CN101193486A

Movatterモバイル変換

Info

Publication number: CN101193486A
Application number: CNA2006101451988A
Authority: CN
Inventors: 简焕文
Original assignee: Beyond Innovation Technology Co Ltd
Current assignee: Beyond Innovation Technology Co Ltd
Priority date: 2006-11-17
Filing date: 2006-11-17
Publication date: 2008-06-04

Abstract

The invention relates to a direct current/alternating current conversion circuit which is used for driving a load. The DC/AC conversion driving circuit includes a switching device, a resonant tank, a voltage detecting circuit and a controller. The switch device is coupled with a direct current power supply. The resonant tank is coupled to the switching device and the load, and converts the power of the DC power supply from the switching device into an AC signal to drive the load. The voltage detection circuit is coupled to the load to generate a voltage detection signal according to the voltage of the load. The controller is coupled to the voltage detection circuit and the switch device, and controls the magnitude of the power of the DC power source transmitted to the resonant tank through the switch device, wherein the controller determines whether to change the operating frequency based on the voltage detection signal.

Description

Translated fromChinese

灯管状态判断电路及其控制器Lamp status judging circuit and its controller

技术领域technical field

本发明涉及一种直流/交流转换萤光灯管驱动电路，特别是涉及一种可根据灯管状态而变频的直流/交流转换控制电路。The invention relates to a DC/AC conversion fluorescent lamp drive circuit, in particular to a DC/AC conversion control circuit capable of frequency conversion according to the state of the lamp tube.

背景技术Background technique

在典型的现有习知技术上的直流/交流转换萤光灯管驱动电路，一般简称为换流器(inverter)，大都采用全桥式的直流/交流转换电路，配合谐振槽的滤波和升压装置，可以将输入的直流电压源转换成高压的交流电，用以驱动萤光灯管。为了使萤光灯管的光源稳定，不会随着输入电压的变动而改变亮度，因此其设计上大都搭配着负回授控制电路，以稳定萤光灯管的操作电流。In the typical prior art DC/AC conversion fluorescent tube drive circuit, generally referred to as inverter (inverter), most of them adopt full-bridge DC/AC conversion circuit, and cooperate with the filtering and boosting of the resonant tank. Voltage device, which can convert the input DC voltage source into high-voltage AC power to drive fluorescent tubes. In order to stabilize the light source of the fluorescent tube and not change the brightness with the change of the input voltage, most of its designs are equipped with a negative feedback control circuit to stabilize the operating current of the fluorescent tube.

由于萤光灯管点亮前后所需的驱动电压不同，且谐振槽的增益(Vout/Vin)相对于频率的特性关系曲线也会改变，故换流器的控制器依灯管是否点亮来提供控制讯号。以往是以侦测灯管电流是否超过一定值来判断灯管点亮与否。Since the driving voltage required before and after the fluorescent tube is lit is different, and the characteristic relationship curve of the gain (Vout/Vin) of the resonant tank relative to the frequency will also change, the controller of the inverter depends on whether the fluorescent tube is lit. Provides control signals. In the past, it was judged whether the lamp was on or not by detecting whether the current of the lamp tube exceeded a certain value.

如图1，灯管驱动电路包含控制器110、开关装置120、谐振槽130、萤光灯管140、灯管电流侦测电路150及灯管电压侦测电路160。控制器110根据灯管电流侦测电路150所产生的回授讯号FB、灯管状态指示讯号CS及灯管电压侦测电路160所产生的灯管电压讯号OV来控制开关装置120的开关状态，进而控制由输入电压Vin传送至谐振槽130的电力。谐振槽130将输入电压Vin的电力转换成交流讯号，以驱动萤光灯管140。当灯管驱动电路刚起动而灯管尚未导通(点亮)时，透过回授讯号FB，使控制器控制开关装置120传送更多的电力至谐振槽130，而萤光灯管140的电压也逐渐提高。As shown in FIG. 1 , the lamp driving circuit includes acontroller 110 , aswitching device 120 , aresonance tank 130 , afluorescent lamp 140 , a lampcurrent detection circuit 150 and a lampvoltage detection circuit 160 . Thecontroller 110 controls the switch state of theswitch device 120 according to the feedback signal FB generated by the lampcurrent detection circuit 150, the lamp state indication signal CS and the lamp voltage signal OV generated by the lampvoltage detection circuit 160, Furthermore, the power transmitted from the input voltage Vin to theresonant tank 130 is controlled. Theresonance tank 130 converts the power of the input voltage Vin into an AC signal to drive thefluorescent tube 140 . When the lamp drive circuit is just started and the lamp is not turned on (lit), the controller controls theswitch device 120 to transmit more power to theresonant tank 130 through the feedback signal FB, and thefluorescent lamp 140 The voltage is also gradually increased.

当灯管电压讯号OV达到一预设值时，控制器110调节输出的电力，使萤光灯管140的电压维持在一预定驱动电压值附近。萤光灯管140在适当的预定驱动电压下经一段时间后即被点亮，此时控制器110透过判断电流侦测电路150所产生的灯管状态指示讯号CS是否高于一预定值，以进一步判断灯管是否点亮。当控制器110判断灯管点亮后立即改变频率，由较高的灯管点亮频率变换至适合灯管一般操作频率。When the lamp voltage signal OV reaches a predetermined value, thecontroller 110 adjusts the output power to maintain the voltage of thefluorescent lamp 140 near a predetermined driving voltage value. Thefluorescent lamp 140 is turned on after a certain period of time under the appropriate predetermined driving voltage. At this time, thecontroller 110 judges whether the lamp state indication signal CS generated by thecurrent detection circuit 150 is higher than a predetermined value. To further judge whether the lamp is lit. When thecontroller 110 judges that the lamp is lit, the frequency is changed immediately, from a higher lamp lighting frequency to a frequency suitable for the general operation of the lamp.

然而，参见图2，萤光灯管140和机壳170等外部装置之间会存在一等效电容Clk，造成部分灯管电流透过此等效电容Clk流出。因此，灯管电流侦测电路150的灯管状态指示讯号CS仅能代表部分灯管电流值，而非真正的灯管电流大小。如此当实际上萤光灯管140已点亮，但控制器110仍会以为萤光灯管140尚未点亮，而以点亮灯管的较高频率操作。而且电容Clk在更高频的灯管点亮频率，其阻抗较小，较多灯管电流经由等效电容Clk流出而使灯管状态的侦测更加困难。另外，萤光灯管长度越长，可能的漏电流路径也越多，这些都增加以电流判断灯管是否导通的难度。However, referring to FIG. 2 , there is an equivalent capacitor Clk between thefluorescent tube 140 and external devices such as thecasing 170 , causing part of the lamp current to flow out through the equivalent capacitor Clk. Therefore, the lamp state indication signal CS of the lampcurrent detection circuit 150 can only represent a part of the lamp current value, rather than the real lamp current. In this way, when thefluorescent tube 140 is actually turned on, thecontroller 110 still thinks that thefluorescent tube 140 has not been turned on, and operates at a higher frequency of lighting the tube. Moreover, the capacitor Clk has a smaller impedance at a higher lighting frequency of the lamp, and more lamp current flows out through the equivalent capacitor Clk, making it more difficult to detect the state of the lamp. In addition, the longer the length of the fluorescent tube, the more possible leakage current paths, all of which increase the difficulty of judging whether the tube is turned on or not based on the current.

由此可见，上述现有的直流/交流转换萤光灯管驱动电路在结构与使用上，显然仍存在有不便与缺陷，而亟待加以进一步改进。为了解决上述存在的问题，相关厂商莫不费尽心思来谋求解决之道，但长久以来一直未见适用的设计被发展完成，而一般产品又没有适切的结构能够解决上述问题，此显然是相关业者急欲解决的问题。因此如何能创设一种新型的灯管状态判断电路及其控制器，实属当前重要研发课题之一，亦成为当前业界极需改进的目标。It can be seen that the above-mentioned existing DC/AC conversion fluorescent tube drive circuit obviously still has inconveniences and defects in structure and use, and needs to be further improved urgently. In order to solve the above-mentioned problems, the relevant manufacturers have tried their best to find a solution, but for a long time no suitable design has been developed, and the general products have no suitable structure to solve the above-mentioned problems. This is obviously related. The problem that the industry is eager to solve. Therefore, how to create a new type of lamp state judging circuit and its controller is one of the current important research and development topics, and it has also become a goal that the industry needs to improve.

有鉴于上述现有的直流/交流转换萤光灯管驱动电路存在的缺陷，本发明人基于从事此类产品设计制造多年丰富的实务经验及专业知识，并配合学理的运用，积极加以研究创新，以期创设一种新型的灯管状态判断电路及其控制器，能够改进一般现有的直流/交流转换萤光灯管驱动电路，使其更具有实用性。经过不断的研究、设计，并经过反复试作样品及改进后，终于创设出确具实用价值的本发明。In view of the defects in the above-mentioned existing DC/AC conversion fluorescent tube drive circuit, the inventor actively researches and innovates based on years of rich practical experience and professional knowledge in the design and manufacture of this type of product, and cooperates with the application of theories. It is expected to create a new type of lamp state judging circuit and its controller, which can improve the general existing DC/AC conversion fluorescent lamp drive circuit and make it more practical. Through continuous research, design, and after repeated trial samples and improvements, the present invention with practical value is finally created.

发明内容Contents of the invention

本发明的主要目的在于，克服现有的直流/交流转换萤光灯管驱动电路存在的缺陷，而提供一种新型的灯管状态判断电路，所要解决的技术问题是使其提供一种直流/交流转换电路，利用侦测负载的端电压来判断负载的状态，并据此调整转换电路的操作频率，以避免现有习知以负载的电流判断负载的状态的问题，从而更加适于实用。The main purpose of the present invention is to overcome the defects existing in the existing DC/AC conversion fluorescent tube drive circuit, and provide a new type of lamp state judgment circuit. The technical problem to be solved is to provide a DC/AC conversion fluorescent tube drive circuit. The AC conversion circuit judges the state of the load by detecting the terminal voltage of the load, and adjusts the operating frequency of the conversion circuit accordingly, so as to avoid the conventional problem of judging the state of the load by the current of the load, and thus is more suitable for practical use.

本发明的另一目的在于，提供一种控制器，所要解决的技术问题是使其用以控制直流/交流转换电路。该控制器利用负载状态转换时的电压变化特性而根据负载的端电压与参考电压间的关系，判断负载的状态，并据此决定调整转换电路的操作频率。Another object of the present invention is to provide a controller, the technical problem to be solved is to use it to control a DC/AC conversion circuit. The controller judges the state of the load according to the relationship between the terminal voltage of the load and the reference voltage by using the characteristic of voltage variation when the state of the load is switched, and determines and adjusts the operating frequency of the conversion circuit accordingly.

本发明的目的及解决其技术问题是采用以下技术方案来实现的。依据本发明提出的一种直流/交流转换电路，用以驱动一负载，其特征在于该直流/交流转换驱动电路包含：一开关装置，是耦接一直流电源；一谐振槽，是耦接该开关装置与该负载，将来自该开关装置的该直流电源的电力转换成一交流讯号，以驱动该负载；一电压侦测电路，耦接该负载，以根据该负载的电压产生一电压侦测讯号；以及一控制器，是耦接该电压侦测电路及该开关装置，并透过该开关装置控制传递至该谐振槽的该直流电源的电力大小；其中，该控制器基于该电压侦测讯号来决定是否改变其操作频率。The purpose of the present invention and the solution to its technical problems are achieved by adopting the following technical solutions. A DC/AC conversion circuit proposed according to the present invention is used to drive a load, which is characterized in that the DC/AC conversion drive circuit includes: a switch device coupled to a DC power supply; a resonant tank coupled to the The switch device and the load convert the power from the DC power supply of the switch device into an AC signal to drive the load; a voltage detection circuit is coupled to the load to generate a voltage detection signal according to the voltage of the load ; and a controller, which is coupled to the voltage detection circuit and the switching device, and controls the power of the DC power supply delivered to the resonance tank through the switching device; wherein, the controller is based on the voltage detection signal to decide whether to change its operating frequency.

本发明的目的及解决其技术问题还可采用以下技术措施进一步实现。The purpose of the present invention and its technical problems can also be further realized by adopting the following technical measures.

前述的直流/交流转换电路，其中所述的控制器在该电压侦测讯号大于一第一预定值超过一第一预定时间长度后，改变其操作频率。In the aforementioned DC/AC conversion circuit, the controller changes its operating frequency after the voltage detection signal is greater than a first predetermined value for a first predetermined time period.

前述的直流/交流转换电路，其中所述的控制器在该电压侦测讯号大于一第二预定值后，开始决定是否改变其操作频率。In the aforementioned DC/AC conversion circuit, the controller starts to determine whether to change its operating frequency after the voltage detection signal is greater than a second predetermined value.

前述的直流/交流转换电路，其中所述的控制器在该电压侦测讯号大于一第三预定值后，开始决定是否改变其操作频率。In the aforementioned DC/AC conversion circuit, the controller starts to determine whether to change its operating frequency after the voltage detection signal is greater than a third predetermined value.

前述的直流/交流转换电路，其中所述的控制器更接收一调光控制讯号，并在改变操作频率的同时，开始根据该调光控制讯号来调节传递至该谐振槽的该直流电源的电力大小。The aforementioned DC/AC conversion circuit, wherein the controller further receives a dimming control signal, and starts to adjust the power of the DC power supply delivered to the resonance tank according to the dimming control signal while changing the operating frequency size.

前述的直流/交流转换电路，其中所述的控制器更基于该电压侦测讯号来决定是否停止传递该直流电源的电力至该谐振槽。In the aforementioned DC/AC conversion circuit, the controller further determines whether to stop transmitting the power of the DC power supply to the resonance tank based on the voltage detection signal.

前述的直流/交流转换电路，其中所述的控制器在一第二预定时间长度后，若决定不改变其操作频率，则停止传递该直流电源的电力至该谐振槽。In the aforesaid DC/AC conversion circuit, if the controller decides not to change its operating frequency after a second predetermined period of time, it stops transmitting the power of the DC power supply to the resonant tank.

前述的直流/交流转换电路，其特征在于更包含一第一电流侦测电路，该电流侦测电路耦接该负载，以根据该负载的电流产生一第一电流侦测讯号，其中该控制器根据该第一电流侦测讯号调整传递至该谐振槽的该直流电源的电力大小。The aforementioned DC/AC conversion circuit is characterized in that it further includes a first current detection circuit coupled to the load to generate a first current detection signal according to the current of the load, wherein the controller According to the first current detection signal, the power of the direct current power supply delivered to the resonance tank is adjusted.

前述的直流/交流转换电路，其中所述的控制器在该第一电压侦测讯号大于一第一预定值后，更基于该电压侦测讯号来决定是否改变其操作频率。In the aforementioned DC/AC conversion circuit, after the first voltage detection signal is greater than a first predetermined value, the controller further determines whether to change its operating frequency based on the voltage detection signal.

前述的直流/交流转换电路，其特征在于更包含一第二电流侦测电路，该电流侦测电路耦接该负载，以根据该负载的电流产生一灯管状态指示讯号，其中该控制器在该第一电压侦测讯号大于一第一预定值后，更基于该灯管状态指示讯号来决定是否改变其操作频率。The aforementioned DC/AC conversion circuit is characterized in that it further includes a second current detection circuit, the current detection circuit is coupled to the load, so as to generate a light tube status indication signal according to the current of the load, wherein the controller is After the first voltage detection signal is greater than a first predetermined value, it is further determined whether to change the operating frequency based on the lamp state indication signal.

本发明的目的及解决其技术问题还采用以下技术方案来实现。依据本发明提出的一种控制器，用以控制一直流/交流转换电路以驱动一负载，该控制器包含：一频率产生器，用以产生一参考讯号；一脉宽调整电路，耦接该频率产生器，并根据该参考讯号以产生一脉宽调整讯号；一驱动电路，耦接该脉宽调整电路并根据该脉宽调整讯号以产生复数个驱动讯号；以及一灯管状态判断电路，包含一第一判断电路，该第一判断电路根据一电压侦测讯号及一第一参考电压以决定是否产生一第一判断讯号；其中该频率产生器基于该第一判断讯号以决定是否调整该参考讯号的频率。The purpose of the present invention and the solution to its technical problem also adopt the following technical solutions to achieve. A controller according to the present invention is used to control a DC/AC conversion circuit to drive a load. The controller includes: a frequency generator for generating a reference signal; a pulse width adjustment circuit coupled to the A frequency generator, which generates a pulse width adjustment signal according to the reference signal; a driving circuit, which is coupled to the pulse width adjustment circuit and generates a plurality of driving signals according to the pulse width adjustment signal; and a lamp state judgment circuit, Including a first judgment circuit, the first judgment circuit determines whether to generate a first judgment signal according to a voltage detection signal and a first reference voltage; wherein the frequency generator decides whether to adjust the frequency generator based on the first judgment signal The frequency of the reference signal.

前述的控制器，其中所述的灯管状态判断电路更包含一第二判断电路，该第二判断电路根据该电压侦测讯号及一第二参考电压以决定是否产生一第二判断讯号，该频率产生器更基于该第二判断讯号以决定是否调整该参考讯号的频率。In the aforementioned controller, the lamp state judging circuit further includes a second judging circuit, and the second judging circuit determines whether to generate a second judging signal according to the voltage detection signal and a second reference voltage. The frequency generator further determines whether to adjust the frequency of the reference signal based on the second judgment signal.

前述的控制器，其中所述的第一判断电路在该电压侦测讯号大于该第一参考电压后产生该第一判断讯号。In the aforementioned controller, the first judging circuit generates the first judging signal after the voltage detection signal is greater than the first reference voltage.

前述的控制器，其中所述的第二判断电路在该电压侦测讯号大于该第二参考电压并再小于该第二参考电压时产生该第二判断讯号。In the aforementioned controller, the second judging circuit generates the second judging signal when the voltage detection signal is greater than the second reference voltage and then less than the second reference voltage.

前述的控制器，其中所述的第二判断电路在该电压侦测讯号大于该第二参考电压时产生一第一重置讯号至该第一判断电路，该第一判断电路更基于该第一重置讯号以决定是否产生该第一判断讯号。The aforementioned controller, wherein the second judging circuit generates a first reset signal to the first judging circuit when the voltage detection signal is greater than the second reference voltage, and the first judging circuit is further based on the first The reset signal is used to determine whether to generate the first judgment signal.

前述的控制器，其中所述的灯管状态判断电路更包含一第三判断电路，该第三判断电路根据该电压侦测讯号及一第三参考电压以决定是否产生一第三判断讯号，该频率产生器更基于该第三判断讯号以决定是否调整该参考讯号的频率。In the aforementioned controller, the lamp state judging circuit further includes a third judging circuit, and the third judging circuit determines whether to generate a third judging signal according to the voltage detection signal and a third reference voltage. The frequency generator further determines whether to adjust the frequency of the reference signal based on the third judgment signal.

前述的控制器，其中所述的第三判断电路在该电压侦测讯号大于该第三参考电压并再小于该第三参考电压时产生该第三判断讯号。In the aforementioned controller, the third judging circuit generates the third judging signal when the voltage detection signal is greater than the third reference voltage and lower than the third reference voltage.

前述的控制器，其中所述的第三判断电路在该电压侦测讯号大于该第三参考电压时产生一第二重置讯号至该第一判断电路，该第一判断电路更基于该第二重置讯号以决定是否产生该第一判断讯号。In the aforementioned controller, wherein the third judging circuit generates a second reset signal to the first judging circuit when the voltage detection signal is greater than the third reference voltage, the first judging circuit is further based on the second The reset signal is used to determine whether to generate the first judgment signal.

前述的控制器，其中所述的灯管状态判断电路更包含一第三判断电路，该第三判断电路根据一灯管状态指示讯号及一第二参考电压以决定是否产生一第三判断讯号，该频率产生器更基于该第三判断讯号以决定是否调整该参考讯号的频率，其中该灯管状态指示讯号是用以指示该负载的电流值。In the aforementioned controller, the lamp status judging circuit further includes a third judging circuit, and the third judging circuit determines whether to generate a third judging signal according to a lamp status indicating signal and a second reference voltage, The frequency generator further determines whether to adjust the frequency of the reference signal based on the third judgment signal, wherein the lamp status indication signal is used to indicate the current value of the load.

前述的控制器，其中所述的脉宽调整电路根据一回授讯号以及一第二参考电压产生一误差放大讯号，该第一判断电路更根据该误差放大讯号与一第三参考电压以决定是否产生该第一判断讯号。In the aforementioned controller, the pulse width adjustment circuit generates an error amplification signal according to a feedback signal and a second reference voltage, and the first judging circuit further determines whether to use the error amplification signal according to the error amplification signal and a third reference voltage Generate the first judgment signal.

前述的控制器，其特征在于更包含一计时器，该计时器在一预定时间后产生一时间到讯号。The aforementioned controller is characterized in that it further includes a timer, and the timer generates a time-out signal after a predetermined time.

前述的控制器，其特征在于更包含一保护电路，该保护电路耦接该驱动电路，用以决定是否发出一保护讯号，并基于该时间到讯号以决定是否开始运作。The aforementioned controller is characterized in that it further includes a protection circuit, which is coupled to the driving circuit, and is used to determine whether to send a protection signal, and to determine whether to start operation based on the time-out signal.

前述的控制器，其特征在于其中所述的灯管状态判断电路基于该第一判断讯号及该第二判断讯号以决定是否发出一异常讯号，该保护电路接收该异常讯号并据此发出该保护讯号。The aforementioned controller is characterized in that the lamp state judging circuit described therein determines whether to send an abnormal signal based on the first judging signal and the second judging signal, and the protection circuit receives the abnormal signal and sends out the protection circuit accordingly. signal.

前述的控制器，其特征在于更包含一调光电路，该调光讯号接收一调光控制讯号，并基于该第一判断讯号及该第二判断讯号以决定是否根据该调光控制讯号调整该复数个驱动讯号。The above-mentioned controller is characterized in that it further includes a dimming circuit, the dimming signal receives a dimming control signal, and based on the first judgment signal and the second judgment signal to determine whether to adjust the dimming signal according to the dimming control signal Multiple driving signals.

本发明与现有技术相比具有明显的优点和有益效果。由以上技术方案可知，本发明的主要技术内容如下：为了达到上述目的，本发明提供了一种直流/交流转换电路，用以驱动一负载。该直流/交流转换驱动电路包含一开关装置、一谐振槽、一电压侦测电路以及一控制器。该开关装置耦接一直流电源。该谐振槽耦接该开关装置与该负载，将来自该开关装置的该直流电源的电力转换成一交流讯号，以驱动该负载。该电压侦测电路耦接该负载，以根据该负载的电压产生一电压侦测讯号。该控制器，是耦接该电压侦测电路及该开关装置，并透过该开关装置控制传递至该谐振槽的该直流电源的电力大小，其中该控制器基于该电压侦测讯号来决定是否改变其操作频率。Compared with the prior art, the present invention has obvious advantages and beneficial effects. It can be seen from the above technical solutions that the main technical content of the present invention is as follows: In order to achieve the above purpose, the present invention provides a DC/AC conversion circuit for driving a load. The DC/AC conversion drive circuit includes a switch device, a resonant tank, a voltage detection circuit and a controller. The switch device is coupled to a DC power source. The resonant slot couples the switch device and the load, and converts the power of the DC power source from the switch device into an AC signal to drive the load. The voltage detection circuit is coupled to the load to generate a voltage detection signal according to the voltage of the load. The controller is coupled to the voltage detection circuit and the switch device, and controls the power of the DC power supply delivered to the resonant tank through the switch device, wherein the controller determines whether to change its operating frequency.

另外，为了达到上述目的，本发明另提供了一种控制器，用以控制一直流/交流转换电路以驱动一负载。该控制器包含一频率产生器、一脉宽调整电路、一驱动电路以及一灯管状态判断电路。该频率产生器是用以产生一参考讯号。该脉宽调整电路耦接该频率产生器，并根据该参考讯号以产生一脉宽调整讯号。该驱动电路耦接该脉宽调整电路并根据该脉宽调整讯号以产生复数个驱动讯号。该灯管状态判断电路包含一第一判断电路，该第一判断电路根据一电压侦测讯号及一第一参考电压以决定是否产生一第一判断讯号。其中，该频率产生器基于该第一判断讯号以决定是否调整该参考讯号的频率。In addition, in order to achieve the above object, the present invention further provides a controller for controlling a DC/AC conversion circuit to drive a load. The controller includes a frequency generator, a pulse width adjustment circuit, a driving circuit and a lamp state judging circuit. The frequency generator is used to generate a reference signal. The pulse width adjustment circuit is coupled to the frequency generator, and generates a pulse width adjustment signal according to the reference signal. The drive circuit is coupled to the pulse width adjustment circuit and generates a plurality of drive signals according to the pulse width adjustment signal. The lamp status judging circuit includes a first judging circuit, and the first judging circuit determines whether to generate a first judging signal according to a voltage detection signal and a first reference voltage. Wherein, the frequency generator determines whether to adjust the frequency of the reference signal based on the first judgment signal.

借由上述技术方案，本发明灯管状态判断电路及其控制器至少具有下列优点：发明是以灯管端电压是否超过灯管正常操作的最低可能电压V1为基础，并以超过电压V1后的一预定时间或负载电流讯号S4是否超过一预定值(使讯号S3的准位下降)，来推断或判断灯管是否起动。另一方面，本发明也利用灯管起动过程，端电压会在起动前上升，并在起动后回落的特性，以一组或以上的判断电路来判断灯管是否起动。当然，本发明也可以辅以现有习知中直接以灯管电流判断的方式来判断灯管状态。By virtue of the above-mentioned technical solution, the lamp state judging circuit and its controller of the present invention have at least the following advantages: the invention is based on whether the lamp terminal voltage exceeds the lowest possible voltage V1 for normal operation of the lamp, and is based on the voltage V1 after exceeding A predetermined time or whether the load current signal S4 exceeds a predetermined value (making the level of the signal S3 drop), to infer or judge whether the lamp is activated. On the other hand, the present invention also utilizes the characteristic that the terminal voltage rises before starting and falls back after starting during the starting process of the lamp tube, and judges whether the lamp tube is started or not with one or more judging circuits. Of course, the present invention can also be supplemented with the conventional way of directly judging the state of the lamp tube by judging the current of the lamp tube.

综上所述，本发明是有关于一种直流/交流转换电路，用以驱动一负载。该直流/交流转换驱动电路包含一开关装置、一谐振槽、一电压侦测电路以及一控制器。该开关装置耦接一直流电源。该谐振槽耦接该开关装置及该负载，将来自该开关装置的该直流电源的电力转换成一交流讯号，以驱动该负载。该电压侦测电路耦接该负载，以根据该负载的电压产生一电压侦测讯号。该控制器，是耦接该电压侦测电路及该开关装置，并透过该开关装置控制传递至该谐振槽的该直流电源的电力大小，其中该控制器基于该电压侦测讯号来决定是否改变其操作频率。本发明具有上述诸多优点及实用价值，其不论在产品结构或功能上皆有较大的改进，在技术上有显著的进步，并产生了好用及实用的效果，且较现有的直流/交流转换萤光灯管驱动电路具有增进的突出功效，从而更加适于实用，并具有产业的广泛利用价值，诚为一新颖、进步、实用的新设计。To sum up, the present invention relates to a DC/AC conversion circuit for driving a load. The DC/AC conversion drive circuit includes a switch device, a resonant tank, a voltage detection circuit and a controller. The switch device is coupled to a DC power source. The resonant tank is coupled to the switch device and the load, and converts the power of the DC power source from the switch device into an AC signal to drive the load. The voltage detection circuit is coupled to the load to generate a voltage detection signal according to the voltage of the load. The controller is coupled to the voltage detection circuit and the switch device, and controls the power of the DC power supply delivered to the resonant tank through the switch device, wherein the controller determines whether to change its operating frequency. The present invention has the above-mentioned many advantages and practical value, it has great improvement no matter in product structure or function, has remarkable progress in technology, and has produced easy-to-use and practical effect, and compared with existing DC/ The driving circuit of the AC conversion fluorescent tube has enhanced outstanding functions, so it is more suitable for practical use, and has wide application value in the industry. It is a novel, progressive and practical new design.

上述说明仅是本发明技术方案的概述，为了能够更清楚了解本发明的技术手段，而可依照说明书的内容予以实施，并且为了让本发明的上述和其他目的、特征和优点能够更明显易懂，以下特举较佳实施例，并配合附图，详细说明如下。The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable , the following preferred embodiments are specifically cited below, and are described in detail as follows in conjunction with the accompanying drawings.

附图说明Description of drawings

图1是为现有习知一种灯管驱动电路的电路示意图。FIG. 1 is a schematic circuit diagram of a conventional lamp driving circuit.

图2是为显示灯管电流的漏流路径的示意图。FIG. 2 is a schematic diagram showing the leakage path of the lamp current.

图3是为萤光灯管起动曲线的示意图。Fig. 3 is a schematic diagram of the starting curve of the fluorescent lamp.

图4是为根据本发明的一实施例的直流/交流转换电路的电路示意图。FIG. 4 is a schematic circuit diagram of a DC/AC conversion circuit according to an embodiment of the present invention.

图5是为根据本发明的一实施例的灯管状态判断电路的电路示意图。FIG. 5 is a schematic circuit diagram of a lamp status judging circuit according to an embodiment of the present invention.

图6是为根据本发明的另一实施例的灯管状态判断电路的电路示意图。FIG. 6 is a schematic circuit diagram of a lamp state judging circuit according to another embodiment of the present invention.

图7是为根据本发明的又一实施例的灯管状态判断电路的电路示意图。FIG. 7 is a schematic circuit diagram of a lamp status judging circuit according to another embodiment of the present invention.

图8是为根据本发明的再一实施例的灯管状态判断电路的电路示意图。FIG. 8 is a schematic circuit diagram of a lamp status judging circuit according to yet another embodiment of the present invention.

110：控制器 120、302：开关装置110:Controller 120, 302: Switching device

130、303：谐振槽 140、304：萤光灯管130, 303:Resonant tank 140, 304: Fluorescent tube

150：灯管电流侦测电路 160：灯管电压侦测电路150: Lamp current detection circuit 160: Lamp voltage detection circuit

Vin：输入电压 FB：回授讯号Vin: input voltage FB: feedback signal

CS：灯管状态指示讯号 OV：灯管电压讯号CS: Lamp status indication signal OV: Lamp voltage signal

Clk：等效电容 300：直流/交流转换电路Clk: equivalent capacitance 300: DC/AC conversion circuit

301：直流电压源 302A、302B：电晶体开关301:DC voltage source 302A, 302B: Transistor switch

305：变压器 306、307、308、313：电容305:transformer 306, 307, 308, 313: capacitor

310：脉宽调整电路 311：误差放大器310: Pulse width adjustment circuit 311: Error amplifier

312：比较器 314、375a、375b：或逻辑312:Comparator 314, 375a, 375b: OR logic

315、352、353：开关 316：电流源315, 352, 353: switch 316: current source

317、354：电阻 320：频率产生器317, 354: Resistor 320: Frequency generator

330：计时器 340：保护电路330: timer 340: protection circuit

341：逻辑控制电路 342、379a～379f：反相器341:logic control circuit 342, 379a～379f: inverter

343、344、355：比较器 350：调光电路343, 344, 355: Comparator 350: Dimming circuit

351：调光频率产生器 360：驱动电路351: Dimming frequency generator 360: Drive circuit

370：灯管状态判断电路 370a、370b：判断电路370: Lampstate judgment circuit 370a, 370b: Judgment circuit

371a～371e：拴锁电路 373：反及逻辑371a～371e: Latch circuit 373: Inversion and logic

374、374a：延迟电路 377a～377c：判断器374, 374a: Delaycircuit 377a～377c: Judger

S1～S18：讯号 380：电流侦测电路S1～S18: Signal 380: Current detection circuit

390：电压侦测电路 POUT、NOUT：驱动输出讯号390: Voltage detection circuit POUT, NOUT: drive output signal

V1～V3、Vref1～Vref3：参考电压V1～V3, Vref1～Vref3: reference voltage

具体实施方式Detailed ways

为更进一步阐述本发明为达成预定发明目的所采取的技术手段及功效，以下结合附图及较佳实施例，对依据本发明提出的灯管状态判断电路及其控制器其具体实施方式、结构、特征及其功效，详细说明如后。In order to further explain the technical means and effects of the present invention to achieve the intended purpose of the invention, the specific implementation and structure of the lamp state judging circuit and its controller according to the present invention will be described below in conjunction with the accompanying drawings and preferred embodiments. , features and their effects are described in detail below.

请参阅图3，是为一般萤光灯管起动可能情况，其中曲线a、e为灯管点亮失败的情况，而曲线b、c、d为点亮成功的情况。曲线a的情况为灯管损毁，故虽然提供了充足的电压Vov(灯管点亮的最大电压)，然萤光灯管依然一直无法点亮而使灯管电压一直维持在Vov。曲线b的情况为一般在比较难点亮的环境下(如：环境温度极低、极端黑暗的环境等)，萤光灯管点亮前后的电压变化，当灯管点亮后，灯管电压会快速下降至一般的操作电压区间。Please refer to FIG. 3 , which shows possible starting conditions of general fluorescent lamps, wherein curves a and e represent the cases where the lamps fail to light up, and curves b, c and d represent cases where the light tubes succeed. In the case of curve a, the lamp tube is damaged, so although a sufficient voltage Vov (the maximum voltage for lighting the lamp tube) is provided, the fluorescent tube still cannot be lit and the voltage of the lamp tube remains at Vov. The situation of curve b is generally in the environment that is difficult to light up (such as: extremely low ambient temperature, extremely dark environment, etc.), the voltage change before and after the lighting of the fluorescent tube, when the tube is lit, the voltage of the tube will quickly drop to the normal operating voltage range.

曲线c的情况为相对容易起动的环境，例如：环境温度较高、有外界光线照射、灯管状况相当良好等，因此灯管电压尚未达到Vov前就已经点亮，进而降至一般的操作电压区。曲线d的情况为最佳的情况，如：灯管状况极佳、灯管刚熄灭而灯管温度仍高、外界光照充足等，此时灯管的电压并未有如曲线b、c般经过高电压起动，而是电压一上升就直接点亮。曲线e的情况为灯管一直无法接收到足够的驱动电压以致无法点亮，造成这情况的原因有谐振槽的输出端短路等。The situation of curve c is relatively easy to start the environment, for example: the ambient temperature is high, there is external light irradiation, the lamp is in good condition, etc. Therefore, the lamp is lit before the voltage of the lamp reaches Vov, and then drops to the normal operating voltage district. The situation of curve d is the best situation, such as: the condition of the lamp is excellent, the temperature of the lamp is still high just after the lamp is extinguished, the external light is sufficient, etc. At this time, the voltage of the lamp has not passed through the high Voltage starts, but lights up directly as soon as the voltage rises. In the case of curve e, the lamp cannot receive enough driving voltage to light up. The reason for this situation is the short circuit of the output end of the resonant tank.

基于上述可能的灯管状况，本发明设定了两个电压V1及V2，其中V1为灯管在正常操作(即点亮后)的最低可能电压，V2为灯管正常操作(即点亮)的最高可能电压，利用上述两个电压来判断灯管是否点亮。如此，即可避免现有习知技艺中以灯管电流判断所面临的判断错误的问题。Based on the above-mentioned possible lamp conditions, the present invention sets two voltages V1 and V2, wherein V1 is the lowest possible voltage of the lamp in normal operation (that is, after lighting), and V2 is the normal operation (that is, lighting) of the lamp. The highest possible voltage, using the above two voltages to determine whether the lamp is lit. In this way, the problem of misjudgment faced by judging the lamp current in the prior art can be avoided.

本发明以下述的数个实施例说明可能变化的实施方式，但不以此为限。在叙述之中所提及的低准位讯号或高准位讯号，也同时可解读成该讯号在低准位等同该讯号未被产生，该讯号在高准位等同该讯号被产生，在此先予以说明。The present invention uses the following several examples to illustrate the implementation of possible changes, but it is not limited thereto. The low-level signal or high-level signal mentioned in the description can also be interpreted as that the signal is equal to the signal not being generated at the low level, and the signal is equal to the signal being generated at the high level. Here Let me explain first.

参阅图4，是为根据本发明的一实施例的直流/交流转换电路的电路示意图。直流/交流转换电路300，用以驱动萤光灯304，其包含：脉宽调整电路310、频率产生器320、计时器330、保护电路340、调光电路350、驱动电路360、灯管状态判断电路370、开关装置302、谐振槽303、电流侦测电路380及电压侦测电路390。其连接关系叙述如下。Referring to FIG. 4 , it is a schematic circuit diagram of a DC/AC conversion circuit according to an embodiment of the present invention. The DC/AC conversion circuit 300 is used to drive thefluorescent lamp 304, which includes: a pulsewidth adjustment circuit 310, afrequency generator 320, atimer 330, aprotection circuit 340, adimming circuit 350, a drivingcircuit 360, and a lampstate judgment Circuit 370 ,switch device 302 ,resonant tank 303 ,current detection circuit 380 andvoltage detection circuit 390 . Its connection relationship is described as follows.

该直流电压源301耦接至该开关装置302。该开关装置302的输出端耦接至该谐振槽303的输入端。该谐振槽303的输出端耦接至该萤光灯管304的一端。本发明中的谐振槽可以是任何种类的变压器，如磁性变压器、压电陶瓷变压器等，但亦不以此为限。该萤光灯管304的两端分别耦接至该电流侦测电路380与该电压侦测电路390。该电流侦测电路380亦耦接至该脉宽调整电路310，且该脉宽调整电路310耦接至该频率产生器320和该驱动电路360。该驱动电路360耦接至该开关装置302，形成所谓的控制回路连接。TheDC voltage source 301 is coupled to theswitching device 302 . The output terminal of theswitching device 302 is coupled to the input terminal of theresonant tank 303 . The output end of theresonant tank 303 is coupled to one end of thefluorescent tube 304 . The resonant tank in the present invention can be any kind of transformer, such as magnetic transformer, piezoelectric ceramic transformer, etc., but it is not limited thereto. Two ends of thefluorescent tube 304 are respectively coupled to thecurrent detection circuit 380 and thevoltage detection circuit 390 . Thecurrent detection circuit 380 is also coupled to the pulsewidth adjustment circuit 310 , and the pulsewidth adjustment circuit 310 is coupled to thefrequency generator 320 and the drivingcircuit 360 . The drivingcircuit 360 is coupled to theswitching device 302 to form a so-called control loop connection.

其中，在本实施例中的直流/交流转换电路为半桥式直流/交流转换电路，但本发明亦适用于全桥式、推挽式直流/交流转换电路等，并不以此为限。该开关装置302包含两个功率开关302A、302B。该功率开关302A可为一P型金氧半导体(PMOS)功率开关，该功率开关302B可为一N型金氧半导体(NMOS)功率开关，但两个功率开关302A、302B并不限于金氧半导体(MOS)功率开关，亦可为各类电晶体开关，如NPN或PNP型的BJT等。Wherein, the DC/AC conversion circuit in this embodiment is a half-bridge DC/AC conversion circuit, but the present invention is also applicable to full-bridge, push-pull DC/AC conversion circuits, etc., and is not limited thereto. Theswitching device 302 includes twopower switches 302A, 302B. Thepower switch 302A can be a P-type metal oxide semiconductor (PMOS) power switch, and thepower switch 302B can be an N-type metal oxide semiconductor (NMOS) power switch, but the twopower switches 302A and 302B are not limited to metal oxide semiconductors. The (MOS) power switch can also be various types of transistor switches, such as NPN or PNP type BJT, etc.

该频率产生器320产生同频率的一三角波讯号S1和一脉波讯号S2。然而在本发明中不限于三角波讯号的使用，凡任何斜坡(Ramp signal)或是锯齿波讯号皆适用于本发明。Thefrequency generator 320 generates a triangular wave signal S1 and a pulse wave signal S2 with the same frequency. However, the present invention is not limited to the use of the triangular wave signal, and any ramp signal or sawtooth signal is applicable to the present invention.

该电流侦测电路380与该萤光灯管304串联，并提供一负载电流讯号S4用以指示流过该萤光灯管的电流值。该电压侦测电路390透过与该萤光灯管304并联的该谐振槽303，利用其中的谐振电容307、308而检测出一负载电压讯号S5用以指示该萤光灯管304的端电压。Thecurrent detection circuit 380 is connected in series with thefluorescent tube 304 and provides a load current signal S4 for indicating the current value flowing through the fluorescent tube. Thevoltage detection circuit 390 detects a load voltage signal S5 to indicate the terminal voltage of thefluorescent lamp 304 through theresonant tank 303 connected in parallel with thefluorescent lamp 304 and theresonant capacitors 307 and 308 therein. .

该脉宽调整电路310包含一误差放大器311、一电阻317与一电容313所组成的一反相积分器以及一比较器312。另外，该脉宽调整电路310更包括一受控电流源315，其经由一开关316连接到该误差放大器311的反相端输入端。The pulsewidth adjustment circuit 310 includes anerror amplifier 311 , an inverting integrator composed of aresistor 317 and acapacitor 313 , and acomparator 312 . In addition, the pulsewidth adjustment circuit 310 further includes a controlledcurrent source 315 connected to the inverting input terminal of theerror amplifier 311 through aswitch 316 .

该保护电路340包含一逻辑控制电路341，该保护电路340接受异常讯号S13，用以指示萤光灯管端电压的该讯号S5以及该脉宽调整电路310中的误差放大器311的一误差放大讯号S3。Theprotection circuit 340 includes alogic control circuit 341. Theprotection circuit 340 receives the abnormal signal S13, the signal S5 indicating the terminal voltage of the fluorescent lamp and an error amplification signal of theerror amplifier 311 in the pulsewidth adjustment circuit 310. S3.

该调光电路350则包括一个调光频率产生器351，其产生的一三角波讯号S7被送至一比较器355的非反相输入端以及一调光控制讯号S8被送入该比较器355的反相输入端，比较后产生一调光脉波讯号S9，该调光脉波讯号S9透过控制开关352、353控制调光电压S20送出至该脉宽调整电路310的时机。Thedimming circuit 350 includes adimming frequency generator 351, a triangular wave signal S7 generated by it is sent to the non-inverting input terminal of acomparator 355 and a dimming control signal S8 is sent to thecomparator 355. The inverting input terminal generates a dimming pulse signal S9 after comparison, and the dimming pulse signal S9 controls the timing of sending the dimming voltage S20 to the pulsewidth adjustment circuit 310 through the control switches 352 and 353 .

须特别注意，在上述中详细说明保护电路340、调光电路350及脉宽调整电路310的结构，是为能清楚说明灯管状态判断电路370与耦接的各电路间的运作关系，非用以限制该些电路的结构设计。Special attention should be paid to the detailed description of the structures of theprotection circuit 340, thedimming circuit 350, and the pulsewidth adjustment circuit 310 in the above description, so as to clearly illustrate the operational relationship between the lampstate judging circuit 370 and the coupled circuits. To limit the structural design of these circuits.

该驱动电路360接收脉宽调整电路310的输出S12，并配合频率产生器320输出的脉波讯号S2以及保护电路340的输出讯号S18产生两个驱动输出讯号POUT、NOUT，用以分别控制开关装置302中的电晶体开关302A、302B。Thedrive circuit 360 receives the output S12 of the pulsewidth adjustment circuit 310, and cooperates with the pulse signal S2 output by thefrequency generator 320 and the output signal S18 of theprotection circuit 340 to generate two drive output signals POUT and NOUT to control the switching device respectively. Transistor switches 302A, 302B in 302.

在本实施例中，该计时器330产生一重设讯号S11及一时间到(TimeOut)讯号S10。重设讯号S11可以作为电路中的类比或数位电路(例如：脉宽调整电路310及逻辑控制电路341)的重设讯号，使该些电路在适当时机能重设电路而输出初始状态的讯号，避免电路在起动或其他情况产生不当的讯号，而使相对应的电路不当运作。时间到讯号S10是用以指示一般灯管起动的时间讯号。当时间到讯号S10输出时，代表正常的灯管应该是处于导通状态。而在灯管未导通前不适合运作的电路，例如保护电路340，在接收到时间到讯号S10后才开始运作。In this embodiment, thetimer 330 generates a reset signal S11 and a time-out (TimeOut) signal S10 . The reset signal S11 can be used as a reset signal for analog or digital circuits (for example: pulsewidth adjustment circuit 310 and logic control circuit 341 ) in the circuit, so that these circuits can reset the circuit at an appropriate time and output the signal of the initial state, Prevent the circuit from generating improper signals during start-up or other situations, and cause the corresponding circuit to operate improperly. The time-out signal S10 is a time signal used to indicate the start-up of general lamps. When the time is up and the signal S10 is output, it means that the normal lamp tube should be in the conduction state. The circuits that are not suitable for operation before the lamp is not turned on, such as theprotection circuit 340 , start to operate after receiving the time-up signal S10 .

频率产生器320还受到一讯号S15控制，该讯号S15是由灯管状态判断电路370所产生，用以指示萤光灯管是否已导通。在该萤光灯管304导通的情况下，送出一萤光灯管操作频率，而在该萤光灯管不导通的情况下，送出另一起动萤光灯管频率到驱动电路360。由于该谐振槽303的共振频率在萤光灯管是否导通下并不相同，这样的设计可以利用不同的萤光灯管操作频率进行不同导通情况的操作。使系统在不论萤光灯管是否导通的情况下都可以在适当的操作频率(例如：共振频率附近)下操作，使系统更有效率运作。Thefrequency generator 320 is also controlled by a signal S15, which is generated by the lampstate judging circuit 370 and used to indicate whether the fluorescent lamp is turned on. When thefluorescent tube 304 is turned on, a fluorescent tube operating frequency is sent, and when the fluorescent tube is not turned on, another starting fluorescent tube frequency is sent to thedriving circuit 360 . Since the resonant frequency of theresonant tank 303 is different when the fluorescent tube is turned on or not, such a design can utilize different operating frequencies of the fluorescent tube to operate under different conduction conditions. The system can operate at an appropriate operating frequency (for example: near the resonance frequency) regardless of whether the fluorescent tube is turned on or not, so that the system can operate more efficiently.

灯管状态判断电路370包含一第一判断电路370a及一第二判断电路370b。第一判断电路370a及第二判断电路370b分别包含判断器377b及377a。其中判断器377a是用以判断图3中的灯管起动曲线a、b、c，而判断器377b是用以判断图3中的灯管起动曲线d、e。在此实施例中，该电压侦测电路390的负载电压讯号S5为半波讯号，故判断器377a、377b是用以判断出每一半波的电压振幅高于比较电压V2、V1；当判断出讯号S5中某一周期的振幅高于比较电压时，即输出适当时间长度的高准位讯号(例如：讯号S2的一个周期或以上的时间长度)。The lampstatus judging circuit 370 includes afirst judging circuit 370a and asecond judging circuit 370b. Thefirst judging circuit 370a and thesecond judging circuit 370b include judgingunits 377b and 377a respectively. The judgingunit 377a is used for judging the lamp starting curves a, b, c in FIG. 3, and the judgingunit 377b is used for judging the lamp starting curves d, e in FIG. In this embodiment, the load voltage signal S5 of thevoltage detection circuit 390 is a half-wave signal, so the judgingdevices 377a, 377b are used to judge that the voltage amplitude of each half-wave is higher than the comparison voltage V2, V1; When the amplitude of a certain period of the signal S5 is higher than the comparison voltage, a high-level signal of an appropriate time length is output (for example, a period or more of the time length of the signal S2).

灯管状态判断电路370分别输出讯号S13及S15，其中讯号S13传递给保护电路340，使保护电路340根据讯号S13来判断是否停止驱动电路360作用。而讯号S15传递给调光电路350及频率产生器320，调光电路350根据讯号S15以决定是否进行调光，而频率产生器320根据讯号S15以决定是否进行变频。一般而言，频率产生器320改变操作频率的同时，调光电路350开始调光(调节传递至该谐振槽303的该直流电源301的电力大小)。The lampstate judging circuit 370 outputs signals S13 and S15 respectively, wherein the signal S13 is transmitted to theprotection circuit 340, so that theprotection circuit 340 judges whether to stop the drivingcircuit 360 according to the signal S13. The signal S15 is transmitted to thedimming circuit 350 and thefrequency generator 320, thedimming circuit 350 determines whether to perform dimming according to the signal S15, and thefrequency generator 320 determines whether to perform frequency conversion according to the signal S15. Generally speaking, when thefrequency generator 320 changes the operating frequency, thedimming circuit 350 starts dimming (adjusting the power of theDC power supply 301 delivered to the resonant tank 303 ).

在正常状况下，本实施例更详细的操作如下所述：Under normal conditions, the more detailed operation of this embodiment is as follows:

当系统开始供电起动后，该计时器330产生重设讯号S11经过一或(OR)逻辑314将一开关316导通(turn on)，使得该电流源315连到该误差放大器311的反相输入端，强迫反相输入端电压高过一参考位准Vref1。如此可迫使该误差放大器311输出为零，以使得脉宽调整电路310的输出S12的工作周期变成0％。这0％的输出S12讯号经过如本实施例的驱动电路360后使得POUT及NOUT的工作周期都变成0％，进而使开关302A、302B截止(turn off)。After the system starts to supply power, thetimer 330 generates a reset signal S11 to turn on aswitch 316 through an ORlogic 314, so that thecurrent source 315 is connected to the inverting input of theerror amplifier 311 terminal, forcing the voltage of the inverting input terminal to be higher than a reference level Vref1. In this way, the output of theerror amplifier 311 can be forced to be zero, so that the duty cycle of the output S12 of the pulsewidth adjustment circuit 310 becomes 0%. After the 0% output S12 signal passes through the drivingcircuit 360 of this embodiment, the duty cycles of POUT and NOUT both become 0%, and then theswitches 302A and 302B are turned off.

当该计时器330在一预定时间后停止输出重设讯号S11，该电流源开关316截止。此时，该脉宽调整电路310开始运作，该误差放大器311的反相端输入因为该萤光灯管304尚未导通而成为一低于该参考位准Vref1的状况。该误差放大器311所输出的该讯号S3，在负回授控制原理之下逐渐上升，而在与该三角波S1比较后，由该比较器312送出一脉波宽度调变讯号S12。该驱动电路360接收此该讯号S12和该脉波讯号S2，产生两组讯号POUT、NOUT，分别用以控制开关装置302中的电晶体开关302A、302B的截止或导通，以调整输出到萤光灯管304的电力。该脉波宽度调变讯号S12工作周期的逐渐变宽而升高，故萤光灯管304的驱动电压也将逐渐上升。When thetimer 330 stops outputting the reset signal S11 after a predetermined time, thecurrent source switch 316 is turned off. At this time, the pulsewidth adjustment circuit 310 starts to operate, and the inverting terminal input of theerror amplifier 311 becomes a state lower than the reference level Vref1 because thefluorescent tube 304 is not turned on. The signal S3 output by theerror amplifier 311 rises gradually under the principle of negative feedback control, and after being compared with the triangular wave S1, thecomparator 312 sends out a pulse width modulation signal S12. Thedrive circuit 360 receives the signal S12 and the pulse signal S2, and generates two sets of signals POUT, NOUT, which are respectively used to control the cut-off or conduction of the transistor switches 302A, 302B in theswitching device 302, so as to adjust the output to the firefly The power of thelight tube 304. The duty cycle of the pulse width modulation signal S12 gradually becomes wider and higher, so the driving voltage of thefluorescent tube 304 will also gradually rise.

当如图3的曲线b的情况，谐振槽303输出至萤光灯管304的驱动电压将逐渐上升。当萤光灯304的电压高于比较电压V1而低于比较电压V2时，灯管状态判断电路370中的判断器377a输出低准位讯号而判断器377b输出高准位讯号。延迟电路374接收判断器377b的高准位讯号后，将在一预定时间延迟后输出高准位讯号。另外，拴锁电路371c接收判断器377a的低准位讯号后，并输出一低准位讯号，透过反相器379a而输出一高准位讯号至拴锁电路371b，使拴锁电路371b处于重设状态而失去作用。As shown in curve b of FIG. 3 , the driving voltage output from theresonant tank 303 to thefluorescent tube 304 will gradually increase. When the voltage of thefluorescent lamp 304 is higher than the comparison voltage V1 and lower than the comparison voltage V2, thejudge 377a in the lampstate judgment circuit 370 outputs a low level signal and thejudge 377b outputs a high level signal. Thedelay circuit 374 outputs a high level signal after a predetermined time delay after receiving the high level signal from thedeterminer 377b. In addition, thelatch circuit 371c outputs a low-level signal after receiving the low-level signal from thejudger 377a, and outputs a high-level signal to thelatch circuit 371b through theinverter 379a, so that thelatch circuit 371b is in the Resetting the state has no effect.

随后萤光灯304的电压高过比较电压V2，判断器377a亦开始输出高准位讯号。拴锁电路371c一旦接收判断器377a的高准位讯号后，将持续输出一高准位讯号。延迟电路374原则上会在该预定时间延迟内接收到拴锁电路371c的高准位讯号后处于重设状态而失去作用。Then the voltage of thefluorescent lamp 304 is higher than the comparison voltage V2, and thejudge 377a also starts to output a high level signal. Once thelatch circuit 371c receives the high-level signal from thejudge 377a, it will continuously output a high-level signal. In principle, thedelay circuit 374 will be in a reset state after receiving the high-level signal of thelatch circuit 371c within the predetermined time delay and lose its function.

另一方面，反相器379a开始输出一低准位讯号至拴锁电路371b，因此拴锁电路371b开始作用。同一时间，判断器377a的高准位讯号经反相器379b而变成低准位讯号，故此时拴锁电路371b也输出低准位讯号。由于或逻辑375a此时的两个输入讯号均为低准位讯号而输出低准位讯号。另外，计时器330的时间到讯号S10还处于低准位，经反相器379c而使拴锁电路371a处于重设状态而失去作用，因此，或逻辑375b的两个输入讯号也均为低准位讯号而输出低准位讯号。On the other hand, theinverter 379a starts to output a low-level signal to thelatch circuit 371b, so thelatch circuit 371b starts to function. At the same time, the high-level signal of the judgingdevice 377a becomes a low-level signal through theinverter 379b, so thelatch circuit 371b also outputs a low-level signal at this time. Since the two input signals of the ORlogic 375 a are both low-level signals at this time, the output is a low-level signal. In addition, the time-out signal S10 of thetimer 330 is still at a low level, and thelatch circuit 371a is in a reset state through theinverter 379c and thus loses its function. Therefore, the two input signals of the ORlogic 375b are also at a low level. bit signal and output a low level signal.

萤光灯管304的驱动电压最后上升至一预定灯管起动电压Vov后，该保护电路340中的比较器343在侦测到该指示萤光灯管端电压讯号S5超过一预设的参考位准Vref2，并送出一萤光灯管端电压超过讯号S16，透过该或逻辑闸314使该开关316导通(Turn On)，该电流源315的电流将流入该误差放大器311的反相输入端，把该误差放大器311输出S3变小，然后减少该脉波宽度调变讯号S12工作周期，以减少输送到该萤光灯管端的电力。然后，当侦测到指示萤光灯管端电压讯号S5小于该预设的参考电位Vref2，则该电流源开关316截止，使得该误差放大器311输出S3变大。于是该萤光灯管端电压就在这样的负回授控制之下得到稳定调节，以持续维持在该预定灯管起动电压Vov附近。After the driving voltage of thefluorescent tube 304 finally rises to a predetermined starting voltage Vov, thecomparator 343 in theprotection circuit 340 detects that the terminal voltage signal S5 of the fluorescent tube exceeds a preset reference level. quasi Vref2, and send a fluorescent lamp terminal voltage exceeding signal S16, through theOR logic gate 314 to make theswitch 316 conduction (Turn On), the current of thecurrent source 315 will flow into the inverting input of theerror amplifier 311 terminal, the output S3 of theerror amplifier 311 is reduced, and then the duty cycle of the pulse width modulation signal S12 is reduced to reduce the power delivered to the fluorescent tube terminal. Then, when it is detected that the fluorescent lamp terminal voltage signal S5 is lower than the preset reference potential Vref2, thecurrent source switch 316 is turned off, so that the output S3 of theerror amplifier 311 becomes large. Thus, the terminal voltage of the fluorescent lamp is stably regulated under such negative feedback control, so as to be continuously maintained near the predetermined starting voltage Vov of the fluorescent lamp.

一旦萤光灯管被足够的驱动电压Vov和时间下被点燃导通，根据萤光灯管特性，该萤光灯管端电压S16会骤降至一半不到的导通且近似固定的操作电压，该操作电压如图3的曲线b所示介于电压V1和V2之间。此时，灯管状态判断电路370中的判断器377a的输出变成低准位讯号，经反相器379b而输出高准位讯号。拴锁电路371b接收反相器379b的高准位讯号后，持续输出高准位讯号。此时或逻辑375a也输出高准位讯号，而或逻辑375b亦输出高准位的讯号S15，指示萤光灯管304已导通。该频率产生器320接收到该指示灯管导通讯号S15后改变讯号S1、S2的频率为一般灯管操作频率。而调光电路350接收该指示灯管导通讯号S15后，开始进行调光功能。Once the fluorescent tube is ignited and turned on with sufficient driving voltage Vov and time, according to the characteristics of the fluorescent tube, the terminal voltage S16 of the fluorescent tube will suddenly drop to less than half of the turned-on and approximately constant operating voltage , the operating voltage is between voltages V1 and V2 as shown in curve b of FIG. 3 . At this time, the output of thejudging unit 377a in the lampstate judging circuit 370 becomes a low level signal, and the output is a high level signal through theinverter 379b. Thelatch circuit 371b continuously outputs the high level signal after receiving the high level signal from theinverter 379b. At this time, theOR logic 375a also outputs a high-level signal, and theOR logic 375b also outputs a high-level signal S15, indicating that thefluorescent tube 304 is turned on. Thefrequency generator 320 changes the frequency of the signals S1 and S2 to the normal operating frequency of the lamp after receiving the signal S15 for turning on the lamp. Thedimming circuit 350 starts to perform the dimming function after receiving the conduction signal S15 of the indicator lamp.

当如图3的曲线c的情况时，将类似于上述曲线b的情况，其差异仅在萤光灯管304的驱动电压未到达电压Vov而使电流源开关316的负回授控制不会起动，故在此不再累述。When the situation of the curve c in Fig. 3 is similar to the situation of the above curve b, the difference is only that the negative feedback control of thecurrent source switch 316 will not start when the driving voltage of thefluorescent tube 304 does not reach the voltage Vov. , so it will not be repeated here.

当如图3的曲线d的情况时，萤光灯管304的驱动电压并不会超过电压V2，故判断器377a的输出一直为低准位讯号，经拴锁电路371c及反相器379a后产生一高准位讯号，使拴锁电路371b一直处于重设状态而失去作用。当延迟电路374接收判断器377b的高准位讯号后，在一预定时间延迟后输出高准位讯号，使或逻辑375a也输出高准位讯号。或逻辑375b接收到或逻辑375a的高准位讯号后亦输出高准位的讯号S15，指示萤光灯管304已导通。In the case of the curve d in Figure 3, the driving voltage of thefluorescent tube 304 will not exceed the voltage V2, so the output of the judgingdevice 377a is always a low level signal, after passing through thelatch circuit 371c and theinverter 379a A high level signal is generated so that thelatch circuit 371b is always in the reset state and loses its function. When thedelay circuit 374 receives the high-level signal from thejudge 377b, it outputs a high-level signal after a predetermined time delay, so that theOR logic 375a also outputs a high-level signal. After receiving the high-level signal of theOR logic 375a, the ORlogic 375b also outputs a high-level signal S15, indicating that thefluorescent lamp 304 is turned on.

延迟电路374的预定时间延迟为一般萤光灯管足够被起动的时间，可以和时间到讯号S10同时或短于时间到讯号S10。当短于时间到讯号S10时，而萤光灯管304并未真正被起动，则当频率产生器320接收到该指示灯管导通讯号S15后改变讯号S1、S2的频率为一般灯管操作频率时，萤光灯管304的端电压会低于电压V1，使讯号S15再度回到低准位。因此，频率产生器320会再改变讯号S1、S2的频率为灯管起动频率，再度尝试起动萤光灯管304，直到萤光灯管304真正起动或时间到讯号S10产生为止。The predetermined time delay of thedelay circuit 374 is enough time for general fluorescent lamps to be activated, which can be the same time as the time-up signal S10 or shorter than the time-up signal S10 . When the time is shorter than the signal S10, and thefluorescent tube 304 is not actually activated, thefrequency generator 320 changes the frequency of the signals S1 and S2 to normal lamp operation after receiving the signal S15 for turning on the indicator tube. frequency, the terminal voltage of thefluorescent tube 304 will be lower than the voltage V1, so that the signal S15 returns to the low level again. Therefore, thefrequency generator 320 will change the frequency of the signals S1 and S2 to the lamp start frequency again, and try to start thefluorescent lamp 304 again until thefluorescent lamp 304 is actually started or the signal S10 is generated until the time is up.

若萤光灯管起动过程为异常状况，而造成如图3的曲线a、e时，灯管状态判断电路370的详细操作过程如下：If the starting process of the fluorescent tube is abnormal, resulting in the curves a and e shown in Figure 3, the detailed operation process of the lampstatus judging circuit 370 is as follows:

当如图3的曲线a的情况时，萤光灯管端电压上升至到电压Vov的过程如上述曲线b所述，在此不重复。然后，由于萤光灯管一直无法被起动，萤光灯管端电压一直维持在电压Vov附近。延迟电路374一直处在重设状态而失去作用；拴锁电路371b则一直输出低准位讯号。因此，讯号S15也将一直处于代表萤光灯管未导通的低准位讯号。In the case of the curve a in FIG. 3 , the process of the terminal voltage of the fluorescent lamp rising to the voltage Vov is as described in the curve b above, and will not be repeated here. Then, since the fluorescent tube cannot be started all the time, the terminal voltage of the fluorescent tube remains near the voltage Vov. Thedelay circuit 374 is always in the reset state and loses its function; thelatch circuit 371b always outputs a low level signal. Therefore, the signal S15 will always be at a low level signal representing that the fluorescent tube is not turned on.

当如图3的曲线e的情况时，由于灯管端电压一直未能超过电压V1而使判断器377a、377b一直输出低准位电压，故延迟电路374亦一直输出低准位电压，而拴锁电路371b则是一直处于重设状态而失去作用。因此，讯号S15也将一直处于代表萤光灯管未导通的低准位讯号。As shown in the case of curve e in Figure 3, since the lamp terminal voltage has not exceeded the voltage V1, thejudges 377a, 377b have been outputting low-level voltages, so thedelay circuit 374 has always output low-level voltages, and the tie Thelock circuit 371b is always in the reset state and loses its function. Therefore, the signal S15 will always be at a low level signal representing that the fluorescent tube is not turned on.

拴锁电路371a在时间到讯号S10发出前处在重置状态而无作用。当萤光灯管304在时间到讯号S10发出前起动成功，则时间到讯号S10发出后透过反相器379c使拴锁电路371a开始运作，此时拴锁电路371a接收到或逻辑375a的高准位讯号后，将发出并锁住于高准位讯号。这样的情况下，灯管状态判断电路370在时间到讯号S10发出后，讯号S15并会锁住于代表灯管起动的高准位讯号。然，若萤光灯管304未在时间到讯号S10发出前起动成功，则灯管状态判断电路370在时间到讯号S10发出后，会输出代表灯管未起动的低准位讯号。Thelatch circuit 371a is in a reset state and has no effect before the time-out signal S10 is sent out. When thefluorescent tube 304 starts successfully before the time-out signal S10 is sent out, thelatch circuit 371a starts to operate through theinverter 379c after the time-out signal S10 is sent out, and at this time thelatch circuit 371a receives the high of theOR logic 375a After the level signal, it will send out and lock in the high level signal. In this case, after the time-out signal S10 is sent out by the lampstate judging circuit 370, the signal S15 will be locked at a high level signal representing lamp activation. However, if thefluorescent lamp 304 fails to start successfully before the time-out signal S10 is sent out, the lampstate judging circuit 370 will output a low-level signal representing that the lamp is not started after the time-out signal S10 is sent out.

另外，灯管状态判断电路370会发出讯号S13通知保护电路340萤光灯管304的状态。保护电路340在接收时间到讯号S10后开始执行保护功能。若萤光灯管304在时间到讯号S10发出前起动，则萤光灯管304的端电压必大于电压V1而使判断器377b发出高准位讯号，而或逻辑375a也输出高准位讯号。因此反及(NAND)逻辑373的两输入讯号均为高准位讯号而输出代表萤光灯管状态正常的低准位讯号。然，当萤光灯管304虽正常起动，却在使用中熄灭，致使端电压低于电压V1，则反及逻辑373的输出代表萤光灯管状态异常的高准位的讯号S13，致使保护电路340也输出高准位的保护讯号S18。驱动电路360接收高准位的保护讯号S18后，会开关停止开关装置302继续传送直流电压源301的电力至谐振槽303。In addition, the lampstate judging circuit 370 sends a signal S13 to notify theprotection circuit 340 of the state of thefluorescent lamp 304 . Theprotection circuit 340 starts to perform the protection function after receiving the time-up signal S10. If thefluorescent lamp 304 starts before the time-out signal S10 is sent out, the terminal voltage of thefluorescent lamp 304 must be greater than the voltage V1, so that thejudge 377b sends a high-level signal, and theOR logic 375a also outputs a high-level signal. Therefore, the two input signals of theNAND logic 373 are both high-level signals and output a low-level signal representing the normal state of the fluorescent tube. However, when thefluorescent tube 304 starts up normally, but goes out during use, causing the terminal voltage to be lower than the voltage V1, then the output of theinverse logic 373 represents the high-level signal S13 indicating that the status of the fluorescent tube is abnormal, causing the protection Thecircuit 340 also outputs a high-level protection signal S18. After receiving the high-level protection signal S18 , thedrive circuit 360 switches and stops theswitching device 302 to continue transmitting the power of theDC voltage source 301 to theresonant tank 303 .

另一方面，若萤光灯管304未能在时间到讯号S10发出前起动，375a输出低准位讯号，故反及逻辑373的输出代表萤光灯管状态异常的高准位的讯号S13，致使开关装置302停止传送电力至谐振槽303。On the other hand, if thefluorescent lamp 304 fails to start before the time-out signal S10 is sent out, 375a outputs a low-level signal, so the output of theinverse logic 373 represents a high-level signal S13 indicating that the state of the fluorescent lamp is abnormal. Theswitch device 302 stops transmitting power to theresonant tank 303 .

另外，保护电路340利用一数位计时单元以低频的调光频率产生器351产生的一脉波讯号S6计时。在接收到代表萤光灯管状态异常的高准位讯号S13后开始计时，一旦超过预设的时间而讯号S13依然维持在高准位讯号，则该逻辑控制电路341送出停止输出的讯号S18到该驱动电路360。如此，可避免调光电路350运作时，误判该萤光灯管304熄灭。In addition, theprotection circuit 340 uses a digital timing unit to time the pulse signal S6 generated by the low-frequencydimming frequency generator 351 . After receiving the high-level signal S13 representing the abnormal state of the fluorescent tube, the timing starts. Once the preset time is exceeded and the signal S13 remains at the high-level signal, thelogic control circuit 341 sends a signal S18 to stop the output to Thedrive circuit 360 . In this way, when thedimming circuit 350 is in operation, it is avoided that thefluorescent lamp 304 is extinguished by mistake.

此外，在一般操作的情形下若遇到该变压器305有漏电严重损坏时，因为漏电造成的额外的负载效应，将使得系统产生过负载现象。在这状况下，该误差放大器311将持续增加其输出S3以提供足够的电力至负载稳定萤光灯管电流。一旦漏电已经超过系统所能提供得最大电力时，该误差放大器311输出S3势必超过该三角波S1的峰值。该保护电路340将该误差放大器311输出S3与一比三角波S1峰值略高的一参考电位Vref3相比可以得到一指示系统是否过载讯号S14。同样，在该计时器330以S10起动该保护电路340的情形下，如果指示系统是否过载讯号S14指示系统过载，且经过该逻辑控制电路341以频率产生器320产生的该脉波讯号S2计时也超过预设时间时，则该逻辑控制电路341送出停止输出的讯号S18到该驱动电路360。In addition, in normal operation, if thetransformer 305 is severely damaged due to leakage, the system will be overloaded due to the additional load effect caused by the leakage. In this situation, theerror amplifier 311 will continue to increase its output S3 to provide enough power to the load to stabilize the fluorescent tube current. Once the leakage current exceeds the maximum power that the system can provide, the output S3 of theerror amplifier 311 must exceed the peak value of the triangular wave S1. Theprotection circuit 340 compares the output S3 of theerror amplifier 311 with a reference potential Vref3 slightly higher than the peak value of the triangular wave S1 to obtain a signal S14 indicating whether the system is overloaded. Similarly, when thetimer 330 activates theprotection circuit 340 with S10, if the signal S14 indicates that the system is overloaded, and the pulse signal S2 generated by thefrequency generator 320 through thelogic control circuit 341 is also timed. When the preset time is exceeded, thelogic control circuit 341 sends a signal S18 to stop the output to thedriving circuit 360 .

本实施例更包括一调光电路350，调光的原理是用一比萤光灯管操作频率低的频率S7，控制停止或恢复对萤光灯管输送电力。利用明暗比例的调整达到调整萤光灯管亮度的目地，而为了避免频率过低造成人眼闪烁的感受，一般都将调光频率控制在大于200Hz以上。本实施例的调光电路350是被指示萤光灯管是否导通讯号S15所控制。当该指示萤光灯管是否导通讯号S15指示萤光灯管导通，控制调光讯号输出的一开关353才会导通(Turn on)。This embodiment further includes adimming circuit 350. The principle of dimming is to use a frequency S7 lower than the operating frequency of the fluorescent lamp to control stop or resume power delivery to the fluorescent lamp. The brightness of fluorescent tubes can be adjusted by adjusting the light-to-dark ratio. In order to avoid flickering in the human eye due to low frequency, the dimming frequency is generally controlled above 200Hz. Thedimming circuit 350 of this embodiment is controlled by the signal S15 indicating whether the fluorescent tube is turned on. When the signal S15 indicating whether the fluorescent tube is turned on indicates that the fluorescent tube is turned on, a switch 353 for controlling the output of the dimming signal will be turned on (Turn on).

调光电路350中的调光电压S20是一比参考位准Vref1更高的电位。当调光电路中的调光电压S20经控制开关353、352与一电阻354与该脉宽调整电路310连接上时，该脉宽调整电路310的误差放大器311输出S3变小，造成系统停止电力输送至负载。而当调光脉波讯号S9截止(Turn Off)该开关352时，调光电压S20与该脉宽调整电路310开路(open circuit)，系统恢复电力供应。利用一低频率控制每一周期中停止或恢复电力供应的比例可以达到调整亮度的效果。而利用萤光灯管导通与否决定调光开始的时机，可以保障萤光灯管有足够而且连续的电力在足够的时间内被点燃。The dimming voltage S20 in thedimming circuit 350 is a potential higher than the reference level Vref1. When the dimming voltage S20 in the dimming circuit is connected to the pulsewidth adjustment circuit 310 through the control switches 353, 352 and aresistor 354, the output S3 of theerror amplifier 311 of the pulsewidth adjustment circuit 310 becomes smaller, causing the system to stop power delivered to the load. And when the dimming pulse signal S9 is turned off (Turn Off) the switch 352, the dimming voltage S20 and the pulsewidth adjustment circuit 310 are open circuited, and the power supply of the system is resumed. Using a low frequency to control the ratio of stopping or resuming power supply in each cycle can achieve the effect of adjusting brightness. Using whether the fluorescent tube is turned on or not determines the timing to start dimming, which can ensure that the fluorescent tube has sufficient and continuous power to be ignited within a sufficient time.

在本实施例中，调光电路350是耦接至脉宽调整电路310中误差放大器311的反相输入端而达到调光功能。然实际上，调光讯号可以传送至驱动电路360、或耦合至比较器312等的耦接方式达到调光功能，此为熟知本领域的普通知识者所熟知。In this embodiment, thedimming circuit 350 is coupled to the inverting input terminal of theerror amplifier 311 in the pulsewidth adjustment circuit 310 to achieve the dimming function. However, in practice, the dimming signal can be transmitted to thedriving circuit 360 or coupled to thecomparator 312 to achieve the dimming function, which is well known to those skilled in the art.

由于萤光灯管起动过程的端电压变化会随着环境温度、光照情况、萤光灯管的种类及萤光灯管的状态而有所不同，为了避免利用灯管电压的判断灯管起动有任何误判的机会，可以将现有习知的灯管状态指示讯号CS加以辅助判断萤光灯管的状态。Since the terminal voltage changes during the starting process of fluorescent tubes will vary with the ambient temperature, light conditions, types of fluorescent tubes, and the state of fluorescent tubes, in order to avoid using the lamp voltage to judge the starting of the fluorescent tubes For any chance of misjudgment, the conventional lamp state indicator signal CS can be used to assist in judging the state of the fluorescent lamp.

参阅图5，为根据本发明的灯管状态判断电路370的另一实施例。与图4的实施例相比较，灯管状态判断电路370多了判断器377c，用以将灯管状态指示讯号CS与一参考电压Vref4进行比较，其中该灯管状态指示讯号CS是为侦测萤光灯管304的电流的侦测讯号。当灯管状态指示讯号CS超过参考电压Vref4后，发出高准位的讯号S17，使经或(OR)逻辑375a、375b后输出高准位的讯号S15。当萤光灯管的起动重如图3的曲线d所示，则在延迟电路374的预定时间延迟未到前，灯管已经起动；或者电压V2的设定过低，无法侦测到萤光灯管304端电压在起动后回落至电压V1及V2之间，透过灯管状态指示讯号CS的辅助判断可避免上述问题。由于现有习知的灯管电流会因漏电流而不易测量出的问题，相较于现有习知技艺，本实施例是以灯管电流的侦测讯号为辅来判断，故仍可避免了因漏电流而造成的误判。Referring to FIG. 5 , it is another embodiment of the lampstatus judging circuit 370 according to the present invention. Compared with the embodiment shown in FIG. 4 , the lampstatus judging circuit 370 has anadditional judger 377c for comparing the lamp status indication signal CS with a reference voltage Vref4, wherein the lamp status indication signal CS is for detecting The detection signal of the current of thefluorescent tube 304 . When the lamp state indication signal CS exceeds the reference voltage Vref4, a high-level signal S17 is sent out, so that a high-level signal S15 is output after theOR logic 375a, 375b. When the starting of the fluorescent tube is as shown in the curve d of Figure 3, the fluorescent tube has already started before the predetermined time delay of thedelay circuit 374; or the setting of the voltage V2 is too low to detect the fluorescent tube. The voltage at the terminal of thelamp 304 drops back to between the voltages V1 and V2 after starting, and the above-mentioned problem can be avoided by assisting judgment of the lamp status indicating signal CS. Due to the problem that the existing known lamp current is not easy to measure due to the leakage current, compared with the prior art, this embodiment uses the detection signal of the lamp current as a supplementary judgment, so it can still be avoided. Misjudgment caused by leakage current is eliminated.

参阅图6，为根据本发明的灯管状态判断电路370的又一实施例。与图4的实施例相比较，灯管状态判断电路370多了反相器379d、379e及拴锁电路371d，其用以根据讯号S14来判断灯管是否起动。由于灯管若已经起动，则负载电流讯号S4会提高，而使误差放大器311的输出讯号S3低于保护电路340中比较器344的参考电压Vref3，使讯号S14为低准位。换句话说，灯管起动后，因为有回授讯号S4的存在，使讯号S3的准位小于三角波讯号S1的波峰准位。Referring to FIG. 6 , it is another embodiment of the lampstate judging circuit 370 according to the present invention. Compared with the embodiment in FIG. 4 , the lampstatus judging circuit 370 hasmore inverters 379 d , 379 e and alatch circuit 371 d for judging whether the lamp is activated according to the signal S14 . Since the lamp has been started, the load current signal S4 will increase, so that the output signal S3 of theerror amplifier 311 is lower than the reference voltage Vref3 of the comparator 344 in theprotection circuit 340, so that the signal S14 is at a low level. In other words, after the lamp is started, the level of the signal S3 is lower than the peak level of the triangular wave signal S1 due to the existence of the feedback signal S4.

在此实施例中，延迟电路374a的预定延迟时间是根据电容313由误差放大器311充电，使讯号S3的准位由三角波讯号S1的波谷准位充电至参考电压Vref3的准位所需的时间。当经过该预定延迟时间后，透过反相器379d，使拴锁电路371d由重置状态回到正常运作状态。此时只要萤光灯管304起动，使讯号S14为低准位，则透过反相器379e输出高准位讯号。如此，拴锁电路371d的输出讯号即可锁住于高准位，而使灯管状态判断电路370输出代表萤光灯管导通的高准位讯号S15。In this embodiment, the predetermined delay time of thedelay circuit 374a is based on the time required for the level of the signal S3 to be charged from the valley level of the triangular wave signal S1 to the level of the reference voltage Vref3 according to thecapacitor 313 being charged by theerror amplifier 311 . After the predetermined delay time passes, thelatch circuit 371d is returned from the reset state to the normal operation state through theinverter 379d. At this time, as long as thefluorescent lamp 304 is activated and the signal S14 is at a low level, theinverter 379e outputs a high level signal. In this way, the output signal of thelatch circuit 371d can be locked at a high level, so that the lampstate judging circuit 370 outputs a high-level signal S15 representing that the fluorescent lamp is turned on.

参阅图7，为根据本发明的灯管状态判断电路370的再一实施例。其是如图6的实施例般，以讯号S14来判断萤光灯管是否起动，不同处在于判断结果是用以决定是否使延迟电路374进入重设状态。当讯号S5超过电压V1，并经延迟电路374a的预定延迟时间后发出高准位讯号。透过反相器379e，拴锁电路371d开始正常运作。此时若，讯号S14仍为高准位，则透过反相器379d、拴锁电路371d及反相器379f输出高准位讯号。如此，或逻辑375c输出高准位讯号依然在重设状态。如此，可避免延迟电路374的预定延迟时间到了而推断灯管已经起动，使频率产生器320变频后才又判断出灯管实际上仍为起动而使频率产生器320又变为灯管起动频率的情况。Referring to FIG. 7 , it is another embodiment of the lampstatus judging circuit 370 according to the present invention. Like the embodiment in FIG. 6 , the signal S14 is used to judge whether the fluorescent tube is activated, but the difference is that the judgment result is used to determine whether to make thedelay circuit 374 enter the reset state. When the signal S5 exceeds the voltage V1 and passes through the predetermined delay time of thedelay circuit 374a, a high level signal is sent out. Through theinverter 379e, thelatch circuit 371d starts to operate normally. At this time, if the signal S14 is still at the high level, the high level signal is output through theinverter 379d, thelatch circuit 371d and theinverter 379f. In this way, the ORlogic 375c outputs a high-level signal and is still in the reset state. In this way, it can be avoided that the predetermined delay time of thedelay circuit 374 arrives and it is inferred that the lamp tube has started, and thefrequency generator 320 is judged that the lamp tube is actually still started after the frequency conversion of thefrequency generator 320, so that thefrequency generator 320 becomes the lamp tube starting frequency again. Case.

参阅图8，为根据本发明的灯管状态判断电路370的又一实施例。由于灯管起动过程端电压的变化会随各种状况而有不同，图4中的实施例以电压V2来判断灯管端电压是否曾超过后又回落来判断，若电压V2的选择不适当会造成判断上的困难。故可以增加多组的判断电压，以判断灯管电压在起动前的超过某一电压值而在起动后回落而至该电压值之下的特性。图8中是增加判断器377c及相对应的拴锁电路371d、371e及反相器379d、379e来判断讯号S5及电压V3间的变化关系。其判断过程如同图4中电压V2的判断过程，在此不再累述。Referring to FIG. 8 , it is another embodiment of the lampstate judging circuit 370 according to the present invention. Because the change of the terminal voltage of the lamp tube will vary with various conditions, the embodiment in Fig. 4 judges whether the voltage of the lamp tube terminal has been exceeded by the voltage V2 and then falls back. If the selection of the voltage V2 is inappropriate, it will cause difficulties in judgment. Therefore, multiple sets of judging voltages can be added to judge the characteristic that the lamp voltage exceeds a certain voltage value before starting and falls back below the voltage value after starting. In FIG. 8, a judgingunit 377c, correspondinglatch circuits 371d, 371e andinverters 379d, 379e are added to judge the variation relationship between the signal S5 and the voltage V3. The judging process is similar to the judging process of the voltage V2 in FIG. 4 , and will not be repeated here.

以上所述，仅是本发明的较佳实施例而已，并非对本发明作任何形式上的限制，虽然本发明已以较佳实施例揭露如上，然而并非用以限定本发明，任何熟悉本专业的技术人员，在不脱离本发明技术方案范围内，当可利用上述揭示的技术内容作出些许更动或修饰为等同变化的等效实施例，但凡是未脱离本发明技术方案的内容，依据本发明的技术实质对以上实施例所作的任何简单修改、等同变化与修饰，均仍属于本发明技术方案的范围内。The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, can use the technical content disclosed above to make some changes or modify equivalent embodiments with equivalent changes, but all the content that does not depart from the technical solution of the present invention, according to the present invention Any simple modifications, equivalent changes and modifications made to the above embodiments by the technical essence still belong to the scope of the technical solutions of the present invention.