrates a control system for use in another embodiment. [Figure 11] 1 illustrates another light emitting element according to an embodiment. [Figure 12] 1 illustrates a control system for use in an embodiment. [Figure 13] 1 illustrates a control system for use in another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] The present invention will be described with reference to the drawings.

[0040] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the devices, systems and methods, are for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects and advantages of the devices, systems and methods of the present invention will become better understood from the following description, appended claims and accompanying drawings. It should be understood that the figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the figures to denote the same or similar parts.

[0041] The present invention provides a driver device for a light emitting device. The driver device has two driver circuits. The power output by each driver circuit is controlled by a respective control loop. The control system has a single manual switch device that is switchable between multiple switch positions. Switching between different positions simultaneously changes which, if any, of one or more setting components form part of each control loop. Changing which setting components form part of the control loop changes or controls the power output by each driver circuit. Thus, by switching the single manual switch device, the output of the two driver circuits is adjusted simultaneously. It is noted that the driver device may have three or more driver circuits, and if the driver device has three or more driver circuits, this also falls within the scope of the claims, since the driver device already has two driver circuits.

[0042] The embodiment introduces one or more setting components that can be connected to separate control loops, each of which controls the power provided by a respective driver circuit. The proposed approach uses a single manual switch device to facilitate simultaneous control of the outputs provided by the driver circuits, e.g., to control those outputs in a complementary manner.

[0043] In certain examples, as described below, the setting component can be controlled to change the output currents of the two driver circuits in a complementary manner, e.g., such that the total output current is relatively stable / constant while the outputs of the two driver circuits are opposite in amplitude, to change the output currents of the two driver circuits simultaneously, and / or to disable one driver circuit and enable another, or to enable both simultaneously.

[0044] The configuration components may be interchangeably connected to the control loops, and a single switch device may be configured such that changing a configuration component connected to one control loop simultaneously changes a configuration component connected to another control loop, in this manner the parameters of each control loop (e.g. bias voltages, reference voltages, etc.) are controlled simultaneously.

[0045] FIG. 1 illustrates a first use-case scenario of an embodiment of the present invention.

[0046] In particular, FIG. 1 illustrates a light emitting device 100 having a driver device 105 .

[0047] The driver device 105 comprises a first driver circuit 111 and a second driver circuit 112, each configured to convert the power provided at the inputs Vin+, Vin- into power as an output. Here, each driver circuit comprises a buck converter, the operation of which is well known to those skilled in the art. Thus, each driver circuit 111, 112 comprises diodes D1, D2, inductors Lm1, Lm2 and capacitors Co1, Co2, suitably connected in the form of a conventional buck converter. Other suitable driver circuits, such as a boost converter or a buck-boost converter, may also be used.

[0048] Each driver circuit 111, 112 supplies power to a respective load Load1, Load2. In particular, the first driver circuit 111 supplies a first power to the first load Load1 via Vo+a, Vo-a, and the second driver circuit 112 supplies a second power to the second load Load2 via Vo+b, Vo-b. Since the loads are LEDs, the first and second powers are preferably regulated in terms of current via terminals CS1 and CS2.

[0049] In the case of a light emitting device, the loads Load1, Load2 are respective LED devices, each of which is powered by a respective driver circuit 111, 112. In some scenarios, each LED device may be configured to output light of a different color or color temperature.

[0050] Each driver circuit 111, 112 may be configured to convert power from a mains power supply into a DC current for driving a respective LED device.

[0051] The driver 105 further comprises a first control loop 121 and a second control loop 122. Each control loop controls the power, and more particularly the current, provided by a respective driver circuit 111, 112. In the example shown this is achieved by respective controllers 124, 125 which control the operation of switches SW1, SW2 which themselves control the operation of the driver circuits.

[0052] Various control schemes for the control loops are known. Generally, each control loop responds to a voltage supplied by at least one terminal or pin.

[0053] In this example, each control loop is responsive to a voltage at a respective sense pin CS1, CS2 (here a current sense pin) that provides / defines a sense signal. In particular, the voltage of the sense signal provides feedback for the current output by the driver circuit controlled by the respective control loop. The voltage (i.e., the sense signal) at the sense pin CS1, CS2 may represent the current supplied by the driver circuit associated with the control loop. In particular, the voltage at a particular sense pin may be the voltage across a sensing impedance arrangement through which a current is output by the driver circuit. The sensing impedance arrangement connects between the sense pin CS1, CS2 and a ground / reference voltage (GND).

[0054] The present disclosure proposes the use of a control system 130 having one or more setting components and a single manual switch device, configured to bias or change the voltage at the sense pins CS1, CS2.

[0055] A setting component of the control system is configured such that, when connected to (or disconnected from) a particular control loop, the setting component changes the amplitude of the power supplied (to a respective load) by a driver circuit associated with the control loop to which the setting component is connected.

[0056] The single manual switch device is configured to control the electrical connections between the configuration components and the control loops and can simultaneously change which configuration components are connected to the first and second control loops. In this manner, the single manual switch device simultaneously controls which configuration components contribute to or form part of each control loop.

[0057] In the illustrated example, the control system 130 functions by facilitating simultaneous variation of the impedance of the sense impedance configuration for the first control loop and the sense impedance configuration for the second control loop. This is accomplished by the control system 130 controllably varying which setting components contribute to or form the sense impedance configuration for each control loop. In particular, the control system controls which setting components are electrically connected to the sense terminals CS1, CS2 of each control loop (i.e., electrically connected to allow current to flow to / from the sense terminals CS1, CS2). This approach facilitates control of the current output by each driver circuit.

[0058] The control system 130 thereby controls the connection (particularly the impedance) between the two sense terminals / pins CS1, CS2 of each control loop 121, 122 and a ground / reference voltage. The sense terminals CS1, CS2 provide / define the voltage of the respective sense signal that controls or sets the operation of the respective control loop.

[0059] This effectively means that control of the current output by each driver circuit can be achieved by changing or adjusting the impedance of the sensing impedance arrangement used for each control loop. The embodiment proposes to utilize the control system 130 to change the impedance of the sensing impedance arrangement. This can be achieved, for example, by controlling which setting components are connected to the control loop via the sense terminals CS1, CS2, thereby controlling the impedance of the sensing impedance arrangement.

[0060] As a further explanation, in the case of the driver device shown in FIG. 1, the current I output by the driver circuits 111 and 112 is o1 , I o2has a negative relationship with the impedances Rcs1, Rcs2 of the sensing impedance arrangement associated with the control loop and a positive relationship with the reference voltage Vref, as shown in the equation below: I ox =V ref / Rcsx (1) In the case of the first driver circuit 111, x can be replaced with "1", and in the case of the second driver circuit 112, x can be replaced with "2".

[0061] Thus, varying the impedance of a sensing impedance arrangement for a control loop facilitates control of the output of a driver circuit associated with said control loop.

[0062] In the context of the present disclosure, controlling whether a setting component is connected to a control loop means controlling whether current can flow from the control loop through that setting component, or vice versa. Thus, connecting a setting component to a control loop may make the setting component part of the control loop, and disconnecting a setting component from the control loop may remove the setting component from the control loop.

[0063] The configuration components may also be able to control the voltage at the protection terminals OV1, OV2 of the driver circuits. Each protection terminal, originally for overvoltage or overtemperature protection etc., may be used as an effective enable / disable circuit for a control loop / driver circuit. This type of embodiment may be used, for example, to control when the overvoltage protection circuit is activated even when there is no overvoltage condition, which may allow control of the output of each driver circuit (e.g., the output may be controlled to provide negligible or zero current). An example of this approach is described later in this disclosure.

[0064] Figure 2 illustrates a control system 230 for use in an embodiment of the invention, such as in a use case scenario illustrated in Figure 1. The control system is connected to each control loop and configured to modify the characteristics of the control loop, thereby controlling the characteristics of the power output by the associated driver circuit.

[0065] The control system 230 has a number of setting components, where each setting component has a respective resistor R1, R2, R3, R4.

[0066] The control system 230 includes a single manual switch device 250. The single manual switch device is configured to controllably select which resistor is electrically connected to (i.e., conducts power for) each control loop. This effectively controls the impedance of the sense impedance arrangement. The single manual switch device is configured to thereby control the electrical connection between one or more setting components and each control loop.

[0067] The single manual switch device 250 can be a button, a rotary knob, a slide switch, or any other mechanical device that can simultaneously control and change which setting components contribute to each control loop. In the illustrated example, the single manual switch device 250 has a slide switch-like device, i.e., a conductive object, that can be moved to change the connection of a resistor between (the sense terminal of) each control loop and ground (GND). The conductive object can be made using / from any conductive material, for example a metal such as copper or iron. The conductive material may be one that is used to conduct electricity in a home appliance.

[0068] This example single manual switch device may be employed in any of the embodiments described herein. Differences between this single manual switch device of other embodiments will be highlighted. Otherwise, the materials and construction of such other single manual switch devices may be the same as the single manual switch device 250 described above.

[0069] The single manual switch device is configured to be manually switchable between multiple switch positions. Changing between each switch position simultaneously changes which configuration components (if any) are connected to both control loops via the sense terminals CS1, CS2, i.e., which configuration components (if any) contribute to each control loop. In this manner, changing between each switch position simultaneously changes the output provided by the driver circuit.

[0070] In this manner, the single manual switch device 250 controls the impedance (Rcs1, Rcs2) between each controller 124, 125 and ground (GND) by controlling which of the resistors R1, R2, R3, R4 connect to each controller 124, 125. Each resistor R1, R2, R3, R4 can effectively be connected to or isolated from each control loop depending on the position of the single manual switch device.

[0071] 2 illustrates three switch positions for a single manual switch device. In the first switch position 291, the first resistor R1 and the second resistor R2 are connected (in parallel) to the first control loop and no resistor is connected to the second control loop. In the second switch position 292, only the second resistor R2 is connected to the first control loop and the third resistor R3 is connected to the second control loop. In the third switch position 293, no resistor is connected to the first control loop and the third resistor R3 and the fourth resistor R4 are connected (in parallel) to the second control loop.

[0072] For further understanding, consider a scenario in which the control system 230 is used as the control system 130 for the driver device shown in FIG. 1, where R1=R2=R3=R4=R, and the total output current is Io.

[0073] In this scenario, in the first switch position 291, R1 and R2 are connected in parallel and connected to GND, i.e., Rcs1=R1 / / R2=0.5×R. Furthermore, in the first switch position, R3 and R4 are open, so Rcs2=+∞. In this case, Io1=Vref / Rcs1=2×Vref / R, Io2=Vref / Rcs2=0, and the control loop of the second driver circuit may enter an open load mode. In essence, the total output is all supplied through the first load, e.g., the first LED, and the total output current Io=Io1+Io2=2×Vref / R.

[0074] In the same scenario, in the second switch position 292, R1 is open and R2 is connected to GND, i.e., Rcs1=R2=R. Furthermore, in the second switch position, R3 is connected to GND and R4 is open, so Rcs2=R3=R. In this case, Io1=Vref / Rcs1=Vref / R and Io2=Vref / Rcs2=Vref / R. Thus, the total output is half through the first load, e.g., the first LED, and half through the second load, e.g., the second LED, and the total output current Io=Io1+Io2=2×Vref / R.

[0075] In the same scenario, in the third switch position 293, R1 and R2 are open, i.e., Rcs1=+∞. Furthermore, in the third switch position, R3 and R4 are connected in parallel and connected to GND, i.e., Rcs2=R3 / / R4=0.5×R. In this case, Io1=Vref / Rcs1=0, and the control loop of the first driver circuit may enter an open load mode, and Io2=Vref / Rcs2=2×Vref / R. In short, the total output is all through the second load, e.g., the second LED, and the total output current is Io=Io1+Io2=2×Vref / R.

[0076] Thus, the total current output Io by the combination of both drivers can be kept constant while varying the current supplied by each driver separately. Of course, it will be appreciated that the total output current Io can be different, at least in part, by configuring R1, R2, R3 and R4 differently.

[0077] Figure 3 illustrates another control system 330 for use in an embodiment of the invention, such as in a use case scenario illustrated in Figure 1. The control system 330 operates on similar principles to the control system 230 illustrated in Figure 2, with the main difference being that configuration components can be shared at different times by the two driver circuits. Such configuration components are sometimes referred to as "common configuration components."

[0078] In this embodiment, the single manual switch device 350 comprises a split slide switch-like device, i.e., a split conductive object, that can be moved to change the resistor connections between the (sense pins of) each control loop and ground (GND) based on its position. Examples of suitable conductive objects are described above.

[0079] Assuming that the control system 330 is used as the control system 130 for the driver device illustrated in FIG. 1, and that R5=R6=R, and the total output current is Io, the following understanding of operation can be obtained.

[0080] When the single manual switch device is in the first switch position 391, the first resistor R5 and the second resistor R6 are connected (in parallel) to the first control loop, and no resistors are connected to the second control loop. Therefore, Rcs1=R5 / / R6=0.5×R, and Rcs2=+∞. In this case, Io1=Vref / Rcs1=2×Vref / R, Io2=Vref / Rcs2=0, and the total output current Io=Io1+Io2=2×Vref / R.

[0081] In the second switch position 392, only the first resistor R5 connects to the first control loop and the second resistor R6 connects to the second control loop. In this manner, Rcs1=R5=R and Rcs2=R6=R. Therefore, Io1=Vref / Rcs1=Vref / R and Io2=Vref / Rcs2=Vref / R, and the total output current Io=Io1+Io2=2×Vref / R.

[0082] In the third switch position 393, no resistor is connected to the first control loop, and the first and second resistors are connected (in parallel) to the second control loop. In this manner, Rcs1=+∞ and Rcs2=R3 / / R4=0.5×R. In this case, Io1=Vref / Rcs1=0, Io2=Vref / Rcs2=2×Vref / R, and the total output current Io=Io1+Io2=2×Vref / R.

[0083] As before, it will be appreciated that in any of these switch positions the total output current Io may be different if R5 ≠ R6.

[0084] FIG. 4 illustrates another control system 430 for use in embodiments of the invention, such as in a use case scenario illustrated in FIG.

[0085] Control system 430 operates on similar principles to control system 330 illustrated in FIG. 3, but is capable of providing five different combinations of sensing impedance configurations instead of just three, i.e., five different switching positions for a single manual switch device.

[0086] The control system has four resistors R7, R8, R9, R10. Different sets of these resistors can be selectively introduced into each control loop. When R7=R8=R9=R10, the total output current Io is constant.

[0087] In a first switch position 491 of the single manual switch device 450, all four resistors form part of the first control loop and are disconnected from the second control loop. In a second switch position 492, three resistors form part of the first control loop and only one resistor forms part of the second control loop. In a third switch position 493, two resistors form part of the first control loop and two resistors form part of the second control loop. In a fourth switch position 494, only one resistor forms part of the first control loop and three resistors form part of the second control loop. In a fifth switch position 495, all resistors are disconnected from the first control loop and instead form part of only the second control loop.

[0088] In any of the modifications to the control systems of Figures 2-4, the respective resistors (arrangements) may be permanently connected to form part of each control loop. This approach can be adopted when neither driver circuit needs to provide zero output current. The permanently connected resistors make the control loops stable during switching. For example, this can prevent failure of the controller and / or driver circuit, since if the current through the impedance arrangement is suddenly stopped during operation of the driver circuit, a high voltage will appear at the output of the driver circuit, which may damage the controller and / or driver circuit.

[0089] Thus, the one or more setting components may have, for each control loop, a fixed section that is fixed to the respective control loop and is not switchable by a single manual switch device, and a variable section that is adapted to be switchable to the respective control loop by a single manual switch device.

[0090] Figure 5 illustrates the resulting control system 530 when this modification is applied to the control system of Figure 4. In this example, resistor R37 always connects to the first control loop and resistor R42 always connects to the second control loop. In this embodiment, sense terminals CS1 and CS2 are never open, so that Io1 and Io2 cannot be driven down to zero.

[0091] Thus, resistor R37 acts as a fixed part for the first control loop and resistor R42 acts as a fixed part for the second control loop. The remaining resistors R38, R39, R40, R41 act as variable parts for each control loop such that the connection between the variable part and each control loop can be controlled by switching the position of a single manual switch device.

[0092] In FIG. 5, if R37=R38=R39=R40=R41=R42 and the total output current is Io, then (if equation (1) applies) the output current of the first control loop (controlled via sense pin CS1) can be Io / 6, Io / 3, Io / 2, 2Io / 3 or 5Io / 6.

[0093] It has already been described how a configuration component, or more broadly a control system, can be used to control the operation of an overvoltage protection circuit for a control loop.

[0094] Returning to Figure 1, the first control loop 121 may have a first protection terminal OVP1 (carrying a first over-voltage protection signal). The second control loop 122 may have a second protection terminal OVP2 (carrying a second over-voltage protection signal).

[0095] As mentioned above, it is preferable to prevent the sense terminals CS1 or CS2 from floating (being held open) when the driver circuit is active (i.e., powered). If the current flowing through the sense terminals CS1, CS2 is suddenly stopped, it may result in a high voltage appearing at CS1, CS2, which may damage or destroy the controller of the driver circuit. In a typical implementation, the sense terminals of the control loop (i.e., the inputs to the controller) are low voltage pins on the controller and can withstand voltages less than 10V.

[0096] It is proposed to utilize existing overvoltage protection circuits to allow the current output by any driver circuit to drop to zero when the driver device is powered up. ICs for control loops in general, and driver circuits in particular, include overvoltage protection terminals, and the voltage that can cause the control loop / driver circuit to go into protection and shutdown operation effectively controls whether the control loop is enabled or disabled (more specifically, whether the controller of the control loop is enabled or disabled).

[0097] In many cases, the voltage (VOVP) at the overvoltage terminal (OVP) of the output loop has either a positive relationship (VOVP=X×ROVP) or a negative relationship (VOVP=X / ROVP) with the OVP resistor (which is the resistor between the OVP terminal and ground). By adjusting or controlling the OVP resistor, the OVP can be triggered during "normal" conditions, i.e., when there is in fact no overvoltage supplied to the driver device. In this way, Io1=0 or Io2=0 can be realized during the normal operation of the driver device.

[0098] One approach for controlling the OVP resistance, which operates under the assumption that VOVP=X×ROVP, is illustrated in FIG.

[0099] 6 illustrates a control system 630 for use in an embodiment of the present invention. The control system again includes a number of setting components 640 and a single manual switch device 650.

[0100] The single manual switch device has a movable element 651 (illustrated as a square) that is always coupled to ground and is switchable between three pairs of terminals indicated by arrows, which can interconnect selected pairs of terminals to ground. The movable element is an example of a conductive object.

[0101] A first group of setting components (comprising resistors R85, R86) can be selectively connected to different sense terminals CS1, CS2 (i.e. to allow or prevent current flow from / to the setting components from said sense terminals). In particular, a single manual switch device can control which of the first group of setting components allows current flow to / from the sense terminals.

[0102] A second group of setting components is selectively electrically connected to the protection (OVP) terminals, thereby allowing control of an OVP resistance at each OVP terminal. In particular, the second group of setting components is configured such that two resistors (connected to the first protection terminal OVP1 and the second protection terminal OVP1, respectively) can be selectively / controllably configured to provide a current path to ground. When the resistors are configured to provide a current path to ground, the OVP resistance in the OVP is set to trigger overvoltage protection.

[0103] If it is assumed that R83=R84=R85=R86=R, then there are three possible switch positions.

[0104] In a first switch position where the movable element 651 is on the left side as shown in Fig. 6, R85 and R88 are connected to ground, Rcs1 = R83 / / R85 = 0.5 x R, Io1 = Io, ROVP2 = R88 / / R90 (which triggers OVP2), and Io2 = 0. In a second switch position where the movable element 651 is moved to the center, it floats, Rcs1 = R83 = R, Io1 = 0.5 x Io, Rcs2 = R84 = R, and Io2 = 0.5 x Io. In this example, for the second switch position, both OVP1 and OVP2 are not triggered. In the third switch position where the movable element 651 is moved to the right, R86 and R87 are connected to ground, ROVP1=R87 / / R89, OVP1 is triggered, Io1=0, Rcs2=R84 / / R86=0.5×R, and Io2=Io.

[0105] The previous embodiment shows an approach where the configuration component has a resistor that controllably / selectively contributes to the sense impedance configuration for the control loop. This is accomplished by selectively connecting resistors in parallel between the sense terminal and a ground voltage.

[0106] However, embodiments may be adapted such that resistors may be selectively connected in series with one another between the sense terminal and the ground voltage.

[0107] 7 illustrates an embodiment of a control system 730 employing this approach. The control system again has a number of setting components 740 and a single manual switch device 750.

[0108] The plurality of setting components 740 here includes two series of resistors. A first series of resistors R29, R30 can be selectively electrically connected to a first sense terminal CS1, and a second series of resistors R31, R32 can be selectively electrically connected to a second sense terminal. In each case, either none, some, or all of the resistors (in each series of resistors) are electrically connected to the sense terminal.

[0109] A single switch device is configured to simultaneously change how many resistors in each series connection are connected in series between each sense terminal and ground voltage. This is accomplished using a slide switch that changes which tap in the series of resistors the ground voltage is connected to, with different taps representing different numbers of resistors connecting the sense terminal to said tap.

[0110] In the first switch position 791 in the upper left diagram of Figure 7, R29 connects CS1 to GND, Rcs1=R, CS2 is open, and Rcs2=+∞. In this case, Io1=Vref / R, Io2=0, and the total output current Io=Io1+Io2=Vref / R.

[0111] 7, R29 and R30 connect CS1 and GND, and Rcs1=R29+R30=2R, and R31 and R32 connect CS2 and GND, and Rcs2=R31+R32=2R. In this case, Io1=0.5×Vref / R, Io2=0.5×Vref / R, and the total output current Io=Io1+Io2=Vref / R.

[0112] In the third switch position in the lower diagram of Figure 7, CS1 is open, Rcs1 = +∞, R31 connects CS2 to GND, and Rcs2 = R. In this case, Io1 = 0, Io2 = Vref / R, and the total output current Io = Io1 + Io2 = Vref / R.

[0113] The above values ​​assume that all resistors are equal in value. It will be appreciated that if R29=R30=R31=R32 is not the case, then the total output current Io will not be constant.

[0114] Figure 8 illustrates a variation to the control system of Figure 7, in which the control system 830 is configured such that at least one resistor (of the control system) always connects the sense terminals CS1, CS2 of each control loop to ground. Resistors R33 and R35 permanently provide a path from the CS terminals to ground.

[0115] This embodiment prevents the occurrence of a sudden cessation of current flow from the sense terminals CS1, CS2 through the control system, which can result in a sudden high voltage occurring at the output of the driver circuit.

[0116] FIG. 9 illustrates a variation on the series resistor embodiment described above, adapted to utilize an overvoltage protection system in the control loop to facilitate the driver circuit outputting zero / negligible current without floating the sense terminal.

[0117] As mentioned above, it is preferable that the sense terminals CS1, CS2 cannot be floating (i.e., open) when the driver is powered. However, there may still be a desire to change Io1 or Io2 to zero. To facilitate this desire, the OVP terminal can be used. More specifically, by controlling the OVP resistance (i.e., the resistance between the OVP terminal and the ground voltage), the overvoltage protection (and turning off the driver circuit) can be triggered during normal / conventional operation of the driver device, and thus Io1=0 or Io2=0 can be realized.

[0118] 9 illustrates such an embodiment of a control system 930 in which a single manual switch device 950 is configured to simultaneously control the resistances provided at each of the sense terminals CS1, CS2 and each of the OVP terminals OVP1, OVP2. The single manual switch device here forms a switch (e.g., a conductive piece of material) movable between three switch positions.

[0119] In a scenario where R65=R66=R67=R68=R, in the first switch position (e.g., the switch is in the leftmost position), Rcs1=R65=R, RVOP1=R91+R93, Io1=Io, and OVP1 is not triggered, while RVOP2=R92, OVP2 is triggered, and Io2=0. In the second switch position, for example, when the switch is in the center position, Rcs1=R65+R66=2×R, Io1=0.5×Io, while Rcs2=R67+R68=2×R, Io2=0.5×Io. Both OVP1 and OVP2 are not triggered. In the third switch position, for example, when the switch is in the right position, RVOP1=R91, OVP1 is triggered, and Io1=0, while Rcs2=R67=R, RVOP2=R92+R94, and Io2=Io.

[0120] 10 illustrates another control system 1030 according to an embodiment. The control system 1030 differs from the previously described control systems in that a respective rheostat 1031, 1032 is used to control the resistance between each sensing terminal CS1, CS2 and the ground voltage. Thus, the one or more setting components now comprise a rheostat connected between each sensing terminal and ground.

[0121] A single manual switch device 1050 controls the resistance provided by each rheostat. In particular, the single manual switch device is movable between a plurality (e.g., an infinite number or continuum) of positions that define the resistance provided by each rheostat between sense pins CS1, CS2 and ground. The single manual switch device is configured such that moving a position along one rheostat simultaneously changes the position along the other rheostat.

[0122] The rheostats may be configured such that the resistance provided by one rheostat (between the sense pin and ground) increases while the resistance of the other rheostat (between the other sense pin and ground) decreases. This provides simultaneous control and, in the case of light emitting devices where the load is a LED device of different light temperatures, provides a continuous spectrum of light temperature combinations.

[0123] The rheostat may be replaced by any other suitable variable resistance element, such as a potentiometer.

[0124] The previous embodiments have been described in the context of a driver apparatus having a control loop that controls the driver circuit based on the current output by the driver circuit, eg, the voltage at a (current) sensing terminal.

[0125] However, other forms of control loops are known.

[0126] For example, some control loops may be configured to control the voltage output by the driver circuit based on the voltage at the dimming pin (the voltage at the dimming pin is independent of the current output by the load).

[0127] 11 illustrates a lighting device 1100 having a driver device 1105 including two control loops 1121, 1122 that operate using this principle. A controller 1124, 1125 for each control loop 1121, 1122 controls the operation of the driver circuit 1111, 1112 associated with each control loop. Each control loop has a respective dimming terminal DIM1, DIM2. The voltage at the dimming terminal DIM1, DIM2 (e.g., relative to high voltages VCC1, VCC2) sets the output of the driver circuit 1111, 1112 associated with the respective control loop 1121, 1122. The output of the driver circuit 1111, 1112 is therefore responsive to the voltage at the dimming terminal DIM1, DIM2.

[0128] It will be appreciated that the voltage at the dimming terminals DIM1, DIM2 can be controlled by controlling the impedance of the impedance arrangements connected to the dimming terminals. In particular, if the voltage at the dimming terminals DIM1, DIM2 is set using a voltage divider formed by an upper impedance arrangement (connected between the high voltage and the dimming terminals) and a lower impedance arrangement (connected between the dimming terminals and ground voltage), changing the impedance of either impedance arrangement will change the voltage supplied at the dimmer.

[0129] The control system 1130 can thereby be used to control the voltage at each dimming terminal.

[0130] 12 illustrates an example of a suitable control system 1230 for controlling the voltages at the dimming terminals DIM1, DIM2. The control system is configured to simultaneously vary the voltages at both dimming terminals, thereby simultaneously controlling the power supplied by the associated driver circuits.

[0131] More specifically, the control system 1230 includes a first voltage divider 1241 and a second voltage divider 1242 .

[0132] The first voltage divider 1241 is formed by a first upper impedance arrangement 1251 connected between the high voltage VCC1 and the first dimming terminal DIM1, and a first lower impedance arrangement 1252 connected between the first dimming terminal DIM1 and the ground voltage.

[0133] The second voltage divider 1242 is formed by a second upper impedance arrangement 1256 connected between the high voltage VCC2 and the second dimming terminal DIM2, and a second lower impedance arrangement 1257 connected between the second dimming terminal DIM2 and the ground voltage. The high voltages VCC1, VCC2 may be the same.

[0134] The control system 1230 is configured to (simultaneously) control the impedance of the first lower impedance arrangement 1251 and the second lower impedance arrangement 1257, thereby varying the voltage supplied at each dimming terminal.

[0135] In this example, the control system 1230 has two resistors R102, R103 and controls which lower impedance configuration each resistor contributes to via a single manual switch device 1250. The single manual switch device 1250 has a sliding element configured to provide different combinations of lower impedance configurations in different positions.

[0136] In the first position shown in Fig. 12, resistors R102 and R103 are connected in parallel with resistor R101 between the first dimming terminal and ground voltage. In the first position, only resistor R104 is connected between the second dimming terminal and ground voltage.

[0137] In the second position, resistor R102 is connected in parallel with resistor R101 between the first dimming terminal and ground voltage. In the second position, resistor R103 is connected in parallel with resistor R104 between the second dimming terminal and ground voltage.

[0138] In the third position, resistors R102 and R103 are connected in parallel with resistor R104 between the second dimming terminal and ground voltage. In this third position, only resistor R101 is connected between the first dimming terminal and ground voltage.

[0139] Each position provides a different combination of resistors to the lower impedance configuration of the voltage divider, which causes a different voltage to be present at the dimming terminal for each position, thereby facilitating control of the dimming voltage and thereby the power output by the driver circuit which is controlled in response to the dimming voltage.

[0140] Another example of a suitable control system 1330 is shown in Figure 13. Control system 1330 differs from control system 1230 in that rather than selectively connecting different resistors in parallel for each switch position, control system 1330 selectively connects different resistors in series, with selected taps of the series resistors connected to ground, thereby effectively adjusting the voltage divider ratio between the voltage at the DIM terminal and voltage VCC.

[0141] Equation (1) defines the reference voltage V ref Therefore, a reference voltage V (e.g., at a reference voltage terminal for a control loop) is used. ref By controlling or varying the value of , it is possible to control the power output by the driver circuit.

[0142] The control system illustrated in Figures 12 and 13 can be reused to vary the voltage at the reference voltage terminal for a control loop. The operation of the control system is similar and therefore will not be repeated for the sake of brevity.

[0143] Those skilled in the art can understand and effect variations to the disclosed embodiments in the practice of the claimed invention from a study of the drawings, the specification and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the singular does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. It should be noted that when the term "adapted to" is used in the claims or the description, the term "adapted to" is intended to be equivalent to the term "configured to". Any reference signs in the claims should not be interpreted as limiting the scope.

Claims

1. A driver device for a light emitting device, a first driver circuit and a second driver circuit, each configured to supply power to a respective load; a first control loop configured to control the power provided by the first driver circuit, and a second control loop configured to control the power provided by the second driver circuit; 1. A control system comprising: one or more setting components that, when connected to a selected one of the control loops, set the amplitude of the power supplied by the driver circuit as controlled by the selected one of the control loops; and a control system including a single manual switch device configured to control an electrical connection between the one or more setting components and each control loop, the single manual switch device configured to be switchable between at least a first switch position and a second switch position; a driver apparatus, wherein switching between the first and second switch positions simultaneously changes the setting components connected to the first and second control loops, such that when the single manual switch device is in the first switch position, the first driver circuit provides a first output and the second driver circuit provides a second output, and when the single manual switch device is in the second switch position, the first driver circuit provides a third output different from the first output and the second driver circuit provides a fourth output different from the second output.

2. when the single switch device is in the first switch position, connecting a first set of the one or more configuration components to the first control loop and connecting a second set of the one or more configuration components to the second control loop; 2. The driver apparatus of claim 1, wherein when the single switch device is in the second switch position, it connects a third set of the one or more setting components, different from the first set, to the first control loop and connects a fourth set of the one or more setting components, different from the second set, to the second control loop.

3. 3. A driver apparatus as claimed in claim 1 or 2, wherein the first output is greater than the third output and the second output is less than the fourth output, whereby the outputs of the first driver circuit and the second driver circuit are complementary.

4. each setting component having a sensing component adapted to sense a value of an output of the driver associated with the control loop to which the sensing component is connected; 4. A driver apparatus as claimed in any one of claims 1 to 3, wherein switching the position of the single manual switch device causes a simultaneous change in the total impedance of each of the sensing components connected to each control loop.

5. each setting component having a bias component to a dimming terminal of the control loop to which the setting component is connected; 5. A driver apparatus as claimed in any preceding claim, wherein switching the position of the single manual switch device causes a change in the total impedance of each of the bias components connected to each control loop.

6. 6. The driver apparatus of claim 5, wherein the total impedance of any bias components connected to a control loop is adapted to set a reference value for an output of the driver circuit associated with the control loop.

7. the one or more setting components include one or more resistors; 7. A driver apparatus as claimed in any preceding claim, wherein switching the position of the single manual switch device changes which resistors, if any, are connected to each control loop.

8. the one or more setting components having a common setting resistor; The single manual switch device is when in said first switch position, connecting said common resistor to said first control loop and isolating said common resistor from said second control loop; 8. A driver arrangement as claimed in any preceding claim, adapted to connect the common set resistor to the second control loop and to isolate the common set resistor from the first control loop when in the second switch position.

9. 9. A driver apparatus as claimed in any one of claims 1 to 8, wherein the one or more setting components have two series resistor configurations, and the single manual switch is adapted to switch where each control loop taps onto a respective one of the two series resistor configurations.

10. the one or more setting components having a plurality of different setting resistors; The single manual switch device is when in said first switch position, connecting a first group of one or more of said different setting resistors to said first control loop and isolating a second, different group of one or more of said different setting resistors from said second control loop; 10. A driver apparatus as claimed in any one of the preceding claims, adapted, when in the second switch position, to isolate the first group of one or more different setting resistors from the first control loop and to connect the second group of one or more different setting resistors to the second control loop.

11. The one or more configuration components, for each control loop: a fixed portion that is fixed to each of the control loops and is not switchable by the single manual switch device; 11. A driver apparatus as claimed in any one of the preceding claims, comprising: a variable portion adapted to be switchable into each of the control loops by the single manual switch device.

12. the first control loop having a first protection terminal; the second control loop having a second protection terminal; The single manual switch device further comprises: in the second switch position, controlling an impedance at the first protection terminal to a level such that the control loop of the first driver is adapted to enter a protection mode, thereby providing a substantially zero third output to its respective load; 12. A driver apparatus as claimed in any one of claims 1 to 11, adapted in the first switch position to control the impedance at the second protection terminal to a level at which the control loop of the second driver is adapted to enter a protection mode and thereby supply substantially zero second output to its respective load.

13. 13. A driver device according to any one of claims 1 to 12, wherein each driver circuit is configured to convert power from a mains power supply into a DC current for driving a respective LED device, the first control loop being configured to control the current supplied by the first driver circuit and the second control loop being configured to control the current supplied by the second driver circuit.

14. A driver device according to claim 13; a first LED device configured to be powered by the first driver circuit; and a second LED device configured to be powered by the second driver circuit.

15. 15. The light emitting device of claim 14, wherein the first LED device is configured to output light of a first color temperature and the second LED device is configured to output light of a second, different color temperature.

Images