Drive device and light-emitting device

Abstract

This drive device for driving a plurality of loads comprises: an inverter that outputs an AC voltage and current; a plurality of filter circuits that are connected in parallel to the inverter and that drive different loads among the plurality of loads; and a control unit that controls the inverter. Each of the plurality of filter circuits includes a band-pass filter and drives a corresponding load among the plurality of loads by using the AC voltage and current passed through the band-pass filter. The pass frequency bands of the band-pass filters differ in the plurality of filter circuits. The control unit controls the inverter such that the frequency of the AC voltage is changed according to the pass frequency band of the band-pass filter in a filter circuit to be actuated among the plurality of filter circuits.

Description

Drive device and light-emitting device

[0001] The present invention relates to a drive device and a light-emitting device.

[0002] In a light-emitting device capable of emitting light in a plurality of colors, it is required to independently drive light-emitting elements having mutually different emission colors among the plurality of light-emitting elements. Non-Patent Document 1 proposes a drive circuit that drives light-emitting elements of the same color.

[0003] M. Esteki, D. Darvishrahimabadi, M. Shahabbasi, and S. A.Khajehoddin, “An Electrolytic-Capacitor-Less PFC LED Driver With Low DC-BusVoltage Stress for High Power Streetlighting Applications,” IEEE Trans. PowerElectron., vol. 38, no. 5, pp. 6294-6310, May 2023, doi:10.1109 / TPEL.2023.3236013.

[0004] In conventional light-emitting devices, one or more active power devices (i.e., switching elements) are used to drive light-emitting elements of the same color. When driving light-emitting elements of multiple colors, the number of active power devices corresponding to the number of emission colors is required. However, since driving an active power device also requires peripheral circuits such as a gate drive circuit, it is desirable to reduce the number of active power devices from the perspective of reducing the cost of the light-emitting device. In other words, cost reduction of a drive device that drives a plurality of light-emitting elements (loads) is required.

[0005] Accordingly, an object of the present invention is to provide a technique that is advantageous in terms of cost reduction for a drive device that drives a plurality of loads.

[0006] To achieve the above objective, a drive device as one aspect of the present invention is a drive device for driving a plurality of loads, comprising: an inverter that outputs AC voltage and current; a plurality of filter circuits connected in parallel to the inverter and driving loads that are different from each other among the plurality of loads; and a control unit that controls the inverter, wherein each of the plurality of filter circuits includes a bandpass filter, and the voltage and current that have passed through the bandpass filter are used to drive the corresponding load among the plurality of loads, the pass frequency bands of the bandpass filters are different from each other among the plurality of filter circuits, and the control unit controls the inverter to change the frequency of the AC voltage according to the pass frequency band of the bandpass filter in the filter circuit to be operated among the plurality of filter circuits.

[0007] According to the present invention, for example, it is possible to provide a technology that is advantageous in terms of reducing the cost of a drive device that drives multiple loads.

[0008] Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. In the accompanying drawings, the same or similar components are given the same reference numeral.

[0009] The attached drawings are included in the specification and constitute part thereof, illustrating embodiments of the present invention and are used together with the description to explain the principles of the present invention.

[0010] A schematic diagram showing a light-emitting device of one embodiment. A diagram showing an example of the time change in the frequency of the AC voltage output from the inverter and the time change in the current supplied to each light-emitting element. A diagram showing an example of the circuit configuration of the inverter. A diagram showing an example of the circuit configuration of the bandpass filter. A diagram showing an example of the circuit configuration of the bandpass filter. A diagram showing an example of the circuit configuration of the rectifier. A diagram showing the circuit configuration of the light-emitting device of Embodiment 1. A diagram showing the frequency characteristics of the bandpass filter 16a in Embodiment 1. A diagram showing the frequency characteristics of the bandpass filter 16b in Embodiment 1. A diagram showing the results of operating the light-emitting device of Embodiment 1. A diagram showing the results of performing a Fast Fourier Transform on a rectangular wave AC voltage. A diagram illustrating a specific example of generating an AC voltage using the SPWM method. A diagram showing the circuit configuration of the light-emitting device of Embodiment 2. A diagram showing the results of operating the light-emitting device of Embodiment 2.

[0011] Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiments, and includes changes and modifications to the configuration within the scope of the spirit of the invention. Furthermore, not all combinations of features described in these embodiments are essential to the present invention. The same reference numeral is used for identical components, and their descriptions are omitted.

[0012] <First Embodiment> The first embodiment of the present invention, a light-emitting device 10, will now be described. Figure 1 is a schematic diagram showing the light-emitting device 10 of this embodiment. The light-emitting device 10 of this embodiment is a device capable of emitting light in multiple colors and comprises a power supply circuit 11, a drive device 12, and a plurality of light-emitting elements 13a to 13n. The power supply circuit 11 includes, for example, a PFC (Power Factor Correction) circuit and supplies DC power to the drive device 12. The drive device 12 drives the plurality of light-emitting elements 13a to 13n. The detailed configuration of the drive device 12 will be described later. Furthermore, the plurality of light-emitting elements 13a to 13n include two or more light-emitting elements with different emission colors. For example, three light-emitting elements 13a to 13c have different emission colors. In this embodiment, each of the plurality of light-emitting elements 13a to 13n may be composed of one or more LEDs (Light Emitting Diodes).

[0013] Incidentally, in conventional light-emitting devices, one or more active power devices (i.e., switch elements) are used to drive light-emitting elements of the same color, and when driving light-emitting elements of multiple colors, the number of active power devices corresponding to the number of colors emitted is required. However, since peripheral circuits such as gate drive circuits are also required to drive active power devices, it is desirable to reduce the number of active power devices from the viewpoint of reducing the cost of light-emitting devices. Therefore, the light-emitting device 10 of this embodiment employs a drive device 12 that has a configuration that can reduce the number of active power devices. The following describes an example of the configuration of the drive device 12 of this embodiment.

[0014] As shown in Figure 1, the drive device 12 of this embodiment comprises an inverter 14, a plurality of filter circuits 15a to 15n, and a control unit 18 (control circuit). The inverter 14 includes one or more switch elements (active power devices), and the control unit 18 controls the on / off state of each switch element, thereby performing DC / AC conversion on the DC power supplied from the power supply circuit 11 and outputting AC voltage and current. The plurality of filter circuits 15a to 15n are connected in parallel to the inverter 14, and the plurality of filter circuits 15a to 15n share one inverter 14. The plurality of filter circuits 15a to 15n are connected to each of the plurality of light-emitting elements 13a to 13n so as to drive different light-emitting elements from among the plurality of light-emitting elements 13a to 13n. Specifically, filter circuit 15a is connected to light-emitting element 13a and drives light-emitting element 13a. Similarly, filter circuit 15b is connected to light-emitting element 13b and drives light-emitting element 13b. The filter circuit 15c is connected to the light-emitting element 13c and drives the light-emitting element 13c. The filter circuit 15n is connected to the light-emitting element 13n and drives the light-emitting element 13n.

[0015] Each of the multiple filter circuits 15a to 15n is provided with a bandpass filter 16 and a rectifier 17. Specifically, filter circuit 15a is provided with a bandpass filter 16a and a rectifier 17a. Similarly, filter circuit 15b is provided with a bandpass filter 16b and a rectifier 17b, filter circuit 15c is provided with a bandpass filter 16c and a rectifier 17c, and filter circuit 15n is provided with a bandpass filter 16n and a rectifier 17n. Note that the bandpass filter 16 may be understood to include a low-pass filter and / or a high-pass filter.

[0016] The bandpass filters 15a to 15n are configured such that the frequency bands of the AC voltage and current that are passed through (i.e., the passband frequency bands) are different for each of the filter circuits 15a to 15n. Each rectifier 17a to 17n is configured as an AC / DC converter and uses the AC voltage and current that has passed through the bandpass filter 16 to drive the corresponding light-emitting element 13 from among the multiple light-emitting elements 13a to 13n. Specifically, rectifier 17a drives the light-emitting element 13a using the AC voltage and current that has passed through the bandpass filter 16a. Similarly, rectifier 17b drives the light-emitting element 13b using the AC voltage and current that has passed through the bandpass filter 16b. Rectifier 17c drives the light-emitting element 13c using the AC voltage and current that has passed through the bandpass filter 16c. Rectifier 17n drives the light-emitting element 13n using the AC voltage and current that has passed through the bandpass filter 16n. In this embodiment, each rectifier 17a to 17n may include a diode bridge circuit composed of multiple diodes.

[0017] The control unit 18 (control circuit) controls the on / off state of each switch element of the inverter 14 so as to change the frequency of the AC voltage output from the inverter 14 according to the pass frequency band of the bandpass filter 16 in the filter circuit 15 to be operated among the plurality of filter circuits 15a to 15n. As described above, the bandpass filters 16a to 16n are configured such that the pass frequency bands of the plurality of filter circuits 15a to 15n are different from each other. Therefore, by changing the frequency of the AC voltage output from the inverter 14, each of the plurality of filter circuits 15a to 15n (rectifiers 17a to 17n) can be operated selectively and individually. That is, each of the plurality of light-emitting elements 13a can be driven selectively and individually.

[0018] Here, the control unit 18 may be composed of a computer including a processor such as a CPU (Central Processing Unit), storage devices such as semiconductor memory, and interfaces with external devices. However, the control unit 18 may also be composed of a PLD (Programmable Logic Device) such as an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or a general-purpose or dedicated computer with a program built in.

[0019] For example, the control unit 18 controls the inverter 14 (on / off of each switch element) so that the frequency of the AC voltage output from the inverter 14 is changed in a time-division manner. This allows multiple filter circuits 15a to 15n to be operated in a time-division manner. In this case, the control unit 18 may apply frequency shift keying (FSK), which changes the frequency using a carrier signal, as the modulation method for the frequency of the AC voltage output from the inverter 14. The control unit 18 may also apply multiple frequency shift keying (M-FSK), which is a type of frequency shift keying. Furthermore, examples of waveforms for the AC voltage output from the inverter 14 include square waves, sine waves, and sine wave pulse width modulated waves. In this embodiment, an example is described in which the control unit 18 controls the inverter 14 (on / off of each switch element) so that the inverter 14 outputs a square wave shaped AC voltage.

[0020] Figure 2 shows the AC voltage v output from the inverter 14. in The time variation of the frequency, and the current I supplied to each light-emitting element 13a to 13n led1 ~I ledn This shows an example of the time variation of the AC voltage v output from the inverter 14. The control unit 18 controls the AC voltage v incontrols the inverter 14 in a time-division manner such that the frequency of [object] is different from each other in a plurality of periods (sections) T1 to Tn. Note that the lengths of the plurality of periods T1 to Tn may be the same as each other or may be different from each other. The AC voltage v in each period T1 to Tn in PWM (Pulse Width Modulation) control, PFM (Pulse Frequency Modulation) control, or PDM (Pulse Density Modulation) control can be applied as the control method for [object]. In the following, the AC voltage v in an example in which PWM (Pulse Width Modulation) control is applied as the control method for [object] will be described. Further, the plurality of periods T1 to Tn can be repeated with a period of 2π.

[0021] In the period T1, the control unit 18 outputs the AC voltage v output from the inverter 14 in controls the inverter 14 such that the frequency of [object] is included in the pass frequency band of the band-pass filter 16a of the filter circuit 15a. Thereby, the AC voltage v in is applied to the rectifier 17a of the filter circuit 15a, so that a current I is applied to the light-emitting element 13a led1 is supplied, and the light-emitting element 13a can be driven. Further, in the other filter circuits 15b to 15n, the AC voltage v output from the inverter 14 in the frequency of [object] is not included in the pass frequency bands of the band-pass filters 16b to 16n, so the other light-emitting elements 13b to 13n do not operate.

[0022] In the period T2 after the period T1, the control unit 18 outputs the AC voltage v output from the inverter 14 in controls the inverter 14 such that the frequency of [object] is included in the pass frequency band of the band-pass filter 16b of the filter circuit 15b. Thereby, the AC voltage v in is applied to the rectifier 17b of the filter circuit 15b, so that a current I is applied to the light-emitting element 13b led2 is supplied, and the light-emitting element 13b can be driven. Further, in the other filter circuits 15a and 15c to 15n, the AC voltage v output from the inverter 14 inSince the frequency of this signal is not included in the passband of the bandpass filters 16a, 16c to 16n, the other light-emitting elements 13a, 13c to 13n will not operate.

[0023] During period T3 following period T2, the control unit 18 controls the AC voltage v output from the inverter 14. in The inverter 14 is controlled so that the frequency of the AC voltage v is included in the passband frequency range of the bandpass filter 16c of the filter circuit 15c. However, in the example of Figure 2, the control unit 18 controls the inverter 14 to supply the AC voltage v during period T3. in To prevent the output from being (i.e., AC voltage v in The inverter 14 is controlled so that the current I led3 Since no voltage is supplied, the light-emitting element 13c does not operate. Also, AC voltage v is supplied from the inverter 14. in Since no output is being produced, the light-emitting elements 13a-13b and 13n also do not operate.

[0024] During period T4 following period T3, the control unit 18 controls the AC voltage v output from the inverter 14. in The inverter 14 is controlled so that the frequency of the AC voltage v falls within the passband frequency range of the bandpass filter 16n of the filter circuit 15n. in This current I is applied to the rectifier 17n of the filter circuit 15n, and the current I is supplied to the light-emitting element 13n. ledn The AC voltage v output from the inverter 14 is supplied and can drive the light-emitting element 13n. In addition, in the other filter circuits 15a to 15c, the AC voltage v output from the inverter 14 is supplied. in Since the frequency of this signal is not included in the passband of the bandpass filters 16a to 16c, the other light-emitting elements 13a to 13c do not operate.

[0025] Next, an example of the circuit configuration of the inverter 14, bandpass filter 16, and rectifier 17 will be explained with reference to Figures 3 to 6. Note that the circuit configuration example in Figures 3 to 6 is merely an example, and other circuit configurations may be applied to the inverter 14, bandpass filter 16, and rectifier 17.

[0026] Figure 3 shows an example of the circuit configuration of the inverter 14. The inverter 14 has contact b１ Two switch elements S connected in series via １ ~S ２ A leg containing a capacitor C connected in parallel to that leg. １ It has a switch element S. １ Capacitor C Ｓ１ These are connected in parallel, and the switch element S ２ Capacitor C Ｓ２ These are connected in parallel. Each switch element S １ ~S ２ As such, transistors (power elements) that perform switching operations, such as IGBTs and MOSFETs, can be used. １ ~S ２ The on / off state (conductive / non-conductive) can be controlled by the control unit 18.

[0027] Figure 4 shows an example of the circuit configuration of one bandpass filter 16. In the bandpass filter 16, resistor R Ｓ And, capacitor C Ｆ１１ And, inductor L Ｆ１１ And, capacitor C Ｆ１４ And, inductor L Ｆ１４ And, capacitor C Ｆ１７ And, inductor L Ｆ１７ And is connected in series to one end of inverter 14. Also, capacitor C Ｆ１２ and inductor L Ｆ１２ A leg and a capacitor C are connected in series. Ｆ１３ and inductor L Ｆ１３ A leg and an inductor L are connected in series. Ｆ１１ and capacitor C Ｆ１４ It is connected between and . Furthermore, capacitor C Ｆ１５ and inductor L Ｆ１５ A leg connected in series with a capacitor C Ｆ１６ and inductor L Ｆ１６ A leg and an inductor L are connected in series. Ｆ１４ and capacitor C Ｆ１７ It is connected between [the two points].

[0028] The bandpass filter 16 may also be configured as shown in Figure 5. Figure 5 shows another example of the circuit configuration of one bandpass filter 16. In the bandpass filter 16 shown in Figure 5, the inductor L Ｆ２１ and capacitor C Ｆ２１ and are connected in series to one end of inverter 14, and capacitor C Ｆ２２ and inductor L Ｆ２２ and resistor R Ｐ Capacitor C is connected in parallel to inverter 14. Ｆ２２ is an inductor L Ｆ２１ and capacitor C Ｆ２１ It is connected between and the inductor L Ｆ２２ and resistor R Ｐ is capacitor C Ｆ２１ It is connected between the output terminal and the output terminal.

[0029] Figure 6 shows an example of the circuit configuration of one rectifier 17. The rectifier 17 consists of multiple (four) diodes D １ ~D ４ It has a diode bridge circuit composed of the following: In the diode bridge circuit, contact b is connected to one end of the bandpass filter 16. ２ Diode D １ and diode D ２ The two are connected in series, and contact b is connected to the other end of the bandpass filter 16. ３ Diode D ３ and diode D ４ The two are connected in series. Also, resistor R １ and capacitor C ２ A leg and a resistor R are connected in series. ２ A leg containing the element is connected in parallel to the diode bridge circuit. An inductor L is placed between these two legs. ｓ A system will be established.

[0030] [Example 1] Hereinafter, Example 1 of this embodiment will be described. Figure 7 shows the circuit configuration of the light-emitting device 10 of Example 1. In Example 1, the light-emitting device 10 is provided with two light-emitting elements 13a to 13b and two filter circuits 15a to 15b, and an example in which the driving of the two light-emitting elements 13a to 13b is controlled by time division will be described. In this example, the light-emitting device 10 of Example 1 employs the circuit configuration of Figure 3 for the inverter 14, the circuit configuration of Figure 5 for the bandpass filters 16 of each filter circuit 15a to 15b, and the circuit configuration of Figure 6 for the rectifiers 17 of each filter circuit 15a to 15b. Note that although the rectifiers 17a to 17b in Figure 7 have some differences in their circuit configuration compared to the rectifier 17 in Figure 6, their substantial configuration and operation are the same.

[0031] In the light-emitting device 10 of Example 1, the DC voltage output from the power supply circuit 11 was set to 20V, and frequency switching (modulation) was performed using the frequency shift modulation (FSK) method. The FSK switching frequency was 1kHz. The frequency Fa that operates the filter circuit 15a (i.e., the pass frequency of the bandpass filter 16a) was set to 47.5kHz, and the frequency Fb that operates the filter circuit 15b (i.e., the pass frequency of the bandpass filter 16b) was set to 1MHz. The duty cycle for frequencies Fa to Fb was 50% in all cases. Figure 8A shows the frequency characteristics of the bandpass filter 16a of the filter circuit 15a, and Figure 8B shows the frequency characteristics of the bandpass filter 16b of the filter circuit 15b. In Figures 8A and 8B, the horizontal axis represents frequency, and the vertical axis on the left represents gain (v out / v in The graph shows the phase, and the vertical axis on the right shows the phase. in " is an AC voltage output from inverter 14 and input to each filter circuit 15a to 15b, and "v out " is the voltage output from each filter circuit 15a to 15b.

[0032] Figure 9 shows the results of operating the light-emitting device 10 of Example 1. In Figure 9, the AC voltage v in , alternating current i in , current i supplied to the light-emitting element 13a led1 , current i supplied to the light-emitting element 13bled2 This shows the time variation of the AC voltage v output from the inverter 14 in the light-emitting device 10 of Example 1. in The control unit 18 controlled the inverter so that the frequency of the current i would switch in a time-division manner between frequency Fa (47.5 kHz) and frequency Fb (1 MHz). With this configuration and control, as shown in Figure 9, the current i led1 and current i led2 By switching to time-division lighting, it becomes possible to properly light up the light-emitting element 13a and the light-emitting element 13b in a time-division manner.

[0033] As described above, in the drive unit 12 of the light-emitting device 10 of this embodiment, multiple filter circuits 15a to 15n, each driving different light-emitting elements 13 from among the multiple light-emitting elements 13a to 13n, are connected in parallel to one inverter 14. The bandpass filters 16 provided in each filter circuit 15a to 15n include different pass-through frequency bands for the multiple filter circuits 15a to 15n. The control unit 18 then outputs an AC voltage v from the inverter 14 according to the pass-through frequency band of the bandpass filter 16 in the filter circuit 15 to be operated from among the multiple filter circuits 15a to 15n. in The inverter 14 is controlled to change the frequency. By configuring the drive unit 12 in this way, the number of switching elements (active power devices) can be reduced, and the cost of the drive unit 12 (and consequently the light-emitting device 10) can be reduced.

[0034] In the above embodiment, multiple light-emitting elements 13 were exemplified as multiple loads driven by the drive device 12, but the multiple loads that the drive device 12 can drive are not limited to multiple light-emitting elements 13. Also, in the above embodiment, the drive device 12 was described as not including a power supply circuit 11, but the drive device 12 may be configured to include a power supply circuit 11. Furthermore, in the above embodiment, the light-emitting device 10 was described as including a power supply circuit 11, but the light-emitting device 10 does not have to include a power supply circuit 11. In this case, the power supply circuit 11 is configured as an external device of the light-emitting device 10, and power is supplied to the light-emitting device 10 from the external device.

[0035] <Second Embodiment> A second embodiment of the present invention will now be described. This embodiment basically follows the first embodiment, and can be followed in all respects except for those mentioned below.

[0036] In the first embodiment described above, an example was explained in which the control unit 18 controls the inverter (on / off each switch element) so that the inverter 14 outputs a rectangular wave AC voltage. It is known that such a rectangular wave AC voltage contains harmonic components. Therefore, due to the influence of harmonic components, not only the filter circuit 15 that is to be operated but also the filter circuit 15 that is not to be operated may be operated, and the light-emitting element 13 connected to such non-operated filter circuit 15 may light up incorrectly. As a method to reduce the incorrect lighting of the light-emitting element 13, one can consider separating the passband frequencies of the bandpass filters 16 between the multiple filter circuits 15, but with this method, the range (degrees of freedom) of the passband frequencies applicable to each bandpass filter 16 is limited, which may be disadvantageous when controlling a large number of light-emitting elements 13 in a time-division manner.

[0037] For example, Figure 10 shows the results of performing a Fast Fourier Transform (FFT) on a rectangular AC voltage for the frequencies Fa (47.5 kHz) and Fb (1 MHz) used in Example 1 of the first embodiment described above. As shown in Figure 10, the AC voltage at frequency Fa (47.5 kHz) required to operate the filter circuit 15a may include not only the fundamental wave 1 but also its harmonic components. When the harmonic components of the fundamental wave 1 occur near the frequency Fb (1 MHz) of the AC voltage required to operate the filter circuit 15b, the light-emitting element 13b connected to the filter circuit 15b may light up incorrectly due to the influence of the harmonic components of the fundamental wave 1. In other words, even if the inverter 14 is controlled to operate only the filter circuit 15a with the AC voltage and current at frequency Fa and not the filter circuit 15b, the filter circuit 15b may also be activated due to the influence of the harmonic components of the AC voltage at frequency Fa, and the light-emitting element 13b may light up incorrectly.

[0038] As a method for reducing erroneous lighting of the light emitting element 13b, use of a sinusoidal AC voltage that basically does not contain harmonic components can be mentioned. However, it is difficult for the inverter 14 to generate a sinusoidal AC voltage. Further, if an analog circuit including an operational amplifier or the like is provided in place of the inverter 14 and a sinusoidal AC voltage is generated by the analog circuit, loss caused by linear amplification increases, which can be disadvantageous in terms of power consumption.

[0039] Therefore, in the light emitting device 10 (driving device 12) of the present embodiment, the inverter 14 uses a sine pulse width modulation (SPWM (Sine Pulse Width Modulation)) method to generate an AC voltage to be supplied to each filter circuit 15. Specifically, as shown in FIG. 11, the control unit 18 inputs a signal 34 obtained by comparing a sine wave signal 31 (reference signal) and a triangular wave signal 32 (carrier signal) with a comparator 33 to each switch element of the inverter 14, thereby controlling the inverter 14 by the SPWM method. Accordingly, an AC voltage having an SPWM waveform is output from the inverter 14. In the SPWM waveform, since the average value of the pulse width is sinusoidal over time, harmonic components are greatly reduced, and this can also be advantageous in terms of power consumption. Further, the control unit 18 can change the frequency of the AC voltage by changing the frequency of the sine wave signal 31.

[0040] [Example 2] Hereinafter, Example 2 of the present embodiment will be described. FIG. 12 shows a circuit configuration of a light emitting device 10 of Example 2. The light emitting device 10 of Example 2 has a configuration obtained by further adding a light emitting element 13c and a filter circuit 15c to the configuration of Example 1 described above. Each of the filter circuits 15a to 15c is configured by a diode bridge circuit. Further, in the light emitting device 10 of Example 2, the inverter 14 is controlled by the SPWM method, and an AC voltage v generated using the SPWM method in is supplied in a time-division manner from the inverter 14 to each of the filter circuits 15a to 15c.

[0041] In the light-emitting device 10 of Example 2, the frequency Fa (pass frequency of the bandpass filter 16a) for activating filter circuit 15a was set to 47.5 kHz. The frequency Fb (pass frequency of the bandpass filter 16b) for activating filter circuit 15b was set to 340 kHz, and the frequency Fc (pass frequency of the bandpass filter 16c) for activating filter circuit 15c was set to 750 kHz. Thus, in Example 2, the interval between the frequencies Fa to Fc for activating filter circuits 15a to 15c is narrower compared to Example 1. The duty cycle for frequencies Fa to Fc is 50% in all cases.

[0042] Figure 13 shows the results of operating the light-emitting device 10 of Example 2. In Figure 13, the current i supplied to the light-emitting element 13a led1 , current i supplied to the light-emitting element 13b led2 , and the current i supplied to the light-emitting element 13c led3 This shows the time variation of the AC voltage v in the light-emitting device 10 of Example 2, even if the interval between the frequencies Fa to Fc that operate each filter circuit 15a to 15c is narrowed, the AC voltage v is still obtained using the SPWM method. in By generating this, as shown in Figure 13, current i led1 ~i led3 By switching to time-division multiplexing, it becomes possible to light up the light-emitting elements 13a to 13c in a time-division multiplexing manner. In other words, by using the SPWM method, it is possible to reduce false light emission caused by the influence of harmonic components.

[0043] The invention is not limited to the embodiments described above, and various modifications and changes are possible within the scope of the gist of the invention.

[0044] This application claims priority based on Japanese Patent Application No. 2025-031889, filed on 28 February 2025, and all of its contents are incorporated herein by reference.

[0045] 10: Light-emitting device, 11: Power supply circuit, 12: Drive device, 13: Light-emitting element (load), 14: Inverter, 15: Filter circuit, 16: Bandpass filter, 17: Rectifier, 18: Control unit

Claims

1. A drive device for driving multiple loads, comprising: an inverter that outputs AC voltage and current; a plurality of filter circuits connected in parallel to the inverter and driving different loads among the plurality of loads; and a control unit that controls the inverter, wherein each of the plurality of filter circuits includes a bandpass filter, and drives a corresponding load among the plurality of loads using the AC voltage and current that has passed through the bandpass filter; the pass frequency bands of the bandpass filters differ among the plurality of filter circuits; and the control unit controls the inverter to change the frequency of the AC voltage according to the pass frequency band of the bandpass filter in the filter circuit to be operated among the plurality of filter circuits.

2. The drive device according to claim 1, characterized in that the control unit controls the inverter to change the frequency of the AC voltage in a time-division manner, thereby operating the plurality of filter circuits in a time-division manner.

3. The drive device according to claim 2, characterized in that the control unit controls the inverter to change the frequency of the AC voltage in a time-division manner by frequency shift modulation.

4. The drive device according to any one of claims 1 to 3, characterized in that the inverter includes one or more switch elements, and the control unit changes the frequency of the AC voltage by controlling the on / off state of the one or more switch elements in the inverter.

5. The drive device according to any one of claims 1 to 3, characterized in that the inverter outputs the AC voltage generated using a sinusoidal pulse width modulation method.

6. The drive device according to any one of claims 1 to 3, characterized in that the inverter includes one or more switch elements, the control unit controls the inverter in a sinusoidal pulse width modulation manner by inputting a signal obtained by comparing a sinusoidal wave signal and a triangular wave signal to the one or more switch elements, and changes the frequency of the AC voltage by changing the frequency of the sinusoidal wave signal.

7. The drive device according to any one of claims 1 to 3, characterized in that the inverter includes one or more switch elements and outputs the AC voltage generated using a sinusoidal pulse width modulation method, and the control unit controls the inverter using the sinusoidal pulse width modulation method by inputting a signal obtained by comparing a sinusoidal signal and a triangular wave signal to the one or more switch elements, thereby changing the frequency of the AC voltage by changing the frequency of the sinusoidal signal.

8. The drive device according to any one of claims 1 to 3, characterized in that each of the plurality of filter circuits includes a rectifier composed of a plurality of diodes.

9. The drive device according to any one of claims 1 to 3, characterized in that the inverter includes one or more switch elements, the control unit changes the frequency of the AC voltage by controlling the on / off state of the one or more switch elements in the inverter, and each of the plurality of filter circuits includes a rectifier composed of a plurality of diodes.

10. The drive device according to any one of claims 1 to 3, characterized in that the inverter includes one or more switch elements, the control unit controls the inverter in a sinusoidal pulse width modulation manner by inputting a signal obtained by comparing a sinusoidal wave signal and a triangular wave signal to the one or more switch elements, the frequency of the AC voltage is changed by changing the frequency of the sinusoidal wave signal, and each of the plurality of filter circuits includes a rectifier composed of a plurality of diodes.

11. The drive device according to any one of claims 1 to 3, characterized in that the inverter includes one or more switch elements and outputs the AC voltage generated using a sinusoidal pulse width modulation method, the control unit controls the inverter using the sinusoidal pulse width modulation method by inputting a signal obtained by comparing a sinusoidal signal and a triangular wave signal to the one or more switch elements, and changes the frequency of the AC voltage by changing the frequency of the sinusoidal signal, and each of the plurality of filter circuits includes a rectifier composed of a plurality of diodes.

12. The drive device according to any one of claims 1 to 3, wherein each of the plurality of loads includes a light-emitting element, and the plurality of filter circuits drive the loads among the plurality of loads that have different light-emitting colors.

13. A light-emitting device comprising a plurality of light-emitting elements and a drive device according to any one of claims 1 to 3, wherein the drive device drives the plurality of light-emitting elements as a plurality of loads.

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