1331320 九、發明說明： • . . 【發明所屬之技術領域】 本發明提供一種參考電壓產生電路，尤指一種使用單一 電壓緩衝器之參考電壓產生電路。 【先前技術】 平面顯示面板如液B曰顯示面板（丨丨叫丨4 cryStai diSpiay pand’ LCDpanel)需要多組的伽瑪（Gamma)電壓，以提供 資料驅動積體電路(data driver integrated circuit)作為數位/ 類比轉換的參考電壓。 請參閱第1圖；第1圖為先前技術中伽碼電路1之示意 圖。伽瑪電路1係由一分壓電路12、一電壓緩衝器電路14 與一低通濾波器電路16所組成，其中分壓電路12包含複 數個電阻.，利用電阻分壓的方式，產生不同大小的電壓。 電壓緩衝器電路14内包含複數個電壓緩衝器，每一個電壓 緩衝器係相對應於一個分壓電路12的輸出端，而低通濾波 器電路16包含複數個由電阻與電容所形成的低通濾波器。 一般來說，液晶顯示面板需要十幾組的伽瑪電壓，傳統 的伽瑪電壓先由分壓電路12再經由電壓緩衝器電路14與 低通濾波器電路16所產生，因此會有十幾個電壓端點，然 而當液晶顯示面板因為製程變異或參數改變造成電壓與穿 1331320 透率特性改變時，往往需要修改分壓電路12内的十幾顆的 ~ 分壓電阻。 % 然而，當使用硬體的方式來達成分壓電路12，若要修改 分壓電路12的分壓電阻，將會提高成本。因為可能造成原 本庫存的電阻無法使用，而需要再購買所需的電阻來因應 現有的液晶顯不®板之需求，實為材料上的浪費。 • 另外，隨著電視影像處理與大尺寸面板對於動態伽瑪電 壓的要求，許多廠商陸續推出可以軟體修改輸出電壓的應 用。請參閱第2圖；第2圖為先前技術中應用可程式化電 壓產生器22的伽瑪電路2之示意圖。 伽瑪電路2包含一可程式化電壓產生器22、一多通道開 關24、複數個電壓緩衝器26、複數個低通濾波器28以及 I 複數個穩壓電容21。利用可程式化電壓產生器22提供如 第1圖中分壓電路12的多組電壓，此可避免因製程等變因 而需更改硬體電阻的問題。另外，藉由同時控制多通道開 關24的切換點，依序地對各穩壓電容21充電，以提供後 端的資料驅動積體電路所需的參考電壓。 • 然而，多通道開關24的每一個電壓輸出端都需要擺放 - 一個電壓緩衝器26,不但成本高，也會因為使用元件過多 6 造成印刷電路板(printed circuit board，PCB)的板材使用增 加。 舉例來說’請參閱第3圖；第3圖為先前技術中液晶顯 示器3採用晶片與玻璃接合(chip on glass，COG)技術之示 意圖。液晶顯示器3包含一液晶顯示面板31、一第一印刷 電路板32、至少一可挽性印刷電路板（flexible printed circuit board，FPC)35、複數個資料驅動積體電路33與一 第二印刷電路板34。可撓性印刷電路板35電性連接於第 一印刷電路板32與該液晶顯示面板31，用以傳輸訊號。 第2圖的伽瑪電路2設於第二印刷電路板34上，第一印刷 電路板32與第二印刷電路板34藉由其上的連接器％％ 以及連接線37傳輸訊號。由於第二印刷電路板34需傳輸 像素資料至資料驅動積體電路33，以及伽瑪電路2需提供 資料驅動積體電路33多組的伽瑪電壓，因此連接線37需 要較多的接腳數，相對地成本也提高了。 另外，第2圖伽瑪電路2可能有雜訊被放大的問題，請參 閱第4圖；第4圖為雜訊放大之示意圖。由於類比開關，如 多通道開關24，在進行切換的瞬間無法避免有細小的雜訊 產生，因此小雜訊可能經由電壓緩衝器26放大，造成訊噪 比（S/N)較差。 * 1331320 【發明内容】 本發明係揭露一種使用單一電壓緩衝器之參 生電路。該參考電壓產生電路包含—電壓產生# 電壓產 緩衝器、一多通道開關、複數個低通濾波器以=複〜電壓 容。該電壓緩衝器之輸入端耦合於該電壓產生1數個電 端，該多通道開關之輸入端耦合於該電壓緩衝二之輪出 端，每一低通濾波器耦合於該多通道開關之一。之輪出 -電容之一端耦合於該多通道開關之一輪出端二：每 之低通滤波器，該電容之另-端接地，該複數個電容用應 分別儲存該多通道開關之各輸出端所輸出的電壓。 u 【實施方式】 凊參閱第5圖；第5圖為本發明伽瑪電路一立 伽瑪電路5包含-電壓產生器52、-電壓緩衝器54、_多 通道開關56、複數個低通遽波器58以及複數個穩壓電容 51 ’其中電壓產生器52係為一可程式化電壓產生器。 . ♦ · . 電壓產生器52輸出一電壓至電壓緩衝器54，再藉由電 壓緩衝器54將電壓推至多通道開關56,多通道開關S56所 切換到的輸出端’其相對應連接的穩壓電容51即可儲存電 壓，再透過低通濾波器58過濾訊號以提供後端的資料驅動 積體電路所需的參考電壓。 8 相較於第2圖的伽瑪電路2，第5圖的伽瑪電路5僅需 要—個電壓緩衝器54,元件的使用量大幅減少，因此可減 少印刷電路板的板材使用。 明參閱第6圖第6圖為本發b月液晶顯示器6採用晶片 與玻填接合技術之之示意圖。液晶顯示器6包含一液晶顯 示面板31、一第一印刷電路板62、一可撓性印刷電路板 35、複數個資料驅動積體電路33與一第二印刷電路板64。 第6圖中資料驅動積體電路33藉由晶片與玻璃接合技術設 置於液晶顯示面板31上’此外，資料驅動積體電路33亦 可藉由捲帶式封裝體（tape carrier package，TCP)的技術或 晶粒軟膜接合(chip on film’ COF)的技術直接設置於可撓性 印刷電路板35上。 由於伽瑪電路5上的元件使用量大幅減少，因此可將伽 瑪電路5設於第一印刷電路板62上，第二印刷電路板64 的面積相較於第3圖的第二印刷電路板34的面積小許多。 第一印刷電路板Θ2與第二印刷電路板64藉由其上的連接 器66、68以及連接線67傳輸訊號，由於伽瑪電路5已設 置於第一印刷電路板62上，伽瑪電路5可直接提供資料驅 動積體電路33所需的伽瑪電壓，因此連接線67接腳數相 較於第3圖中連槔線37的接腳數少，使得成本降低。 1331320 由於第5圖的電壓緩衝器54設置於多通道開關％前 端，因此多通道開關56在進行切換的瞬間所產生的細小雜 訊’不會被放大’因此第5圖伽瑪電路5擁有較好的雜訊 容忍性。另外，本發明伽瑪電路5主要應用於負載較小的 領域’如液晶顯不系統。因為伽瑪電路5中僅有單一電壓 緩衝器54’而多通道開關56的各輸出端只有在切換到該 輸出端時才會對該輸出端的穩壓電容51充電，在沒充電的 狀態下’穩壓電容51的電壓大小會隨著時間與負载大小而 遞減’因此若負載太大’多通道開關56若來不及對該輸出 端充電’電壓是無法維持的。 相較於先前技術，本發明所提供的伽瑪電路有以下優 點，利用單-電壓緩衝器，可減少許多聽的使用，進而 減少印刷電路板的板材、連接線的接腳數，可大幅降低成 本。另外，本發明的伽瑪電路之雜訊容忍性也優於先前技 術的伽瑪電路。 Μ上所賴為本發明之健實關，凡依本發明_請專利範 斤做之均等變化與修飾，皆應屬本發明之涵蓋範圍。 【圖式簡單說明】 第I ， 第圖為先則技術中伽瑪電路之示意圖。 2圖為先前技射應用可程式化電壓產生料你瑪電路 1331320 t > 之示意圖。 ' 第3圖為先前技術中液晶顯示器採用晶片與玻璃接合技術 • 之示意圖。 第4圖為雜訊放大之示意圖。 第5圖為本發明伽瑪電路之示意圖。 第6圖為本發明之液晶顯示器採用晶片與玻璃接合技術之 示意圖。 • 【主要元件符號說明】 12 分壓電路 14 電壓緩衝器電路 16 低通濾波器電路 31 液晶顯不面板 33 資料驅動積體電路 35 可撓性印刷電路板 3 ' 6 液晶顯不 21、51 穩壓電容 22、52 電壓產生器 24、56 多通道開關 26、54 電壓緩衝器 28 ' 58 低通遽波器 32、62 第一印刷電路板 34、64 第二印刷電路板 37、67 連接線 1、2、5 伽瑪電路 36、38、 66、68 連接器1331320 IX. Description of the Invention: 1. Technical Field of the Invention The present invention provides a reference voltage generating circuit, and more particularly to a reference voltage generating circuit using a single voltage buffer. [Prior Art] A flat display panel such as a liquid B display panel (Cry 丨 4 cryStai diSpiay pand' LCDpanel) requires a plurality of sets of gamma voltages to provide a data driver integrated circuit as a data driver integrated circuit. Reference voltage for digital/analog conversion. Please refer to Fig. 1; Fig. 1 is a schematic diagram of a gamma circuit 1 in the prior art. The gamma circuit 1 is composed of a voltage dividing circuit 12, a voltage buffer circuit 14 and a low-pass filter circuit 16, wherein the voltage dividing circuit 12 includes a plurality of resistors, which are generated by means of resistor voltage division. Different sized voltages. The voltage buffer circuit 14 includes a plurality of voltage buffers, each of which corresponds to an output of a voltage dividing circuit 12, and the low pass filter circuit 16 includes a plurality of low voltages and capacitors. Pass filter. Generally, a liquid crystal display panel requires a dozen or more sets of gamma voltages, and the conventional gamma voltage is first generated by the voltage dividing circuit 12 via the voltage buffer circuit 14 and the low pass filter circuit 16, so that there are more than a dozen One voltage end point, however, when the liquid crystal display panel changes the voltage and the transmissivity of the 1331320 due to process variation or parameter change, it is often necessary to modify more than a dozen voltage dividing resistors in the voltage dividing circuit 12. % However, when the component voltage circuit 12 is used in a hard manner, if the voltage dividing resistor of the voltage dividing circuit 12 is to be modified, the cost will be increased. Since it is possible to make the original stock resistor unusable, it is necessary to purchase the required resistor to meet the demand of the existing liquid crystal display panel, which is a waste of material. • In addition, with the demand for dynamic gamma voltage for TV image processing and large-size panels, many manufacturers have introduced applications that can modify the output voltage in software. Please refer to FIG. 2; FIG. 2 is a schematic diagram of the gamma circuit 2 of the prior art in which the programmable voltage generator 22 is applied. The gamma circuit 2 includes a programmable voltage generator 22, a multi-channel switch 24, a plurality of voltage buffers 26, a plurality of low pass filters 28, and a plurality of voltage stabilizing capacitors 21. The plurality of sets of voltages of the voltage dividing circuit 12 as shown in Fig. 1 are supplied by the programmable voltage generator 22, which avoids the problem of changing the hardware resistance due to process variations and the like. In addition, by simultaneously controlling the switching points of the multi-channel switch 24, the respective stabilizing capacitors 21 are sequentially charged to provide a reference voltage required for the data driving integrated circuit at the rear end. • However, each voltage output of the multi-channel switch 24 needs to be placed - a voltage buffer 26, which is not only costly, but also causes the use of printed circuit board (PCB) boards due to excessive use of components 6 . For example, please refer to FIG. 3; FIG. 3 is a schematic view of the prior art liquid crystal display 3 using chip-on-glass (COG) technology. The liquid crystal display 3 includes a liquid crystal display panel 31, a first printed circuit board 32, at least one flexible printed circuit board (FPC) 35, a plurality of data driving integrated circuits 33 and a second printed circuit. Board 34. The flexible printed circuit board 35 is electrically connected to the first printed circuit board 32 and the liquid crystal display panel 31 for transmitting signals. The gamma circuit 2 of Fig. 2 is disposed on the second printed circuit board 34, and the first printed circuit board 32 and the second printed circuit board 34 transmit signals by the connector %% and the connecting line 37 thereon. Since the second printed circuit board 34 needs to transmit pixel data to the data driving integrated circuit 33, and the gamma circuit 2 needs to provide a plurality of sets of gamma voltages of the data driving integrated circuit 33, the connecting line 37 requires a larger number of pins. The relative cost has also increased. In addition, the second gamma circuit 2 may have a problem that the noise is amplified, please refer to FIG. 4; FIG. 4 is a schematic diagram of the noise amplification. Since the analog switch, such as the multi-channel switch 24, cannot avoid the occurrence of fine noise at the moment of switching, small noise may be amplified by the voltage buffer 26, resulting in poor signal-to-noise ratio (S/N). * 1331320 SUMMARY OF THE INVENTION The present invention discloses a parametric circuit using a single voltage buffer. The reference voltage generating circuit includes a voltage generating #voltage generating buffer, a multi-channel switch, and a plurality of low-pass filters to determine the voltage to the voltage. The input end of the voltage buffer is coupled to the voltage to generate a plurality of electrical terminals, the input end of the multi-channel switch is coupled to the output of the voltage buffer 2, and each low pass filter is coupled to one of the multi-channel switches . One end of the capacitor-capacitor is coupled to one of the multi-channel switches: each low-pass filter, the other end of the capacitor is grounded, and the plurality of capacitors should respectively store the output ends of the multi-channel switch The voltage that is output. u [Embodiment] 第 Refer to FIG. 5; FIG. 5 is a gamma circuit of the present invention. The vertical gamma circuit 5 includes a voltage generator 52, a voltage buffer 54, a multi-channel switch 56, and a plurality of low-pass switches. The waver 58 and the plurality of voltage stabilizing capacitors 51' are among which the voltage generator 52 is a programmable voltage generator. The voltage generator 52 outputs a voltage to the voltage buffer 54, and then pushes the voltage to the multi-channel switch 56 through the voltage buffer 54, and the output terminal of the multi-channel switch S56 is switched to the corresponding regulated voltage. Capacitor 51 stores the voltage and filters the signal through low pass filter 58 to provide the reference voltage required by the back-end data-driven integrated circuit. 8 Compared to the gamma circuit 2 of Fig. 2, the gamma circuit 5 of Fig. 5 requires only a voltage buffer 54, and the amount of components used is greatly reduced, thereby reducing the use of the printed circuit board. Referring to Figure 6 and Figure 6, the liquid crystal display 6 of the present invention is a schematic diagram of a wafer-to-glass bonding technique. The liquid crystal display 6 includes a liquid crystal display panel 31, a first printed circuit board 62, a flexible printed circuit board 35, a plurality of data driving integrated circuits 33, and a second printed circuit board 64. In Fig. 6, the data driving integrated circuit 33 is disposed on the liquid crystal display panel 31 by a wafer bonding method. Further, the data driving integrated circuit 33 can also be used by a tape carrier package (TCP). Technique or chip on film 'COF' technology is directly disposed on the flexible printed circuit board 35. Since the amount of components used on the gamma circuit 5 is greatly reduced, the gamma circuit 5 can be disposed on the first printed circuit board 62, and the area of the second printed circuit board 64 is compared to the second printed circuit board of FIG. The area of 34 is much smaller. The first printed circuit board 2 and the second printed circuit board 64 transmit signals by the connectors 66, 68 and the connecting lines 67 thereon. Since the gamma circuit 5 has been disposed on the first printed circuit board 62, the gamma circuit 5 Since the gamma voltage required for the data driving integrated circuit 33 can be directly supplied, the number of pins of the connecting line 67 is smaller than the number of pins of the connecting line 37 in Fig. 3, so that the cost is lowered. 1331320 Since the voltage buffer 54 of FIG. 5 is disposed at the front end of the multi-channel switch %, the small noise generated by the multi-channel switch 56 at the moment of switching is 'not amplified', so the fifth gamma circuit 5 has a comparison Good noise tolerance. Further, the gamma circuit 5 of the present invention is mainly applied to a field where the load is small, such as a liquid crystal display system. Because there is only a single voltage buffer 54' in the gamma circuit 5, and each output terminal of the multi-channel switch 56 only charges the voltage stabilizing capacitor 51 of the output terminal when switching to the output terminal, in the state of no charging. The voltage of the voltage stabilizing capacitor 51 decreases with time and load size. Therefore, if the load is too large, the multi-channel switch 56 cannot be maintained if it is too late to charge the output terminal. Compared with the prior art, the gamma circuit provided by the present invention has the following advantages, and the single-voltage buffer can reduce the use of many listeners, thereby reducing the number of pins of the printed circuit board and the connecting wires, and can greatly reduce the number of pins. cost. In addition, the noise tolerance of the gamma circuit of the present invention is also superior to that of the prior art gamma circuit. It is the scope of the present invention that the above-mentioned singularity of the present invention is a substantial change and modification of the invention. [Simple description of the diagram] The first and second figures are schematic diagrams of the gamma circuit in the prior art. 2 is a schematic diagram of the conventional technology application programmable voltage generating material 1310320 t >. Figure 3 is a schematic diagram of a prior art liquid crystal display using wafer and glass bonding technology. Figure 4 is a schematic diagram of noise amplification. Figure 5 is a schematic diagram of a gamma circuit of the present invention. Figure 6 is a schematic view showing a wafer-to-glass bonding technique for a liquid crystal display of the present invention. • [Main component symbol description] 12 voltage divider circuit 14 voltage buffer circuit 16 low-pass filter circuit 31 liquid crystal display panel 33 data drive integrated circuit 35 flexible printed circuit board 3 ' 6 liquid crystal display 21, 51 Voltage regulator 22, 52 voltage generator 24, 56 multi-channel switch 26, 54 voltage buffer 28' 58 low-pass chopper 32, 62 first printed circuit board 34, 64 second printed circuit board 37, 67 connection line 1, 2, 5 gamma circuits 36, 38, 66, 68 connectors