Lighting devices and lighting fixtures

Abstract

To provide a lighting device and lighting fixture that can detect the voltage between the electrodes of a switching element with a simple and inexpensive circuit configuration. [Solution] According to the embodiment, the lighting device 5 includes a power conversion unit 8 which has a switching element 41, an inductor 43, and an output capacitor 44, and converts the input power supplied from the power source into a desired DC current supply power and supplies it to the light source 2a, and a control unit 100 which controls the operation of the power conversion unit 8. The control unit 100 includes an auxiliary winding 121 which detects the voltage of the inductor 43, a diode 124 which rectifies the negative voltage of the auxiliary winding 121, and a smoothing capacitor 123, and an on-timing processing circuit 120 which adds the rectified portion to the voltage of the auxiliary winding and outputs a switch-on command, and a control circuit 110 which controls the operation of the power conversion unit 8 based on the dimming signal and the switch-on command.

Description

Technical Field

[0001] Embodiments of the present invention relate to a lighting device and a lighting fixture.

Background Art

[0002] Conventionally, various light source lighting devices for lighting a light source such as a light emitting diode have been known. The lighting device has at least one switching element, an inductor, and an output capacitor, and has a power conversion unit that converts input power supplied from a DC power source or an AC power source into DC supply power and supplies the supply power to the light source. The power conversion unit performs power conversion by switching the switching element.

[0003] The voltage applied between the electrodes of the switching element vibrates according to the current flowing through the inductor after the switching element is switched to the off state. At this time, it has been proposed to switch the switching element from the off state to the on state when the voltage between the electrodes of the switching element is low. Thereby, the loss at the time of switching to the on state can be reduced.

[0004] As a method for detecting the voltage applied between the electrodes of the switching element, a method of detecting the current flowing through the inductor by a detection winding has been proposed. For example, after the elapse of the first off period until the oscillating voltage of the detection winding falls, the off state of the switching element is continued until the elapse of a predetermined second off period, and the switching element is turned on after the elapse of the second off period.

[0005] In this way, by adding up the duration of the second off period, the switching element can be switched to the ON state during the trough of the oscillating voltage (the state where the voltage between the electrodes of the switching element is low). However, since this second off period is integrated using an MCU or similar device, the circuit is expensive. Also, because the winding voltage swings between positive and negative and the negative voltage is rectified, there is a possibility that the trough portion cannot be detected. For this reason, it is desirable for lighting devices to be able to detect the voltage between the electrodes of the switching element with a simple and inexpensive circuit configuration. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 6725075 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The embodiment of the present invention aims to provide a lighting device and lighting fixture capable of detecting the voltage between the electrodes of a switching element with a simple and inexpensive circuit configuration. [Means for solving the problem]

[0008] To achieve the above objective, the lighting device according to the embodiment comprises a power conversion unit that has at least one switching element, an inductor, and an output capacitor, converts input power supplied from a DC power supply or AC power supply into DC supply power, and supplies the supply power to a light source, and a control unit that controls the operation of the power conversion unit, wherein the control unit comprises an auxiliary winding for detecting the voltage of the inductor, a diode and a smoothing capacitor for rectifying the negative voltage of the auxiliary winding, an on-timing processing circuit that adds the rectified portion to the voltage of the auxiliary winding and outputs a switch-on command when the switching element is off, and a control circuit that receives the switch-on command and controls the operation of the power conversion unit. [Effects of the Invention]

[0009] According to embodiments of the present invention, it is possible to provide a lighting device and a lighting fixture that can detect the voltage between the electrodes of a switching element with a simple and inexpensive circuit configuration. [Brief explanation of the drawing]

[0010] [Figure 1] This is a block diagram showing an example configuration of a lighting device according to the first embodiment. [Figure 2] This graph shows the response waveform of the converter in the lighting device according to the first embodiment. [Figure 3] This graph shows the response waveform of the on-timing processing circuit in the lighting device according to the first embodiment. [Figure 4] This is a block diagram showing an example configuration of a lighting device according to the second embodiment. [Figure 5] This graph shows the response waveforms of each part in the lighting device according to the second embodiment. [Modes for carrying out the invention]

[0011] The following describes the lighting device and lighting fixture according to the embodiment of the present invention with reference to the drawings. Note that the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes of the parts, etc., are not necessarily the same as those of actual objects. Furthermore, even when representing the same part, the dimensions and ratios may differ between drawings. Also, parts that are identical or similar to each other are denoted by a common reference numeral, and overlapping explanations are omitted.

[0012] [First Embodiment] Figure 1 is a block diagram showing an example configuration of the lighting device 5 according to the first embodiment.

[0013] Figure 1 is a block diagram showing an example configuration of a lighting fixture 3 including a lighting device 5 according to an embodiment. The lighting fixture 3 has a light source module 2 and a lighting device 5 that supplies DC current to it.

[0014] The light source module 2 includes one or more light sources 2a and a connection part 2b. The light source module 2 is detachably connected to the lighting device 5 via the connection part 2b.

[0015] FIG. 1 illustrates the case where there is one light source 2a. The number of light sources 2a may be any plural number. When there are a plurality of light sources 2a, each light source 2a may be connected in series or in parallel. Alternatively, a plurality of light sources 2a may be arranged by combining series connection and parallel connection.

[0016] For example, a light emitting diode (LED) is used as the light source 2a. The light source 2a may be, for example, an organic light emitting diode (OLED), an inorganic electroluminescence light emitting element, an organic electroluminescence light emitting element, or other field emission type light emitting elements. Alternatively, the light source 2a may be, for example, an incandescent lamp.

[0017] The lighting device 5 converts the input power supplied from a power source 1, which is a DC power source or an AC power source, into a desired supply power, and supplies this DC current to the light source module 2.

[0018] Here, the power source 1 is, for example, a commercial power source or a self - generating generator that supplies AC power. Note that the power source 1 may be a DC power source. When the power source 1 is a DC power source, the lighting device 5 converts the DC power into another DC power having a different current value or voltage value and supplies it to the light source module 2.

[0019] The lighting device 5 is commonly used for a plurality of types of light source modules 2 in which at least one of the brightness and color (color temperature) of the irradiated light is different. Thereby, for example, an increase in the manufacturing cost of the lighting fixture 3 can be suppressed as compared with the case of manufacturing dedicated - designed lighting devices corresponding to each of a plurality of types of light source modules 2.

[0020] The lighting device 5 converts the AC power supplied from the power source 1 into DC power corresponding to the light source module 2, and supplies the converted DC power to the light source module 2. Thereby, the lighting device 5 lights the light source module 2.

[0021] The lighting device 5 includes a power conversion unit 8 and a control unit 100.

[0022] The power conversion unit 8 is a power path from receiving AC power from the power source 1 to supplying DC power to the light source module 2, and is composed of elements for power conversion. The control unit 100 controls the operation of the elements for power conversion in the power conversion unit 8.

[0023] The power conversion unit 8 includes a rectifier circuit 10, a high-frequency removal capacitor 11, a power factor correction circuit 20, a smoothing capacitor 30, a converter 40, and a connection unit 50 that is detachably connected to the connection part 2b of the light source module 2.

[0024] When the power source 1 is a DC power source, the rectifier circuit 10, the high-frequency removal capacitor 11, the power factor correction circuit 20, and the smoothing capacitor 30 may not be provided.

[0025] In the following description, in the arrangement from the rectifier circuit 10 connected to the power source 1 to the connection unit 50 connected to the light source module 2, the upstream side means the side relatively closer to the power source 1, and the downstream side means the side relatively closer to the light source module 2.

[0026] The rectifier circuit 10 rectifies the AC power input from the power source 1 and converts it into rectified power. For example, a diode bridge combining four rectifying elements is used for the rectifier circuit 10. That is, the rectifier circuit 10 is a full-wave rectifier. The rectified power is, for example, pulsating power.

[0027] The rectifier circuit 10 has a pair of input terminals 10a and 10b, a high-potential output terminal 10c, and a low-potential output terminal 10d. The input terminals 10a and 10b convert power from the power supply 1 into rectified power, which is output from the high-potential output terminal 10c and the low-potential output terminal 10d. The potential of the low-potential output terminal 10d is set to a reference potential (e.g., ground potential). The potential of the high-potential output terminal 10c is set to a potential higher than the potential of the low-potential output terminal 10d.

[0028] The rectifier circuit 10 may be a half-wave rectifier or the like. Alternatively, the rectified voltage may be a full-wave rectified pulsating current or a half-wave rectified pulsating current. For example, a Schottky barrier diode can be used in the rectifier circuit 10. This improves the responsiveness of the rectifier circuit 10.

[0029] The high-frequency rejection capacitor 11 removes the high-frequency components of the rectified high-frequency power and smooths the rectified high-frequency power, thereby converting it into pulsating power.

[0030] In the example shown in Figure 1, the power factor correction circuit 20 includes an inductor 21, a switching element 22, and a diode 23. Specifically, the power factor correction circuit 20 is a boost chopper configured with the forward-upstream end of the diode 23 connected to the downstream side of the inductor 21, and one end of the switching element 22 connected to the connection point between the inductor 21 and the diode 23. Note that the power factor correction circuit 20 is not limited to a boost chopper; other configurations are also possible as long as they can improve the power factor of the input power.

[0031] The power factor correction circuit 20 improves the power factor by controlling the on / off state of a switching element 22 based on the output from the high-frequency rejection capacitor 11 and the full-wave rectified voltage from the rectifier circuit 10.

[0032] The switching element 22 has electrodes 22a, 22b, and 22c. One end of the inductor 21 is electrically connected to the high-potential output terminal 10c. The other end of the inductor 21 is electrically connected to electrode 22a. Electrode 22b is electrically connected to the low-potential output terminal 10d. The anode of the diode 23 is electrically connected to electrode 22a. The cathode of the diode 23 is electrically connected to one end of the smoothing capacitor 30. The other end of the smoothing capacitor 30 is electrically connected to the low-potential output terminal 10d.

[0033] Electrode 22c is electrically connected to the control unit 100. Electrode 22c is a so-called control electrode. The switching element 22 switches in response to a signal from the control unit 100. The power factor correction circuit 20 improves the power factor, for example, by switching the switching element 22 and bringing the input current closer to the half-cut waveform of a sinusoidal voltage.

[0034] The switching element 22 is, for example, an n-channel FET. For example, electrode 22a is the drain, electrode 22b is the source, and electrode 22c is the gate. The switching element 22 may also be, for example, a p-channel FET or a bipolar transistor.

[0035] The smoothing capacitor 30 converts the power after power factor correction into DC power by smoothing the output voltage after power factor correction. The smoothing capacitor 30 supplies the DC power to the converter 40.

[0036] The converter 40 converts the DC power from the smoothing capacitor 30 into a desired DC current supply power and supplies this DC current to the light source 2a.

[0037] The converter 40 has a first input terminal 31, a second input terminal 32, a first output terminal 45a, and a second output terminal 45b. The first input terminal 31 is electrically connected to one end of the high-potential side of the smoothing capacitor 30. The second input terminal 32 is electrically connected to the low-potential output terminal 10d of the smoothing capacitor 30. As a result, DC power is supplied to the converter 40 from the smoothing capacitor 30.

[0038] The converter 40 consists of a step-down chopper, an output capacitor 44 downstream of the step-down chopper, and a current sensing resistor 46 that detects the load current and converts it into a supply voltage. In other words, in the example shown in Figure 1, the converter 40 has a switching element 41, a diode 42, an inductor 43, an output capacitor 44, and a current sensing resistor 46. Specifically, the converter 40 has a step-down chopper in which the inductor 43 is connected downstream of the switching element 41, and the forward downstream end of the diode 42 is connected to the connection point between the switching element 41 and the inductor 43. Note that the converter 40 is not limited to a step-down chopper, and may have other circuits as long as it can convert the input DC power into DC power having a desired DC current.

[0039] The switching element 41 has electrodes 41a, 41b, and 41c. Electrode 41a is electrically connected to the first input terminal 31. Electrode 41b is electrically connected to the cathode of diode 42. The anode of diode 42 is electrically connected to the low-potential output terminal 10d. One end of inductor 43 is electrically connected to electrode 41b. The other end of inductor 43 is electrically connected to the first output terminal 45a. The second output terminal 45b is electrically connected to the low-potential output terminal 10d (second input terminal 32). Electrode 41c of the switching element 41 controls the switching element 41 by command from the control unit 100.

[0040] The switching element 41 is, for example, an n-channel field-effect transistor (FET). For example, electrode 41a is the drain, electrode 41b is the source, and electrode 41c is the gate. Alternatively, the switching element 41 may be, for example, a p-channel FET or a bipolar transistor. Electrode 41c switches the switching element 41 on and off according to a command from the control unit 100.

[0041] The output capacitor 44 has a first electrode 44a and a second electrode 44b. The first electrode 44a is electrically connected to the first output terminal 45a. The second electrode 44b is electrically connected to the second output terminal 45b. The output capacitor 44 is connected in parallel between the first output terminal 45a and the second output terminal 45b. The output capacitor 44 smooths the current flowing between the electrodes 41a and 41b of the switching element 41 through the switching operation of the switching element 41. As a result, DC power is output from the first output terminal 45a and the second output terminal 45b.

[0042] In this example, the converter 40 is a step-down chopper circuit as described above. The converter 40 converts DC power to another DC power by stepping down the voltage of the input power. Thus, the converter 40 is, for example, a constant current circuit and supplies a substantially constant DC current to the light source module 2 (light source 2a).

[0043] The first output terminal 45a is the high-potential output terminal, and the second output terminal 45b is the low-potential output terminal. The potential of the first output terminal 45a is higher than the potential of the second output terminal 45b. The potential of the first electrode 44a is set higher than the potential of the second electrode 44b. The first electrode 44a is, for example, the anode, and the second electrode 44b is, for example, the cathode. Conversely, the potential of the second output terminal 45b may be set higher than the potential of the first output terminal 45a.

[0044] The configuration of the converter 40 described above is not limited to the circuit described above. The converter 40 can be any configuration capable of converting DC power to another DC power.

[0045] The control unit 100 receives a dimming signal from an external dimming signal unit 4, which is a request for the dimming level, and controls the switching element 41 of the converter 40 so that the converter 40 supplies a DC current to the light source module 2 according to the dimming level. The control unit 100 also includes a control circuit 110 and an on-timing processing circuit 120.

[0046] The control circuit 110 includes a reference value generation unit 111, a control calculation unit 112, and a drive signal generation unit 113. The control circuit 110 is, for example, an integrated circuit (IC).

[0047] The reference value generation unit 111 receives the dimming signal from the dimming signal unit 4, converts and corrects it as needed, and generates a reference value for control calculations in the control calculation unit 112. The dimming signal is input to the reference value generation unit 111 via wired or wireless connection from, for example, a remote control, a switch on the wall, or an operating unit on the lighting fixture 3 (lighting device 5). Here, the dimming signal is a signal that can appropriately represent the dimming degree, such as a PWM signal with a duty cycle corresponding to the dimming degree, or an AC voltage whose conduction angle is controlled by a dimmer or the like.

[0048] The control calculation unit 112 converts the feedback voltage from the downstream side of the current sensing resistor 46 as needed, such as by AD conversion, and calculates a feedback signal. The control calculation unit 112 further compares the feedback signal with a reference signal, which has been converted to a dimming level as needed, using, for example, a comparator (not shown), and performs control calculations so that the feedback signal matches the reference signal. Alternatively, the control calculation unit 112 calculates the deviation between the feedback signal and the reference signal, performs PI calculations, etc., and calculates a control signal.

[0049] The drive signal generation unit 113 converts the control signal calculated by the control calculation unit 112 to generate and output a drive signal to the electrode 41c, which is the control electrode of the switching element 41 of the converter 40. Specifically, the drive signal is a signal that changes the on-time ratio (duty cycle) of the switching element 41. Furthermore, when the drive signal generation unit 113 receives a switch-on command from the on-timing processing circuit 120, it outputs a switch-on drive signal to the electrode 41c, which is the control electrode of the switching element 41.

[0050] Here, the off state of the switching element 41 is, for example, a state in which substantially no current flows between the main electrodes 41a and 41b. In the off state, for example, a weak current that does not affect the operation of the converter 40 may flow between the electrodes 41a and 41b. In other words, the on state of the switching element 41 is, in other words, a first state in which current flows between the electrodes 41a and 41b, and the off state is a second state in which the current flowing between the electrodes 41a and 41b is smaller than that of the first state. The on and off states of the switching element 22 are the same as those of the switching element 41.

[0051] The ON-timing processing circuit 120 determines and outputs the point in time (timing) at which the switching element 41 should transition from the OFF state to the ON state.

[0052] The on-timing processing circuit 120 includes a detection winding 121, a current limiting resistor 122, a smoothing capacitor 123, a diode 124, a voltage divider resistor 125, and a comparator 130. The voltage divider resistor 125 has a first voltage divider resistor 125a and a second voltage divider resistor 125b.

[0053] The detection winding 121 is provided as an auxiliary winding for the inductor 43 of the converter 40 in order to detect the voltage of the inductor 43. For this purpose, the detection winding 121 is coupled to the same iron core as the inductor 43, with opposite polarity to the inductor 43.

[0054] The current-limiting resistor 122, the smoothing capacitor 123, and the diode 124 are connected in series between the detection winding 121 and ground. The current-limiting resistor 122 and the smoothing capacitor 123 also function as filters to remove high-frequency components superimposed on the voltage of the inductor 43. The diode 124 is positioned in the forward direction from the ground side toward the smoothing capacitor 123 side. The output side of the diode 124 will be referred to as the summing section 129. The smoothing capacitor 123 has an electrode on the inductor side line 123a and a diode side electrode 123b toward the diode 124 side. The voltage in the summing section 129 will be referred to as the summing voltage VV.

[0055] The voltage divider resistor 125 divides the summation voltage VV to generate a resistive voltage divider VX. One end of the first voltage divider resistor 125a and one end of the second voltage divider resistor 125b are connected to each other at a connection point 128. That is, the first voltage divider resistor 125a and the second voltage divider resistor 125b are arranged in series. The other end of the first voltage divider resistor 125a is connected to the output side of the diode 124. The second voltage divider resistor 125b is on the ground side. If the resistance value of the first voltage divider resistor 125a is R1 and the resistance value of the second voltage divider resistor 125b is R2, then the voltage division ratio k is given by R2 / (R1+R2). The voltage at the connection point 128 is output to the comparator 130 for switch-on determination.

[0056] The comparator 130 receives the voltage signal (resistive voltage divider VX) from the connection section 128, performs a switch-on determination, and outputs a switch-on command to the control calculation unit 112 of the control circuit 110. In detail, the comparator 130 compares the received resistive voltage divider VX with a predetermined value and performs a switch-on determination to determine whether the summed voltage VV is less than or equal to a reference value. Here, the predetermined value is a value corresponding to the reference value for the summed voltage VV. When the comparator 130 determines that the summed voltage VV is less than or equal to the reference value, it outputs a switch-on command to the drive signal generation unit 113. Note that in Figure 1, the case in which the switch-on command is output from the comparator 130 to the drive signal generation unit 113 is shown as an example, but it may also be output to the control calculation unit 112, for example.

[0057] Here, the reference value for the summation voltage VV is a predetermined positive value with a small absolute value. By making this determination, detection near the trough of the summation voltage VV becomes possible. Here, a trough refers to the range in the response waveform that includes the portion that gives a minimum value. Furthermore, the vicinity of a trough refers to the range that includes the portion that gives a value greater than the minimum value, but the difference is within a predetermined acceptable range.

[0058] Figure 1 illustrates a case where the on-timing processing circuit 120 has a voltage divider resistor 125, but is not limited to this. That is, the comparator 130 and the control circuit 110 may accept the summation voltage VV and perform their respective processing. <effect>

[0059] Figure 2 is a graph showing the response waveform of the converter 40 in the lighting device 5 according to the first embodiment. Figure 3 is a graph showing the response waveform of the on-timing processing circuit 120 in the lighting device 5 according to the first embodiment. In both Figure 2 and Figure 3, the horizontal axis represents time, and times t1, t2, and t3 represent points in time that are common to both figures.

[0060] First, I will explain the graphs of SW element voltage and SW element current, referring to Figure 2. Here, SW element voltage refers to the potential difference across the terminals of the switching element 41, and SW element current refers to the current flowing between the two poles of the switching element 41.

[0061] When the switching element 41 is in the ON state (SW ON state), the voltage applied to the inductor 43 is constant. The voltage across the inductor 43 is proportional to the rate of change of the current flowing into the inductor 43. As a result, the current flowing into the inductor 43 after passing through the switching element 41 increases at a constant rate. In this SW ON state, energy is stored in the inductor 43, and a constant current is supplied to the light source module 2.

[0062] First, at time t1, the switching element 41 switches to the off state (SW off state) by command from the drive signal generation unit 113. In the SW off state, the current passing through the switching element 41 is zero. When the SW off state is reached, the inductor 43 releases a current that decreases at a constant rate to release the stored energy. Also, a constant current is supplied to the light source module 2 even while the SW off state is active.

[0063] At time t2, the current from inductor 43 becomes zero. After this, a resonance phenomenon occurs between the inductor 43 and the capacitance between the electrodes of the switching element 41, and as shown in Figure 2, the voltage between the electrodes of the switching element 41 also oscillates.

[0064] Next, the response of the on-timing processing circuit 120 will be explained with reference to Figure 3.

[0065] The voltage across inductor 43 moves in the opposite direction to the peaks and troughs of the voltage between the electrodes of the series-connected switching element 41. Furthermore, since the detection winding 121 has the opposite polarity to inductor 43, it consequently moves in the same direction as the peaks and troughs of the voltage between the electrodes of the switching element 41. In other words, the timing of the peaks and troughs of the voltage VL2 of the detection winding 121 shown in Figure 3 coincides with the timing of the peaks and troughs of the voltage between the electrodes of the switching element 41 shown in Figure 2.

[0066] In a step-down chopper, the voltage across inductor 43 is positive when the switch is on, and negative when the switch is off, except during the resonance phase in the latter half of the cycle. Therefore, the voltage VL2 across the detection winding 121, which has the opposite polarity to inductor 43, is negative when the switch is on, and positive when the switch is off, except during the resonance phase in the latter half of the cycle, as shown by the dashed line in Figure 3. Note that, as shown in Figure 3, the voltage VL2 across the detection winding 121 may also be negative during resonance.

[0067] As shown in Figure 1, the diode 124 is positioned so that it is forward from the ground side toward the smoothing capacitor 123 side. Therefore, when the voltage VL2 of the detection winding 121 is negative with respect to the ground voltage (GND), that is, when the voltage of the inductor side line 123a is negative, a forward voltage is applied to the diode 124. Consequently, the diode 124 rectifies the negative voltage, and a positive charge is charged to the diode side electrode 123b of the smoothing capacitor 123.

[0068] Here, diode 124 has an electrode voltage V of approximately 0.6V as its forward voltage component. F Therefore, the voltage at the diode-side electrode 123b of the smoothing capacitor 123 does not go down to a completely zero voltage, but rather (-V F ), for example, (-0.6V). As a result of the above, if the voltage VL2 of the detection winding 121 is negative with respect to the ground voltage (GND), the summing voltage VV, which is the voltage of the summing unit 129, is (-V F )

[0069] First, the voltage across smoothing capacitor 123 (-V F The difference (rectification component) between the voltage VL2 of the detection winding 121 and ΔVC is denoted by ΔVC. When the voltage VL2 of the detection winding 121 is positive with respect to GND, that is, when the voltage of the inductor-side line 123a is positive, the value of the added voltage VV is the voltage VL2 of the detection winding 121 plus the rectification component ΔVC, which is a positive shift. As a result, as shown by the dotted line in Figure 3, the added voltage VV is the voltage VL2 of the detection winding 121 shifted to the positive voltage side by the rectification component ΔVC.

[0070] A voltage divider resistor 125, having a first voltage divider resistor 125a (resistance value R1) and a second voltage divider resistor 125b (resistance value R2), divides the summation voltage VV to generate a resistive voltage divider VX. That is, the resistive voltage divider VX at the connection point 128 is the value obtained by dividing the summation voltage VV by R1 and R2. Here, the resistive voltage divider VX is a voltage (-k·V) when the SW is ON. F ), the voltage becomes positive when the switch is off.

[0071] In the IC-based control circuit 110, there is a lower limit to the allowable input voltage, such as (-0.3V) when the input voltage is negative. If the input voltage falls below this lower limit, a special circuit configuration is required. By dividing the summing voltage VV into a resistive voltage division VX using the voltage divider resistor 125, the resistive voltage division VX can be made to be above the allowable lower limit. As a result, the control circuit 110 does not require special input terminals, and a general-purpose IC can be used.

[0072] The resistive voltage divider VX at connection point 128 is input to comparator 130 for switch-on determination.

[0073] When the comparator 130 determines that the resistive voltage divider VX is below a predetermined reference value, it outputs a switch-on command to the drive signal generation unit 113 of the control unit 100. With such a comparator 130, the on-timing processing circuit 120 can detect the voltage near the trough (voltage near the trough) in the voltage change of the resistive voltage divider VX.

[0074] When the drive signal generation unit 113 of the control unit 100 receives a switch-on command from the comparator 130, it outputs an ON signal to the electrode 41c of the switching element 41 of the converter 40. In Figure 2, the case in which the switching element 41 turns on at the third trough is illustrated, but this number is not limited. In other words, depending on the temporal changes in the resonant state, the switching element 41 may turn on at, for example, the first, second, or fourth trough or later. The reference value of the comparator 130 can be adjusted so that the switching element 41 turns on at an appropriate timing. <Effects>

[0075] According to this embodiment configured as described above, the following effects can be obtained.

[0076] (1) The on-timing processing circuit 120 has a diode 124 and a smoothing capacitor 123 and generates an added voltage VV that is shifted to the positive voltage side, so that even when the voltage between the electrodes of the switching element is in a negative voltage state, the voltage between the electrodes of the switching element 41 can be detected near the valley.

[0077] (2) The on-timing processing circuit 120 further has a voltage divider resistor 125, so that the negative voltage (-V) in the case of the summing voltage VV is F The value is reduced to within the acceptable range. As a result, the control circuit 110 does not require special input terminals, and a general-purpose IC can be used.

[0078] (3) The on-timing processing circuit 120 has a comparator 130 and determines that the summation voltage VV is below a predetermined reference value, thereby enabling detection of the voltage near the trough of the voltage between the electrodes of the switching element 41. In other words, a special determination circuit like that in the prior example is not required.

[0079] The control unit 100 in this embodiment does not have any special elements like those in the prior art. Therefore, according to this embodiment, detection of the voltage near the trough is possible with a simple and inexpensive circuit configuration. In other words, according to this embodiment, the voltage between the electrodes of the switching element 41 can be detected with a simple and inexpensive circuit configuration. According to this embodiment, the switching element 41 can be switched to the ON state near the trough of the voltage between the electrodes of the switching element 41. This reduces the loss when switching to the ON state.

[0080] [Second Embodiment] Figure 4 is a block diagram showing an example configuration of the lighting device 5a according to the second embodiment.

[0081] This embodiment is a modification of the first embodiment. In this embodiment, the on-timing processing circuit 120a in the lighting device 5a of the lighting fixture 3a has a Zener diode 124a instead of the diode 124 in the first embodiment. Furthermore, the on-timing processing circuit 120a in this embodiment has a shaping capacitor 127. The shaping capacitor 127 is connected to the output line from the connection part 128 to the comparator 130, and the other end is grounded. The shaping capacitor 127 has a filtering function and mitigates the time change, i.e., voltage fluctuation, of the voltage output from the connection part 128 to the comparator 130. This embodiment is otherwise the same as the first embodiment.

[0082] Figure 5 is a graph showing the response waveform of the on-timing processing circuit 120a in the lighting device 5a according to the second embodiment. The horizontal and vertical axes are the same as in Figure 3.

[0083] By using a Zener diode 124a instead of diode 124, when the voltage VL2 of the detection winding 121 is positive with respect to GND, the summing voltage VV in the summing unit 129 is clamped to the Zener voltage, limiting the excess voltage on the positive side.

[0084] On the other hand, using the Zener diode 124a results in the trough of the summation voltage VV becoming nearly flat. This situation reduces the accuracy of detecting the voltage near the trough, i.e., the accuracy of determining the timing of the trough. To counteract this, the filtering effect of the shaping capacitor 127 mitigates the time variation of the voltage output from the connection 128 to the comparator 130, making it easier to detect the timing of the trough.

[0085] As described above, in addition to the effects of the first embodiment, this embodiment further provides the effects of improved circuit integrity and improved detection accuracy.

[0086] According to the embodiments described above, it is possible to provide a lighting device and lighting fixture that can detect near valleys with a simple and inexpensive circuit configuration.

[0087] [Other embodiments] Although embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. Furthermore, the features of each embodiment may be combined. Moreover, the embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0088] 1...Power supply, 2...Light source module, 2a...Light source, 2b...Connected part, 3, 3a...Lighting fixture, 4...Dimming signal section, 5, 5a...Lighting device, 10...Rectifier circuit, 10a, 10b...Input terminals, 10c...High potential output terminal, 10d...Low potential output terminal, 11...High frequency rejection capacitor, 20...Power factor correction circuit, 21...Inductor, 22...Switching element, 23...Diode, 30...Smoothing capacitor, 40...Converter, 41...Switching element, 41a, 41b, 41c...Electrodes, 42...Diode, 43...Inductor, 44...Output capacitor, 44a...First electrode, 44b...Second electrode, 45a...First output Terminals, 45b…Second output terminal, 46…Current detection resistor, 50…Connection section, 100…Control section, 110…Control circuit, 111…Reference value calculation section, 112…Control calculation section, 113…Drive signal generation section, 120, 120a…On-timing processing circuit, 121…Detection winding, 122…Current limiting resistor, 123…Smoothing capacitor, 123a…Inductor side line, 123b…Diode side electrode, 124…Diode, 124a…Zener diode, 125…Voltage divider resistor, 125a…First resistor for voltage division, 125b…Second resistor for voltage division, 127…Shaping capacitor, 128…Connection section, 129…Adding section, 130…Comparator

Claims

1. A power conversion unit having at least one switching element, an inductor, and an output capacitor, which converts input power supplied from a DC power supply or AC power supply into DC supply power and supplies the supply power to a light source, A control unit that controls the operation of the power conversion unit, Equipped with, The control unit, An on-timing processing circuit having an auxiliary winding for detecting the voltage of the inductor, a diode and a smoothing capacitor for rectifying the negative voltage of the auxiliary winding, and adding the rectified portion to the voltage of the auxiliary winding to output a switch-on command when the switching element is in the off state, A control circuit that receives the switch-on command and controls the operation of the power conversion unit, A lighting device characterized by comprising the following:

2. The on-timing processing circuit further includes a voltage divider resistor that divides the added voltage, which is the rectified component added to the voltage of the auxiliary winding, and outputs a resistive voltage divider. The lighting device according to claim 1, characterized in that the comparator determines that the summed voltage is less than or equal to the reference value when the resistive voltage division is less than or equal to a predetermined value.

3. The lighting device according to claim 1, characterized in that the diode in the on-timing processing circuit is a Zener diode.

4. The lighting device according to claim 1, further comprising a shaping capacitor on the output side of the added voltage for mitigating voltage fluctuations in the on-timing processing circuit.

5. The light source described in claim 1, A lighting device according to any one of claims 1 to 4, Equipped with lighting fixtures.

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