JPH0318816A - Liquid crystal display device - Google Patents
Liquid crystal display deviceInfo
- Publication number
- JPH0318816A JPH0318816A JP15235189A JP15235189A JPH0318816A JP H0318816 A JPH0318816 A JP H0318816A JP 15235189 A JP15235189 A JP 15235189A JP 15235189 A JP15235189 A JP 15235189A JP H0318816 A JPH0318816 A JP H0318816A
- Authority
- JP
- Japan
- Prior art keywords
- liquid crystal
- frequency
- crystal display
- inverter circuit
- display device
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000004973 liquid crystal related substance Substances 0.000 title claims description 38
- 238000010586 diagram Methods 0.000 description 6
- 230000004907 flux Effects 0.000 description 1
Landscapes
- Liquid Crystal Display Device Control (AREA)
- Liquid Crystal (AREA)
Abstract
(57)【要約】本公報は電子出願前の出願データであるた
め要約のデータは記録されません。(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は、背後光源点灯用のインバータ回路周波数と液
晶駆動回路の周波数との関係が適正でないと、液晶表示
画面に波が現われるのを防止するために、インバータ回
路の周波数を適正化する手段を設けた液晶表示装置に関
する・
［従来の技術］
液晶表示装置で明るい見易い表示を行わせるために背後
光源（バックライト）を備えたものが使用されている（
実開昭５２−１２７７９３号公報）。[Detailed Description of the Invention] [Industrial Application Field] The present invention prevents waves from appearing on a liquid crystal display screen if the relationship between the frequency of an inverter circuit for backlight source lighting and the frequency of a liquid crystal drive circuit is not appropriate. Related to a liquid crystal display device equipped with a means for optimizing the frequency of an inverter circuit in order to has been done (
Utility Model Publication No. 52-127793).
此の種の液晶表示装置は、携帯形のパーソナル・コンピ
ュータなどと組合せて使用される場合が多いので、液晶
表示装置の奥行きをなるべく短く押さえるために、背後
光源として管径の小さい冷陰極放電管を用いる場合が多
い。冷陰極放電管は点灯電圧が比較的高いので、点灯電
源にはインバータ回路を用い、冷陰極放電管の明るさの
調節はインバータ回路の周波数を変えて行う。しかし、
冷陰極放電管は共の光束、明暗が点灯電圧波形に応じて
変動するので、点灯ｔＵ、ａ用インバインバー２回路数
と背後光源のシャッタとなる液晶表示素子の駆動回路の
周波数との関係が適切でない場合には、液晶表示画面に
インバータ回路の周波数の影響、干渉による波が現われ
るという問題が発生した。This type of liquid crystal display device is often used in combination with a portable personal computer, etc., so in order to keep the depth of the liquid crystal display device as short as possible, a cold cathode discharge tube with a small tube diameter is used as a backlight source. is often used. Since the lighting voltage of cold cathode discharge tubes is relatively high, an inverter circuit is used as the lighting power source, and the brightness of the cold cathode discharge tube is adjusted by changing the frequency of the inverter circuit. but,
Since the luminous flux and brightness of cold cathode discharge tubes vary depending on the lighting voltage waveform, the relationship between the number of two inverter circuits for lighting tU and a and the frequency of the drive circuit of the liquid crystal display element that serves as the shutter of the back light source is If it is not appropriate, a problem arises in that waves due to the influence of the frequency of the inverter circuit and interference appear on the liquid crystal display screen.
［発明が解決しようとする課題］
従来は上記問題に、液晶表示装置の品種ごとに異なる使
用条件（液晶駆動周波数）に対し、それぞれ冷陰極放電
管を点灯するインバータ回路の周波数を調整して対応し
ていた。[Problems to be Solved by the Invention] Conventionally, the above problem has been addressed by adjusting the frequency of the inverter circuit that lights up the cold cathode discharge tube, depending on the usage conditions (liquid crystal driving frequency) that vary depending on the type of liquid crystal display device. Was.
しかし、冷陰極放電管の明るさを調整する必要があり、
そのためにはインバータ回路の周波数を変化させるので
、液晶表示装置の品種ごとに、液晶表示駆動回路の周波
数とインバータ回路の周波数との適正化を図るのは相当
に困難な作業になっていた。However, it is necessary to adjust the brightness of the cold cathode discharge tube,
To achieve this, the frequency of the inverter circuit must be changed, so it has been a very difficult task to optimize the frequency of the liquid crystal display drive circuit and the frequency of the inverter circuit for each type of liquid crystal display device.
本発明は、上記従来の問題を解決するために、液晶駆動
周波数（フレーム周波数）に対して、インバータ回路周
波数が自動的に適正な関係に維持されるようにした液晶
表示装置を提供することを目的とする。In order to solve the above-mentioned conventional problems, the present invention provides a liquid crystal display device in which the inverter circuit frequency is automatically maintained in a proper relationship with the liquid crystal drive frequency (frame frequency). purpose.
［課題を解決するための手段］
本発明者が上記干渉現象について調べた結果、液晶駆動
周波数ｆｌｅｄとインバータ回路の周波数ｆ。[Means for Solving the Problems] As a result of the inventor's research on the above-mentioned interference phenomenon, the liquid crystal drive frequency fled and the frequency f of the inverter circuit were determined.
とか、ｎを自然数として、ｆ ＝、、＝（ｎ 十〇’−
５） ｆ ｌ、、なる関係にあれば干渉現象は見られな
いことが判った。そのために上記両周波数を自動的に上
記関係に保持する手段をインバータ回路に付加して設け
ることにした。For example, if n is a natural number, then f =,, =(n 10'-
5) It was found that no interference phenomenon was observed if the relationship was f l. For this purpose, it was decided to add means to the inverter circuit to automatically maintain the above-mentioned frequencies in the above-mentioned relationship.
［作用］
上記のような手段をとれば、液晶駆動周波数とインバー
タ回路の冷陰極放電管点灯周波数とは常に適切な関係に
保持され、液晶表示に波が現われるようなことはなくな
る。[Operation] By taking the above measures, the liquid crystal drive frequency and the cold cathode discharge tube lighting frequency of the inverter circuit are always maintained in an appropriate relationship, and no waves appear on the liquid crystal display.
［実施例］
第１図は本発明一実施例のブロック図で、図中、１は液
晶表示素子、２は冷陰極放電管、３は液晶駆動回路、４
は冷陰極放電管点灯用のインバータ回路、５は本発明に
係る液晶駆動周波数ｆ に対り一
し表示画面に干渉が現われないようにインバータ回路周
波数ｆ−を定める液晶駆動周波数逓倍回路である。また
、第２図は液晶駆動周波数（フレーム周波数）と、冷陰
極放電管の調光を行っても表示画面に波が発生しないイ
ンバータ回路の周波数との関係を示す図である。ここで
本実施例装置では時分割数２００で液晶を駆動しており
、液晶駆動周波数逓倍回路は、インバータ回路周波数を
液晶表示フレーム周波数の２．５倍にする。第３図は上
記液晶駆動周波数逓倍回路の一例を示す図である。時分
割数２００の場合、走査側信号ＣＬＩの周波数は、フレ
ーム周波数×２００であるから、これを元に、フレーム
周波数の２．５倍の調光周波数を作り出す場合、上記走
査信号ＣＬＩを４０カウントずつして低減したものを調
光周波数とすれば良い。液晶駆動周波数逓倍回路は、図
示のように、通常の４出力のバイナリ・カウンタを２個
用いてパルスを４０カウントするカウンタを形成させ、
その出力をデユーティ比可変回路に入力している。デユ
ーティ比可変回路は、上記カウンタ回路出力が丁度液晶
駆動周波数の２．５倍と一致しない場合には、−ｆｉす
るようにデユーティ比したがってＣＬＩを微調整（両周
波数の適切な関係は、厳密に所望の周波数比が成立する
ことを求めており、それは一般にデユーティ比の僅かな
増減によって達成される）し、−３’３したときの値を
調光信号として出力する。[Embodiment] Fig. 1 is a block diagram of an embodiment of the present invention, in which 1 is a liquid crystal display element, 2 is a cold cathode discharge tube, 3 is a liquid crystal drive circuit, and 4 is a block diagram of an embodiment of the present invention.
5 is an inverter circuit for lighting the cold cathode discharge tube, and 5 is a liquid crystal drive frequency multiplier circuit for determining the inverter circuit frequency f- so that no interference appears on the display screen with respect to the liquid crystal drive frequency f according to the present invention. Further, FIG. 2 is a diagram showing the relationship between the liquid crystal drive frequency (frame frequency) and the frequency of the inverter circuit in which no wave is generated on the display screen even when the cold cathode discharge tube is dimmed. Here, in the device of this embodiment, the liquid crystal is driven in a time division number of 200, and the liquid crystal drive frequency multiplier circuit makes the inverter circuit frequency 2.5 times the liquid crystal display frame frequency. FIG. 3 is a diagram showing an example of the liquid crystal drive frequency multiplier circuit. When the number of time divisions is 200, the frequency of the scanning signal CLI is the frame frequency x 200, so when creating a dimming frequency that is 2.5 times the frame frequency based on this, the scanning signal CLI is counted 40 times. The dimming frequency may be set as the dimming frequency. As shown in the figure, the liquid crystal drive frequency multiplier circuit uses two ordinary 4-output binary counters to form a counter that counts 40 pulses.
The output is input to a variable duty ratio circuit. The variable duty ratio circuit finely adjusts the duty ratio and CLI to -fi when the counter circuit output does not exactly match 2.5 times the liquid crystal drive frequency (the appropriate relationship between both frequencies is strictly It is desired that a desired frequency ratio be established, which is generally achieved by a slight increase or decrease in the duty ratio), and the value obtained by -3'3 is output as a dimming signal.
［発明の効果］
以上説明したように本発明によれば、冷陰極放電管点灯
電源のインバータ回路の周波数が、自１）Ｊ的に、液晶
表示素子駆動回路周波数に対して常に適切な値に保持さ
れ、液晶表示画面に両周波数の干渉による波が現われな
くなる。[Effects of the Invention] As explained above, according to the present invention, the frequency of the inverter circuit of the cold cathode discharge tube lighting power supply is always at a value appropriate to the liquid crystal display element driving circuit frequency in terms of (1) J-wise; is maintained, and waves due to interference between both frequencies no longer appear on the liquid crystal display screen.
第１図は本発明一実施例のブロック図、第２図は液晶駆
動周波数と、表示画面に波が発生しないインバータ回路
周波数との関係を示す図、第３図は液晶駆動周波数逓倍
回路の一例を示す図である。
１・・・液晶表示素子、 ２・・・冷陰極放電管、 ３
・・・液晶駆動回路、 ４・・・冷陰極放電管点灯用の
インバータ回路、 ５・・・本発明に係る液晶駆動周波
数逓倍回路、 ＣＬＩ・・・走査側信号。
第
１
図
第
図Figure 1 is a block diagram of an embodiment of the present invention, Figure 2 is a diagram showing the relationship between the liquid crystal drive frequency and the inverter circuit frequency at which no waves are generated on the display screen, and Figure 3 is an example of a liquid crystal drive frequency multiplier circuit. FIG. 1...Liquid crystal display element, 2...Cold cathode discharge tube, 3
...Liquid crystal drive circuit, 4...Inverter circuit for lighting a cold cathode discharge tube, 5...Liquid crystal drive frequency multiplier circuit according to the present invention, CLI...Scanning side signal. Figure 1 Figure
Claims (1)
バータ回路を内蔵し、インバータ回路の周波数を変えて
調光するようにした背後光源形液晶表示装置において、
液晶駆動周波数ｆ＿ｌ＿ｃ＿ｄに対し、インバータ回路
の周波数ｆ＿ｉ＿ｎ＿ｖを、ｎを自然数として、ｆ＿ｉ
＿ｎ＿ｖ＝（ｎ＋０．５）ｆ＿ｌ＿ｃ＿ｄとする手段を
設けたことを特徴とする液晶表示装置。1. In a back-light source type liquid crystal display device that has a built-in cold cathode discharge tube for the back light source and an inverter circuit to light it, and adjusts the brightness by changing the frequency of the inverter circuit,
For the liquid crystal drive frequency f_l_c_d, the frequency f_i_n_v of the inverter circuit is expressed as f_i, where n is a natural number.
A liquid crystal display device characterized by comprising means for setting _n_v=(n+0.5)f_l_c_d.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15235189A JPH0318816A (en) | 1989-06-16 | 1989-06-16 | Liquid crystal display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15235189A JPH0318816A (en) | 1989-06-16 | 1989-06-16 | Liquid crystal display device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0318816A true JPH0318816A (en) | 1991-01-28 |
Family
ID=15538643
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15235189A Pending JPH0318816A (en) | 1989-06-16 | 1989-06-16 | Liquid crystal display device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0318816A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5342569A (en) * | 1992-03-23 | 1994-08-30 | Yoshida Kogyo K.K. | Method of attaching a fastening tape to a molded article |
| US6339236B1 (en) | 1999-09-27 | 2002-01-15 | Matsushita Electric Works, Ltd. | Light responsive semiconductor switch with shorted load protection |
| JP2004258668A (en) * | 2003-02-27 | 2004-09-16 | Chi Mei Optoelectronics Corp | Method for adjusting switching frequency of burst mode of liquid crystal display, and switching frequency adjustment system |
| JP2006119206A (en) * | 2004-10-19 | 2006-05-11 | Toshiba Matsushita Display Technology Co Ltd | Liquid crystal display |
| JP2007219322A (en) * | 2006-02-17 | 2007-08-30 | Matsushita Electric Ind Co Ltd | Backlight device for liquid crystal display |
| WO2009001409A1 (en) * | 2007-06-27 | 2008-12-31 | Tamura Corporation | Controller and control method of driving frequency of light emitting substance |
-
1989
- 1989-06-16 JP JP15235189A patent/JPH0318816A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5342569A (en) * | 1992-03-23 | 1994-08-30 | Yoshida Kogyo K.K. | Method of attaching a fastening tape to a molded article |
| US6339236B1 (en) | 1999-09-27 | 2002-01-15 | Matsushita Electric Works, Ltd. | Light responsive semiconductor switch with shorted load protection |
| JP2004258668A (en) * | 2003-02-27 | 2004-09-16 | Chi Mei Optoelectronics Corp | Method for adjusting switching frequency of burst mode of liquid crystal display, and switching frequency adjustment system |
| JP2006119206A (en) * | 2004-10-19 | 2006-05-11 | Toshiba Matsushita Display Technology Co Ltd | Liquid crystal display |
| JP2007219322A (en) * | 2006-02-17 | 2007-08-30 | Matsushita Electric Ind Co Ltd | Backlight device for liquid crystal display |
| WO2009001409A1 (en) * | 2007-06-27 | 2008-12-31 | Tamura Corporation | Controller and control method of driving frequency of light emitting substance |
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