KR20050120901A - Analog dimming circuit with temperature compensation - Google Patents
Analog dimming circuit with temperature compensation Download PDFInfo
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- KR20050120901A KR20050120901A KR1020040046015A KR20040046015A KR20050120901A KR 20050120901 A KR20050120901 A KR 20050120901A KR 1020040046015 A KR1020040046015 A KR 1020040046015A KR 20040046015 A KR20040046015 A KR 20040046015A KR 20050120901 A KR20050120901 A KR 20050120901A
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
- G05F1/565—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor
- G05F1/567—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for temperature compensation
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F3/00—Non-retroactive systems for regulating electric variables by using an uncontrolled element, or an uncontrolled combination of elements, such element or such combination having self-regulating properties
- G05F3/02—Regulating voltage or current
- G05F3/08—Regulating voltage or current wherein the variable is dc
- G05F3/10—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics
- G05F3/16—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics being semiconductor devices
- G05F3/20—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics being semiconductor devices using diode- transistor combinations
- G05F3/22—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics being semiconductor devices using diode- transistor combinations wherein the transistors are of the bipolar type only
- G05F3/222—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics being semiconductor devices using diode- transistor combinations wherein the transistors are of the bipolar type only with compensation for device parameters, e.g. Early effect, gain, manufacturing process, or external variations, e.g. temperature, loading, supply voltage
- G05F3/225—Regulating voltage or current wherein the variable is dc using uncontrolled devices with non-linear characteristics being semiconductor devices using diode- transistor combinations wherein the transistors are of the bipolar type only with compensation for device parameters, e.g. Early effect, gain, manufacturing process, or external variations, e.g. temperature, loading, supply voltage producing a current or voltage as a predetermined function of the temperature
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/14—Circuit arrangements
- H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
- H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
- H05B41/282—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices
- H05B41/2821—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices by means of a single-switch converter or a parallel push-pull converter in the final stage
- H05B41/2822—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices by means of a single-switch converter or a parallel push-pull converter in the final stage using specially adapted components in the load circuit, e.g. feed-back transformers, piezoelectric transformers; using specially adapted load circuit configurations
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/14—Circuit arrangements
- H05B41/36—Controlling
- H05B41/38—Controlling the intensity of light
- H05B41/39—Controlling the intensity of light continuously
- H05B41/392—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor
- H05B41/3921—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations
- H05B41/3927—Controlling the intensity of light continuously using semiconductor devices, e.g. thyristor with possibility of light intensity variations by pulse width modulation
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Automation & Control Theory (AREA)
- Power Engineering (AREA)
- Nonlinear Science (AREA)
- Discharge-Lamp Control Circuits And Pulse- Feed Circuits (AREA)
Abstract
본 발명은 주위온도 변화에 의한 밝기의 변화를 보상하도록 한 온도보상 기능 갖는 아날로그 디밍회로를 제공하는데 그 목적이 있다.An object of the present invention is to provide an analog dimming circuit having a temperature compensation function to compensate for a change in brightness caused by a change in ambient temperature.
본 발명의 온도보상 기능 갖는 아날로그 디밍회로는, 동작전압(Vcc)단에서 접지로 직렬 연결된 제1,제2 저항(R1,R2)과, 상기 제1,제2 저항(R1,R2)의 접속노드를 디밍 전압(Vd)단에 연결하는 입력 저항(RI)을 포함하는 바이어스 저항부(110); 상기 바이어스 저항부(110)의 제2 저항(R2)에 연결된 애노드단과, 접지에 연결된 캐소드단을 갖는 다이오드(D1); 및 상기 바이어스 저항부(110)의 제1,제2 저항(R1,R2)의 접속노드에 연결된 베이스단과, 이미터 저항(RE)을 통해 집지에 연결된 에미터 단과, 출력단에 연결된 컬렉터단을 갖는 트랜지스터(Q10)를 구비하는 것을 특징으로 한다.The analog dimming circuit having a temperature compensation function according to the present invention includes a connection between the first and second resistors R1 and R2 connected in series to the ground at an operating voltage Vcc, and the first and second resistors R1 and R2. A bias resistor unit 110 including an input resistor RI connecting a node to a dimming voltage Vd terminal; A diode (D1) having an anode terminal connected to the second resistor (R2) of the bias resistor unit (110) and a cathode terminal connected to ground; And a base terminal connected to the connection nodes of the first and second resistors R1 and R2 of the bias resistor unit 110, an emitter terminal connected to the collector through the emitter resistor RE, and a collector terminal connected to the output terminal. It is characterized by including the transistor Q10.
이러한 본 발명에 의하면, 주위온도 변화에 관계없이 밝기(brightness) 조절을 안정적으로 수행할 수 있는 효과가 있다.According to the present invention, there is an effect that can be performed stably the brightness (brightness) control regardless of the change in the ambient temperature.
Description
본 발명은 LCD 모니터 및 TV의 백라이트 인버터에 적용되는 아날로그 디밍회로(Analog Dimming circuit)에 관한 것으로, 특히 주위온도 변화에 의한 밝기의 변화를 보상하도록 함으로써, 주위온도 변화에 관계없이 밝기(brightness) 조절을 안정적으로 수행할 수 있는 온도보상 기능 갖는 아날로그 디밍회로에 관한 것이다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analog dimming circuit applied to a backlight inverter of an LCD monitor and a TV, and in particular, to compensate for a change in brightness due to a change in ambient temperature, thereby adjusting brightness regardless of a change in ambient temperature. It relates to an analog dimming circuit having a temperature compensation function capable of performing a stable.
일반적으로, LCD 모니터 및 TV의 백라이트(Back Light) 인버터는 백라이트에 적용된 램프의 동작 및 그 밝기를 제어하는데, 이 인버터에 사용되는 램프는 CCFL(Cold Cathode Flourscent Lamp, 냉음극형광램프), EEFL(External Electrode Flourscent Lamp, 외부전극형광램프) 등이 있다. 그리고, 이러한 인버터는 피드백 제어방식이 적용되어 설정된 밝기로 제어할 수 있고, 또한, 사용자의 밝기 조절(Dimming)에 따라 밝기를 임의로 조절할 수도 있다.In general, the back light inverters of LCD monitors and TVs control the operation of the lamps applied to the backlight and their brightness. The lamps used in these inverters are CCFL (Cold Cathode Flourscent Lamp) and EEFL ( External Electrode Flourscent Lamp, etc.). In addition, the inverter may be controlled to the set brightness by applying a feedback control method, and may also arbitrarily adjust the brightness according to the user's dimming.
이러한 종래의 백라이트 인버터중의 하나가 도 1에 도시되어 있다.One such conventional backlight inverter is shown in FIG. 1.
도 1은 종래의 백라이트 인버터의 구성도로서, 도 1에 도시된 백라이트 인버터는 피드백전압 및 디밍 전압에 따라 펄스폭 변조(Pulse Width Modulation,PWM) 방식으로 듀티를 제어하는 PWM IC(11)와, 상기 PWM IC(11)의 펄스폭 변조 방식의 듀티 제어에 따라 40kHz~60kHz의 범위내의 주파수를 갖는 구형파 전압을 생성하는 스위칭 회로부(12)와, 상기 스위칭 회로부(12)로부터의 구형파 전압을 1차 및 2차의 권선비로 승압하고, 구형파 전압을 교류 전압으로 변환하는 트랜스포머(13)와, 상기 트랜스포머(13)로부터의 교류전압에 의해 동작되는 램프부(14)와, 상기 램프부(14)에 흐르는 전류를 검출하여 피드백 전압을 상기 PWM IC(11)에 제공하는 피드백 회로부(15)와, 사용자의 밝기 선택에 해당되는 아날로그 디밍 전압(Vd)에 따라 상기 피드백 회로부(15)로부터의 피드백 전압(Vfd)을 조절하는 아날로그 디밍회로(16)를 포함한다.FIG. 1 is a block diagram of a conventional backlight inverter, and the backlight inverter illustrated in FIG. 1 includes a PWM IC 11 controlling a duty in a pulse width modulation (PWM) scheme according to a feedback voltage and a dimming voltage. The switching circuit section 12 for generating a square wave voltage having a frequency in the range of 40 kHz to 60 kHz according to the duty control of the pulse width modulation method of the PWM IC 11, and the square wave voltage from the switching circuit section 12 as a primary. And a transformer 13 for boosting at a secondary winding ratio and converting a square wave voltage into an alternating voltage, a lamp unit 14 operated by an alternating voltage from the transformer 13, and the lamp unit 14; A feedback circuit unit 15 which detects a flowing current and provides a feedback voltage to the PWM IC 11 and a feedback voltage from the feedback circuit unit 15 according to an analog dimming voltage Vd corresponding to a user's brightness selection. Joe Vfd It includes an analog dimming circuit 16 for.
이와 같은 종래의 아날로그 디밍회로중의 하나가 도 2에 도시되어 있다.One such conventional analog dimming circuit is shown in FIG.
도 2는 종래의 아날로그 디밍회로도로서, 도 2에 도시된 아날로그 디밍부는 바이어스 저항(R0,R1,R2,R3)과 트랜지스터(Q1)로 이루어져 있다. 상기 트랜지스터(Q1)의 컬렉터단을 통해 피드백회로부 및 PWM IC와 연결되어 있으며, 상기 PWM IC로 공급되는 피드백 전압(Vfd)을 조절한다.FIG. 2 is a conventional analog dimming circuit diagram. The analog dimming unit illustrated in FIG. 2 includes bias resistors R0, R1, R2, and R3 and a transistor Q1. It is connected to a feedback circuit unit and a PWM IC through a collector terminal of the transistor Q1, and adjusts a feedback voltage Vfd supplied to the PWM IC.
이러한 아날로그 디밍회로에 대한 동작을 살펴보면, 상기 디밍 전압(Vd)에 따라 상기 트랜지스터(Q1)를 통해 흐르는 전류가 제어되어 도 3에 도시된 바와 같이 상기 피드백 전압(Vfd)이 조절된다. 예를 들어, 디밍전압이 높아지면, 상기 트랜지스터(Q1)의 베이스전류가 증가하게 되고, 이에 따라 상기 트랜지스터(Q1)의 컬렉터에서 에미터로 흐르는 전류가 증가하면서 피드백 전압이 낮아지게 된다. 즉, 도 3에 도시된 바와 같이 디밍전압이 높아지면 피드백 전압을 낮아지게 한다.Referring to the operation of the analog dimming circuit, the current flowing through the transistor Q1 is controlled according to the dimming voltage Vd to adjust the feedback voltage Vfd as shown in FIG. 3. For example, as the dimming voltage increases, the base current of the transistor Q1 increases, thereby increasing the current flowing from the collector of the transistor Q1 to the emitter, thereby lowering the feedback voltage. That is, as shown in FIG. 3, when the dimming voltage is increased, the feedback voltage is decreased.
도 3은 디밍전압-피드백전압 상관 그래프이다.3 is a dimming voltage-feedback voltage correlation graph.
도 3을 참조하여 디밍전압-피드백전압 상관 관계를 설명하면, 대략 0V~3.4V 범위에서 가변되는 디밍전압(Vd)이 높아지면 피드백 전압(Vfd)은 낮아지고, 반대로 디밍전압(Vd)이 낮아지면 피드백 전압(Vfd)은 높아진다.Referring to FIG. 3, when the dimming voltage-feedback voltage correlation is explained, when the dimming voltage Vd, which is variable in the range of approximately 0V to 3.4V, is high, the feedback voltage Vfd is low, and conversely, the dimming voltage Vd is low. Ground feedback voltage Vfd becomes high.
그러나, 이러한 종래의 아날로그 디밍회로는, 주위온도 변화에 민감하여, 주위온도가 변화면 피드백 전압을 변화시켜 밝기를 변화시키는 문제점이 있다.However, such a conventional analog dimming circuit is sensitive to a change in the ambient temperature, and there is a problem of changing the brightness by changing the feedback voltage when the ambient temperature changes.
즉, 이러한 종래의 아날로그 디밍회로에 포함된 트랜지스터(Q1)는 도 4에 도시한 바와 같이 주위온도 1℃ 상승시 마다 베이스-에미터 전압(Vbe)이 "2mV"씩 감소하는 특성을 갖는데, 이에 따라 주위온도가 변화하는 경우에는 트랜지스터(Q1)의 베이스-에미터 전압(Vbe)이 가변되고, 상기 트랜지스터(Q1)의 컬렉터 및 에미터를 통해 흐르는 전류가 가변되며, 이에 따라 도 5에 도시한 바와 같이 피드백 전압을 변화시키게 되는 문제점이 있다.That is, the transistor Q1 included in the conventional analog dimming circuit has a characteristic that the base-emitter voltage Vbe decreases by "2mV" as the ambient temperature rises by 1 ° C, as shown in FIG. Accordingly, when the ambient temperature changes, the base-emitter voltage Vbe of the transistor Q1 is variable, and the current flowing through the collector and emitter of the transistor Q1 is variable, and thus, as shown in FIG. 5. As described above, there is a problem of changing the feedback voltage.
본 발명은 상기한 문제점을 해결하기 위해 제안된 것으로, 그 목적은 주위온도 변화에 의한 밝기의 변화를 보상하도록 함으로써, 주위온도 변화에 관계없이 밝기(brightness) 조절을 안정적으로 수행할 수 있는 온도보상 기능 갖는 아날로그 디밍회로를 제공하는데 있다. The present invention has been proposed to solve the above problems, the object of which is to compensate for the change in the brightness caused by the change in the ambient temperature, temperature compensation that can stably perform the brightness (brightness) control regardless of the change in the ambient temperature An analog dimming circuit having a function is provided.
상기한 본 발명의 목적을 달성하기 위해서, 본 발명의 온도보상 기능 갖는 아날로그 디밍회로는In order to achieve the above object of the present invention, the analog dimming circuit having a temperature compensation function of the present invention
동작전압단에서 접지로 직렬 연결된 제1,제2 저항과, 상기 제1,제2 저항의 접속노드를 디밍 전압단에 연결하는 입력 저항을 포함하는 바이어스 저항부;A bias resistor unit including a first resistor and a second resistor connected in series to ground at an operating voltage terminal and an input resistor connecting a connection node of the first and second resistors to a dimming voltage terminal;
상기 바이어스 저항부의 제2 저항에 연결된 애노드단과, 접지에 연결된 캐소드단을 갖는 다이오드; 및A diode having an anode terminal connected to the second resistor of the bias resistor unit and a cathode terminal connected to ground; And
상기 바이어스 저항부의 제1,제2 저항의 접속노드에 연결된 베이스단과, 이미터 저항을 통해 집지에 연결된 에미터 단과, 출력단에 연결된 컬렉터단을 갖는 트랜지스터A transistor having a base terminal connected to a connection node of the first and second resistors of the bias resistor unit, an emitter terminal connected to a collector through an emitter resistor, and a collector terminal connected to an output terminal;
를 구비하는 것을 특징으로 한다.Characterized in having a.
이하, 본 발명의 바람직한 실시 예를 첨부한 도면을 참조하여 상세히 설명한다. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.
도 6은 본 발명에 따른 아날로그의 디밍회로도이다. 6 is an analog dimming circuit diagram according to the present invention.
도 6을 참조하면, 본 발명에 따른 아날로그 디밍회로는 PWM IC로 제공되는 피드백 전압을 조절하여 백라이트의 램프 밝기를 임의로 조절하기 위해 이용되며, 이는 바이어스 저항부(110), 트랜지스터(Q10) 및 다이오드(D1)를 포함한다.Referring to FIG. 6, an analog dimming circuit according to the present invention is used to arbitrarily adjust a lamp brightness of a backlight by adjusting a feedback voltage provided to a PWM IC, which is a bias resistor 110, a transistor Q10, and a diode. (D1).
상기 바이어스 회로부(110)는 상기 트랜지스터(Q10)를 동작 가능한 상태인 안정된 바이어스를 잡어주기 위해 이용되며, 이는 동작전압(Vcc)단에서 접지로 직렬 연결된 제1,제2 저항(R1,R2)과, 상기 제1,제2 저항(R1,R2)의 접속노드를 디밍 전압(Vd)단에 연결하는 입력 저항(RI)을 포함한다.The bias circuit unit 110 is used to hold a stable bias in which the transistor Q10 is operable, which is connected to the first and second resistors R1 and R2 connected in series to the ground at an operating voltage Vcc. And an input resistor RI for connecting the connection nodes of the first and second resistors R1 and R2 to the dimming voltage Vd.
상기 트랜지스터(Q10)는 상기 바이어스 회로부(110)에 의한 동작 가능한 상태에서, 디밍전압(Vd)에 따라 피드백전압(Vfd)을 조절하기 위한 이용되며, 이는 상기 바이어스 저항부(110)의 제1,제2 저항(R1,R2)의 접속노드에 연결된 베이스단과, 이미터 저항(RE)을 통해 집지에 연결된 에미터 단과, 출력단에 연결된 컬렉터단을 포함한다. 여기서 출력단에는 PWM IC 및 피드백 제어가 접속된다.The transistor Q10 is used to adjust the feedback voltage Vfd according to the dimming voltage Vd in an operable state by the bias circuit unit 110. And a base terminal connected to the connection node of the second resistors R1 and R2, an emitter terminal connected to the collector through the emitter resistor RE, and a collector terminal connected to the output terminal. Here, the output terminal is connected with a PWM IC and feedback control.
상기 다이오드(D1)는 상기 트랜지스터(Q10)의 온도특성을 보상하기 위해 적용된 것으로, 상기 바이어스 저항부(110)의 제2 저항(R2)에 연결된 애노드단과, 접지에 연결된 캐소드단을 포함한다. 이러한 다이오드(D1)는 보다 정확한 온도 보상을 위해서는 상기 트랜지스터(Q10)와 동일한 온도 특성을 갖는 것이 바람직하다.The diode D1 is applied to compensate for the temperature characteristic of the transistor Q10 and includes an anode terminal connected to the second resistor R2 of the bias resistor unit 110 and a cathode terminal connected to ground. The diode D1 preferably has the same temperature characteristics as the transistor Q10 for more accurate temperature compensation.
도 7은 디밍전압-피드백전압 상관 그래프로서, 도 7에 도시된 바와 같이, 피드백전압(Vfd)은 디밍전압(Vd)의 변화와는 반비례 관계에 있음을 알 수 있다.FIG. 7 is a dimming-feedback voltage correlation graph. As shown in FIG. 7, it can be seen that the feedback voltage Vfd is inversely related to the change in the dimming voltage Vd.
도 8은 주위온도-베이스-이미터 전압(Vbe) 상관 그래프로서, 도 8에 도시된 바와 같이, 베이스-이미터 전압(Vbe)은 주위온도(T)의 변화에 반비례 관계에 있음을 알 수 있다.FIG. 8 is a correlation graph of the ambient temperature-base-emitter voltage Vbe, and as shown in FIG. 8, it can be seen that the base-emitter voltage Vbe is inversely related to the change of the ambient temperature T. have.
도 9는 주위온도-피드백전압(Vfd) 상관 그래프로서, 도 9에 도시된 바와 같이, 본 발명의 아날로그 디밍회로에 의해서, 피드백전압(Vfd)은 주위온도(T)의 변화와는 아무런 관계없이 일정함을 알 수 있다. FIG. 9 is an ambient temperature-feedback voltage (Vfd) correlation graph. As shown in FIG. 9, by the analog dimming circuit of the present invention, the feedback voltage Vfd is independent of the change in the ambient temperature T. It can be seen that it is constant.
여기서, 도면중 미설명후호인 Vbe는 트랜지스터의 베이스-에미터 전압이고, Vf는 다이오드의 순방향 전압이다.Here, Vbe, which is not described in the drawings, is a base-emitter voltage of a transistor, and Vf is a forward voltage of a diode.
이하, 본 발명의 작용 및 효과를 첨부한 도면에 의거하여 상세히 설명한다. Hereinafter, the operation and effects of the present invention will be described in detail with reference to the accompanying drawings.
도 6 내지 9를 참조하면, 먼저, 바이어스 회로부(110)의 제1,제2 저항(R1,R2)에 의해서 트랜지스터(Q10)는 동작 가능한 상태로 되는데, 이때, 디밍전압(Vd)이 입력저항(RI)을 통해 상기 트랜지스터(Q10)의 베이스에 인간된다.6 to 9, first, the transistor Q10 is operated by the first and second resistors R1 and R2 of the bias circuit unit 110. In this case, the dimming voltage Vd is the input resistance. It is humanized to the base of the transistor Q10 via RI.
이때, 상기 디밍전압(Vd)이 높아지면, 상기 트랜지스터(Q10)의 베이스 전류(Ib)가 상승하고, 이에 따라 트랜지스터(Q10)의 컬렉터-에미터간의 전류(Ic)도 상승하게 된다. 상기 트랜지스터(Q10)의 컬렉터단에 연결된 피드백 전압에서 많은 전류가 접지로 흐르므로, 피드백 전압(Vfd)은 감소하게 된다.At this time, when the dimming voltage Vd increases, the base current Ib of the transistor Q10 increases, and accordingly, the current Ic between the collector and emitter of the transistor Q10 also increases. Since a large amount of current flows to ground at the feedback voltage connected to the collector terminal of the transistor Q10, the feedback voltage Vfd is reduced.
이와 반대로, 상기 디밍전압(Vd)이 낮아지면, 상기 트랜지스터(Q10)의 베이스 전류(Ib)가 감소하고, 이에 따라 트랜지스터(Q10)의 컬렉터-에미터간의 전류(Ic)도 감소하게 된다. 상기 트랜지스터(Q10)의 컬렉터단에 연결된 피드백 전압에서 작은 전류가 접지로 흐르므로, 피드백 전압(Vfd)은 큰 전류가 흐르는 경우에 비해 상대적으로 증가하게 된다.On the contrary, when the dimming voltage Vd is lowered, the base current Ib of the transistor Q10 decreases, thereby reducing the collector-emitter current Ic of the transistor Q10. Since a small current flows to the ground at the feedback voltage connected to the collector terminal of the transistor Q10, the feedback voltage Vfd increases relatively compared to the case where a large current flows.
이러한 동작중에 주위온도(T)는 항상 변하는데, 먼저, 주위온도(T)가 상승하는 경우에는 도 7에 도시한 바와 같이 상기 트랜지스터(Q10)의 베이스-에미터간 전압(Vbe)이 낮아지게 되고, 이와 동시에 다이오드(D1)의 순방향 전압(Vf)도 도 8에 도시한 바와 같이 낮아지게 된다.During this operation, the ambient temperature T is always changed. First, when the ambient temperature T rises, the base-emitter voltage Vbe of the transistor Q10 is lowered as shown in FIG. 7. At the same time, the forward voltage Vf of the diode D1 is also lowered as shown in FIG. 8.
이때, 상기 트랜지스터(Q10)의 베이스-에미터간 전압(Vbe)이 낮아지는 경우에, 상기 트랜지스터(Q10)의 온도특성과 동일한 온도특성을 갖는 다이오드(D1)의 순방향 전압(Vf)도 낮아지게 되므로, 이에 따라 베이스전류(Ib) 및 컬렉터-이미터 전류(Ic)는 온도 변화에 관계없이 일정하게 된다. 즉, 도 9에 도시한 바와 같이 온도변화에 대해서 피드백 전압은 일정하게 유지된다.In this case, when the base-emitter voltage Vbe of the transistor Q10 is lowered, the forward voltage Vf of the diode D1 having the same temperature characteristic as that of the transistor Q10 is also lowered. Accordingly, the base current Ib and the collector-emitter current Ic become constant regardless of the temperature change. That is, as shown in FIG. 9, the feedback voltage is kept constant with respect to the temperature change.
이와 반대로, 주위온도(T)가 떨어지는 경우에는 도 7에 도시한 바와 같이 상기 트랜지스터(Q10)의 베이스-에미터간 전압(Vbe)이 상승하게 되고, 이와 동시에 다이오드(D1)의 순방향 전압(Vf)도 도 8에 도시한 바와 같이 상승하게 된다.On the contrary, when the ambient temperature T falls, the base-emitter voltage Vbe of the transistor Q10 increases as shown in FIG. 7, and at the same time, the forward voltage Vf of the diode D1. It rises as shown in FIG.
이때, 상기 트랜지스터(Q10)의 베이스-에미터간 전압(Vbe)이 상승하는 경우에, 상기 트랜지스터(Q10)의 온도특성과 동일한 온도특성을 갖는 다이오드(D1)의 순방향 전압(Vf)도 상승하게 되므로, 이에 따라 베이스전류(Ib) 및 컬렉터-이미터 전류(Ic)는 온도 변화에 관계없이 일정하게 된다. 즉, 도 9에 도시한 바와 같이 온도변화에 대해서 피드백 전압은 일정하게 유지된다.At this time, when the base-emitter voltage Vbe of the transistor Q10 increases, the forward voltage Vf of the diode D1 having the same temperature characteristic as that of the transistor Q10 also increases. Accordingly, the base current Ib and the collector-emitter current Ic become constant regardless of the temperature change. That is, as shown in FIG. 9, the feedback voltage is kept constant with respect to the temperature change.
전술한 바와 같이, 주위온도가 상승하거나 떨어지는 경우에, 트랜지스터의 온도특성을 다이오드의 온도특성으로 보상함으로서, 피드백 전압은 온도변화에 영향을 받지 않게 된다.As described above, when the ambient temperature rises or falls, the feedback voltage is not affected by the temperature change by compensating the temperature characteristic of the transistor with the temperature characteristic of the diode.
상술한 바와 같은 본 발명에 따르면, LCD 모니터 및 TV의 백라이트 인버터에 적용되고 있는 아날로그 디밍회로(Analog Dimming circuit)에서, 주위온도 변화에 의한 밝기의 변화를 보상하도록 함으로써, 주위온도 변화에 관계없이 밝기(brightness) 조절을 안정적으로 수행할 수 있는 효과가 있다.According to the present invention as described above, in the analog dimming circuit (Analog Dimming circuit) applied to the backlight inverter of the LCD monitor and TV, to compensate for the change in the brightness due to the change in the ambient temperature, the brightness regardless of the change in the ambient temperature It has the effect of making the brightness adjustment stable.
도 1은 종래의 백라이트 인버터의 구성도이다.1 is a block diagram of a conventional backlight inverter.
도 2는 종래의 아날로그 디밍회로도이다.2 is a conventional analog dimming circuit diagram.
도 3은 디밍전압-피드백전압 상관 그래프이다.3 is a dimming voltage-feedback voltage correlation graph.
도 4는 주위온도-베이스-이미터 전압(Vbe) 상관 그래프이다.4 is a graph of ambient temperature-base-emitter voltage (Vbe) correlation.
도 5는 주위온도-피드백전압(Vfd) 상관 그래프이다.5 is a graph of ambient temperature-feedback voltage (Vfd) correlation.
도 6은 본 발명에 따른 아날로그의 디밍회로도이다. 6 is an analog dimming circuit diagram according to the present invention.
도 7은 디밍전압-피드백전압 상관 그래프이다.7 is a dimming voltage-feedback voltage correlation graph.
도 8은 주위온도-베이스-이미터 전압(Vbe) 상관 그래프이다.8 is a graph of ambient temperature-base-emitter voltage (Vbe) correlation.
도 9는 주위온도-피드백전압(Vfd) 상관 그래프이다.9 is a graph of ambient temperature-feedback voltage (Vfd) correlation.
* 도면의 주요부분에 대한 부호의 설명 *Explanation of symbols on main parts of drawing
110 : 바이어스 저항부 Vcc : 동작전압110: bias resistor Vcc: operating voltage
R1,R2 : 제1,제2 저항 RI : 입력 저항R1, R2: first and second resistor RI: input resistance
Vd : 디밍 전압 D1 : 다이오드Vd: Dimming Voltage D1: Diode
Q10 : 트랜지스터 RE : 이미터 저항Q10: transistor RE: emitter resistor
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| KR1020040046015A KR20050120901A (en) | 2004-06-21 | 2004-06-21 | Analog dimming circuit with temperature compensation |
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| Application Number | Priority Date | Filing Date | Title |
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| KR1020040046015A KR20050120901A (en) | 2004-06-21 | 2004-06-21 | Analog dimming circuit with temperature compensation |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9514689B2 (en) | 2014-09-15 | 2016-12-06 | Samsung Display Co., Ltd. | Display device |
| US10009967B2 (en) | 2015-04-30 | 2018-06-26 | Samsung Display Co., Ltd. | Backlight unit, method of driving the same, and display apparatus having the same |
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2004
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9514689B2 (en) | 2014-09-15 | 2016-12-06 | Samsung Display Co., Ltd. | Display device |
| US10009967B2 (en) | 2015-04-30 | 2018-06-26 | Samsung Display Co., Ltd. | Backlight unit, method of driving the same, and display apparatus having the same |
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