JP4364462B2 - Signal line level holding circuit for ESD countermeasures - Google Patents
Signal line level holding circuit for ESD countermeasures Download PDFInfo
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- JP4364462B2 JP4364462B2 JP2001240890A JP2001240890A JP4364462B2 JP 4364462 B2 JP4364462 B2 JP 4364462B2 JP 2001240890 A JP2001240890 A JP 2001240890A JP 2001240890 A JP2001240890 A JP 2001240890A JP 4364462 B2 JP4364462 B2 JP 4364462B2
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Description
【０００１】
【発明の属する技術分野】
本発明は、ＥＳＤ（Ｅｌｅｃｔｒｏｓｔａｔｉｃ Ｄｉｓｃｈａｒｇｅ：静電荷放電）対策用の回路技術に関する。
【０００２】
【従来の技術】
折り畳み型の携帯電話機等の携帯機器は、ＬＣＤ（Ｌｉｑｕｉｄ Ｃｒｙｓｔａｌ Ｄｉｓｐｌａｙ）表示部と本体回路部の２つのブロックに別れ、これらは通常フレキシブル基板により接続されている（図２参照）。こうした折り畳み型の携帯機器では、ＥＳＤに対し、通常ＬＣＤ表示部にはフレームＧＮＤとロジックＧＮＤの両方を設け、ＥＳＤ電流をフレームＧＮＤに流す対策をとっている。しかしながら、フレームＧＮＤとロジックＧＮＤ間の容量結合とフレキシブル基板の抵抗から、正電荷の放電を受けると、本体回路部ＧＮＤ電位に対してＬＣＤ表示部のロジックＧＮＤ電位が上昇する。一方信号線電位は本体回路部ＧＮＤ電位を基準としたレベルをもつため、ロジックＧＮＤ電位が上昇するとＬＣＤ表示部の信号線電位はこのロジックＧＮＤ電位に近づき、“Ｈ”（ハイ・レベル）の信号が“Ｌ”（ロー・レベル）と誤って検出される。こうして、誤ったリセットまたはチップセレクト信号により、ＬＣＤ表示部が誤動作を起こす。
【０００３】
したがって、本体回路部ＧＮＤに対するＬＣＤ表示部のロジックＧＮＤの電位上昇を少なくするため、これらを接続するフレキシブル基板のＧＮＤ部分の抵抗を下げる必要がある。一般的にはフレキシブル基板を２層（２重：片面をＧＮＤ）にしたり、別な銅箔を貼り付けたり導電塗装を行っている。
【０００４】
【発明が解決しようとする課題】
しかしこれらの対策は、フレキシブル基板が使用される部分が可動部であり、さらにこのフレキシブル基板が通常この可動部で一回転捻られているため耐久性に問題があり（屈曲試験に耐えられない）、信頼性の確保が難しく、また可動部であることから接続作業の困難性を伴うとともに、コストの上昇を招いていた。
【０００５】
本発明は、上記の点に鑑みてなされたもので、折り畳み型携帯電話機のように、２つの回路ブロック間で信号が送受信される機器において、簡単な回路構成で、ＥＳＤによる誤ったリセットや誤データ書き込みを防ぐことができる信号線レベル保持回路を提供するものである。
【０００６】
【課題を解決するための手段】
本発明のＥＳＤ対策用信号線レベル保持回路は、折り畳み型携帯電話機のように、本体回路部とフレキシブル基板を介して接続されるサブ回路部の２つの回路ブロックから構成される機器において、前記２つの回路ブロック間で接続されるリセットおよび／またはチップセレクト信号線にコンデンサの一端を接続し、該コンデンサの他端をダイオードのカソード側に接続し、該ダイオードのアノード側を前記サブ回路部のＧＮＤに接続し、該ダイオードのカソード側に抵抗の一端を接続し、該抵抗の他端を本体回路部のＧＮＤに接続することを特徴とする。
【０００７】
本発明は、本体回路部とフレキシブル基板を介して接続される表示部の２つの回路ブロックから構成される折り畳み型携帯機器であって、前記本体回路部と表示部の２つの回路ブロック間で接続されるリセットおよび／またはチップセレクト信号線にコンデンサの一端を接続し、該コンデンサの他端をダイオードのカソード側に接続し、該ダイオードのアノード側を前記サブ回路部のＧＮＤに接続し、該ダイオードのカソード側に抵抗の一端を接続し、該抵抗の他端を本体回路部のＧＮＤに接続したことを特徴とする。
【０００８】
【発明の実施の形態】
以下、本発明の実施の形態を、図面を参照して説明する。
図１は、本発明の実施の形態であるＥＳＤ対策用信号線レベル保持回路の回路図である。以下では、サブ回路部としてのＬＣＤ表示部と、本体回路部と、フレキシブル基板からなる折り畳み型携帯電話機（図２参照）に、本発明のＥＳＤ対策用信号線レベル保持回路を組み込んだ形態を説明する。
【０００９】
図１において、符号１は、本体回路部のバッファ回路であり、本体回路部からＬＣＤ表示部へ、リセット信号あるいはチップセレクト信号を出力する。
符号２は、バッファ回路１から出力されるリセット信号あるいはチップセレクト信号を受けるＬＣＤ表示部側のバッファ回路である。
符号３はコンデンサであり、符号４はダイオードであり、符号５は抵抗である。このコンデンサ３の一端は、上記リセット信号あるいはチップセレクト信号が流れる信号線に接続される。また、このコンデンサ３の他端は、ダイオード４のカソード側に接続され、ダイオード４のアノード側は、ＬＣＤ表示部のロジックＧＮＤに接続される。また、ダイオード４のカソード側には、抵抗５の一端が接続されその他端が本体回路部ＧＮＤに接続されている。
なお、ダイオード６ａ，６ｂは、ロジックＧＮＤ電位が降下した場合の対策用として従来から設けられていたものである。
【００１０】
このように構成された信号線レベル保持回路は、下記のように動作する。
【００１１】
ＥＳＤによる正電荷の放電がＬＣＤ表示部にあった場合で、さらに、前述のフレームＧＮＤで吸収できないロジックＧＮＤの電位上昇が発生した場合、ダイオード４は“ＯＮ”状態となる。ダイオード４が“ＯＮ”状態となると、抵抗５を経由して電位上昇したＬＣＤ回路部のロジックＧＮＤから本体回路部ＧＮＤに電流が流れ、本体回路部ＧＮＤとＬＣＤ表示部のロジックＧＮＤ間の電位差を抑える。同時にＬＣＤ表示部のロジックＧＮＤの電位上昇はコンデンサ３を通して信号線電位を上昇させる。
こうしてＬＣＤ表示部の信号線レベルは保持され、誤って“Ｌ”（ロー・レベル）を検出することなく誤動作に至らない。
【００１２】
以上、この発明の実施形態を、図面を参照して詳述してきたが、具体的な構成はこの実施形態に限られるものではなく、この発明の要旨を逸脱しない範囲の構成等も含まれる。例えば、抵抗５は、ＬＣＤ表示部側にあっても、フレキシブル基板の信号線上にあっても、本体回路部側にあってもよい。また、本発明は、折り畳み型携帯電話機等の携帯機器以外でも、２つの回路ブロックから構成される様々な機器に対し適用可能であることは明らかである。
【００１３】
【発明の効果】
以上、詳細に説明したように、本発明によれば、折り畳み型携帯電話機のように、本体回路部とフレキシブル基板を介して接続されるサブ回路部の２つの回路ブロックから構成される機器において、これら２つの回路ブロック間で接続されるリセットおよび／またはチップセレクト信号線の電位レベルを正規レベルの範囲に保持することができ、誤ったリセットや誤データ書き込みを防ぐことができる。また、従来のフレキシブル基板の２層（２重）化や銅箔の貼り付けによる対策では、信頼性の問題や作業の困難性、さらにはコストアップを招いていたが、本発明によれば、フレキシブル基板は、１層（１重）でよく、また簡単な回路追加によりＥＳＤ対策として同様な効果を上げることができる。
【図面の簡単な説明】
【図１】 本発明のＥＳＤ対策用信号線レベル保持回路の回路図である。
【図２】 一般的な折り畳み型携帯電話機の構成（概要）を示すブロック図である。
【符号の説明】
１，２…バッファ回路
３…コンデンサ
４，６ａ，６ｂ…ダイオード
５…抵抗
７…電源ライン[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit technology for countermeasures against ESD (Electrostatic Discharge).
[0002]
[Prior art]
A portable device such as a folding cellular phone is divided into two blocks, an LCD (Liquid Crystal Display) display unit and a main body circuit unit, which are usually connected by a flexible substrate (see FIG. 2). In such a foldable portable device, with respect to ESD, both the frame GND and the logic GND are usually provided on the LCD display unit, and measures are taken to allow an ESD current to flow to the frame GND. However, when a positive charge is discharged from the capacitive coupling between the frame GND and the logic GND and the resistance of the flexible substrate, the logic GND potential of the LCD display portion rises with respect to the main body circuit portion GND potential. On the other hand, since the signal line potential has a level with respect to the main body circuit portion GND potential, when the logic GND potential rises, the signal line potential of the LCD display portion approaches this logic GND potential, and the signal of “H” (high level). Is erroneously detected as “L” (low level). Thus, the LCD display unit malfunctions due to an erroneous reset or chip select signal.
[0003]
Therefore, in order to reduce an increase in the potential of the logic GND of the LCD display unit with respect to the main body circuit unit GND, it is necessary to reduce the resistance of the GND portion of the flexible substrate connecting them. In general, the flexible substrate is made into two layers (double: GND on one side), another copper foil is attached, or conductive coating is performed.
[0004]
[Problems to be solved by the invention]
However, these measures have a problem in durability because the part where the flexible substrate is used is a movable part, and this flexible substrate is usually twisted once by this movable part (it cannot withstand the bending test). In addition, it is difficult to ensure reliability, and since it is a movable part, it is difficult to connect, and the cost is increased.
[0005]
The present invention has been made in view of the above points. In a device in which signals are transmitted and received between two circuit blocks, such as a folding mobile phone, an erroneous reset or error due to ESD can be achieved with a simple circuit configuration. A signal line level holding circuit capable of preventing data writing is provided.
[0006]
[Means for Solving the Problems]
The signal line level holding circuit for ESD countermeasure according to the present invention is a device comprising two circuit blocks of a sub circuit unit connected to a main circuit unit via a flexible substrate, such as a foldable mobile phone. One end of a capacitor is connected to a reset and / or chip select signal line connected between two circuit blocks, the other end of the capacitor is connected to the cathode side of the diode, and the anode side of the diode is connected to the GND of the sub-circuit unit , One end of a resistor is connected to the cathode side of the diode, and the other end of the resistor is connected to GND of the main body circuit portion.
[0007]
The present invention relates to a foldable portable device composed of two circuit blocks of a display unit connected to a main circuit unit via a flexible substrate, and is connected between the two circuit blocks of the main circuit unit and the display unit One end of a capacitor is connected to the reset and / or chip select signal line, the other end of the capacitor is connected to the cathode side of the diode, and the anode side of the diode is connected to GND of the sub-circuit unit, One end of a resistor is connected to the cathode side, and the other end of the resistor is connected to GND of the main body circuit portion.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram of an ESD countermeasure signal line level holding circuit according to an embodiment of the present invention. In the following, an embodiment in which the signal line level holding circuit for ESD countermeasure of the present invention is incorporated in a foldable mobile phone (see FIG. 2) composed of an LCD display section as a sub circuit section, a main body circuit section, and a flexible substrate will be described. To do.
[0009]
In FIG. 1, reference numeral 1 denotes a buffer circuit of the main body circuit section, which outputs a reset signal or a chip select signal from the main body circuit section to the LCD display section.
Reference numeral 3 is a capacitor, reference numeral 4 is a diode, and reference numeral 5 is a resistor. One end of the capacitor 3 is connected to a signal line through which the reset signal or chip select signal flows. The other end of the capacitor 3 is connected to the cathode side of the diode 4, and the anode side of the diode 4 is connected to the logic GND of the LCD display unit. Further, one end of the resistor 5 is connected to the cathode side of the diode 4 and the other end is connected to the main body circuit portion GND.
The
[0010]
The signal line level holding circuit configured as described above operates as follows.
[0011]
When a positive charge discharge due to ESD occurs in the LCD display unit, and further, when the potential rise of the logic GND that cannot be absorbed by the frame GND described above occurs, the diode 4 is turned on. When the diode 4 is in the “ON” state, a current flows from the logic GND of the LCD circuit portion that has increased in potential via the resistor 5 to the main body circuit portion GND, and the potential difference between the main body circuit portion GND and the logic GND of the LCD display portion is reduced. suppress. At the same time, the increase in the potential of the logic GND of the LCD display unit raises the signal line potential through the capacitor 3.
Thus, the signal line level of the LCD display section is maintained, and no erroneous operation is caused without erroneously detecting “L” (low level).
[0012]
The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes a configuration that does not depart from the gist of the present invention. For example, the resistor 5 may be on the LCD display unit side, on the signal line of the flexible substrate, or on the main body circuit unit side. Further, it is obvious that the present invention can be applied to various devices including two circuit blocks other than a portable device such as a foldable mobile phone.
[0013]
【The invention's effect】
As described above in detail, according to the present invention, in a device configured by two circuit blocks of a main circuit unit and a sub circuit unit connected via a flexible substrate, such as a folding mobile phone, The potential level of the reset and / or chip select signal line connected between these two circuit blocks can be held within the normal level range, and erroneous reset and erroneous data writing can be prevented. In addition, the conventional countermeasures by double layering (double) of the flexible substrate and the pasting of the copper foil have led to a problem of reliability, difficulty of work, and further cost increase. The flexible substrate may be a single layer (single layer), and a similar effect can be achieved as an ESD countermeasure by adding a simple circuit.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of an ESD countermeasure signal line level holding circuit according to the present invention.
FIG. 2 is a block diagram showing a configuration (outline) of a general folding mobile phone.
[Explanation of symbols]
DESCRIPTION OF
Claims (2)
前記２つの回路ブロック間で接続されるリセットおよび／またはチップセレクト信号線にコンデンサの一端を接続し、該コンデンサの他端をダイオードのカソード側に接続し、該ダイオードのアノード側を前記サブ回路部のＧＮＤに接続し、該ダイオードのカソード側に抵抗の一端を接続し、該抵抗の他端を本体回路部のＧＮＤに接続する
ことを特徴とするＥＳＤ対策用信号線レベル保持回路。In a device composed of two circuit blocks, a main circuit part and a sub circuit part connected via a flexible substrate,
One end of a capacitor is connected to the reset and / or chip select signal line connected between the two circuit blocks, the other end of the capacitor is connected to the cathode side of the diode, and the anode side of the diode is connected to the sub-circuit section A signal line level holding circuit for ESD countermeasures, characterized in that one end of a resistor is connected to the GND of the diode, the other end of the resistor is connected to the GND of the main circuit portion.
前記本体回路部と表示部の２つの回路ブロック間で接続されるリセットおよび／またはチップセレクト信号線にコンデンサの一端を接続し、該コンデンサの他端をダイオードのカソード側に接続し、該ダイオードのアノード側を前記サブ回路部のＧＮＤに接続し、該ダイオードのカソード側に抵抗の一端を接続し、該抵抗の他端を本体回路部のＧＮＤに接続した
ことを特徴とする折り畳み型携帯機器。A foldable portable device composed of two circuit blocks of a display unit connected via a main body circuit unit and a flexible substrate,
One end of a capacitor is connected to the reset and / or chip select signal line connected between the two circuit blocks of the main body circuit portion and the display portion, the other end of the capacitor is connected to the cathode side of the diode, A foldable portable device characterized in that an anode side is connected to GND of the sub-circuit portion, one end of a resistor is connected to the cathode side of the diode, and the other end of the resistor is connected to GND of a main circuit portion.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001240890A JP4364462B2 (en) | 2001-08-08 | 2001-08-08 | Signal line level holding circuit for ESD countermeasures |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001240890A JP4364462B2 (en) | 2001-08-08 | 2001-08-08 | Signal line level holding circuit for ESD countermeasures |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2003051862A JP2003051862A (en) | 2003-02-21 |
| JP4364462B2 true JP4364462B2 (en) | 2009-11-18 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001240890A Expired - Fee Related JP4364462B2 (en) | 2001-08-08 | 2001-08-08 | Signal line level holding circuit for ESD countermeasures |
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| JP (1) | JP4364462B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101125346B1 (en) * | 2005-11-08 | 2012-03-27 | 엘지이노텍 주식회사 | Prevention circuit of memory initialization |
| CN100544205C (en) * | 2005-12-07 | 2009-09-23 | 群康科技(深圳)有限公司 | The method of control electrostatic discharge to result in electronic apparatus resetting |
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| JP2003051862A (en) | 2003-02-21 |
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