TWI406598B - An electronic ballast that senses the brightness of the power line - Google Patents

Abstract

The invention discloses an electronic ballast of modulating brightness by sensing power line which is applicable to fluorescent lamp. The electronic ballast comprises: a on/off sense circuit of power line for generating a on/off sense signal by applying voltage comparison operation on a direct voltage and generating a reset signal according to turn off time of the power line; a dimming voltage generator for generating a dimming voltage according to attribute value of the on/off sense signal; and a phase-control non-overlapping actuator for generating a high-side driving signal and a low-side driving signal according to the dimming voltage so as to transmit a lamp tube current wherein the dimming voltage is used to generate a phase which is used to generate the lamp tube current.

Description

Electronic ballast that senses brightness by power line sensing

The present invention relates to electronic ballasts, and more particularly to electronic ballasts that modulate brightness with power line sensing.

In the case of powering a lighting device such as a fluorescent lamp or a cold cathode ray fluorescent lamp or a compact fluorescent lamp, an electronic ballast is generally used to keep the lamp current stable.

Figure 1 shows a typical architecture of an electronic ballast with a fluorescent brightness control function. As shown in FIG. 1, the electronic ballast mainly has a full bridge rectifier 101, a V _CC starting circuit 102, an electronic ballast controller 103, NMOS transistors 104-105 and a voltage dividing circuit 106.

In this architecture, the full bridge rectifier 101 is used to rectify an AC power source to generate a main input voltage V _IN . The V _CC starting circuit 102 is coupled to the main input voltage V _{IN for} starting the generation of the DC voltage V _CC . The electronic ballast controller 103 is configured to generate a high side driving signal V _HS to drive the NMOS transistor 104 and a low side driving signal V _LS to drive the NMOS transistor in response to the voltage of the DIM input pin 3 . 105 delivers a current I _LMP to the fluorescent lamp. The NMOS transistors 104-105 are used to generate a square wave to an LC resonant network. The LC resonant network then converts the square wave to the current I _LMP to drive the fluorescent lamp.

The voltage dividing circuit 106 is coupled to a 1~10V DIM input terminal to generate a DIM control voltage at the DIM input pin 3 of the electronic ballast controller 103. The 1~10V DIM input is an additional connection to the electronic ballast. In the prior art, the 1~10V DIM input terminal is generally coupled to an additional disc switch (a dimmer switch provided on the wall) or a remote control device, so that the user must have an existing rocker switch. The additional disc switch or remote control is operated externally to trigger the electronic ballast to adjust the brightness of the fluorescent lamp.

By setting a voltage value at the input of the DIM, the NMOS transistors _{104-105 are} periodically turned on and off by the high-side driving signal V _HS and the low-side driving signal V _LS , respectively, so that the input power is The main input voltage V _{IN is} converted into the current signal I _LMP to drive the lamp, wherein the root mean square value of the current signal I _LMP corresponds to the voltage value of the DIM input terminal.

However, since conventional dimming practices must utilize an additional disk switch or a remote control device, it is not possible to complete the setting of the DIM input on the existing fluorescent light switch, so that the user must have the additional disk type. Switch or remote control for an additional fee. Moreover, since the additional disk switch may have to be mounted on the wall, the wiring between the disk switch and the ballast may also cause trouble. As for the remote control device, since the communication between the transmitter and the receiver requires electric energy, when the battery power of the remote control device is used up, the fluorescent lamp cannot be dimmed unless the battery is replaced.

Therefore, there is a need to provide a solution that enables an electronic ballast with dimming function at a lower cost and without the need for additional disk switches or remote controls. In view of this bottleneck, the present invention proposes a novel electronic ballast architecture that regulates the brightness of the fluorescent tube according to the number of times the fluorescent lamp switch is turned on and off, without any additional disc switches or remote controls.

It is an object of the present invention to provide an electronic ballast that senses brightness with power line sensing without the need for any additional disc switches or remote controls to adjust the brightness of the fluorescent lamp.

Another object of the present invention is to provide an electronic ballast with a dimming function, which controls the brightness of the fluorescent tube according to the number of times the corresponding fluorescent lamp switch is turned on and off.

Another object of the present invention is to provide an electronic ballast with a compact architecture that is fully integrated into a single chip, which can adjust the brightness of the fluorescent lamp according to the number of times the fluorescent lamp switch is turned on and off.

In order to achieve the above objects, the present invention provides an electronic ballast for controlling brightness by a power line, which is suitable for a fluorescent lamp. The electronic ballast has a power line opening and closing sensing circuit, which is used for continuous flow. The voltage is subjected to a voltage comparison operation to generate an on and off sensing signal, and to detect a filtered DC voltage that falls below a reset threshold level to generate a reset signal, wherein the DC voltage and The filtered DC voltage is obtained from a main input voltage, and the main input voltage is rectified by a power line, and the reset threshold level is higher than a minimum operating voltage of the electronic ballast; a dimming voltage a generator for generating a dimming voltage according to the count value of one of the opening and closing sensing signals, and the dimming voltage generator is reset by the reset signal when the power line is turned off for more than a predetermined time And a phase control non-overlapping driver for generating a high side driving signal and a low side driving signal to deliver a lamp current according to the dimming voltage, wherein the dimming voltage is used to generate a phase , Which is the phase for generating the lamp current.

The detailed description of the drawings and the preferred embodiments are set forth in the accompanying drawings.

Referring to FIG. 2, a block diagram of a preferred embodiment of the single-chip electronic ballast of the present invention is shown. As shown in FIG. 2, the electronic ballast has a power line on/off sensing circuit 201, a counter 202, a digital analog converter 203, and a phase control non-overlapping driver 204.

The power line on and off sensing circuit 201 is configured to perform a first voltage comparison operation on the DC voltage to generate an ON and OFF sensing signal V _CNT , and to count the turn-off time of a power line or a pair of times Filtering the DC voltage to perform a second voltage comparison operation to generate a reset signal RESET, wherein the DC voltage and the filtered DC voltage are obtained from a main input voltage V _IN , and the first voltage comparison operation can borrow a comparator Or a Schmitt trigger.

The counter 202 is configured to generate a digital count value B _n B _n-1 ... B ₁ B ₀ according to the on and off sensing signal V _CNT and the counter 202 is reset by the reset signal RESET.

The digital analog converter 203 is configured to generate a dimming voltage V _DIM according to the digital count value B _n B _n-1 ... B ₁ B ₀ . The digital analog converter 203 and the counter 202 form a dimming voltage generator for generating the tone according to the digital count value B _n B _n-1 ... B ₁ B _{0 of} the on and off sensing signal V _CNT . The photo voltage V _DIM , and the dimming voltage generator is reset by the reset signal RESET when the power line is turned off for more than a predetermined time.

The phase control non-overlapping driver 204 is configured to generate a high side driving signal V _HS and a low side driving signal V _LS according to the dimming voltage V _DIM , wherein the high side driving signal V _HS and the low side driving signal V _LS They are used to drive a high side transistor Q1 and a low side transistor Q2, respectively. The phase control non-overlapping driver 204 can be IR21592 or IR21593, and the waveform of the phase-controlled modulation luminance range is illustrated in FIG. 5. As shown, a user sets the dimmer voltage V _DIM is converted to a 5 V _MIN level, by the V _MIN is compared with the voltage level of a sawtooth signal V _CT, which is the level V _MIN is converted A phase signal Ψ _{REF is formed} , and the pulse width of the phase signal Ψ _REF corresponds to 0° to −90° to determine a lamp current I _LMP to generate a lamp brightness. The dimming range can be adjusted by selecting the values of R _MAX and R _MIN in FIG. 2 .

Please refer to FIG. 3a, which is a block diagram of a preferred embodiment of the power line on and off sensing circuit of FIG. As shown in FIG. 3a, the preferred embodiment of the present invention includes at least a capacitor 301, resistors 302-303, and comparators 304-305.

The capacitor 301 is used to filter out noise of the main input voltage V _IN .

The resistors 302-303 are used as a voltage dividing circuit to generate a DC voltage V _X according to the main input voltage V _IN .

The comparator 304 is configured to generate the on/off sensing signal V _CNT according to a sensing threshold voltage V _TH and the DC voltage V _X . The sense threshold voltage V _{TH is} preferably, for example but not limited to, 11V. Figure 3c shows the waveforms of the V _IN , V _X and V _CNT signals when the fluorescent lamp switch is turned on and off. As shown in FIG. 3c, when V _X falls below the sensing threshold voltage V _TH , the on and off sensing signal V _CNT changes from a low potential state to a high potential; when V _X climbs to the sensing threshold voltage V _TH Above, the on and off sensing signal V _CNT changes from a high potential state to a low potential.

The comparator 305 is configured to generate the reset signal RESET according to a reset threshold voltage V _LOW and a filtered DC voltage V _CC supplied to the comparator 305, wherein the reset threshold voltage V _{LOW is} , for example but not limited to, 6V Is higher than the minimum operating voltage of the electronic ballast controller. When the fluorescent lamp switch is turned off, the main input voltage is pulled low, and at the same time, the filtered DC voltage V _CC can be gradually decreased due to the charge stored by a filter capacitor. Therefore, when the fluorescent lamp switch is turned off, the filtered DC voltage V _{CC is} only lower than the reset threshold voltage V _LOW after the off time exceeds a predetermined time, for example, 1 sec, wherein the predetermined time is related to the filter capacitor value. .

Referring to FIG. 3b, a block diagram of another preferred embodiment of the power line on and off sensing circuit of FIG. 2 of the present invention is shown. As shown in FIG. 3b, the preferred embodiment of the present invention includes at least a capacitor 301, resistors 302-303, a comparator 304, a delay unit 306, and a gate 307.

The capacitor 301 is used to filter out noise of the main input voltage V _IN . The resistors 302-303 are used as a voltage dividing circuit to generate a DC voltage V _X according to the main input voltage V _IN .

The comparator 304 is configured to generate the on/off sensing signal V _CNT according to a sensing threshold voltage V _TH and the DC voltage V _X . The sense threshold voltage V _{TH is} preferably, for example but not limited to, 11V. Figure 3c shows the waveforms of the V _IN , V _X and V _CNT signals when the fluorescent lamp switch is turned on and off. As shown in FIG. 3c, when V _X falls below the sensing threshold voltage V _TH , the on and off sensing signal V _CNT changes from a low potential state to a high potential; when V _X climbs to the sensing threshold voltage V _TH Above, the on and off sensing signal V _CNT changes from a high potential state to a low potential.

The delay unit 306 is configured to delay the opening and closing of the sensing signal V _{CNT for} a predetermined time to generate a delayed signal V _CNTD .

The gate 307 is configured to generate the reset signal RESET according to the on and off sensing signal V _CNT and the delayed signal V _CNTD . When the pulse width of the on/off sensing signal V _CNT is less than the predetermined time, the reset signal RESET is kept at a low potential; when the pulse width of the on and off sensing signal V _CNT is greater than the predetermined time, the reset The signal RESET changes state to high.

4a is a block diagram of still another preferred embodiment of the power line turn-on and turn-off sensing circuit of FIG. 2 of the present invention. As shown in FIG. 4a, the preferred embodiment of the present invention includes at least a V _CC starting circuit 401, a filter capacitor 402, a comparator 403, resistors 404-405, and a comparator 406.

The V _CC starting circuit 401 is configured to generate the filtered DC voltage V _CC according to the main input voltage V _IN . The filter capacitor 402 is configured to filter out the noise of the filtered DC voltage V _CC .

The comparator 403 and the resistors 404-405 are configured to implement a Schmitt trigger to generate the on/off sensing signal V _CNT according to the filtered DC voltage V _CC . The low threshold voltage of the Schmitt trigger is set according to a UVLO (Under Voltage Lock _Out ) turn-off level V _{UVLO_OFF} , and its value is, for example but not limited to, 9V, and the high threshold voltage of the Schmitt trigger It is set according to a UVLO conduction level V _{UVLO_ON} , and its value is, for example, but not limited to, 13V. Figure 4c shows the waveforms of the V _IN , V _CC and V _CNT signals when the fluorescent lamp switch is turned on and off. When V _CC falls below the UVLO turn-off level V _{UVLO_OFF} , the turn-on and turn-off sensing signal V _CNT changes from a low potential state to a high potential; when V _CC climbs above the UVLO turn-on level V _{UVLO_ON} , the turn-on, The off sensing signal V _CNT changes from a high potential state to a low potential.

The comparator 406 is configured to generate the reset signal RESET according to a reset threshold voltage V _LOW and the filtered DC voltage V _CC , wherein the reset threshold voltage V _LOW , for example but not limited to 6V, is higher than the electronic stability The minimum operating voltage of the controller. When the fluorescent lamp switch is turned off, the main input voltage V _IN is pulled low, and at the same time, the filtered DC voltage V _CC may gradually decrease due to the charge stored by the filter capacitor 402. Therefore, when the fluorescent lamp switch is turned off, the filtered DC voltage V _CC is lower than the reset threshold voltage V _LOW only after the off time exceeds a predetermined time, for example, 1 sec, wherein the predetermined time and the filter capacitor 402 are The capacitance value is related.

4b is a block diagram of still another preferred embodiment of the power line turn-on and turn-off sensing circuit of FIG. 2 of the present invention. As shown in FIG. 4b, the preferred embodiment of the present invention includes at least a V _CC starting circuit 401, a filter capacitor 402, a comparator 403, resistors 404-405, a delay unit 407, and a gate 408.

The V _CC starting circuit 401 is configured to generate the filtered DC voltage V _CC according to the main input voltage V _IN .

The filter capacitor 402 is configured to filter out the noise of the filtered DC voltage V _CC .

The comparator 403 and the resistors 404-405 are configured to implement a Schmitt trigger to generate the on/off sensing signal V _CNT according to the filtered DC voltage V _CC . The low threshold voltage of the Schmitt trigger is set according to a UVLO (Under Voltage Lock _Out ) turn-off level V _{UVLO_OFF} , and its value is, for example but not limited to, 9V, and the high threshold voltage of the Schmitt trigger It is set according to a UVLO conduction level V _{UVLO_ON} , and its value is, for example, but not limited to, 13V. Figure 4c shows the waveforms of the V _IN , V _CC and V _CNT signals when the fluorescent lamp switch is turned on and off. When V _CC falls below the UVLO turn-off level V _{UVLO_OFF} , the turn-on and turn-off sensing signal V _CNT changes from a low potential state to a high potential; when V _CC climbs above the UVLO turn-on level V _{UVLO_ON} , the turn-on, The off sensing signal V _CNT changes from a high potential state to a low potential.

The delay unit 407 is configured to delay the opening and closing of the sensing signal V _{CNT for} a predetermined time to generate a delayed signal V _CNTD .

The gate 408 is configured to generate the reset signal RESET according to the on and off sensing signal V _CNT and the delayed signal V _CNTD . When the pulse width of the on/off sensing signal V _CNT is less than the predetermined time, the reset signal RESET is kept at a low potential; when the pulse width of the on and off sensing signal V _CNT is greater than the predetermined time, the reset The signal RESET changes state to high.

Therefore, through the implementation of the present invention, a fully integrated single-chip electronic ballast can be presented, which senses the brightness of a fluorescent lamp by sensing the number of times the fluorescent lamp is turned on and off, so the present invention with a simplified structure does overcome The shortcomings of the conventional circuit.

The disclosure of the present invention is a preferred embodiment. Any change or modification of the present invention originating from the technical idea of the present invention and being easily inferred by those skilled in the art will not deviate from the scope of patent rights of the present invention.

In summary, this case, regardless of its purpose, means and efficacy, is showing its technical characteristics that are different from the conventional ones, and its first invention is practical and practical, and it is also in compliance with the patent requirements of the invention. I will be granted a patent at an early date.

101. . . Full bridge rectifier

102, 401. . . V _CC start circuit

103. . . Electronic ballast controller

104~105. . . NMOS transistor

106. . . Voltage dividing circuit

201. . . Power line on and off sensing circuit

202. . . counter

203. . . Digital analog converter

204. . . Phase control does not overlap the driver

308. . . Non-overlapping drives

301, 402. . . Filter capacitor

302~303, 404~405. . . resistance

304~305, 403, 406. . . Comparators

306, 407. . . Delay unit

307, 408. . . Gate

FIG. 1 is a schematic diagram showing a typical architecture of an electronic ballast having a brightness adjustment function of a fluorescent lamp.

2 is a schematic block diagram showing a preferred embodiment of the electronic ballast of the present invention.

FIG. 3a is a schematic diagram showing a preferred embodiment of the power line on and off sensing circuit of FIG. 2 of the present invention.

FIG. 3b is a schematic diagram showing another preferred embodiment of the power line opening and closing sensing circuit of FIG. 2 of the present invention.

FIG. 3c is a schematic diagram showing waveforms of the V _X and V _CNT signals in FIGS. 3 a and 3 b of the present invention when the AC power source is turned on and off in succession.

4a is a schematic diagram showing another preferred embodiment of the power line on and off sensing circuit of FIG. 2 of the present invention.

FIG. 4b is a schematic diagram showing another preferred embodiment of the power line turn-on and turn-off sensing circuit of FIG. 2 of the present invention.

4c is a schematic diagram showing the waveforms of the V _CC and V _CNT signals in FIG. 4a and FIG. 4b when the AC power source is turned on and off in succession.

FIG. 5 is a schematic diagram showing the waveform of the phase-controlled modulation luminance range of FIG. 2 of the present invention.

201. . . Power line on and off sensing circuit

202. . . counter

203. . . Digital analog converter

204. . . Phase control does not overlap the driver

Claims (7)

The utility model relates to an electronic ballast for controlling brightness by a power line, which is suitable for a fluorescent lamp. The electronic ballast has a power line opening and closing sensing circuit, which is used for performing a voltage comparison operation on the DC voltage to generate an opening. And detecting a signal, and detecting a time when the filtered DC voltage drops below a reset threshold level to generate a reset signal, wherein the DC voltage and the filtered DC voltage are obtained from a master Input voltage, and the main input voltage is rectified by a power line, and the reset threshold level is higher than the minimum working voltage of the electronic ballast; a dimming voltage generator is used to open And turning off one of the sensing signals to generate a dimming voltage, and the dimming voltage generator is reset by the reset signal when the power line is turned off for more than a predetermined time; and a phase control does not overlap the driver, The method is configured to generate a high side driving signal and a low side driving signal to deliver a lamp current according to the dimming voltage, wherein the dimming voltage is used to generate a phase, and the phase is used to generate the lamp tube. The power line open and close sensing circuit has: a capacitor for filtering noise of the main input voltage; and a voltage dividing circuit for generating the DC voltage according to the main input voltage a first comparator for generating the on and off sensing signals according to the DC voltage and a sensing threshold voltage; and a second comparator for filtering the DC voltage and a weight Setting the threshold voltage generates the reset signal, wherein the level of the reset threshold voltage corresponds to a level at which the filtered DC voltage is turned off after the power line is turned off for a predetermined time. For example, in the first application of the patent scope, the power ballast senses the brightness of the electronic ballast, wherein the power line on and off sensing circuit has: a capacitor for filtering the noise of the main input voltage; a voltage dividing circuit for generating the DC voltage according to the main input voltage; a comparator for generating the current voltage according to the DC voltage and a sensing threshold voltage Turning on and off the sensing signal; a delay unit for delaying the opening and closing of the sensing signal for a predetermined time to generate a delayed signal; and a gate for the opening and closing of the sensing signal and The delayed signal produces the reset signal. For example, in the first application of the patent scope, the power ballast senses the brightness of the electronic ballast, wherein the power line on and off sensing circuit has: a moving circuit for generating the filtered DC according to the main input voltage. a capacitor, which is used to filter out the filtered DC voltage noise; a Schmitt trigger circuit for generating the on and off sensing signals according to the filtered DC voltage, wherein the Schmitt The trigger circuit has a high threshold voltage corresponding to a UVLO turn-on level, and a low threshold voltage corresponding to a UVLO turn-off level; and a comparator for filtering the DC voltage and The reset threshold voltage is generated by a reset threshold voltage, wherein the level of the reset threshold voltage corresponds to a level at which the filtered DC voltage is turned off after the power line is turned off for a predetermined time. For example, in the first application of the patent scope, the power ballast senses the brightness of the electronic ballast, wherein the power line on and off sensing circuit has: a moving circuit for generating the filtered DC according to the main input voltage. a capacitor, which is used to filter out the filtered DC voltage noise; a Schmitt trigger circuit for generating the on and off sensing signals according to the filtered DC voltage, wherein the Schmitt The trigger circuit has a high threshold voltage corresponding to a UVLO turn-on level, and a low threshold voltage corresponding to a UVLO turn-off level; a delay unit for delaying the turn-on and turn-off sensing signals The predetermined time to generate a delayed signal; and a gate and a gate for generating the signal according to the opening and closing and the delayed signal The reset signal. For example, the electronic ballast for power line sensing and adjusting brightness is in the first aspect of the patent application, wherein the dimming voltage generator has: a counter for generating a digital counter value according to the opening and closing sensing signals, And the counter is reset by the reset signal when the power line is turned off for more than the predetermined time; and a digital analog converter is configured to generate the dimming voltage according to the digital count value. For example, the electronic ballast for power line sensing and brightness adjustment is applied in the first item of the patent scope, wherein the phase control non-overlapping driver is implemented by a ballast controller IR21592. For example, in the first application of the patent scope, the power ballast senses the brightness of the electronic ballast, wherein the phase control non-overlapping driver is implemented by a ballast controller IR21593.