Lighting device and luminaire

Abstract

To provide a lighting device and a luminaire capable of controlling a power conversion operation according to the magnitude of a current flowing through an inductor with a simpler configuration.SOLUTION: A power conversion unit that converts input power into power corresponding to a light source and supplies the converted power to the light source; and a control unit that controls an operation of power conversion by the power conversion unit, wherein the power conversion unit includes a converter that includes a switching element and an inductor and performs power conversion by switching of the switching element, and detects a magnitude of a current flowing through the inductor, and a current detector configured to input a detection result to the controller, wherein the controller is configured to, after switching the switching element from the ON state to the OFF state, perform a prediction operation regarding a timing at which a magnitude of a current flowing through the inductor becomes a predetermined value, based on the detection result of the current detector, and switch the switching element from the OFF state to the ON state at the timing of the prediction operation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a lighting device and a lighting fixture. [Background technology]

[0002] There is a lighting device that converts power supplied from a power source into power appropriate for a light source and supplies the converted power to the light source to light the light source, and there is also a lighting fixture that includes a light source and a lighting device. The lighting device has a switching element and an inductor, and converts power supplied from the power source into power appropriate for the light source by controlling the switching of the switching element according to the magnitude of the current flowing through the inductor.

[0003] In such lighting devices, there are cases where a relatively low current value flowing through the inductor, such as zero current, needs to be controlled. However, in order to be able to detect the low current value flowing through the inductor, special circuits such as a conversion circuit for converting the level of the current signal and an auxiliary winding for the inductor are required, which makes the circuit configuration of the lighting device complicated.

[0004] For this reason, in lighting devices and lighting fixtures, it is desirable to be able to control the power conversion operation according to the magnitude of the current flowing through the inductor with a simpler configuration, even when a low current value of the current flowing through the inductor is required for control. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5382216 Summary of the Invention [Problem to be solved by the invention]

[0006] An embodiment of the present invention provides a lighting device and a lighting fixture that can control the operation of power conversion according to the magnitude of the current flowing through the inductor with a simpler configuration, even when a low current value of the current flowing through the inductor is required for control. [Means for solving the problem]

[0007] According to an embodiment, a lighting device is provided that includes: a power conversion unit that converts input power into power corresponding to a light source and supplies the converted power to the light source; and a control unit that controls the power conversion operation by the power conversion unit, wherein the power conversion unit includes a converter that has a switching element and an inductor and converts power by switching the switching element; and a current detection unit that detects the magnitude of a current flowing in the inductor and inputs the detection result to the control unit, wherein the switching element has a pair of main terminals and a control terminal, and has an on state in which a current flows between the pair of main terminals and an off state in which the current flowing between the pair of main terminals is blocked, and after switching the switching element from the off state to the on state, the control unit switches the switching element from the on state to the off state at an arbitrary timing, and after switching the switching element from the on state to the off state, performs a predictive calculation regarding the timing at which the magnitude of the current flowing in the inductor will reach a predetermined value based on the detection result of the current detection unit, and switches the switching element from the off state to the on state at the predicted timing, thereby controlling the power conversion operation by the power conversion unit. [Effects of the Invention]

[0008] A lighting device and a lighting fixture are provided that can control the operation of power conversion according to the magnitude of the current flowing through the inductor with a simpler configuration, even when a low current value of the current flowing through the inductor is required for control. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram schematically illustrating a lighting fixture according to an embodiment. [Figure 2] 4 is a graph schematically illustrating an example of the operation of the lighting device according to the embodiment. [Figure 3] 10 is a graph schematically illustrating a modified example of the operation of the lighting device according to the embodiment. [Figure 4] 4(a) and 4(b) are graphs that schematically show modified examples of the operation of the lighting device according to the embodiment. [Figure 5] FIG. 10 is a block diagram schematically illustrating a modified example of the lighting fixture according to the embodiment. [Figure 6] 10 is a graph schematically illustrating a modified example of the operation of the lighting device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Each embodiment will be described below with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In the present specification and the drawings, elements similar to those described above with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0011] FIG. 1 is a block diagram schematically illustrating a lighting fixture according to an embodiment. As shown in FIG. 1 , the lighting fixture 2 includes a lighting device 10 and a light source module 100. The lighting device 10 is connected to the light source module 100. The light source module 100 is, for example, detachably connected to the lighting device 10. The lighting device 10 is also connected to a power source PS. The lighting device 10 is, for example, detachably connected to the power source PS. The lighting device 10 supplies a predetermined power to the light source module 100 based on the power supplied from the power source PS, thereby lighting the light source module 100.

[0012] The light source module 100 includes a light source 102 and a receptacle 104. The light source module 100 includes, for example, a plurality of light sources 102. In this example, the light sources 102 are connected in series. The light sources 102 may be connected in parallel, or a combination of series and parallel connections. The number of light sources 102 may be any number. For example, the number of light sources 102 may be one.

[0013] For example, a light emitting diode (LED) is used as the light source 102. The light source 102 may be, for example, an organic light emitting diode (OLED), an inorganic electroluminescence light emitting element, an organic electroluminescence light emitting element, or other electroluminescence type light emitting element. The light source 102 may be, for example, a light bulb.

[0014] The receptacle 104 is used for connection to the lighting device 10. The light source module 100 is detachably connected to the lighting device 10 via the receptacle 104. The light source module 100 is mechanically and electrically connected to the lighting device 10 via the receptacle 104.

[0015] The light source module 100 is, for example, an LED lamp. However, the light source module 100 is not limited to this and may be any light source module that includes at least a light source 102.

[0016] The lighting device 10 includes a connection unit 12, a power conversion unit 14, and a control unit 16. The connection unit 12 is connected to a receptacle 104 of the light source module 100. The light source module 100 is detachably connected to the lighting device 10 by connecting the receptacle 104 to the connection unit 12 of the lighting device 10.

[0017] The lighting device 10 is commonly used for a plurality of models of light source modules 100 that emit light that is different in at least one of brightness and color (color temperature). This makes it possible to suppress increases in the manufacturing costs of the lighting fixture 2 compared to, for example, manufacturing lighting devices that are specifically designed to be compatible with each of a plurality of models of light source modules 100.

[0018] The connection portion 12 has, for example, a first terminal 12a and a second terminal 12b. The first terminal 12a is connected to one end of the light source 102. The second terminal 12b is connected to the other end of the light source 102.

[0019] The receptacle 104 has a terminal 104a to be connected to the first terminal 12a and a terminal 104b to be connected to the second terminal 12b. In this way, the connecting portion 12 and the receptacle 104 are, for example, a two-terminal connector.

[0020] The power conversion unit 14 is connected to the power source PS and receives input power from the power source PS. The power conversion unit 14 converts the input power into power compatible with the light source module 100 and supplies the converted power to the light source module 100 connected to the connection unit 12. In other words, the power conversion unit 14 converts the input power into power compatible with the light source 102 and supplies the converted power to the light source 102, thereby turning on the light source 102.

[0021] The power conversion unit 14 has, for example, a pair of input terminals te1 and te2 and a pair of output terminals te3 and te4. The power conversion unit 14 is connected to a power supply PS via the pair of input terminals te1 and te2, and receives input power from the pair of input terminals te1 and te2. The power conversion unit 14 then outputs the converted power from the pair of output terminals te3 and te4.

[0022] The power supply PS supplies, for example, AC power as input power to the power conversion unit 14. The power supply PS is, for example, a commercial power supply. The power supply PS may also be, for example, a private power generator. The power conversion unit 14 converts the AC power supplied from the power supply PS into DC power compatible with the light source module 100 and supplies the converted DC power to the light source module 100. In this way, the power conversion unit 14 lights up the light source module 100 (light source 102). The power conversion unit 14 outputs DC power to a pair of output terminals te3 and te4. For example, the potential of the output terminal te4 is lower than the potential of the output terminal te3. The output terminal te3 is a high-potential output terminal, and the output terminal te4 is a low-potential output terminal.

[0023] The input power supplied to the lighting device 10 is not limited to AC power, but may be DC power, etc. The power conversion unit 14 may convert the DC power into another DC power having a different current value or voltage value and supply it to the light source module 100 (light source 102).

[0024] The control unit 16 controls the power conversion operation by the power conversion unit 14. The control unit 16 may receive a dimming signal from a dimmer or the like, for example, and control the operation of the power conversion unit 14 so as to light the light source module 100 (light source 102) at a brightness according to the dimming level indicated by the input dimming signal.

[0025] The power conversion unit 14 has, for example, a rectifier circuit 20, a high-frequency removal capacitor 22, a power factor correction circuit 24 (converter), a smoothing capacitor 26, and a converter 28. The rectifier circuit 20, the high-frequency removal capacitor 22, the power factor correction circuit 24, and the smoothing capacitor 26 may be omitted, for example, when DC power is supplied to the lighting device 10 from a power source PS. Each of these units is provided in the power conversion unit 14 as needed and may be omitted.

[0026] The rectifier circuit 20 rectifies AC power input from the power supply PS and converts it into rectified power. The rectifier circuit 20 may be, for example, a diode bridge formed by combining four rectifier elements. In other words, the rectifier circuit 20 is a full-wave rectifier. The rectified power may be, for example, pulsating power.

[0027] The rectifier circuit 20 has a pair of input terminals 20a and 20b, a high-potential output terminal 20c, and a low-potential output terminal 20d. The input terminals 20a and 20b are electrically connected to a power supply PS. The rectifier circuit 20 converts AC power input via the input terminals 20a and 20b into rectified power, and outputs it from the high-potential output terminal 20c and the low-potential output terminal 20d. The potential of the low-potential output terminal 20d is set to a reference potential (e.g., ground potential). The potential of the high-potential output terminal 20c is set to a potential higher than the potential of the low-potential output terminal 20d.

[0028] The rectifier circuit 20 may be a half-wave rectifier or the like. The rectified voltage may be a full-wave rectified pulsating current or a half-wave rectified pulsating current. For example, a Schottky barrier diode is used for the rectifier circuit 20. This allows, for example, good responsiveness to be obtained.

[0029] The high frequency removal capacitor 22 smoothes the rectified high frequency power, thereby converting it into pulsating power.

[0030] The power factor correction circuit 24 suppresses the generation of harmonics that are integer multiples of the power supply frequency in the input current of the rectifier circuit 20. In this way, the power factor correction circuit 24 improves the power factor of the input power.

[0031] The power factor correction circuit 24 includes, for example, a switching element 31, an inductor 32, and a diode 33. The switching element 31 includes a pair of main terminals 31a, 31b and a control terminal 31c. The switching element 31 has an ON state in which a current flows between the pair of main terminals 31a, 31b, and an OFF state in which the current flowing between the pair of main terminals 31a, 31b is interrupted.

[0032] One end of the inductor 32 is electrically connected to the high-potential output terminal 20c. The other end of the inductor 32 is electrically connected to the main terminal 31a. The main terminal 31b is electrically connected to the low-potential output terminal 20d. The anode of the diode 33 is electrically connected to the main terminal 31a. The cathode of the diode 33 is electrically connected to one end of the smoothing capacitor 26. The other end of the smoothing capacitor 26 is electrically connected to the low-potential output terminal 20d.

[0033] That is, in this example, the power factor correction circuit 24 is a boost chopper circuit. The power factor correction circuit 24 converts, for example, an AC voltage of 100 V to 242 V (effective value) of the power supply PS into a DC voltage of 420 V. The power factor correction circuit 24 is not limited to this and may be any circuit that can improve the power factor of the input power.

[0034] The control terminal 31c is electrically connected to the control unit 16. The switching element 31 performs switching in response to a signal from the control unit 16. The power factor correction circuit 24, for example, switches the switching element 31 to make the input current closer to a fractional waveform of a sine wave, thereby correcting the power factor.

[0035] The switching element 31 is, for example, an n-channel FET. For example, the main terminal 31a is a drain, the main terminal 31b is a source, and the control terminal 31c is a gate. The switching element 31 may be, for example, a p-channel FET or a bipolar transistor.

[0036] The smoothing capacitor 26 smoothes the output voltage after the power factor correction, thereby converting the power factor corrected electric power into DC power. The smoothing capacitor 26 supplies the DC power to the converter 28.

[0037] Converter 28 has a first input terminal 28a, a second input terminal 28b, a first output terminal 28c, and a second output terminal 28d. First input terminal 28a is electrically connected to one end on the high potential side of smoothing capacitor 26. Second input terminal 28b is electrically connected to low potential output terminal 20d. Thus, DC power is supplied from smoothing capacitor 26 to converter 28.

[0038] The converter 28 has, for example, a switching element 35, a diode 36, an inductor 37, and an output capacitor 38. The switching element 35 has electrodes 35a to 35c. The electrode 35a is electrically connected to the first input terminal 12a. The electrode 35b is electrically connected to the cathode of the diode 36. The anode of the diode 36 is electrically connected to the low potential output terminal 20d. One end of the inductor 37 is electrically connected to the electrode 35b. The other end of the inductor 37 is electrically connected to the first output terminal 28c. The second output terminal 28d is electrically connected to the low potential output terminal 20d (second input terminal 28b).

[0039] The output capacitor 38 has a first electrode 38a and a second electrode 38b. The first electrode 38a is electrically connected to the first output terminal 28c. The second electrode 38b is electrically connected to the second output terminal 28d. The output capacitor 38 is connected in parallel between the first output terminal 28c and the second output terminal 28d. The output capacitor 38 smoothes the current flowing between the electrodes 35a, 35b of the switching element 35 by switching the switching element 35. As a result, DC power is output from the first output terminal 28c and the second output terminal 28d.

[0040] In this example, the converter 28 is a step-down chopper circuit. The converter 28 converts DC power into another DC power by stepping down the voltage of the input power. The converter 28 converts, for example, a 420V DC voltage of the power factor correction circuit 24 into a DC voltage of 50V to 300V. The converter 28 is, for example, a constant current circuit. The converter 28 supplies, for example, a substantially constant DC current to the light source module 100 (light source 102).

[0041] The first output terminal 28c is a high-potential output terminal, and the second output terminal 28d is a low-potential output terminal. The potential of the first output terminal 28c is higher than the potential of the second output terminal 28d. The potential of the first electrode 38a is set higher than the potential of the second electrode 38b. The first electrode 38a is, for example, an anode, and the second electrode 38b is, for example, a cathode. Conversely, the potential of the second output terminal 28d may be higher than the potential of the first output terminal 28c.

[0042] The switching element 35 is, for example, an n-channel FET. For example, the electrode 35a is a drain, the electrode 35b is a source, and the electrode 35c is a gate. The switching element 35 may be, for example, a p-channel FET or a bipolar transistor.

[0043] The configuration of the converter 28 is not limited to the above circuit, and the converter 28 may have any configuration that can convert DC power into another DC power.

[0044] The control unit 16 is electrically connected to the control terminal 31c of the switching element 31. The control unit 16 controls the switching of the switching element 31. That is, the control unit 16 switches the switching element 31 on and off. The control unit 16 switches the switching element 31 on and off using a voltage (control signal) input to the control terminal 31c. The control unit 16 controls the improvement of the power factor of the input power by the power factor improvement circuit 24, for example, by switching the switching element 31.

[0045] The control unit 16 is electrically connected to the electrode 35c of the switching element 35. The electrode 35c is a so-called control electrode. The control unit 16 controls the switching of the switching element 35. That is, the control unit 16 switches the switching element 35 on and off. The control unit 16 switches the switching element 35 on and off by a voltage (control signal) input to the electrode 35c. The control unit 16 generates a DC voltage between the electrodes 38a, 38b of the output capacitor 38, for example, by switching the switching element 35. This causes DC power to be supplied from the converter 28 to the light source module 100.

[0046] The control unit 16 stops the supply of DC power from the converter 28 to the light source module 100, for example, by turning off the switching element 35. In addition, the control unit 16 changes the voltage value and current value of the DC power supplied to the light source module 100, for example, by changing the on / off cycle (duty ratio) of the switching element 35.

[0047] Here, the off state of the switching element 31 refers to, for example, a state in which substantially no current flows between the main terminals 31a and 31b. In the off state, for example, a weak current that does not affect the operation of the power factor correction circuit 24 may flow between the main terminals 31a and 31b. In other words, the on state of the switching element 31 refers to a first state in which a current flows between the main terminals 31a and 31b, and the off state refers to a second state in which the current flowing between the main terminals 31a and 31b is smaller than that in the first state. The on and off states of the switching element 35 are similar to those of the switching element 31.

[0048] The configuration of the power conversion unit 14 is not limited to the above, and may be any configuration that can convert input power into power compatible with the light source module 100 (light source 102) and supply the converted power to the light source module 100 (light source 102) connected to the connection unit 12.

[0049] The power conversion unit 14 further includes current detection units 40 and 42. The current detection unit 40 detects the magnitude of the current flowing through the inductor 32 of the power factor correction circuit 24 and inputs the detection result to the control unit 16. The current detection unit 42 detects the magnitude of the current flowing through the inductor 37 of the converter 28 and inputs the detection result to the control unit 16. The current detection units 40 and 42 are, for example, current detection resistors. This makes it possible to detect the magnitude of the current flowing through the inductors 32 and 37 with a simple configuration. However, the current detection units 40 and 42 are not limited to current detection resistors and may be any device or component that can appropriately detect the magnitude of the current flowing through the inductors 32 and 37.

[0050] The control unit 16 controls the power conversion operation by the power conversion unit 14 based on the detection results of the current detection units 40 and 42. The control unit 16 controls the switching of the switching element 31 based on the detection result of the current detection unit 40. In other words, the control unit 16 controls the operation of the power factor correction circuit 24 to improve the power factor of the input power based on the detection result of the current detection unit 40. The control unit 16 controls the switching of the switching element 35 based on the detection result of the current detection unit 42. In other words, the control unit 16 controls the operation of the converter 28 to convert DC power into another DC power based on the detection result of the current detection unit 42.

[0051] FIG. 2 is a graph schematically illustrating an example of the operation of the lighting device according to the embodiment. FIG. 2 shows a schematic example of a current flowing through the inductor 32 of the power factor correction circuit 24. As shown in FIG. 2, the magnitude of the current flowing through inductor 32 gradually increases over time during an ON period in which switching element 31 is in an ON state (for example, from time t0 to t1 in FIG. 2). Then, the magnitude of the current flowing through inductor 32 gradually decreases over time during an OFF period in which switching element 31 is in an OFF state (for example, from time t1 to t2 in FIG. 2).

[0052] At this time, the magnitude of the current flowing through the inductor 32 decreases linearly in accordance with, for example, the inductance of the inductor 32. Note that the linear change in the magnitude of the current flowing through the inductor 32 does not have to be a perfect straight line, and may include fluctuations or discrete changes due to measurement errors, etc. The linear change in the magnitude of the current flowing through the inductor 32 may be a change that appears to be roughly linear.

[0053] After switching the switching element 31 from the off state to the on state, the control unit 16 switches the switching element 31 from the on state to the off state at any timing, such as when the current flowing through the inductor 32 reaches a predetermined value.

[0054] After switching the switching element 31 from the on state to the off state, the control unit 16 switches the switching element 31 from the off state back to the on state at the timing when the magnitude of the current flowing through the inductor 32 becomes zero. By controlling the switching between the on state and the off state of the switching element 31 in this way, the control unit 16 controls the operation of the power factor correction circuit 24 to improve the power factor of the input power. In other words, the control unit 16 controls the operation of the power factor correction circuit 24 by controlling the switching of the switching element 31 in the critical current mode.

[0055] Based on the detection result of the current detection unit 40, the control unit 16 switches the switching element 31 from the OFF state to the ON state at the timing when the magnitude of the current flowing through the inductor 32 becomes zero. At this time, it is difficult for a current detection unit 40 having a simple configuration such as a current detection resistor to properly detect when the magnitude of the current flowing through the inductor 32 becomes zero due to the influence of noise and the like. For this reason, the control unit 16 performs a calculation to predict the timing when the magnitude of the current flowing through the inductor 32 will become zero based on the detection result of the current detection unit 40.

[0056] For example, as shown in FIG. 2, the control unit 16 switches the switching element 31 from an ON state to an OFF state, and performs a predictive calculation of the timing at which the magnitude of the current flowing through the inductor 32 will become zero based on two current values: a first current value detected by the current detection unit 40 at a first timing (e.g., time t1 in FIG. 2) after the current flowing through the inductor 32 begins to decrease, and a second current value detected by the current detection unit 40 at a second timing (e.g., time t2 in FIG. 2) a predetermined time after the first timing.

[0057] The control unit 16 calculates the slope of the magnitude of the current flowing through the inductor 32, which decreases linearly, based on, for example, the first current value, the second current value, and the elapsed time from the first timing to the second timing, and predicts the timing at which the magnitude of the current flowing through the inductor 32 will become zero based on the calculated slope.

[0058] The control unit 16 predicts the timing when the magnitude of the current flowing through the inductor 32 will be zero, and then switches the switching element 31 from the OFF state to the ON state at the predicted timing (for example, time t3 in FIG. 2). In this way, the control unit 16 controls the switching of the switching element 31 in the current critical mode.

[0059] The control unit 16 may be implemented by a processor such as a microcomputer or a DSP (Digital Signal Processor). As described above, in order to perform the calculation to predict the timing when the magnitude of the current flowing through the inductor 32 will become zero, the operating frequency (clock frequency) of the control unit 16 needs to be sufficiently faster than the switching frequency of the switching element 31. The switching frequency of the switching element 31 is, for example, 20 kHz or higher. The operating frequency of the control unit 16 is set to be faster than the switching frequency of the switching element 31. It is preferable that the operating frequency of the control unit 16 is, for example, 10 times or more the switching frequency of the switching element 31. This allows the control unit 16 to appropriately perform the calculation to predict the timing when the magnitude of the current flowing through the inductor 32 will become zero.

[0060] In the above prediction calculation, it is preferable to make the interval between the first timing and the second timing as wide as possible, which improves the calculation accuracy of the gradient of the linearly decreasing magnitude of the current flowing through the inductor 32 and the timing at which the current reaches zero.

[0061] The first timing is preferably set immediately after the switching element 31 is switched from the on state to the off state, as in time t1 in Fig. 2. However, at the timing when the switching element 31 is switched from the on state to the off state, the magnitude of the current flowing through the inductor 32 may change significantly due to a transient phenomenon. Therefore, it is more preferable to set the first timing at the timing when the transient phenomenon subsides after the switching element 31 is switched from the on state to the off state, and the magnitude of the current flowing through the inductor 32 stabilizes and begins to decrease.

[0062] The second timing is set, for example, so that the time from the second timing to switching the switching element 31 to the ON state is the minimum time required for the control unit 16 to perform predictive calculations and switch the switching element 31 to the ON state. In this case, the second timing is set appropriately depending on, for example, the operating frequency (calculation speed) of the control unit 16, the gradient of the magnitude of the current flowing through the inductor 32 (the inductance of the inductor 32), etc.

[0063] In this way, the first timing is set to, for example, the timing when the switching element 31 is switched from the on state to the off state and the magnitude of the current flowing through the inductor 32 starts to decrease. The second timing is set, for example, so that the time from the second timing to when the switching element 31 is switched on is the minimum time required for control by the control unit 16. This makes it possible to maximize the interval between the first timing and the second timing, for example, and improve the accuracy of calculating the slope of the linearly decreasing magnitude of the current flowing through the inductor 32 and the timing when the current becomes zero.

[0064] However, the first timing and the second timing are not limited to the above, and may be any timing after the switching element 31 is switched from the on state to the off state and the current flowing through the inductor 32 starts to decrease. In other words, the first timing and the second timing may be any timing at which the prediction calculation can be performed appropriately.

[0065] For example, if the second timing is set to match the time required for control by the control unit 16 and the current detection unit 40 is unable to properly detect the magnitude of the current flowing through the inductor 32, the second timing is set to the lowest timing at which the current detection unit 40 can properly detect the magnitude of the current flowing through the inductor 32.

[0066] The magnitude of the current flowing through inductor 37 of converter 28 gradually increases over time during the on-period when switching element 35 is in the on-state, and gradually decreases over time during the off-period when switching element 35 is in the off-state, similar to inductor 32 of power factor correction circuit 24. Furthermore, when switching element 35 is in the off-state, the magnitude of the current flowing through inductor 37 also decreases linearly according to the inductance of inductor 37, etc.

[0067] In this case, the control unit 16 controls the operation of the converter 28 by controlling the switching of the switching element 35 in a critical current mode, for example, similar to the power factor correction circuit 24. For example, the control unit 16 switches the switching element 35 from an off state to an on state, and then switches the switching element 35 from an on state to an off state at an arbitrary timing. Then, for example, after switching the switching element 35 from an on state to an off state, the control unit 16 predicts the timing at which the magnitude of the current flowing through the inductor 37 will become zero based on the detection result of the current detection unit 42, and switches the switching element 35 from an off state to an on state at the predicted timing.

[0068] However, the control of the operation of converter 28 is not limited to the control of performing a predictive calculation of the timing when the magnitude of the current flowing through inductor 37 becomes zero, and other control may be used. In controlling the operation of converter 28, control unit 16 does not necessarily have to perform a predictive calculation of the timing when the magnitude of the current flowing through inductor 37 becomes zero.

[0069] Alternatively, the control unit 16 may perform control based on a predictive calculation of the timing at which the magnitude of the current flowing through the inductor 37 in the converter 28 becomes zero, and perform other control in the power factor correction circuit 24. The control unit 16 may perform control based on a predictive calculation of the timing at which the magnitude of the current flowing through the inductor becomes zero in at least one of the power factor correction circuit 24 and the converter 28.

[0070] As described above, in the lighting fixture 2 and lighting device 10 according to this embodiment, the control unit 16 switches the switching elements 31, 35 from the off state to the on state, and then switches the switching elements 31, 35 from the on state to the off state at any timing. After switching the switching elements 31, 35 from the on state to the off state, the control unit 16 performs a predictive calculation regarding the timing at which the magnitude of the current flowing through the inductors 32, 37 will reach a predetermined value based on the detection results of the current detection units 40, 42, and switches the switching elements 31, 35 from the off state to the on state at the predicted timing, thereby controlling the power conversion operation by the power conversion unit 14.

[0071] The control unit 16, for example, performs a calculation to predict the timing when the magnitude of the current flowing through the inductors 32 and 37 will become zero. As a result, even if the current detection units 40 and 42 have a simple configuration, by performing a calculation to predict the timing when the magnitude of the current flowing through the inductors 32 and 37 will become zero, it is possible to appropriately control the switching of the switching elements 31 and 35.

[0072] Therefore, in the lighting fixture 2 and lighting device 10 of this embodiment, even when a low current value of the current flowing through the inductors 32 and 37 is required for control, the need for a special circuit is suppressed, and the control of the power conversion operation according to the magnitude of the current flowing through the inductors 32 and 37 can be performed with a simpler configuration.

[0073] FIG. 3 is a graph schematically showing a modified example of the operation of the lighting device according to the embodiment. FIG. 3 shows a schematic diagram of a modification of the current flowing through the inductor 32 of the power factor correction circuit 24. In FIG. As shown in FIG. 3, in this example, the control unit 16 performs a calculation to predict the timing when the magnitude of the current flowing through the inductor 32 will reach a predetermined value before it becomes zero, based on the detection result of the current detection unit 40.

[0074] For example, as in the above embodiment, the control unit 16 calculates the slope of the magnitude of the current flowing through the inductor 32, which decreases linearly, based on the first current value, the second current value, and the elapsed time from the first timing to the second timing, and predicts the timing at which the magnitude of the current flowing through the inductor 32 will reach a predetermined value before becoming zero, based on the calculated slope.

[0075] The control unit 16 predicts the timing at which the magnitude of the current flowing through the inductor 32 will reach a predetermined value before becoming zero, and then switches the switching element 31 from the OFF state to the ON state at the predicted timing. That is, in this example, the control unit 16 controls the operation of the power factor correction circuit 24 by controlling the switching of the switching element 31 in the continuous current mode. In this way, the control unit 16 may control the switching of the switching element 31 in the continuous current mode, without being limited to the critical current mode. Similarly, the control unit 16 may control the switching of the switching element 35 in the continuous current mode, without being limited to the critical current mode.

[0076] 4(a) and 4(b) are graphs that schematically show modified examples of the operation of the lighting device according to the embodiment. FIG. 4(a) schematically shows an example of another behavior of the current flowing through the inductor 32 of the power factor correction circuit 24. FIG. 4(b) shows a schematic diagram of an example of the voltage between the main terminals 31a and 31b of the switching element 31 of the power factor correction circuit .

[0077] As shown in Figures 4(a) and 4(b), in this example, after switching the switching element 31 from an off state to an on state, the control unit 16 switches the switching element 31 from an on state to an off state at an arbitrary timing, and after switching the switching element 31 from an on state to an off state, based on the detection result of the current detection unit 40, performs a predictive calculation of the timing at which the voltage between the pair of main terminals 31a, 31b of the switching element 31 will become equal to or less than a predetermined value after the magnitude of the current flowing through the inductor 32 becomes zero, and switches the switching element 31 from an off state to an on state at the predicted timing.

[0078] In the example shown in FIGS. 4(a) and 4(b), the control unit 16 switches the switching element 31 from an OFF state to an ON state at time t10, and switches the switching element 31 from an ON state to an OFF state at time t11. Also, in the example shown in FIGS. 4(a) and 4(b), the magnitude of the current flowing through the inductor 32 becomes zero at time t12. In this case, the control unit 16 switches the switching element 31 from an OFF state to an ON state at time t13, for example. However, for convenience, FIGS. 4(a) and 4(b) illustrate a state in which the switching element 31 remains in the OFF state even at time t13.

[0079] 4(a) and 4(b), after the current of the inductor 32 becomes zero, the current of the inductor 32 and the voltage of the switching element 31 resonate in accordance with the characteristics of the switching element 31 and the inductor 32. For example, after the current of the inductor 32 becomes zero, the current of the inductor 32 and the voltage of the switching element 31 resonate in accordance with the capacitance component between the pair of main terminals 31a, 31b of the switching element 31 and the inductance of the inductor 32.

[0080] After the current in inductor 32 becomes zero when switching element 31 is switched off, it flows in the negative direction (toward high-frequency removal capacitor 22) and then oscillates around zero. The voltage of switching element 31 oscillates so as to decrease during the period when the current in inductor 32 flows in the negative direction and to increase during the period when the current in inductor 32 flows in the positive direction.

[0081] In this case, the control unit 16 predicts and calculates the timing delayed by, for example, half the period of the resonant frequency of the voltage of the switching element 31 from the timing when the current of the inductor 32 becomes zero. This allows the switching element 31 to be switched on at the timing when the voltage between the pair of main terminals 31a, 31b of the switching element 31 becomes equal to or lower than a predetermined value. In the above case, for example, the switching element 31 can be switched on at the timing when the voltage between the pair of main terminals 31a, 31b of the switching element 31 becomes the lowest.

[0082] The control unit 16 sets the predetermined time to, for example, half the period of the resonant frequency of the voltage of the switching element 31. The predetermined time is calculated in advance based on the characteristics of the switching element 31 and the inductor 32, such as the capacitance component between the main terminals 31a and 31b of the switching element 31 and the inductance of the inductor 32, and is set in the control unit 16.

[0083] For example, the control unit 16 predicts the timing when the magnitude of the current flowing through the inductor 32 becomes zero, and predicts the timing when a predetermined time has elapsed since the time when the current becomes zero as the timing when the voltage between the pair of main terminals 31a, 31b of the switching element 31 becomes equal to or less than a predetermined value. In other words, the control unit 16 predicts the timing when a predetermined time has elapsed since the magnitude of the current flowing through the inductor 32 becomes zero.

[0084] However, the predetermined time is not limited to ½ the period of the resonant frequency of the voltage of the switching element 31, and may be, for example, 3½ the period of the resonant frequency of the voltage of the switching element 31. Furthermore, the timing at which the voltage across the pair of main terminals 31a, 31b of the switching element 31 becomes equal to or lower than the predetermined value is not limited to the timing at which the voltage across the pair of main terminals 31a, 31b of the switching element 31 becomes lowest, and may be any timing at which the voltage across the pair of main terminals 31a, 31b of the switching element 31 becomes equal to or lower than the predetermined value.

[0085] In this example, the control unit 16 controls the switching of the switching element 31 using quasi-resonant switching control, thereby controlling the operation of the power factor correction circuit 24. In quasi-resonant switching control, the switching element 31 is switched to the on state when the voltage across the pair of main terminals 31a, 31b of the switching element 31 becomes equal to or lower than a predetermined value, thereby suppressing the switching loss of the switching element 31.

[0086] In this way, the control unit 16 may control the switching of the switching element 31 by quasi-resonant switching control, without being limited to the critical current mode or the continuous current mode. Similarly, the control unit 16 may control the switching of the switching element 35 by quasi-resonant switching control, without being limited to the critical current mode or the continuous current mode.

[0087] The control unit 16 may be configured to arbitrarily switch between the current critical mode, the current continuous mode, and the quasi-resonant switching control by receiving a setting signal input from, for example, an operation unit or an external device.

[0088] FIG. 5 is a block diagram schematically illustrating a modified example of the lighting fixture according to the embodiment. 5, in lighting device 10a of lighting fixture 2a, power conversion unit 14a further includes voltage detection units 50, 52, and 54. Note that components that are substantially the same in function and configuration as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0089] The voltage detection unit 50 detects the pulsating voltage Vin supplied from the rectifier circuit 20 and the high-frequency removal capacitor 22 to the power factor correction circuit 24, and inputs the detected voltage Vin to the control unit 16a. In other words, the voltage Vin is the input voltage of the power factor correction circuit 24.

[0090] The voltage detection unit 52 detects the DC voltage VDC of the smoothing capacitor 26 and inputs the detected voltage VDC to the control unit 16a. In other words, the voltage VDC is the output voltage of the power factor correction circuit 24 and the input voltage of the converter 28.

[0091] The voltage detection unit 54 detects the DC voltage Vout supplied from the power conversion unit 14a to the light source module 100 (light source 102) and inputs the detected voltage Vout to the control unit 16a. In other words, the voltage Vout is the output voltage of the converter 28.

[0092] FIG. 6 is a graph schematically showing a modified example of the operation of the lighting device according to the embodiment. FIG. 6 shows a schematic example of a current flowing through the inductor 32 of the power factor correction circuit 24. As shown in FIG. As shown in Figure 6, the control unit 16a switches the switching element 31 from the on state to the off state, and based on one current value ILb detected by the current detection unit 40 after the current flowing through the inductor 32 begins to decrease, performs a predictive calculation of the timing at which the magnitude of the current flowing through the inductor 32 will become zero.

[0093] The control unit 16a predicts the timing tz at which the magnitude of the current flowing through the inductor 32 becomes zero, for example, based on the detected current value ILb, the time ts at which the current value ILb was detected, the voltage Vin and voltage VDC at the time ts, and the inductance Lb of the inductor 32, using the following equation: VDC-Vin=Lb×(0-ILb) / (ts-tz) →(tz-ts)=Lb×ILb / (VDC-Vin)

[0094] In this way, the method of predictive calculation by the control unit 16a is not limited to a method of predictive calculation based on two detected current values, but may also be a method of predictive calculation based on one detected current value, the time when the current value was detected, the input voltage, the output voltage, and the inductance of the inductor 32, as described above.

[0095] Even in the method using one current value, control in the continuous current mode can be performed by replacing the timing at which the magnitude of the current flowing through the inductor 32 becomes zero with the timing at which the magnitude of the current flowing through the inductor 32 becomes a predetermined value before becoming zero. Also, in the method using one current value, quasi-resonant switching control can be performed by adding a predetermined time to the timing tz at which the current becomes zero.

[0096] In addition, the control unit 16a can also perform a predictive calculation of the timing at which the magnitude of the current flowing through the inductor 37 will become zero based on one current value ILd detected by the current detection unit 42 after the switching element 35 has switched from the on state to the off state and the current flowing through the inductor 37 has begun to decrease.

[0097] In this case, the control unit 16a predicts the timing tz at which the magnitude of the current flowing through the inductor 37 becomes zero, for example, based on the detected current value ILd, the time ts at which the current value ILd was detected, the voltage Vout at the time ts, and the inductance Ld of the inductor 37, using the following equation: Vout = Ld × (0 - ILd) / (ts - tz) →(tz-ts)=Ld×ILd / Vout

[0098] In the above embodiment, the lighting fixture 2 (2a) is shown to include the lighting device 10 (10a) and the light source module 100. However, the lighting fixture 2 (2a) is not limited to this, and may be any lighting fixture including a light source 102 and a lighting device 10 (10a). For example, the light source 102 may be integrated into the lighting device 10 (10a). Furthermore, the power supplied from the lighting device 10 (10a) to the light source 102 is not limited to DC power, and may be AC ​​power or the like. The power conversion operation by the power conversion unit 14 (14a) may be any operation that converts input power into power compatible with the light source 102.

[0099] The present embodiment includes the following aspects. (Appendix 1) a power conversion unit that converts input power into power corresponding to a light source and supplies the converted power to the light source; a control unit that controls the power conversion operation by the power conversion unit; Equipped with The power conversion unit a converter including a switching element and an inductor, the converter converting power by switching the switching element; a current detection unit that detects the magnitude of a current flowing through the inductor and inputs the detection result to the control unit; and the switching element has a pair of main terminals and a control terminal, and has an ON state in which a current flows between the pair of main terminals and an OFF state in which the current flowing between the pair of main terminals is interrupted; The control unit switches the switching element from an on state to an on state at an arbitrary timing after switching the switching element from an on state to an on state, and after switching the switching element from an on state to an off state, performs a predictive calculation regarding the timing at which the magnitude of the current flowing through the inductor will reach a predetermined value based on the detection result of the current detection unit, and switches the switching element from an off state to an on state at the predicted timing, thereby controlling the power conversion operation by the power conversion unit.

[0100] (Appendix 2) 2. The lighting device according to claim 1, wherein the control unit performs a calculation to predict the timing at which the magnitude of the current flowing through the inductor becomes zero.

[0101] (Appendix 3) 2. The lighting device according to claim 1, wherein the control unit performs a predictive calculation of the timing at which the magnitude of the current flowing through the inductor will reach a predetermined value before it becomes zero.

[0102] (Appendix 4) The lighting device according to claim 1, wherein the control unit performs a predictive calculation of the timing at which the voltage between the pair of main terminals of the switching element will become equal to or less than a predetermined value after the magnitude of the current flowing through the inductor becomes zero.

[0103] (Appendix 5) The lighting device of any one of Appendices 1 to 4, wherein the control unit switches the switching element from an on state to an off state and performs the predictive calculation based on two current values: a first current value detected by the current detection unit at a first timing after the current flowing through the inductor begins to decrease, and a second current value detected by the current detection unit at a second timing a predetermined time after the first timing.

[0104] (Appendix 6) The lighting device of any one of appendices 1 to 4, wherein the control unit switches the switching element from an on state to an off state and performs the predictive calculation based on one current value detected by the current detection unit after the current flowing through the inductor begins to decrease, the time when the current value was detected, the output voltage of the converter, and the inductance of the inductor.

[0105] (Appendix 7) A light source and A lighting device according to any one of appendices 1 to 6; A lighting fixture equipped with

[0106] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0107] DESCRIPTION OF SYMBOLS 2, 2a...Lighting fixture, 10, 10a...Lighting device, 12...Connection part, 14, 14a...Power conversion part, 16, 16a...Control part, 20...Rectifier circuit, 22...High frequency removal capacitor, 24...Power factor correction circuit, 26...Smoothing capacitor, 28...Converter, 31...Switching element, 32...Inductor, 33...Diode, 35...Switching element, 36...Diode, 37...Inductor, 38...Output capacitor, 40, 42...Current detection part, 50, 52, 54...Voltage detection part, 100...Light source module, 102...Light source, 104...Connected part, PS...Power supply

Claims

1. A power conversion unit that converts input power into power corresponding to a light source and supplies the converted power to the light source, A control unit that controls the operation of power conversion by the power conversion unit, Comprising, The power conversion unit, Has a switching element and an inductor, and a converter that performs power conversion by switching the switching element, A current detection unit that detects the magnitude of the current flowing through the inductor and inputs the detection result to the control unit, Having, The switching element has a pair of main terminals and a control terminal, and has an on state in which current flows between the pair of main terminals and an off state in which the current flowing between the pair of main terminals is interrupted, The control unit switches the switching element from the off state to the on state, then switches the switching element from the on state to the off state at an arbitrary timing, and after switching the switching element from the on state to the off state, based on the detection result of the current detection unit, performs a prediction calculation regarding the timing at which the magnitude of the current flowing through the inductor becomes a predetermined value, and switches the switching element from the off state to the on state at the predicted timing, thereby controlling the operation of power conversion by the power conversion unit. A lighting device.

2. The lighting device according to claim 1, wherein the control unit performs a prediction calculation of the timing at which the magnitude of the current flowing through the inductor becomes zero.

3. The lighting device according to claim 1, wherein the control unit performs a prediction calculation of the timing at which the magnitude of the current flowing through the inductor becomes a predetermined value before becoming zero.

4. The lighting device according to claim 1, wherein the control unit performs a prediction calculation of the timing at which the voltage between the pair of main terminals of the switching element becomes a predetermined value or less after the magnitude of the current flowing through the inductor becomes zero.

5. The lighting device according to claim 1, wherein the control unit switches the switching element from the on state to the off state, and based on two current values, a first current value detected by the current detection unit at a first timing after the current flowing through the inductor starts to decrease and a second current value detected by the current detection unit at a second timing after a predetermined time has elapsed from the first timing, performs the prediction calculation.

6. The lighting device according to claim 1, wherein the control unit switches the switching element from an on state to an off state, and based on one current value detected by the current detection unit after the current flowing through the inductor starts to decrease, the time when the current value is detected, the output voltage of the converter, and the inductance of the inductor, the prediction calculation is performed.

7. A light source, The lighting device according to any one of claims 1 to 6, and a lighting fixture including the same.

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