KR20000003732A - Liquid drive voltage generating circuit having current consumption saving function - Google Patents

Liquid drive voltage generating circuit having current consumption saving function Download PDF

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Publication number
KR20000003732A
KR20000003732A KR1019980025003A KR19980025003A KR20000003732A KR 20000003732 A KR20000003732 A KR 20000003732A KR 1019980025003 A KR1019980025003 A KR 1019980025003A KR 19980025003 A KR19980025003 A KR 19980025003A KR 20000003732 A KR20000003732 A KR 20000003732A
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South Korea
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voltage
liquid crystal
current consumption
liquid drive
generating circuit
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KR1019980025003A
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Korean (ko)
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김봉남
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윤종용
삼성전자 주식회사
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Priority to KR1019980025003A priority Critical patent/KR20000003732A/en
Publication of KR20000003732A publication Critical patent/KR20000003732A/en

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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3611—Control of matrices with row and column drivers
    • G09G3/3696—Generation of voltages supplied to electrode drivers
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00—Aspects of the constitution of display devices
    • G09G2300/04—Structural and physical details of display devices
    • G09G2300/0469—Details of the physics of pixel operation
    • G09G2300/0478—Details of the physics of pixel operation related to liquid crystal pixels
    • G09G2300/0482—Use of memory effects in nematic liquid crystals
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/02—Details of power systems and of start or stop of display operation
    • G09G2330/021—Power management, e.g. power saving

Abstract

PURPOSE: A liquid drive voltage generating circuit is provided to reduce current consumption by improving a power line so as to boosted voltages of an intermediate level instead of maximum boosted voltage. CONSTITUTION: The liquid drive voltage generating circuit comprises: N resistors(R11 to R15) for voltage division connected in series between a predetermined reference voltage(VREF) and a ground voltage(GND), for dividing the reference voltage at a predetermined rate; and (N-1) voltage followers(10 to 16) each having a positive input terminal connected to one end of a corresponding resistor and negative input and output terminals connected to each other, each for buffering a divided voltage from the one end of the corresponding resistor to output the divided voltage thus buffered as a liquid drive voltage, wherein the (N-1) voltage followers are supplied with an intermediate boosted voltage(VPP) between a power supply voltage and a maximum boosted voltage.

Description

전류 소비 절감 기능을 갖는 액정 구동 전압 발생 장치Liquid Crystal Driving Voltage Generator with Current Consumption Reduction

본 발명은 휴대용 단말기에 이용되는 STN(Super-Twisted Nematic)액정 드라이버에 관한 것으로서, 특히, 전압 분배기와 전압 폴로어를 구비하는 STN드라이버의 액정 구동 전압 발생 장치에서 전원 라인을 변경하여 전류 소비를 줄인 전류 소비 절감 기능을 갖는 액정 구동 전압 발생 장치에 관한 것이다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a super-twisted nematic (STN) liquid crystal driver used in a portable terminal, and more particularly, to reduce current consumption by changing a power supply line in a liquid crystal driving voltage generator of an STN driver having a voltage divider and a voltage follower. A liquid crystal drive voltage generator having a current consumption reduction function.

현재에는 무선 휴대 전화기와 같은 휴대용 단말기의 급속한 발달로 인하여 문자 또는 기호들을 디스플레이하기 위한 액정 표시 장치(Liquid Crystal Device:LCD)가 매우 발달되었으며, 그에 따라 액정 표시 장치 중 하나인 STN액정을 드라이브하기 위한 STN드라이버의 시장도 급격히 성장하였다. 또한, STN드라이버의 요구 사양 역시 휴대 단말기에 적합하도록 그 기능과 성능을 요구하게 되었다. 특히, 휴대 단말기에 적합한 여러 가지 사양 중에서 전류의 소비를 최대한 줄이고자하는 저소비 전류형은 매우 중요한 사양 중 하나가 되고 있다.At present, due to the rapid development of portable terminals such as wireless cellular phones, liquid crystal devices (LCDs) for displaying characters or symbols have been very developed, and accordingly, one of the liquid crystal display devices for driving STN liquid crystals has been developed. The market for STN drivers also grew rapidly. In addition, the requirements of the STN driver also demanded its functionality and performance to fit the portable terminal. In particular, among the various specifications suitable for a mobile terminal, a low current consumption type that wants to reduce the current consumption as much as possible becomes one of the very important specifications.

일반적인 STN드라이버는 커패시터와 큰 저항을 제외하고 아날로그 방식으로 구현되는 승압 회로와 액정 구동 전압 발생 장치를 내장한다. 즉, STN드라이버에 내장된 아날로그 회로는 대부분 승압 전압을 전원 전압으로하여 동작함으로써 많은 전류를 소비하게 된다. 특히, 아날로그 회로들 중에서 가장 많은 전류를 소모하는 부분 중의 하나가 액정 구동 전압 발생 장치의 전압 분배기와 전압 폴로어이다.A typical STN driver includes a liquid crystal drive voltage generator and a boost circuit implemented in an analog manner except for a capacitor and a large resistor. In other words, the analog circuit built into the STN driver consumes a lot of current by operating with the boosted voltage as the power supply voltage. In particular, one of the most current-consuming parts of the analog circuits are the voltage divider and the voltage follower of the liquid crystal driving voltage generator.

도 1은 종래의 STN드라이버에서 사용되는 액정 구동 전압 발생 장치를 설명하기 위한 회로도로서, 직렬 연결된 전압 분배용 저항들(R11,R12,R13,R14)과 전압 폴로어들(10,12,14,16)을 포함한다.FIG. 1 is a circuit diagram illustrating a liquid crystal driving voltage generator used in a conventional STN driver. The resistors R11, R12, R13, and R14 connected in series and the voltage followers 10, 12, 14, 16).

도 1을 참조하면, 저항(R11)의 일측에는 기준 전압(VREF)이 인가되고, 저항(R11)의 타측은 전압 폴로어(10)의 정입력 단자와 연결된다. 또한, 저항(R12)의 일측은 저항(R11)의 타측에 연결되고, 타측은 전압 폴로어(12)의 정입력 단자와 연결된다. 저항들(R13, R14)과 전압 폴로어들(14, 16)도 같은 연결관계를 갖는다. 전압 폴로어들(10~16)은 입력된 전압을 버퍼링하는 역할을 하며, STN드라이버에 내장된 승압회로(미도시)에서 생성된 승압 전압(VPP)을 전원 전압으로 인가하고, 저항들(R11~R16)에서 분배된 저항 값에 상응하는 전압을 버퍼링하여 STN액정을 구동하기 위한 출력 전압들(V1~V4)을 생성한다.Referring to FIG. 1, a reference voltage VREF is applied to one side of the resistor R11, and the other side of the resistor R11 is connected to the positive input terminal of the voltage follower 10. In addition, one side of the resistor R12 is connected to the other side of the resistor R11, and the other side thereof is connected to the positive input terminal of the voltage follower 12. Resistors R13 and R14 and voltage followers 14 and 16 have the same connection relationship. The voltage followers 10 to 16 buffer the input voltage, apply the boosted voltage VPP generated by the booster circuit (not shown) built in the STN driver as the power supply voltage, and resistors R11. The output voltages V1 to V4 for driving the STN liquid crystal are generated by buffering a voltage corresponding to the resistance value divided at R16.

도 1에 도시된 액정 구동 전압 발생 장치에서 기준 전압(VREF)은 STN드라이버에 내장된 정류기 또는 외부에서 입력된 전압을 이용할 수 있고, 전압 분배용 저항들(R11~R15)은 기준 전압(VREF)이하의 서로 다른 목표 전압을 얻기위해 각 저항의 일측에서 출력 전압을 얻음으로써 저항 비에 상응하는 4개의 출력 전압이 생성된다. 도 1은 기준 전압(VREF)을 1/5로 나누는 1/5바이어스를 이용하여 서로 다른 출력 전압을 얻는 경우의 예를 나타낸다.In the liquid crystal driving voltage generator shown in FIG. 1, the reference voltage VREF may use a rectifier built in the STN driver or an externally input voltage, and the voltage divider resistors R11 to R15 may be reference voltages VREF. Four output voltages corresponding to the resistance ratios are generated by obtaining the output voltage at one side of each resistor to obtain different target voltages below. FIG. 1 shows an example of obtaining different output voltages by using a 1/5 bias that divides the reference voltage VREF by 1/5.

즉, 도 1에서와 같이 1/5바이어스를 이용하는 경우에 전압 폴로어(10)의 출력 전압(V1)은 4/5*VREF가 되고, 전압 폴로어(12)의 출력 전압(V2)은 3/5*VREF가 되고, 전압 폴로어(14)의 출력 전압(V3)은 2/5*VREF가 되고, 전압 폴로어(16)의 출력 전압(V4)은 1/5*VREF가 된다. 또한, 일반적으로 휴대 단말기용 드라이버로 공급되는 전원을 VDD라 할 때, 승압 전압은 4배 승압일 경우 4*VDD가 되고, 기준 전압(VREF)은 3/4*VPP가 된다. 따라서, 각 출력 전압(V1~V4)은 다음과 같이 나타낼 수 있다.That is, when 1/5 bias is used as shown in FIG. 1, the output voltage V1 of the voltage follower 10 is 4/5 * VREF, and the output voltage V2 of the voltage follower 12 is 3. / 5 * VREF, the output voltage V3 of the voltage follower 14 becomes 2/5 * VREF, and the output voltage V4 of the voltage follower 16 becomes 1/5 * VREF. In general, when the power supplied to the driver for a mobile terminal is referred to as VDD, the boosted voltage is 4 * VDD when the voltage is increased 4 times, and the reference voltage VREF is 3/4 * VPP. Accordingly, each output voltage V1 to V4 may be represented as follows.

상술한 바와 같이, 전압 폴로어의 전원은 분배된 전압 레벨보다 10%이상의 마진(MARGIN)을 갖는 전원을 사용해야하기 때문에, 내부 승압 회로에서 발생되는 최고 전원인 승압 전압(VPP)을 이용한다. 즉, 승압 회로를 내장한 STN드라이버의 전압 폴로어에서는 전원 전압을 승압 전원(VPP)으로 이용하기 때문에, 전류 소비가 매우 크게 된다는 문제점이 있다. 따라서, 전류를 많이 소모하는 STN액정 구동 전압 발생 장치의 전원 라인을 개선하여 전류 소비를 줄여주어야 한다.As described above, since the power of the voltage follower must use a power supply having a margin MARGIN of 10% or more than the divided voltage level, it uses the boost voltage VPP, which is the highest power generated in the internal boost circuit. In other words, the voltage follower of the STN driver incorporating the boost circuit uses the power supply voltage as the boost power supply (VPP), resulting in a very large current consumption. Therefore, the current consumption must be reduced by improving the power line of the STN liquid crystal driving voltage generator that consumes a lot of current.

본 발명이 이루고자하는 기술적 과제는, 최대 승압 전압이 아닌 중간 레벨의 승압 전압들을 이용하도록 전원 라인을 개선함으로써 소비되는 전류를 줄일 수 있는 소비 전류 절감 기능을 갖는 액정 구동 전압 발생 장치를 제공하는데 있다.SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a liquid crystal driving voltage generating device having a power consumption reduction function capable of reducing current consumed by improving a power supply line so as to use intermediate voltage boost voltages instead of maximum boost voltages.

도 1은 종래의 액정 구동 전압 발생 장치를 설명하기 위한 회로도이다.1 is a circuit diagram for explaining a conventional liquid crystal driving voltage generator.

도 2는 본 발명에 따른 전류 소비 절감 기능을 갖는 액정 구동 전압 발생 장치를 설명하기 위한 바람직한 일실시예의 회로도이다.2 is a circuit diagram of a preferred embodiment for explaining a liquid crystal drive voltage generator having a current consumption reduction function according to the present invention.

상기 과제를 이루기위해, 본 발명에 따른 액정 구동 전압 발생 장치는, 본 발명에 따른 전류 소비 절감 기능을 갖는 액정 구동 전압 발생 장치는, 소정의 기준 전압과 접지 사이에 직렬 연결되어 기준 전압을 소정율로 분배하는 제N(>1)개의 전압 분배용 저항들, 각 저항의 일측과 연결된 정입력 단자를 갖고, 부입력 단자와 출력 단자가 연결되어 분배된 전압을 버퍼링하고, 각각의 버퍼링된 결과를 액정 구동 전압으로서 출력하는 제N-1개의 전압 폴로어들로 구성되는 것이 바람직하다.In order to achieve the above object, the liquid crystal drive voltage generator according to the present invention, the liquid crystal drive voltage generator having a current consumption reduction function according to the present invention is connected in series between a predetermined reference voltage and the ground to a predetermined rate N (> 1) voltage divider resistors, each having a positive input terminal connected to one side of each resistor, a negative input terminal and an output terminal connected to buffer the divided voltage, and the respective buffered results. It is preferable that the N-1 voltage follower outputs the liquid crystal driving voltage.

이하, 본 발명에 따른 소비 전류 절감기능을 갖는 액정 구동 전압 발생 장치에 관하여 첨부된 도면을 참조하여 다음과 같이 설명한다.Hereinafter, a liquid crystal driving voltage generator having a power consumption reduction function according to the present invention will be described with reference to the accompanying drawings.

도 2는 본 발명에 따른 액정 구동 전압 발생 장치의 바람직한 일실시예의 회로도로서, 전압 분배용 저항들(R21,R22,R23,R24)과 전압 폴로어들(20,22,24, 26)을 포함한다. 여기에서, 회로 설계 방식에 따라서 저항과 전압 폴로어의 수는 임의로 설정하는 것이 가능하며, 도 2의 실시예에서는 입력되는 기준 전압(VREF)을 1/5로 분배한 경우를 나타낸다.2 is a circuit diagram of a preferred embodiment of a liquid crystal driving voltage generator according to the present invention, which includes voltage distribution resistors R21, R22, R23, and R24 and voltage followers 20, 22, 24, and 26. do. Here, the number of resistors and voltage followers can be arbitrarily set according to the circuit design scheme. In the embodiment of FIG. 2, the input reference voltage VREF is divided by 1/5.

도 1에 도시된 전압 분배용 저항들(R21~R25)는 기준 전압(VREF)과 접지 (GND) 사이에 직렬로 연결되어 기준 전압(VREF)을 1/5로 각각 분배한다.The voltage divider resistors R21 to R25 shown in FIG. 1 are connected in series between the reference voltage VREF and the ground GND to divide the reference voltage VREF into 1/5, respectively.

전압 폴로어들(20~26)은 각 저항들(R21~R25)의 일측과 연결된 정입력 단자를 갖고, 부입력 단자는 출력 단자와 연결되며, 각 정입력 단자로 인가되는 전압 즉, 각 저항들(R21~R25)에서 분배된 전압을 입력하여 버퍼링한다. 이 때, 각 전압 폴로어들(20~26)은 STN드라이버 내부의 승압 회로에서 발생되는 최고 승압 전압 (VPP)을 전원 전압으로 인가하는 것이 아니라, 중간 승압 전압을 이용함으로써 전류 소비를 줄일 수 있다. 즉, 전압 폴로어(20)에 인가되는 승압 전압을 VPP1라 하고, 전압 폴로어(22)에 인가되는 승압 전압을 VPP2라하고, 전압 폴로어(24)에 인가되는 승압 전압을 VPP3라 하고, 전압 폴로어(26)에 인가되는 승압 전압을 VPP4라 할 때 그 값은 서로 다르게 나타난다.The voltage followers 20 to 26 have positive input terminals connected to one side of each of the resistors R21 to R25, and the negative input terminal is connected to the output terminal and the voltage applied to each positive input terminal, that is, each resistor. Buffered by inputting the voltage divided in R21 to R25. At this time, each voltage follower 20 to 26 may reduce the current consumption by using an intermediate boost voltage instead of applying the highest boost voltage VPP generated in the boost circuit inside the STN driver as the power supply voltage. . That is, the boosted voltage applied to the voltage follower 20 is called VPP1, the boosted voltage applied to the voltage follower 22 is called VPP2, and the boosted voltage applied to the voltage follower 24 is called VPP3, When the boosted voltage applied to the voltage follower 26 is VPP4, the value is different from each other.

예를 들어, 일반적인 로직의 전원 전압인 VDD를 기준으로 하여 4배 승압하는 경우에 각각 2VDD, 3VDD 및 4VDD를 얻을 수 있다. 따라서, 상기의 중간 승압 전압 들 VPP1, VPP2, VPP3 및 VPP4는 전원 전압(VDD)을 기준으로 각각 4VDD, 3VDD, 2VDD, 및 1VDD가 된다. 또한, 상술한 바와 같이, 기준 전압(VREF)은 3/4*VPP가 된다.For example, 2VDD, 3VDD, and 4VDD can be obtained when the voltage is boosted four times based on VDD, which is a power supply voltage of general logic. Accordingly, the intermediate boost voltages VPP1, VPP2, VPP3, and VPP4 become 4VDD, 3VDD, 2VDD, and 1VDD based on the power supply voltage VDD, respectively. In addition, as described above, the reference voltage VREF becomes 3/4 * VPP.

즉, 도 2에서와 같이 1/5바이어스를 이용하는 경우에 전압 폴로어(20)의 출력 전압(V1)은 4/5*VREF가 되고, 전압 폴로어(22)의 출력 전압(V2)은 3/5*VREF가 되고, 전압 폴로어(24)의 출력 전압(V3)은 2/5*VREF가 되고, 전압 폴로어(26)의 출력 전압(V4)은 1/5*VREF가 된다. 따라서, 각 출력 전압(V1~V4)은 다음의 수학식 2와 같이 나타낼 수 있다. 또한, 출력 전압 V4는 전원 전압(VDD)보다 작고, V3는 2VDD보다 작고, V2는 2VDD보다 작고, V1은 3VDD보다 작다는 것을 알 수 있다.That is, when 1/5 bias is used as shown in FIG. 2, the output voltage V1 of the voltage follower 20 is 4/5 * VREF, and the output voltage V2 of the voltage follower 22 is 3. It becomes / 5 * VREF, the output voltage V3 of the voltage follower 24 becomes 2/5 * VREF, and the output voltage V4 of the voltage follower 26 becomes 1/5 * VREF. Therefore, each output voltage (V1 ~ V4) can be represented by the following equation (2). In addition, it can be seen that the output voltage V4 is smaller than the power supply voltage VDD, V3 is smaller than 2VDD, V2 is smaller than 2VDD, and V1 is smaller than 3VDD.

즉, 본 발명에서는 전압 폴로어에 인가된 전압 레벨보다 높은 중간 승압 전압을 전원 전압으로 이용함으로써 종래의 액정 구동 전압 발생 장치에서 보다 소비되는 전류의 양을 줄일 수 있다.That is, in the present invention, by using an intermediate boost voltage higher than the voltage level applied to the voltage follower as the power supply voltage, the amount of current consumed in the conventional liquid crystal driving voltage generator can be reduced.

본 발명에 따르면, STN드라이버 내부의 전압 분배기와 전압 폴로어에 인가되는 승압 전압을 내부 승압 회로에서 얻을 수 있는 최대 승압 전압이 아닌 중간 승압 전압을 인가하도록 전원 라인을 변경함으로써 소비 전류를 줄일 수 있다는 효과가 있다.According to the present invention, the current consumption can be reduced by changing the power supply line so that the voltage booster applied to the voltage divider and voltage follower inside the STN driver is applied to the intermediate boosting voltage instead of the maximum boosting voltage that can be obtained from the internal boosting circuit. It works.

Claims (1)

소정의 기준 전압과 접지 사이에 직렬 연결되어 상기 기준 전압을 소정율로 분배하는 제N(>1)개의 전압 분배용 저항들;N (> 1) voltage distribution resistors connected in series between a predetermined reference voltage and ground to divide the reference voltage at a predetermined rate; 상기 각 저항의 일측과 연결된 정입력 단자를 갖고, 부입력 단자와 출력 단자가 연결되어 상기 분배된 전압을 버퍼링하고, 상기 각각의 버퍼링된 결과를 액정 구동 전압으로서 출력하는 제N-1개의 전압 폴로어들을 구비하고,An N-1 voltage polo having a positive input terminal connected to one side of each of the resistors, a negative input terminal and an output terminal connected to buffer the divided voltage, and output the respective buffered results as a liquid crystal driving voltage. Equipped with fish, 상기 제N-1전압 폴로어들은 전원 전압과 최대 승압 전압 사이의 서로 다른 중간 승압 전압이 인가되는 것을 특징으로하는 액정 구동 전압 발생 장치.The N-th voltage follower is a liquid crystal driving voltage generator, characterized in that a different intermediate boost voltage between the power supply voltage and the maximum boost voltage.
KR1019980025003A 1998-06-29 1998-06-29 Liquid drive voltage generating circuit having current consumption saving function KR20000003732A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100384379B1 (en) * 2000-03-23 2003-05-22 인터내셔널 비지네스 머신즈 코포레이션 Voltage supply circuit and display device
KR100402872B1 (en) * 2000-01-25 2003-10-22 세이코 엡슨 가부시키가이샤 A DC-DC voltage boosting method and power supply circuit using the same
US10157566B2 (en) 2016-03-04 2018-12-18 Samsung Electronics Co., Ltd. Display driving device and display device having the same

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100402872B1 (en) * 2000-01-25 2003-10-22 세이코 엡슨 가부시키가이샤 A DC-DC voltage boosting method and power supply circuit using the same
KR100384379B1 (en) * 2000-03-23 2003-05-22 인터내셔널 비지네스 머신즈 코포레이션 Voltage supply circuit and display device
US10157566B2 (en) 2016-03-04 2018-12-18 Samsung Electronics Co., Ltd. Display driving device and display device having the same

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