HK1192994B

HK1192994B - Led lamp and lighting device including led lamp

Info

Publication number: HK1192994B
Application number: HK14106415.8A
Authority: HK
Inventors: 宫道三郎
Original assignee: 爱模系统有限公司
Filing date: 2012-04-09
Publication date: 2015-10-09

Description

LED lamp and lighting device comprising same

Technical Field

The present invention relates to an LED lamp and an illumination device including the LED lamp, which can drive and light an LED light emitting unit incorporated therein at a high frequency even when the LED lamp is mounted in place of a fluorescent lamp of various commercially available glow starter type, rapid start type, and inverter type lighting devices.

Background

As a typical lighting device for a fluorescent lamp generally used, there are various fluorescent lamp lighting devices such as a glow starter type, a rapid start type, and a converter type called an electronic ballast, which are called magnetic ballasts.

The inverter type fluorescent lamp lighting device, which has been rapidly spread in recent years, is a device that converts an alternating current into a direct current and then generates a high voltage of a high frequency (20 kHz to 100 kHz) near a resonance frequency by an inverter circuit including a transistor, a capacitor, a choke coil, and the like.

It is a device for lighting a fluorescent lamp by using the high voltage and stably lighting the fluorescent lamp at a low voltage by using a current flowing in the fluorescent lamp after lighting.

Compared with the existing glow start type and quick start type magnetic stabilizers using a choke coil, the magnetic stabilizer has the remarkable advantages of power saving, high efficiency, 50 Hz/60 Hz combination, low noise, no flicker, and the like.

The following description refers to the accompanying drawings.

Fig. 8 (a) is a diagram showing an example of a glow-start type stabilizer, fig. 8 (b) is a diagram showing an example of a rapid-start type stabilizer, and fig. 8 (c) is a diagram showing an example of a converter type stabilizer.

The glow starter type ballast shown in fig. 8 (a) is a type that can be lit within several seconds after the switch is turned on by preheating the electrode (also referred to as a filament, the same applies hereinafter) of the fluorescent lamp by a starter using a lighting tube (glow starter G), and is the most popular type.

In addition, the rapid start type ballast shown in fig. 8 (b) is a ballast used in combination with a rapid start type lamp, and is of a type that lights up immediately while warming up if a switch is turned on.

On the other hand, the stabilizer of the inverter type lighting device shown in fig. 8 (c) converts an AC current within an AC input voltage of 85 to 450V into a dc current, and then drives and lights the LED lamp at a high frequency as described above by an integrated circuit (see, for example, page 4 and fig. 2 of patent document 1).

At this time, the choke coil L is inserted in series with the LED lamp in order to smooth the current flowing through the LED lamp, but an electrolytic capacitor (not shown) is usually inserted in parallel with the LED lamp.

Fig. 9 is a diagram showing an example in which two fluorescent lamps are connected in series to a series type fast stabilizer.

Since two fluorescent lamps are connected in series and are lighted by one ballast, the ballast for one lamp can be used in two lamps, and is simpler and cheaper than a flicker-free ballast.

When a power supply is inputted, the electrodes of the fluorescent lamp A and the fluorescent lamp B are preheated, and the starting capacitor has a high impedance, so that the voltage on the secondary side does not turn into normal discharge and becomes a micro-discharge state. The voltage drop across the starting capacitor due to the micro discharge current is applied to the fluorescent lamp B, and the discharge of the fluorescent lamp B is started.

If the two fluorescent lamps are discharged, the high-impedance starting capacitor is basically in a non-operating state, and the two fluorescent lamps are normally discharged to maintain a lighting state.

Since the fluorescent lamps are connected in series and discharge one lamp by one lamp, the fluorescent lamps connected in series can be lit by a comparatively low secondary side voltage, but there is a disadvantage that one fluorescent lamp is removed for power saving or both fluorescent lamps cannot be lit when one fluorescent lamp is turned off.

< patent document 1> Japanese patent application laid-open No. 2010-34012

Disclosure of Invention

(problems to be solved by the invention)

However, for reasons of power saving, lamp life extension, and the like, LED lamps are often used in place of conventional fluorescent lamps by being mounted on the above-described stabilizers of various types.

In this case, the peak value and the frequency of the ac current input to the pair of input terminal portions of the LED lamp greatly differ depending on the type of the stabilizer of the lighting device to be mounted, and therefore, it is necessary to use an LED lamp corresponding to each stabilizer.

For example, if the lighting device of the fluorescent lamp is a glow starter type or a rapid start type, the output of the stabilizer (secondary side output) is controlled by about AC200V corresponding to AC100V to 240V (50 Hz/60 Hz) input from the power supply side, but the frequency is the same as the frequency input from the power supply side because the control for increasing the frequency is not performed.

Therefore, in the LED lamp, in order to use an alternating current having a frequency equal to the frequency input from the power supply side, the alternating current is rectified into a direct current by an internal rectifier circuit, and then a circuit configuration (a configuration of a circuit in which a plurality of LEDs are connected, the same applies hereinafter) of the LED light emitting portion of the LED lamp is fixed so as to obtain a desired illuminance, and the current flowing through each LED falls within a desired predetermined range.

Therefore, in the related art, when the ballast of the lighting device of the fluorescent lamp is of a glow start type or a rapid start type, if a dedicated LED lamp that can be adapted to a socket for the fluorescent lamp is used, each built-in LED can be lit.

On the other hand, as described above, if the lighting device of the fluorescent lamp is of the inverter type, even if the power supply side input is AC100V to 240V (50 Hz/60 Hz), the output (secondary side output) of the stabilizer is controlled to a constant voltage of about AC280V (at no load) and constant current control or constant power control is performed so that the frequency falls within the range of 20kHz to 100 kHz.

Therefore, when the ballast of the lighting device of the fluorescent lamp is of the inverter type, it is necessary to perform a corresponding operation on the lighting device side or the LED lamp side, accompanied by a circuit change process on the lighting device side or by using a conversion adapter or the like necessary for direct connection, in order to directly supply power on the power supply side to an AC/DC transformer (rectifier circuit) incorporated in the LED lamp without using the inverter type ballast (without a driving operation).

When the LED lamp is turned on by the inverter type, the lighting device incorporating the inverter type stabilizer and the LED lamp dedicated therefor are replaced by a complete set.

As described above, it is also a cause of trouble in the user side in order to perform the introduction processing (for example, it is necessary to perform an additional operation such as a selection of an LED lamp depending on the mode of the lighting device (confirmation of suitability), a circuit processing of the lighting device side, a direct connection operation, and the like), and the like, and to grasp the current situation, the work period adjustment, and the like, and the introduction cost increases accordingly.

That is, these are obstacles to the use of LED lamps in conventional fluorescent lamp lighting devices at home and work.

As a result, since conventional fluorescent lamps are used continuously, they have been a significant obstacle to market popularization of LED lamps, which greatly contribute to power saving and extension of lamp life.

The present invention provides an LED lamp and an illumination device including the same, which can be driven and lighted by a high-frequency pulse drive, regardless of whether a ballast of a fluorescent lamp lighting device is of a glow start type, a rapid start type, an inverter type, or the like, as long as the ballast is replaced with a fluorescent lamp (or an LED lamp) that has been installed.

(means for solving the problems)

In order to solve the above conventional problems, an LED lamp according to the present invention includes: a pair of input terminal portions, a rectifier circuit portion for rectifying an alternating current inputted from the outside to the pair of input terminal portions into a direct current, and an LED light emitting portion for emitting light by energization of the direct current outputted from the rectifier circuit portion, characterized in that: a PWM control unit that is provided in a circuit between the rectifier circuit unit and the LED light emitting unit and that can PWM-control a current flowing in the LED light emitting unit based on a duty ratio; the PWM control unit switches between a case of PWM controlling a current flowing through the LED light emitting unit and a case of not PWM controlling the current flowing through the LED light emitting unit, according to a frequency of an alternating current inputted to the outside of the pair of input terminal units.

Thus, regardless of whether the ballast of the fluorescent lamp lighting device is of a glow start type, a rapid start type, or an inverter type, the fluorescent lamp lighting device can be used as lighting capable of PWM lighting by pulse driving, as long as it is replaced with a fluorescent lamp (or an LED lamp) that has been installed in the past.

In addition, according to the LED lamp of the present invention, in addition to the above configuration, preferably, the PWM control section PWM-controls the current flowing through the LED light emitting section by pulse driving at a frequency higher than a predetermined frequency when the frequency of the ac current inputted to the outside of the pair of input terminal sections is lower than the predetermined frequency; when the frequency of the alternating current inputted to the outside of the pair of input terminal portions is higher than the predetermined frequency, the current flowing in the LED light emitting portion is not PWM-controlled.

With this configuration, regardless of whether the ballast of the fluorescent lamp lighting device is of a glow start type, a rapid start type, or an inverter type, the fluorescent lamp lighting device can be turned on as illumination capable of being driven and turned on by a pulse at a frequency higher than a predetermined frequency, as long as the fluorescent lamp (or the LED lamp) is replaced with a fluorescent lamp that has been mounted in the past.

Therefore, it is easy to eliminate the trouble of performing the current situation check and the schedule adjustment for the user side to perform the introduction processing (for example, the additional operation such as selecting the LED lamp depending on the mode of the lighting device (confirmation of the suitability) or performing the circuit processing and the direct connection operation on the lighting device side is necessary), and the introduction cost is increased.

As a result, the obstacles faced by the conventional fluorescent lamp lighting device (or LED lighting device) at home and work place to use LED lamps are eliminated.

In addition, the LED lamp which greatly contributes to power saving and prolonging the service life of the lamp can be popularized in the market.

For example, if the ballast of the fluorescent lamp lighting device is of a glow start type or a rapid start type, the frequency of the ac current inputted from the pair of input terminal portions is 50 Hz/60 Hz, which is the commercial frequency.

Therefore, since the PWM control section PWM-controls the current flowing through the LED light emitting section by the drive pulse having a frequency at least higher than a predetermined frequency (for example, 5 kHz), the current flowing through the LED light emitting section is repeatedly turned on and off at a high speed, and a stable effective value (RMS value) without causing flicker can be obtained.

On the other hand, if the ballast of the fluorescent lamp lighting device is of the inverter type, the ac current input from the pair of input terminal portions has a high frequency of 20kHz to 100kHz, so the PWM control portion does not perform PWM control, and uses the original frequency rectified by the rectifier circuit portion (if full-wave rectified, the pulsating voltage waveform portion superimposed on the dc current has a frequency of 2 times), so that the current flowing through the LED light emitting portion can be controlled (for example, PWM control) by the external inverter type ballast, and a stable effective value (RMS value) without causing flicker can be obtained.

Therefore, it is possible to reliably prevent the control modes of the same kind from overlapping between the outside and the inside of the LED lamp, and to eliminate the cause of incompatibility such as unstable current flowing through the LED light emitting unit.

In addition, according to the LED lamp of the present invention, in addition to the above configuration, it is preferable that a bypass circuit portion is provided between a cathode-side terminal of the LED light emitting portion and a ground-side output terminal of the rectifier circuit portion; the bypass circuit unit includes a switching element and a high-pass filter circuit for outputting a drive voltage of the switching element; the switching element does not flow current from the cathode-side terminal of the LED light-emitting unit to the ground-side output terminal of the rectifier circuit unit when the frequency of the AC current input to the pair of input terminal units is lower than a predetermined frequency; when the frequency of the alternating current input to the pair of input terminal portions is higher than a predetermined frequency, a current flows from the cathode-side terminal of the LED light emitting portion to the ground-side output terminal of the rectifier circuit portion.

With this configuration, when the ac current input from the input terminal of the rectifier circuit unit is higher than the predetermined frequency, the bypass circuit unit bypasses (bypasses) the current flowing through the LED light emitting unit around the switching element of the PWM control unit for performing PWM control, and the PWM control unit built in the LED lamp may not perform PWM control.

In addition, according to the LED lamp of the present invention, in addition to the above configuration, it is preferable that the switching element of the bypass circuit portion is an N-channel MOS FET that controls a flow of current between the drain terminal and the source terminal in accordance with a gate voltage input to the gate terminal; a drain terminal connected to a cathode-side terminal of the LED light-emitting unit, and a source terminal connected to a ground-side output terminal of the rectifier circuit; a gate terminal connected to any one of the input terminals of the rectifier circuit unit via a high-pass filter circuit; a high-pass filter circuit for outputting, to the gate terminal, a gate voltage that is driven to flow current from the drain terminal to the source terminal when the frequency of the alternating current input to the pair of input terminal portions is higher than a predetermined frequency; when the frequency of the alternating current input to the pair of input terminal portions is lower than a predetermined frequency, a gate voltage that is driven so as not to cause a current to flow from the drain terminal to the source terminal is output to the gate terminal.

With this configuration, since the N-channel MOS FET functions as a switching element of the bypass circuit, a current can be caused to flow through the LED light emitting section with a sufficient margin, and the current can be prevented from flowing into the PWM control section.

That is, when the ac current input from the input terminal of the rectifier circuit unit is higher than the predetermined frequency, the PWM control unit is bypassed (bypassed), so that the current flowing through the LED light emitting unit does not flow into the PWM control unit, and the PWM control unit does not need to perform the PWM control.

In addition, according to the LED lamp of the present invention, in addition to the above configuration, preferably, the high-pass filter circuit includes: a1 st capacitor; a1 st resistor having a terminal connected to one terminal of the 1 st capacitor and connected in series with the 1 st capacitor; a1 st diode connected in a forward direction from the other terminal of the 1 st resistor to the gate terminal; a2 nd capacitor connected between the source terminal and the gate terminal; a2 nd resistor connected between the source terminal and the gate terminal; a zener diode connected in a forward direction from the source terminal to the gate terminal; and a2 nd diode connected in the forward direction from the source terminal to the other terminal of the 1 st resistor, and the other terminal of the 1 st capacitor is connected to any one of the input terminals of the rectifier circuit section.

With this configuration, only a current having a frequency higher than a predetermined frequency can be passed to the next stage, and the switching element of the bypass circuit can be reliably turned ON/OFF according to the frequency.

As a result, only when the frequency of the alternating current input from the input terminal of the rectifier circuit unit is higher than a predetermined frequency, the current flows to the next stage, so that the N-channel MOS FET as the switching element can be reliably turned ON, and the current flowing through the LED light emitting unit can be not PWM controlled.

In addition, according to the LED lamp of the present invention, in addition to the above-described configuration, it is preferable that the predetermined frequency is a frequency greater than 65Hz and less than 20 kHz.

With this configuration, even when variations including the accuracy of the power supply frequency are taken into consideration, the frequency (60 ± 1 Hz) at the time of glow start or rapid start of the ballast can be clearly distinguished from the frequency (20 to 100 kHz) at the time of inverter type which is commercially available, and therefore, the ballast can be switched between the case of performing PWM control by pulse driving and the case of not performing PWM control by pulse driving according to the result of the distinction, and can be lit for lighting purposes which can be lit by pulse driving at a high frequency.

In particular, by making the predetermined frequency to be distinguished a frequency that is less than 20kHz and that falls within the range of an audible band (a frequency band in which sound can be perceived by humans), PWM control is performed by pulse driving of a frequency in a higher frequency band than that, so that the perception of noise as being harsh is also alleviated.

Further, the lighting device according to the present invention includes the LED lamp having any one of the above configurations.

With this configuration, since the LED lamp of the present invention is mounted on the lighting device of the present invention, lighting as illumination can be realized by supplying external ac current to the pair of input terminal sections without newly providing a stabilizer for adjusting the light of the LED light emitting section on the side of the lighting device.

Further, since the lighting device itself does not include a stabilizer, the configuration of the lighting device is simplified, and it is easy to eliminate the problems of troublesome current situation grasping and investigation, work period adjustment, and the like, and an increase in introduction cost accompanying this, which are required for the user side to perform introduction processing (for example, to perform selection of an LED lamp depending on the mode of the lighting device (to confirm suitability), or to perform additional operations such as circuit processing and direct connection operation on the lighting device side, and the like).

(Effect of the invention)

According to the LED lamp and the illumination device including the LED lamp of the present invention, it is possible to provide an LED lamp and an illumination device including the LED lamp, which can be driven and lit by a high-frequency pulse regardless of whether the ballast of the fluorescent lamp lighting device is of a glow start type, a rapid start type, or an inverter type.

Drawings

Fig. 1 is a block diagram showing the entire circuit of a lighting device according to an embodiment of the present invention.

Fig. 2 is a circuit diagram of an LED lamp in an embodiment of the present invention.

Fig. 3 is a block diagram illustrating the interior of integrated circuit IC 1.

Fig. 4 (a) is a waveform of the input voltage Vin, fig. 4 (b) is a waveform of a voltage Vg1 of the gate terminal of the switching element Q1, fig. 4 (c) is a waveform of a current sensor terminal voltage Vcs of the integrated circuit IC1, fig. 4 (d) is a waveform of a voltage Vg2 of the gate terminal of the switching element Q2, and fig. 4 (e) is a waveform of a current i flowing through the LED light emitting unit 24.

Fig. 5 (a) is a waveform of the input voltage Vin, fig. 5 (b) is a waveform of the voltage Vg1 of the gate terminal of the switching element Q1, fig. 5 (c) is a waveform of the voltage Vcs of the current sensor terminal of the integrated circuit IC1, fig. 5 (d) is a waveform of the voltage Vg2 of the gate terminal of the switching element Q2, and fig. 5 (e) is a waveform of the current i flowing through the LED light emitting unit 24.

Fig. 6 (a) is a waveform of the input voltage Vin, fig. 6 (b) is a waveform of the voltage Vg1 of the gate terminal of the switching element Q1, fig. 6 (c) is a waveform of the voltage Vcs of the current sensor terminal of the integrated circuit IC1, fig. 6 (d) is a waveform of the voltage Vg2 of the gate terminal of the switching element Q2, and fig. 6 (e) is a waveform of the current i flowing through the LED light emitting unit 24.

Fig. 7 (a) is a diagram showing a part of a circuit in which a threshold voltage can be changed according to the magnitude of a High Voltage (HV), and fig. 7 (b) is an overall configuration diagram in which the LED lamp in the present embodiment is connected in series to a series type snap-action stabilizer.

Fig. 9 is a diagram showing an example of the series type fast stabilizer.

(description of reference numerals)

10: an illumination device; 11: plugging; 12: a stabilizer; 20. 50, 60: an LED lamp; 20a, 20b, 20c, 20 d: an input terminal section; 21: a protection circuit unit; 22: a rectifier circuit section; 23: a smoothing circuit unit; 24: an LED light emitting section; 25: a PWM control unit; 26: a bypass circuit unit; c1, C2, C9, C10, C11, C12, C20: a capacitor; c3, C4, C5: an electrolytic capacitor; c6: a1 st capacitor; c7: a2 nd capacitor; d2, D3, D4, D5, D6, D7: a diode; d8: a2 nd diode; d9: a1 st diode; d1, D10, D20: a Zener diode; z9, Z10, Z11, Z12: an input circuit section; HV: a high voltage; f1: a fuse; IC 1: an integrated circuit; l1, L2, L3, L4: a choke coil; l5: a coil; l6: a coil; q1, Q2: a switching element; r1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R20, R21, R22: a resistance; r13: a1 st resistor; r14: a2 nd resistor; SA 1: a two-pole discharge tube; SA 2: a varistor; t1, T2, T3, T4, T6, T8, T9: a terminal; t5: a ground side output terminal; t7: a High Voltage (HV) side output terminal; TA: an anode-side terminal; TK: a cathode-side terminal; TG: a GND terminal; vin: inputting a voltage; vcs: a current sensor terminal voltage; vg 1: the voltage of the gate terminal of the switching element Q1; vg 2: the voltage of the gate terminal of the switching element Q2; i: a current flowing through the LED light emitting section; t is t_OSC: period of oscillation

Detailed Description

The following describes a mode for carrying out the present invention with reference to the drawings.

(embodiment mode)

Fig. 1 is a block diagram showing the entire circuit of an illumination device in an embodiment of the present invention, fig. 2 is a circuit diagram of an LED lamp in an embodiment of the present invention, fig. 3 is a block diagram showing the inside of an integrated circuit IC1, fig. 4 (a) to (e) are voltage waveform diagrams at each measurement point when a glow start type is used as a stabilizer of an illumination device in an embodiment of the present invention, fig. 5 (a) to (e) are voltage waveform diagrams at each measurement point when a rapid start type is used as a stabilizer of an illumination device in an embodiment of the present invention, fig. 6 (a) to (e) are voltage waveform diagrams at each measurement point when an inverter type is used as a stabilizer of an illumination device in an embodiment of the present invention, fig. 7 (a) is a diagram showing a part of a circuit in which a threshold voltage can be changed according to the magnitude of a High Voltage (HV), and fig. 7 (b) is a diagram showing the entire configuration diagram in which an LED lamp in an embodiment is connected in series to a rapid stabilizer in series .

First, as shown in fig. 1, the lighting device 10 according to the embodiment of the present invention includes: the LED lamp includes a plug 11 connected to supply power from an external power source having an AC voltage of 100 to 240V (50 Hz/60 Hz) for home use, for example, a stabilizer 12 for controlling the power input from the plug 11 to light a fluorescent lamp, and an LED lamp 20 for inputting a predetermined voltage between a pair of input terminal portions (between an input terminal portion 20a and an input terminal portion 20 c) in accordance with the type of the stabilizer 12.

Here, the ballast 12 may be any one of well-known glow start, rapid start, or inverter types for lighting an existing fluorescent lamp.

Since the LED lamp 20 normally operates as long as the external power supply connected to the plug 11 has an AC voltage of 100 to 240V (50 Hz/60 Hz), there is no problem even in a configuration in which the external power is directly input to the LED lamp 20 without passing through the stabilizer 12.

Here, lines that output an alternating current from the stabilizer 12 are connected: the input may be made between either or both of a pair of input terminals (between the input terminal portion 20a and the input terminal portion 20 c) or a pair of input terminals (between the input terminal portion 20b and the input terminal portion 20 d).

On the other hand, an input circuit unit Z9 (see fig. 2) including an RC parallel circuit of a resistor R9 and a capacitor C9 is connected between the input terminal portion 20a of the LED lamp 20 and the terminal T1.

Similarly, an input circuit unit Z10 (see fig. 2) including an RC parallel circuit of a resistor R10 and a capacitor C10 is connected between the input terminal unit 20b and the terminal T1 of the LED lamp 20.

Similarly, an input circuit unit Z11 (see fig. 2) including an RC parallel circuit of a resistor R11 and a capacitor C11 is connected between the input terminal unit 20C of the LED lamp 20 and the terminal T2.

Similarly, an input circuit unit Z12 (see fig. 2) including an RC parallel circuit of a resistor R12 and a capacitor C12 is connected between the input terminal unit 20d of the LED lamp 20 and the terminal T2.

Thus, the resistance values of the resistor R9 and the resistor R10 between the input terminal portion 20a and the input terminal portion 20b are selected to be about several Ω to about 100 Ω, respectively, so as to correspond to the resistance component of the filament of the fluorescent lamp.

Similarly, the resistance values of the resistor R11 and the resistor R12 between the input terminal portion 20c and the input terminal portion 20d are selected to be about several Ω to about 100 Ω, respectively, so as to correspond to the resistance component of the filament of the fluorescent lamp.

If the resistance values of the resistors R9 to R12 are selected as described above, the resistors R9 to R12 function as dummy resistors, and thus, power is normally supplied to the LED lamp 20 even if the stabilizer 12 is of a type in which it automatically detects whether a fluorescent lamp is mounted on the load side (whether the filament resistor is on) and does not output power when the fluorescent lamp is not mounted (when the filament resistor is not on).

Further, the protection circuit portion 21 (see fig. 2) is inserted between the terminal T1 and the terminal T2.

The protection circuit unit 21 is formed by connecting a diode discharge tube SA1 filled with an inert gas such as neon or argon and a varistor SA2 in series.

By appropriately setting the discharge start voltage of the diode discharge tube SA1 and the limit voltage of the varistor SA2, the surge voltage between the terminals T1 and T2 from the power supply side can be suppressed to, for example, a peak value of about 400V or less. In addition, by combining diode discharge tube SA1 and varistor SA2 in series, varistor SA2 can effectively prevent a follow current (follow current) caused by the continued discharge of diode discharge tube SA1 after the surge voltage is over.

Thus, even if a surge or an induced surge enters from the external input power supply side, for example, the surge current is absorbed, and the surge current is prevented from entering the rectifier circuit section 22 side.

Therefore, the electronic components such as diodes and capacitors constituting the rectifier circuit unit 22 and the LED light emitting unit 24 can be protected.

Further, a coil L5 is inserted between the terminal T1 and the terminal T3 on the one input side of the rectifier circuit unit 22, and similarly, a coil L6 is inserted between the terminal T2 and the terminal T6 on the other input side of the rectifier circuit unit 22.

Thus, the coil L5 and the coil L6 act as impedances with respect to a high-frequency pulse.

Therefore, if the stabilizer 12 is of a glow start type or a rapid start type, for example, the switching noise (high-frequency noise pulse) of the switching element Q1 can be prevented from flowing out to the external ac current side (input power supply) side through any of the input terminal parts 20a to 20d by the on/off operation of the switching element Q1.

In addition, if the stabilizer 12 is of the inverter type, since the ac current of 20kHz to 100kHz at a high frequency is input, the coil L5 and the coil L6 function as loads that do not involve loss of active power (loss of reactive power).

Accordingly, if the load impedance of the LED lamp 20 falls within a predetermined range as viewed from either or both of the pair of input terminal portions (between the input terminal portion 20a and the input terminal portion 20 c) and the pair of input terminal portions (between the input terminal portion 20b and the input terminal portion 20 d), the power can be stably output from the inverter-type stabilizer 12.

In addition, the rectifier circuit portion 22 includes: a bridge diode composed of 4 diodes D4 to D7, and an electrolytic capacitor C4 and an electrolytic capacitor C5 (see fig. 2) connected in parallel to smooth the full-wave rectified waveform in the output stage.

Further, in the output-side terminal of the rectifier circuit section 22, a direct-current voltage is output between the high-voltage (HV) side output terminal T7 and the ground side output terminal T5.

The High Voltage (HV) side output terminal T7 is connected to the anode side terminal TA of the LED light emitting unit 24 via the smoothing circuit unit 23, and the cathode side terminal TK of the LED light emitting unit 24 is connected to the PWM control unit 25 via the smoothing circuit unit 23.

Here, the LED light emitting unit 24 is formed of a circuit in which 3 circuits of LED groups in which 30 LEDs (light emitting diodes) having a forward voltage of about 3V are connected in series are connected in parallel, and a current i flows in a direction (arrow direction) from the anode side terminal TA to the cathode side terminal TK.

The GND terminal TG of the PWM control unit 25 is connected to the ground-side output terminal T5 on the output side of the rectifier circuit unit 22.

With the above circuit configuration, the PWM control unit 25 PWM-controls the current i flowing through the LED light emitting unit 24 by pulse driving at a frequency higher than a predetermined frequency, and controls the current i within a predetermined current value range.

On the other hand, the bypass circuit unit 26 is connected between the cathode-side terminal TK of the LED light emitting unit 24 and the ground-side output terminal T5 of the rectifier circuit unit 22.

Thus, even when the frequency of the ac current input to the one terminal T3 of the rectifier circuit unit 22 is higher than a predetermined frequency, even if the switching element Q1 is in the on state (the state in which the current flows from the drain terminal to the source terminal, the same applies hereinafter), the resistor R3, the resistor R4, and the resistor R5 are connected in parallel between the terminal T9 and the terminal TG, so that the PWM control unit 25 is bypassed (detoured), and the current i flowing through the LED light emitting unit 24 flows directly from the cathode-side terminal TK to the ground-side output terminal T5 of the rectifier circuit unit 22 via the GND terminal TG of the PWM control unit 25.

Therefore, since the current i hardly flows to the PWM control unit 25, the current i is not PWM-controlled.

In the above and the following description, PWM control of the current i based on the duty ratio (PWM is abbreviated as PULSE WIDTH MODULATION, and the same applies hereinafter) is defined as: the period of the drive pulse is made constant, and the current i is on/off controlled based on the duty ratio of the drive pulse (the ratio of the pulse width to the pulse period is synonymous with the on duty ratio and hereinafter the same) in accordance with the magnitude of the input signal (in the present embodiment, the magnitude of the voltage detected by the #2 pin as the current sensor terminal), and the duty ratio at this time is more than 0% and less than 100%.

This stabilizes the magnitude of the current i flowing through the LED light emitting unit 24.

On the other hand, PWM control of the current i not based on the duty ratio is defined as: the PWM control unit does not perform on/off control of the current i based on the duty ratio, and includes a case where the duty ratio of the drive pulse is 0% and the switching element Q1 is always in the off state during the operation, and a case where the duty ratio of the drive pulse is 100% and the switching element Q1 is always in the on state during the operation, in addition to the case where almost no current i flows to the PWM control unit as described above.

Next, each component will be described in more detail with reference to fig. 2 and 3.

As described above, the resistor R9 between the input terminal portion 20a and the terminal T1 functions as a dummy resistor corresponding to the filament of the fluorescent lamp, and the capacitor C9 allows an ac current to pass therethrough in a normal operating state (during lighting of the LED light emitting unit 24).

Thus, since the shunt can be made in inverse proportion to the ratio of the capacitance reactance determined by the frequency of the alternating current and the capacitance of the capacitor C9 to the resistance value of the resistor R9, the heat generation of the sub-resistor R9 is suppressed.

Similarly, the resistor R11 between the input terminal portion 20C and the terminal T2 functions as a dummy resistor corresponding to a filament, and the capacitor C11 allows an alternating current to pass therethrough in a normal operation state, so that heat generation of the resistor R11 is suppressed.

The fuse F1 is used for overcurrent protection of the power supply current input to either or both of the pair of input terminals (between the input terminal portion 20a and the input terminal portion 20 c) and the pair of input terminals (between the input terminal portion 20b and the input terminal portion 20 d).

Then, the rectifier circuit unit 22 includes bridge diodes including diodes D4, D5, D6, and D7, and in the former stage, the diode D4 has an anode connected to the terminal T3 and a cathode connected to the High Voltage (HV) side output terminal T7, the diode D5 has an anode connected to the terminal T6 and a cathode connected to the High Voltage (HV) side output terminal T7, the diode D6 has an anode connected to the ground side output terminal T5 and a cathode connected to the terminal T4 having the same potential as the terminal T3, and the diode D7 has an anode connected to the ground side output terminal T5 and a cathode connected to the terminal T6.

In the subsequent stage of the bridge diode, in order to smooth the full-wave rectified waveform, the electrolytic capacitor C4 and the electrolytic capacitor C5 are connected in parallel between the high-voltage (HV) side output terminal T7 and the ground side output terminal T5, with the high-voltage (HV) side output terminal T7 side serving as a positive (+) terminal and the ground side output terminal T5 side serving as a negative (-) terminal.

Thus, the smoothed and dc output voltage is output to the High Voltage (HV) side output terminal T7 and is output to the low voltage side ground side output terminal T5.

Then, the high-voltage dc voltage output to the high-voltage (HV) side output terminal T7 is removed of the pulsating component by the smoothing circuit section 23, which is called a so-called choke coil input type smoothing circuit, and is constituted by a parallel circuit of a series circuit of choke coils L1 to L4 and an electrolytic capacitor C3 with respect to the LED light emitting section 24.

Then, the current i from which the pulsating component is removed by the smoothing circuit unit 23 flows from the anode side terminal TA to the cathode side terminal TK of the LED light emitting unit 24, and is used to cause the aforementioned 90 LEDs (light emitting diodes) constituting the LED light emitting unit 24 to emit light.

The current i passing through the smoothing circuit 23 from the LED light emitting unit 24 is passed through a predetermined oscillation period t by an integrated circuit IC1 constituting the PWM control unit 25, and resistors R1 to R8, a capacitor C1, a capacitor C2, a zener diode D1, a diode D2, and a switching element Q1 connected to the respective pins (# 1 to # 8)_OSCPulse driving of (μ s) performs PWM control.

For example, when HV9910B (see fig. 3) manufactured by SUPERTEX inc. and sold on the market is used as the integrated circuit IC1, the oscillation period t is_OSC(μ s) with a resistance value R according to the resistance R1 connected to the #8 pin_T(k Ω) is controlled by the time obtained by the following formula 1.(formula 1)

In the present embodiment, if the resistance R1 is set to about 499 (k Ω), for example, the oscillation period t is set to be the oscillation period t_OSC(. mu.s) about 20.84 (. mu.s) was determined by the above formula 1.

Therefore, if the oscillation period is about 20.84 (μ s) as calculated, a high frequency pulse drive of about 48kHz can be obtained.

The switching element Q1 for controlling on/off of the current i flowing through the LED light emitting unit 24 is an N-channel MOS FET capable of controlling the flow of current between the drain terminal and the source terminal in accordance with the input voltage to the gate terminal.

Here, in the integrated circuit IC1, the drain terminal of the switching element Q1 is connected to the anode terminal of the diode D3 constituting a part of the smoothing circuit unit 23, the source terminal is connected to the terminal T9 connected to the #2 pin as the current sensor terminal of the integrated circuit IC1 via the resistor R6, and the voltage obtained by dividing the voltage output from the #4 pin of the integrated circuit IC1 by the resistor R2 and the resistor R7, that is, the voltage of the portion corresponding to the resistor R7 is input to the gate terminal.

Further, since the #1 pin of the integrated circuit IC1 is connected to the High Voltage (HV) side output terminal T7 via the resistor R8 and the zener diode D1, the dc high voltage output from the rectifier circuit unit 22 is supplied to the #1 pin.

Thus, the voltage supplied from the pin #1 (about DC8V to about DC 450V) is reduced to a predetermined VDD voltage (about DC 12V) by an internal voltage regulator, rectified and stabilized, and is output to the pin #6 (see fig. 3) while functioning as a driving power source for the internal circuit of the integrated circuit IC 1.

With the above-described connection, if the voltage detected by the #2 pin as the current sensor terminal exceeds about DC250mV as the threshold voltage by the pulse driving of the integrated circuit IC1, a high-level (about DC7.5V) voltage is output to the gate terminal of the switching element Q1 to be in an on state, and if the voltage detected by the #2 pin as the current sensor terminal reaches about DC250mV as the threshold voltage, a low-level (about 0V) voltage is output to the gate terminal of the switching element Q1 to be in an off state (a state in which a current does not flow from the drain terminal to the source terminal, which will be the same hereinafter).

In this way, the current i flowing through the LED light emitting unit is controlled by the operation of the integrated circuit IC1 so that the period of the drive pulse of the voltage Vg1 at the gate terminal of the output switching element Q1 is constant, and the duty ratio of the pulse width of the voltage Vg1 at the gate terminal is changed in accordance with the level of the voltage (current sensor terminal voltage Vcs) detected at pin # 2.

That is, since the current i is PWM-controlled by the high-frequency pulse driving of the PWM control unit 25, the switching element Q1 repeatedly turned on/off is controlled to have the oscillation period t obtained by the above expression 1_OSCThe increase and decrease are repeated in a pulsed (triangular wave) manner (μ s).

In the present embodiment, since the #7 pin and the #6 pin are connected (shared), the voltage VDD (about DC 12V) exceeding the threshold voltage (about DC250 mV) is input to the #7 pin.

In the present embodiment, the threshold voltage to be compared with the voltage detected at pin #2, which is a current sensor terminal, is set to approximately DC250mV (see fig. 3) described above, which is generated inside the integrated circuit IC 1.

On the other hand, as the voltage input to the #7 pin of the integrated circuit IC1, if a voltage in a range not exceeding about DC250mV is set, since the voltage can set a threshold as a threshold voltage compared with the voltage detected by the current sensor terminal (# 2 pin), it is also possible to change in a direction to further reduce the duty ratio.

This also reduces the effective value (RMS value) of the current i flowing through the LED light emitting unit 24, thereby enabling dimming (light reduction).

Here, if the switching element Q1 is turned off, a reverse potential in the same direction as the current i flows is excited in the series circuit of the choke coils L1 to L4, and the diode D3 for absorbing the current caused by the reverse potential is connected from the terminal T8 of the terminal of the choke coil L1 to the anode-side terminal TA of the LED light emitting unit 24 in the forward direction.

On the other hand, as described above, the bypass circuit portion 26 is provided between the cathode-side terminal TK of the LED light emitting portion 24 and the ground-side output terminal T5 of the rectifier circuit portion 22.

The bypass circuit unit 26 includes: a switching element Q2, and a high-pass filter circuit for outputting a drive voltage (gate terminal voltage) to the switching element Q2.

Here, the switching element Q2 of the bypass circuit unit 26 is an N-channel MOS FET that controls the flow of current between a drain terminal and a source terminal in accordance with a voltage input to a gate terminal, the drain terminal is connected to the cathode-side terminal TK of the LED light emitting unit 24, the source terminal is connected to the ground-side output terminal T5 of the rectifier circuit unit 22, and the gate terminal is connected to the terminal T4 of the rectifier circuit unit 22 via a high-pass filter circuit.

The high-pass filter circuit includes: the 1 st capacitor C6; a1 st resistor R13 having a terminal connected to a terminal of the 1 st capacitor C6 and connected in series with the 1 st capacitor; a1 st diode D9 connected in a forward direction from the other terminal of the 1 st resistor R13 toward the gate terminal of the switching element Q2; a2 nd capacitor C7 connected between the source terminal and the gate terminal of the switching element Q2; a2 nd resistor R14 connected between the source terminal and the gate terminal; a zener diode D10 connected in the forward direction from the source terminal toward the gate terminal; and a2 nd diode D8 connected in a forward direction from the source terminal toward the other terminal of the 1 st resistor R13.

Then, the other terminal of the 1 st capacitor C6 is connected to any one of the input terminals (the terminal T3 or the terminal T6 via the terminal T4) of the rectifier circuit section 22.

In this high-pass filter circuit, if the circuit constants of the 1 st capacitor C6, the 1 st resistor R13, and the 2 nd resistor R14 are selected so that the ac current input to the terminal T3 is cut off at a predetermined frequency or less, the CR circuit constituted by the capacitors and the resistors functions as a high-pass filter, so that only the ac current having a frequency exceeding the predetermined frequency passes through the subsequent stage.

That is, a dc voltage is generated on the high voltage side of the 2 nd capacitor C7, the 2 nd resistor R14, and the zener diode D10 by an ac current having a frequency higher than a predetermined frequency inputted to the terminal T3, and a voltage capable of turning on the switching element Q2 is outputted to the gate terminal.

The voltage of the gate terminal may be appropriately set according to the voltage division ratio between the 1 st resistor R13 and the 2 nd resistor R14 and the zener voltage of the zener diode D10 that limits the voltage input to the gate terminal, and may be set within a high-level voltage range of the gate terminal that can turn on the switching element Q2.

Since the high-pass filter circuit is an input circuit for filtering which passes an alternating current when the frequency of the alternating current is higher than a predetermined frequency and sets the gate terminal of the switching element Q2 to a high level (for example, approximately DC 14V), the high-pass filter circuit may be connected to the terminal T6 to which the same alternating current (only 180 degrees out of phase) as the ground-side output terminal T5 of the rectifier circuit unit 22 is input.

With the above configuration, the high-pass filter circuit outputs a predetermined gate voltage at which an electric current flows from the drain terminal to the source terminal when an ac current inputted to the input terminal of the rectifier circuit section 22 is higher than a predetermined frequency (in the present embodiment, the capacity of the 1 st capacitor C6 is selected to be 100PF, the resistance value of the 1 st resistor R13 is selected to be 51k Ω, and the resistance value of the 2 nd resistor R14 is selected to be 51k Ω, and the cutoff frequency is set to be about 5kHz in actual measurement, which is the same below); when the alternating current is lower than a predetermined frequency, a gate voltage is output without flowing a current from the drain terminal to the source terminal.

That is, when the ac current input from the input terminal of the rectifier circuit unit 22 has a frequency lower than a predetermined frequency (about 5 kHz), the switching element Q2 does not allow a current to flow from the cathode-side terminal TK of the LED light emitting unit 24 to the ground-side output terminal T5 of the rectifier circuit unit 22 through the GND terminal TG of the PWM control unit 25; when the ac current input from the input terminal of the rectifier circuit portion 22 has a frequency higher than a predetermined frequency (hereinafter, referred to as a cutoff frequency, about 5 kHz), a current can flow from the cathode-side terminal TK of the LED light emitting portion 24 to the ground-side output terminal T5 of the rectifier circuit portion 22 via the GND terminal TG of the PWM control portion 25.

As a result, when the frequency of the ac current input to the outside of the pair of input terminal portions is lower than a predetermined frequency (for example, when the ac current is input from a glow starter type or a rapid start type stabilizer), the current i flowing through the LED light emitting portion 24 is PWM-controlled by the PWM control portion 25 by pulse driving at a frequency higher than the predetermined frequency, and becomes a pulse wave (triangular wave).

On the other hand, when the frequency of the ac current input to the outside of the pair of input terminal portions is higher than a predetermined frequency (for example, when the ac current is input from an inverter-type stabilizer), the PWM control unit 25 bypasses (detours) the bypass circuit unit 26, so that the current i flowing through the LED light emitting unit 24 flows to the ground side output terminal T5 of the rectifier circuit unit 22 without being PWM-controlled by the PWM control unit 25.

Therefore, since the high-frequency ac current input to the pair of input terminal portions passes only through the rectifier circuit portion 22, the smoothing circuit portion 23, and the LED light emitting portion 24, the current i flowing through the LED light emitting portion 24 is full-wave rectified into a dc waveform by the ac current input to the pair of input terminal portions (see, for example, fig. 6 (e)).

Next, referring to fig. 4 to 6, observed waveforms of the input voltage Vin of the pair of input terminal portions (between the input terminal portion 20a and the input terminal portion 20 c), the voltage Vg1 of the gate terminal of the switching element Q1, the current sensor terminal voltage Vcs as the #2 pin of the integrated circuit IC1, the voltage Vg2 of the gate terminal of the switching element Q2, and the current i flowing through the LED light emitting unit 24 will be described according to the respective modes of the stabilizer 12.

The gate terminal voltages Vg1, Vg2 and the current sensor terminal voltage Vcs are measured with reference to the GND terminal TG of the PWM control unit 25 (ground level).

The current i flowing through the LED light emitting unit 24 shown in fig. 4 (e), 5 (e), and 6 (e) is obtained by flowing the total current flowing through the LED light emitting unit 24 (90 LEDs in total) into the insertion resistor (1 Ω) and observing the voltage drop across the resistor, and the vertical axis of fig. 4 (e) and 5 (e) corresponds to 500 mA/div and the vertical axis of fig. 6 (e) corresponds to 200 mA/div.

First, fig. 4 (a) to (e) show the case where the glow-start type (secondary voltage 200V/secondary current 0.42A) is used as the stabilizer 12, fig. 4 (a) shows the waveform of the input voltage Vin, fig. 4 (b) shows the waveform of the voltage Vg1 of the gate terminal of the switching element Q1, fig. 4 (c) shows the waveform of the current sensor terminal voltage Vcs of the integrated circuit IC1, fig. 4 (d) shows the waveform of the voltage Vg2 of the gate terminal of the switching element Q2, and fig. 4 (e) shows the waveform of the current i flowing through the LED light emitting unit 24.

First, as shown in fig. 4 (a), 60.1Hz, which is the commercial frequency, is observed as the frequency of the waveform of the input voltage Vin.

Since this frequency is lower than the cutoff frequency set to about 5kHz, the actual measurement of the oscillation period t is performed as shown in fig. 4 (b) by the pulse drive output of the integrated circuit IC1 of the PWM control unit 25_OSC(μ s) is about 22.78 (μ s) of the voltage Vg1 of the gate terminal of the switching element Q1.

Here, the switching element Q1 alternately receives a high-level (about DC7.5V) and a low-level (about 0V) voltage at a duty ratio of about 33% at the gate terminal, and is pulse-driven at a frequency of about 43.9 kHz.

This is achieved by the PWM-controlled operation of the integrated circuit IC1, as shown in fig. 4 (c), outputting a high-level (about DC7.5V) voltage to the gate terminal of the switching element Q1 before the current sensor terminal voltage Vcs reaches about DC250 mV; if the current sensor terminal voltage Vcs reaches about DC250mV, a voltage of a low level (about 0V) is output to the gate terminal of the switching element Q1.

Here, if a high-level (about DC7.5V) voltage is input to the gate terminal of the switching element Q1 and the switching element Q1 is turned on, a current flows through the resistors R3 to R5, and the current i flowing through the LED light emitting unit 24 linearly increases; when a low-level (about 0V) voltage is input to the gate terminal of the switching element Q1, the switching element Q1 is turned off, and thus the current sensor terminal voltage Vcs falls to the ground level (0V).

On the other hand, since the frequency of the waveform of the input voltage Vin is lower than the cutoff frequency set to about 5kHz, as shown in fig. 4 (d), only about DC50mV is input to the gate terminal of the switching element Q2 through the high-pass filter circuit, and the switching element Q2 is turned off, and therefore no current flows from the drain terminal to the source terminal.

Therefore, as shown in fig. 4 (e), the current i flowing through the LED light emitting unit 24 flows in synchronization with the voltage Vg1 of the gate terminal of the switching element Q1, rises when the switching element Q1 is in the on state, and starts to fall when the switching element Q1 is in the off state (the current i does not immediately fall to 0A due to the reverse potential caused by the choke coils L1 to L4).

That is, as shown in fig. 4 (b), the current i flowing through the LED light emitting unit 24 is PWM-controlled by the pulse driving of the PWM control unit 25 at a frequency of about 43.9 kHz.

As a result, as shown in fig. 4 (e), the current i flowing through the LED light emitting unit 24 was output in a pulse form (triangular wave) of 43.7kHz higher than 5kHz, which is a cutoff frequency, during the frequency measurement, and about 192.2mA was observed during the effective value (RMS value) measurement.

Next, fig. 5 (a) to (e) show the case where the rapid start type (secondary voltage 190V/secondary current 0.42A) is used as the stabilizer 12, fig. 5 (a) shows the waveform of the input voltage Vin, fig. 5 (b) shows the waveform of the voltage Vg1 of the gate terminal of the switching element Q1, fig. 5 (c) shows the waveform of the current sensor terminal voltage Vcs of the integrated circuit IC1, fig. 5 (d) shows the waveform of the voltage Vg2 of the gate terminal of the switching element Q2, and fig. 5 (e) shows the waveform of the current i flowing through the LED light emitting unit 24.

First, as shown in fig. 5 (a), 60.1Hz, which is the commercial frequency, is observed as the frequency of the waveform of the input voltage Vin.

Since this frequency is lower than the cutoff frequency set to about 5kHz, the actual measurement of the oscillation period t is performed as shown in fig. 5 (b) by the pulse drive output of the integrated circuit IC1 of the PWM control unit 25_OSC(μ s) is about 22.78 (μ s) of the voltage Vg1 of the gate terminal of the switching element Q1.

Here, the switching element Q1 alternately inputs a high-level (about DC7.5V) and low-level (about 0V) voltage to the gate terminal at a duty ratio of about 33%, and is pulse-driven at a frequency of about 43.9 kHz.

This is achieved by the PWM-controlled operation of the integrated circuit IC1, as shown in fig. 5 (c), outputting a high-level (about DC7.5V) voltage to the gate terminal of the switching element Q1 before the current sensor terminal voltage Vcs reaches about DC250 mV; if the current sensor terminal voltage Vcs reaches about DC250mV, a voltage of a low level (about 0V) is output to the gate terminal of the switching element Q1.

On the other hand, since the frequency of the waveform of the input voltage Vin is lower than the cutoff frequency set to about 5kHz, as shown in fig. 5 (d), only about DC50mV is input to the gate terminal of the switching element Q2 through the high-pass filter circuit, and the switching element Q2 is turned off, and therefore no current flows from the drain terminal to the source terminal.

Therefore, as shown in fig. 5 (e), the current i flowing through the LED light emitting unit 24 flows in synchronization with the voltage Vg1 of the gate terminal of the switching element Q1, rises when the switching element Q1 is in the on state, and starts to fall when the switching element Q1 is in the off state (the current i does not immediately fall to 0A due to the reverse potential caused by the choke coils L1 to L4).

That is, as shown in fig. 5 (b), the current i flowing through the LED light emitting unit 24 is PWM-controlled by the pulse driving of the PWM control unit 25 at a frequency of about 43.9 kHz.

As a result, as shown in fig. 5 (e), the current i flowing through the LED light emitting unit 24 was output in a pulse form (triangular wave) of 43.6kHz higher than 5kHz, which is a cutoff frequency, in frequency measurement, and about 195.7mA was observed in effective value (RMS value) measurement.

Finally, fig. 6 (a) to (e) show the case where a converter type (no-load secondary voltage 280V/secondary current 0.225A) is used as the stabilizer 12, fig. 6 (a) shows the waveform of the input voltage Vin, fig. 6 (b) shows the waveform of the voltage Vg1 at the gate terminal of the switching element Q1, fig. 6 (c) shows the waveform of the current sensor terminal voltage Vcs of the integrated circuit IC1, fig. 6 (d) shows the waveform of the voltage Vg2 at the gate terminal of the switching element Q2, and fig. 6 (e) shows the waveform of the current i flowing through the LED light emitting unit 24.

First, as shown in fig. 6 (a), in the waveform of the input voltage Vin, the period t1 is about 13.7 (μ s), and 73.0kHz is observed as the frequency.

Since this frequency ratio is higher than the cutoff frequency set at about 5kHz, as shown in fig. 6 (d), a high-level (about DC 14V) voltage Vg2 is input to the gate terminal of the switching element Q2, and the switching element Q2 is always in the on state.

However, as described above, since the resistor R3, the resistor R4, and the resistor R5 are connected in parallel between the terminal T9 and the terminal TG, the current i flowing through the LED light emitting unit 24 hardly flows to the PWM control unit 25, but flows directly from the cathode-side terminal TK of the LED light emitting unit 24 to the ground-side output terminal T5 of the rectifier circuit unit 22 via the GND terminal TG of the PWM control unit 25.

As a result, since the current i does not flow through the resistors R3 to R5, the current sensor terminal voltage Vcs is at the ground level (0V) and is constant as shown in fig. 6 (c), and therefore, as shown in fig. 6 (b), the duty ratio of the drive pulse is 100%, the voltage Vg1 of the gate terminal of the switching element Q1 in the PWM control unit 25 is always at the high level (about DC7.5V), and the switching element Q1 is in the on state.

Therefore, the PWM control unit 25 does not PWM-control the current i flowing through the LED light emitting unit 24.

As shown in fig. 6 (e), the current i flowing through the LED light emitting unit 24 is not PWM-controlled by the PWM control unit 25, but is a waveform in which the input voltage Vin is full-wave rectified, and about 199.3mA is observed in the effective value (RMS value) measurement.

Since the pulse drive PWM control by PWM control unit 25 is not performed, the period t2 of the ripple voltage waveform portion superimposed on the direct current is about 6.9 (μ s), and the frequency of current i flowing through LED light emitting unit 24 is observed to be 2 times the frequency of input voltage Vin, which is about 145.4 kHz.

Therefore, it is confirmed that the frequency of the ripple voltage waveform portion of the current i flowing through the LED light emitting unit 24 is a frequency about 2 times the waveform frequency of the input voltage Vin by full-wave rectification.

As a result of the above observation, it was confirmed that, regardless of whether the ballast 12 of the lighting device 10 is of a glow-start type, a rapid-start type, or a converter type, 190mA to 200mA was obtained as an execution value (RMS value) of the current i flowing through the LED light emitting unit 24 in actual measurement, and the lighting device was able to be lit for lighting.

It was also confirmed that if the stabilizer 12 is of the glow start type or the rapid start type, the frequency of the input voltage Vin is about 60Hz, and therefore the current i flowing through the LED light emitting unit 24 is PWM-controlled by the PWM control unit 25 by pulse driving at a frequency of about 43.6 to 43.7kHz higher than 5kHz of the cutoff frequency.

On the other hand, it was confirmed that if the stabilizer 12 is of the inverter type, the frequency of the input voltage Vin is about 73.0kHz higher than 5kHz of the cutoff frequency, and therefore the current i flowing through the LED light emitting unit 24 is about 145.4kHz, and PWM control is not performed by the pulse driving of the PWM control unit 25.

The technical scope of the present invention is not limited to any of the above-described embodiments, and various modifications may be made within the scope of the claims, and modifications of the embodiments, such as those obtained by appropriately combining technical means shown in the respective different embodiments, are also included in the technical scope of the present invention.

For example, when the pair of input terminal portions includes at least one pair of input terminal portions, and 4 (two on one side) input terminal portions are shared, for example, like the terminals at both end portions of the straight tube type fluorescent lamp, it is sufficient that an external alternating current is input to at least two of the input terminal portions (either one of the two terminals on one side or both of the two terminals on both sides).

In the description of the present embodiment, when two terminals are simply connected to each other via another terminal, the two terminals are considered to be directly connected to each other (the same potential) with wiring resistance or the like being ignored.

The predetermined frequency different from the frequency of the ac current input to the pair of input terminals is preferably about 5kHz as a frequency (cutoff frequency) that can be distinguished from a commercial frequency (50 Hz/60 Hz) when the stabilizer is of a glow start type or a rapid start type and a high frequency (about 20 to 100 kHz) when the stabilizer is of an inverter type, but may be set to a desired frequency by changing a circuit constant of the high-pass filter circuit in a frequency range greater than 65Hz and smaller than 20 kHz.

Similarly, the frequency and duty ratio of the pulse driving by the PWM control unit may be set appropriately by setting the resistance, driving voltage, and the like connected to each pin within the specification of the integrated circuit IC1, taking into account the current (illuminance) flowing through the LED light emitting unit, the heat generation of the switching element of the PWM control unit, and the like.

In particular, the circuit configuration and the circuit constant in the circuit diagram to be used as reference may be appropriately selected within the range included in the technical scope of the present invention, unless otherwise apparent from the description of the above embodiments, as long as the desired object of the present invention can be achieved and the desired effect can be obtained.

As shown in fig. 7 a, a plurality of resistors R20, R21, zener diode D20 and R22 are connected in series between the High Voltage (HV) side output terminal T7 and the ground side output terminal T5, and if a DC voltage (a voltage smaller than about DC250mV and proportional to the magnitude of the High Voltage (HV)) divided by the resistor R22 is input to the #7 pin of the integrated circuit IC1, the threshold voltage may be changed in proportion to the magnitude of the voltage input to the pair of input terminal units.

For example, if 1M Ω is selected as the resistance value of the resistor R20, 1M Ω is selected as the resistance value of the resistor R21, 51V is selected as the zener voltage of the zener diode D20, 3.65k Ω is selected as the resistance value of the resistor R22, and 1 μ F is selected as the capacitance of the capacitor C20, then about 215mV is actually measured as an input at pin #7 of the integrated circuit IC1 when 165V is output to the High Voltage (HV) side output terminal T7.

In this way, since the voltage input to the pair of input terminal portions and the current flowing through the LED light emitting unit controlled by PWM increase and decrease in proportion to each other, the input impedance of the entire LED lamp is positive when viewed from the side of the pair of input terminal portions (the current flowing increases in proportion to the increase of the input voltage).

Therefore, even when the LED lamp 50 and the LED lamp 60 according to the present embodiment are connected in series in the series-type chopper as shown in fig. 7 (b), the voltage inputted from the series-type chopper is proportionally distributed according to the respective input impedances, so that the same drive current can easily flow in both of them, and the LED lamps in the present embodiment can be connected in series.

Industrial applicability of the invention

As described above, the LED lamp and the lighting device including the LED lamp according to the present invention can be used as an LED lamp and a lighting device including the LED lamp, which can be driven and lighted by a high-frequency pulse drive as long as the ballast of the lighting device for a fluorescent lamp is replaced with a fluorescent lamp (or an LED lamp) installed in the past, regardless of whether the ballast is of a glow start type, a rapid start type, an inverter type, or the like.

Claims

1. An LED lamp, comprising: a pair of input terminal portions, a rectifier circuit portion for rectifying an alternating current inputted from the outside to a direct current, and an LED light emitting portion for emitting light by energization of the direct current outputted from the rectifier circuit portion, wherein:

a PWM control unit that is provided in a circuit between the rectifier circuit unit and the LED light emitting unit and is capable of performing Pulse Width Modulation (PWM) control of a current flowing through the LED light emitting unit based on a duty ratio;

the PWM control unit performs the PWM control of the current flowing through the LED light emitting unit by pulse driving, which is pulse driving having a frequency higher than a predetermined frequency, when a frequency of an alternating current inputted to the outside of the pair of input terminal units is lower than the predetermined frequency; when the frequency of the alternating current inputted to the outside of the pair of input terminal parts is higher than the predetermined frequency, the PWM control is not performed to the current flowing in the LED light emitting part,

the predetermined frequency is a frequency greater than 65Hz and less than 20 kHz.

2. The LED lamp of claim 1, wherein:

a bypass circuit unit provided between a cathode-side terminal of the LED light emitting unit and a ground-side output terminal of the rectifier circuit unit;

the bypass circuit unit includes a switching element and a high-pass filter circuit for outputting a drive voltage of the switching element;

the switching element does not allow a current to flow from the cathode-side terminal of the LED light emitting unit to the ground-side output terminal of the rectifier circuit unit when the frequency of the ac current input to the pair of input terminal units is lower than the predetermined frequency; when the frequency of the alternating current input to the pair of input terminal portions is higher than the predetermined frequency, a current flows from the cathode-side terminal of the LED light emitting portion to the ground-side output terminal of the rectifier circuit portion.

3. The LED lamp of claim 2, wherein:

the switching element of the bypass circuit unit is an N-channel metal oxide semiconductor field effect transistor (MOS FET) that controls a flow of current between a drain terminal and a source terminal in accordance with a gate voltage input to a gate terminal;

the drain terminal is connected to the cathode-side terminal of the LED light emitting unit, and the source terminal is connected to the ground-side output terminal of the rectifier circuit unit;

the gate terminal is connected to any one of the input terminals of the rectifier circuit unit via the high-pass filter circuit;

a high-pass filter circuit configured to output a gate voltage to the gate terminal, the gate voltage being driven to cause a current to flow from the drain terminal to the source terminal when a frequency of an alternating current input to the pair of input terminal sections is higher than the predetermined frequency; when the frequency of the ac current input to the pair of input terminal portions is lower than the predetermined frequency, a gate voltage that drives the gate terminal so as not to cause a current to flow from the drain terminal to the source terminal is output to the gate terminal.

4. The LED lamp of claim 3, wherein:

the high-pass filter circuit includes:

a1 st capacitor;

a1 st resistor having one terminal connected to one terminal of the 1 st capacitor, the 1 st resistor being connected in series with the 1 st capacitor;

a1 st diode connected in a forward direction from the other terminal of the 1 st resistor to the gate terminal;

a2 nd capacitor connected between the source terminal and the gate terminal;

a2 nd resistor connected between the source terminal and the gate terminal;

a zener diode connected in a forward direction from the source terminal to the gate terminal; and

a2 nd diode connected in a forward direction from the source terminal to the other terminal of the 1 st resistor,

the other terminal of the 1 st capacitor is connected to any one of the input terminals of the rectifier circuit unit.

5. An illumination device, comprising: the LED lamp of any one of claims 1 to 4.