JPH04352188A - Liquid crystal display unit controller - Google Patents
Liquid crystal display unit controllerInfo
- Publication number
- JPH04352188A JPH04352188A JP12769491A JP12769491A JPH04352188A JP H04352188 A JPH04352188 A JP H04352188A JP 12769491 A JP12769491 A JP 12769491A JP 12769491 A JP12769491 A JP 12769491A JP H04352188 A JPH04352188 A JP H04352188A
- Authority
- JP
- Japan
- Prior art keywords
- liquid crystal
- power source
- turned
- circuit
- crystal display
- 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 abstract description 61
- 238000007599 discharging Methods 0.000 abstract description 5
- 238000010586 diagram Methods 0.000 description 5
- 238000004364 calculation method Methods 0.000 description 1
- 238000013500 data storage Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
Landscapes
- Liquid Crystal (AREA)
- Liquid Crystal Display Device Control (AREA)
Abstract
Description
【０００１】0001
【産業上の利用分野】この発明は、液晶表示器の制御装
置に関し、特に液晶のオフ時の制御の改良に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a liquid crystal display, and more particularly to an improvement in control when the liquid crystal is turned off.
【０００２】0002
【従来の技術】バッテリ内蔵型の小型電子機器に使用さ
れる液晶表示器の制御装置は従来、図３に示したように
昇圧回路２１でバッテリ電圧を昇圧してから液晶駆動回
路２２に駆動電圧として供給している。液晶オフ時には
昇圧回路２１への電源供給を停止することによって液晶
への電圧供給を停止し、液晶を消灯させるようにしてい
た。2. Description of the Related Art Conventionally, a control device for a liquid crystal display used in a small electronic device with a built-in battery boosts the battery voltage using a booster circuit 21, and then supplies the drive voltage to a liquid crystal drive circuit 22, as shown in FIG. It is supplied as. When the liquid crystal is turned off, the voltage supply to the liquid crystal is stopped by stopping the power supply to the booster circuit 21, and the liquid crystal is turned off.
【０００３】0003
【発明が解決しようとする課題】ところが従来のような
制御では、電源がオフされた後にもしばらくの間液晶の
一部が完全には消灯されない問題があった。これは、表
示制御信号はすぐにオフしても、液晶駆動回路２２およ
び液晶の容量によって液晶駆動電圧ＶＥＥがすぐにはＧ
ＮＤレベルにはならず、自然放電によってＧＮＤレベル
に低下するまでに数秒間経過するからである。このため
、ＶＥＥがＧＮＤレベルになるまでの数秒間、表示制御
信号がオフする直前に選択されていた表示ラインが点灯
状態になってしまい、表示器としての品質を低下させる
とともに、液晶の寿命にも悪影響を与えていた。However, with conventional control, a part of the liquid crystal is not completely turned off for a while even after the power is turned off. This is because even if the display control signal is turned off immediately, the liquid crystal drive voltage VEE may not reach G due to the capacitance of the liquid crystal drive circuit 22 and the liquid crystal.
This is because it does not reach the ND level and several seconds elapse before it drops to the GND level due to natural discharge. For this reason, for several seconds until VEE reaches the GND level, the display line that was selected just before the display control signal was turned off remains lit, which degrades the quality of the display and shortens the life of the liquid crystal. was also having a negative impact.
【０００４】この発明の目的は、電源オフ後液晶に加わ
っている電荷を直ちに放電するようにして品質の向上と
長寿命化を図ることのできる液晶表示器の制御装置を提
供することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide a control device for a liquid crystal display that can improve quality and extend life by immediately discharging the charge added to the liquid crystal after the power is turned off.
【０００５】[0005]
【課題を解決するための手段】この発明は、液晶表示器
を駆動させる液晶駆動部とその液晶駆動部に駆動電圧を
供給する電源部との間に、前記電源部のオフ時にオンし
て前記液晶駆動部を放電する放電部を備えたことを特徴
とする。[Means for Solving the Problems] The present invention provides an arrangement between a liquid crystal drive section that drives a liquid crystal display and a power supply section that supplies a driving voltage to the liquid crystal drive section, which is turned on when the power supply section is turned off. The present invention is characterized in that it includes a discharge section that discharges the liquid crystal drive section.
【０００６】[0006]
【作用】この発明においては、電源部がオフされたとき
に放電部がオンして液晶駆動部に加わっている電荷が直
ちに放電される。すなわち液晶駆動電圧ＶＥＥが電源オ
フ後直ちにＧＮＤレベルまで低下して液晶表示画面が消
灯する。According to the present invention, when the power supply section is turned off, the discharge section is turned on and the electric charge applied to the liquid crystal drive section is immediately discharged. That is, the liquid crystal drive voltage VEE drops to the GND level immediately after the power is turned off, and the liquid crystal display screen turns off.
【０００７】[0007]
【実施例】図１はこの発明の実施例である液晶表示器を
備える電子機器のブロック図である。電子機器はＣＰＵ
１によって制御される。ＣＰＵ１はＲＯＭ２に記憶され
たプログラムにしたがってデータの記憶，演算，表示等
の処理を行う。ＲＡＭ３には入力されたデータ等が記憶
される。なおデータの入力はキー４から行われ、液晶表
示器５にデータが表示される。DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an electronic device equipped with a liquid crystal display according to an embodiment of the present invention. Electronic equipment is CPU
1. The CPU 1 performs processing such as data storage, calculation, and display according to a program stored in the ROM 2. The RAM 3 stores input data and the like. Note that data is input using the keys 4, and the data is displayed on the liquid crystal display 5.
【０００８】図２は液晶表示器５の駆動回路部分を示し
たブロック図である。液晶表示器５は液晶駆動回路６が
動作することによって点灯される。液晶駆動回路６には
昇圧回路７を介して電源制御部８から駆動電圧が供給さ
れる。液晶駆動回路６はＣＰＵ１からの表示データに基
づいて液晶表示器５を走査しながら表示ライン毎に駆動
する。昇圧回路７と液晶駆動回路６との間には電荷放電
回路９が設けられている。電荷放電回路９はスイッチ素
子で構成され、ＶＥＥ ＧＮＤ間に設けられている。
電荷放電回路９は電源制御信号によって制御される。電
源がオフすると電源制御信号によって電源制御部８から
の電源供給を停止させるとともに電荷放電回路９をオン
して液晶および液晶駆動回路に残留している電荷を放電
する。電源がオフすると電源制御信号は電源電圧が完全
に立ち下がってしまうまでの間を最大時間として電荷放
電回路９をオンするが、この間に電荷は完全に放電され
てしまう。これによってＶＥＥがＧＮＤレベルになる。
すなわちこの制御装置によれば、電源がオフされたとき
にはＶＥＥ電位が直ちにＧＮＤレベルになり液晶に電圧
が印加されなくなるため液晶面への表示が残留してしま
うことがない。FIG. 2 is a block diagram showing the driving circuit portion of the liquid crystal display 5. As shown in FIG. The liquid crystal display 5 is turned on by the operation of the liquid crystal drive circuit 6. A drive voltage is supplied to the liquid crystal drive circuit 6 from a power supply control section 8 via a booster circuit 7 . The liquid crystal drive circuit 6 drives the liquid crystal display 5 for each display line while scanning it based on display data from the CPU 1. A charge discharge circuit 9 is provided between the booster circuit 7 and the liquid crystal drive circuit 6. The charge discharge circuit 9 is composed of a switching element and is provided between VEE and GND. Charge discharge circuit 9 is controlled by a power supply control signal. When the power is turned off, the power supply from the power control section 8 is stopped using the power control signal, and the charge discharge circuit 9 is turned on to discharge the charge remaining in the liquid crystal and the liquid crystal drive circuit. When the power is turned off, the power supply control signal turns on the charge discharge circuit 9 for a maximum time until the power supply voltage completely falls, but the charge is completely discharged during this time. This brings VEE to the GND level. That is, according to this control device, when the power is turned off, the VEE potential immediately goes to the GND level and no voltage is applied to the liquid crystal, so that no display remains on the liquid crystal surface.
【０００９】[0009]
【発明の効果】この発明によれば、電源のオフとほぼ同
時に液晶駆動回路の電圧がＧＮＤレベルになり液晶が直
ちに消灯される。すなわち液晶の表示制御動作が停止す
るのとほぼ同時に液晶が消灯されることになり、不必要
な像（表示ライン）が液晶画面に残ってしまうことがな
い。これによって液晶表示器としての品質の低下、液晶
の短命化を防止することができる。According to the present invention, the voltage of the liquid crystal drive circuit goes to the GND level almost at the same time as the power is turned off, and the liquid crystal is immediately turned off. In other words, the liquid crystal is turned off almost at the same time as the display control operation of the liquid crystal stops, and unnecessary images (display lines) are not left on the liquid crystal screen. This can prevent deterioration in the quality of the liquid crystal display and shorten the lifespan of the liquid crystal.
【図１】この発明の実施例である液晶表示器制御装置を
備える電子手帳全体のブロック図FIG. 1 is a block diagram of an entire electronic notebook equipped with a liquid crystal display control device according to an embodiment of the present invention.
【図２】同制御装置の要部ブロック図[Figure 2] Block diagram of main parts of the control device
【図３】従来の液晶表示器制御装置の要部ブロック図[Figure 3] Main part block diagram of a conventional liquid crystal display control device
６ 液晶駆動回路 ７ 昇圧回路 ８ 電源制御部 ９ 電荷放電回路 6 Liquid crystal drive circuit 7 Boost circuit 8 Power control section 9 Charge discharge circuit
Claims (1)
液晶駆動部に駆動電圧を供給する電源部との間に、前記
電源部のオフ時にオンして前記液晶駆動部を放電する放
電部を備えたことを特徴とする液晶表示器の制御装置。1. A discharge section that is turned on when the power supply section is off to discharge the liquid crystal drive section, between a liquid crystal drive section that drives a liquid crystal display and a power supply section that supplies a driving voltage to the liquid crystal drive section. A control device for a liquid crystal display, comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12769491A JPH04352188A (en) | 1991-05-30 | 1991-05-30 | Liquid crystal display unit controller |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12769491A JPH04352188A (en) | 1991-05-30 | 1991-05-30 | Liquid crystal display unit controller |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04352188A true JPH04352188A (en) | 1992-12-07 |
Family
ID=14966395
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12769491A Pending JPH04352188A (en) | 1991-05-30 | 1991-05-30 | Liquid crystal display unit controller |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04352188A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007298737A (en) * | 2006-04-28 | 2007-11-15 | Kyocera Mita Corp | Power supply control unit, information processing apparatus |
| JP2008205036A (en) * | 2007-02-16 | 2008-09-04 | Alpine Electronics Inc | Driver circuit |
-
1991
- 1991-05-30 JP JP12769491A patent/JPH04352188A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007298737A (en) * | 2006-04-28 | 2007-11-15 | Kyocera Mita Corp | Power supply control unit, information processing apparatus |
| JP2008205036A (en) * | 2007-02-16 | 2008-09-04 | Alpine Electronics Inc | Driver circuit |
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