JP5870575B2

JP5870575B2 - Capacitive touch panel

Info

Publication number: JP5870575B2
Application number: JP2011206561A
Authority: JP
Inventors: 元俊南部; 晴彦近藤
Original assignee: SMK Corp
Current assignee: SMK Corp
Priority date: 2011-09-21
Filing date: 2011-09-21
Publication date: 2016-03-01
Anticipated expiration: 2031-09-21
Also published as: JP2013069079A

Description

本発明は、絶縁保護層を介して絶縁パネル上の導電層に入力操作体を接近させる入力操作の入力操作位置を検出する静電容量式タッチパネルに関し、更に詳しくは、単位長さあたりの抵抗値が一定の均一導電層の周囲に複数の検出電極が接続され、各検出電極に現れる信号電圧を比較して入力操作位置を検出する表面型静電容量式タッチパネルに関する。 The present invention relates to a capacitive touch panel that detects an input operation position of an input operation that causes an input operation body to approach a conductive layer on an insulating panel via an insulating protective layer, and more specifically, a resistance value per unit length. The present invention relates to a surface-type capacitive touch panel in which a plurality of detection electrodes are connected around a uniform conductive layer, and a signal voltage appearing on each detection electrode is compared to detect an input operation position.

電子機器、携帯電話機等の上位機種へ入力操作位置を示す位置座標を入力するポインティングデバイスとして、絶縁性基板上の入力操作面に合成樹脂、ガラス等の絶縁保護層で覆われた導電層が形成され、絶縁保護層による静電容量を介して導電層に接近する指などの入力操作体の入力操作位置を検出する静電容量式タッチパネルが知られている。この静電容量式タッチパネルは、絶縁性基板とその表面に積層する導電層及び絶縁保護層を透明材料で形成することができるので、液晶表示装置などのディスプレー上に配置し、ディスプレーに表示されるアイコンを見ながら、入力やカーソルの移動操作を行うことができ、また、硬質の絶縁性基板によってディスプレーを機械的な外力から保護できる。 A conductive layer covered with an insulating protective layer such as synthetic resin or glass is formed on the input operation surface on an insulating substrate as a pointing device that inputs position coordinates indicating the input operation position to higher-level models such as electronic devices and mobile phones. There is also known a capacitive touch panel that detects an input operation position of an input operation body such as a finger approaching a conductive layer through an electrostatic capacitance of an insulating protective layer. In this capacitive touch panel, an insulating substrate, a conductive layer and an insulating protective layer laminated on the surface thereof can be formed of a transparent material, so that they are arranged on a display such as a liquid crystal display device and displayed on the display. While looking at the icon, input and cursor movement operations can be performed, and the display can be protected from mechanical external force by a hard insulating substrate.

静電容量式タッチパネルは、更に絶縁性基板上の検出方向に沿って複数の検出電極パターンを配置し、入力操作体が接近して静電容量が増加する検出電極パターンの配設位置から入力操作位置を検出する投影型と、入力操作面の表面に均一導電層をむらなく形成し、入力操作体に流れる固有発振信号を均一導電層の四隅に接続する検出電極においてその信号レベルを比較して、入力操作位置を検出する表面型（特許文献１）とに分かれる。 In the capacitive touch panel, a plurality of detection electrode patterns are further arranged along the detection direction on the insulating substrate, and an input operation is performed from the detection electrode pattern arrangement position where the input operation body approaches and the capacitance increases. Compare the signal level of the projection type that detects the position and the detection electrode that forms the uniform conductive layer evenly on the surface of the input operation surface and connects the natural oscillation signal flowing through the input operation body to the four corners of the uniform conductive layer. And surface type for detecting the input operation position (Patent Document 1).

投影型は、入力操作面が大型化すると、それに応じて検出電極パターン数も増大し、全てを走査して入力操作位置を検出するための検出時間が延びるので、入力操作面が大型化したタッチパネルでは、表面型静電容量式タッチパネルが用いられている。以下、特許文献１に記載の表面型静電容量式タッチパネル１００を、図５を用いて説明する。 In the projection type, when the input operation surface is enlarged, the number of detection electrode patterns is increased accordingly, and the detection time for scanning all to detect the input operation position is extended, so the input operation surface is enlarged. The surface type capacitive touch panel is used. Hereinafter, the surface-type capacitive touch panel 100 described in Patent Document 1 will be described with reference to FIG.

この従来の表面型静電容量式タッチパネル１００は、絶縁性基板１０１表面の入力操作面に単位長さあたりの抵抗値が一定の均一な透明導電層１０２が形成されている。透明導電層１０２の周囲の４隅には、検出電極１０３ａ、〜１０３ｄが接続され、また、表面の全体は絶縁保護層１０４によって覆われている。各検出電極１０３ａ、〜１０３ｄには、検出電極１０３ａ、〜１０３ｄに流れる信号電流Ｉａ、〜Ｉｄを検出する電流検出回路１０５と、所定の基準ノード（例えば、タッチパネル１００内に配線されたグランドパターン）１０６の電位に対して検出電極１０３ａ、〜１０３ｄへ所定周波数の交流電圧を印加するＡＣ電源１０７が接続されている。 In this conventional surface capacitive touch panel 100, a uniform transparent conductive layer 102 having a constant resistance value per unit length is formed on the input operation surface of the surface of the insulating substrate 101. Detection electrodes 103 a and 103 d are connected to the four corners around the transparent conductive layer 102, and the entire surface is covered with an insulating protective layer 104. Each of the detection electrodes 103a and 103d includes a current detection circuit 105 that detects the signal currents Ia and ~ Id flowing through the detection electrodes 103a and 103d, and a predetermined reference node (for example, a ground pattern wired in the touch panel 100). An AC power source 107 that applies an alternating voltage of a predetermined frequency to the detection electrodes 103a and 103d with respect to the potential of 106 is connected.

従って、各検出電極１０３ａ、〜１０３ｄと透明導電層１０２の電位は、ＡＣ電源１０７から出力される交流電圧の電位で変動している。図示するように、入力操作体である指１１０を入力操作面に接近させて入力操作を行うと、絶縁保護層１０４の静電容量を介して透明導電層１０２の入力操作位置から指１１０に微少電流Ｉが流れる。この微少電流Ｉは、各検出電極１０３ａ、〜１０３ｄに流れる信号電流Ｉａ、〜Ｉｄの総和であり、各検出電極１０３ａ、〜１０３ｄに接続する電流検出回路１０５やＡＣ電源１０６の回路定数を同一とすれば、信号電流Ｉａ、〜Ｉｄは、各検出電極１０３ａ、〜１０３ｄと入力操作位置間の距離に比例する透明導電層１０２の抵抗値Ｒａ、〜Ｒｄによって分流される。 Therefore, the potentials of the detection electrodes 103 a to 103 d and the transparent conductive layer 102 vary with the potential of the AC voltage output from the AC power source 107. As shown in the figure, when an input operation is performed with the finger 110 as an input operation body approaching the input operation surface, the finger 110 is slightly moved from the input operation position of the transparent conductive layer 102 via the capacitance of the insulating protective layer 104. Current I flows. This minute current I is the sum of the signal currents Ia and .about.Id flowing through the detection electrodes 103a and 103d, and the circuit constants of the current detection circuit 105 and the AC power source 106 connected to the detection electrodes 103a and 103d are the same. In this case, the signal currents Ia and ˜Id are shunted by the resistance values Ra and ˜Rd of the transparent conductive layer 102 that are proportional to the distances between the detection electrodes 103a and 103d and the input operation positions.

図示するＸＹ方向の入力操作位置（ｘ、ｙ）は、例えば、ｋ１、ｋ２を定数として、
ｘ＝ｋ１＋ｋ２・（Ｉｂ＋Ｉｃ）／（Ｉａ＋Ｉｂ＋Ｉｃ＋Ｉｄ）・・・（１）式と、
ｙ＝ｋ１＋ｋ２・（Ｉａ＋Ｉｂ）／（Ｉａ＋Ｉｂ＋Ｉｃ＋Ｉｄ）・・・（２）式とから得られるので、電流検出回路１０５を用いて信号電流Ｉａ、〜Ｉｄを検出し、（１）式と（２）式を用いて入力操作位置（ｘ、ｙ）が検出される。 The input operation position (x, y) in the XY direction shown in the figure is, for example, with k1 and k2 as constants.
x = k1 + k2 · (Ib + Ic) / (Ia + Ib + Ic + Id) (1)
y = k1 + k2 · (Ia + Ib) / (Ia + Ib + Ic + Id) (2) is obtained from the equation (2). Therefore, the signal currents Ia and ˜Id are detected using the current detection circuit 105, and the equations (1) and (2) are obtained. Is used to detect the input operation position (x, y).

特開２０１０−２６２６２６号公報JP 2010-262626 A

しかしながら、特許文献１に例示される従来の静電容量式タッチパネル１００では、入力操作面に接近させて入力操作体１１０に流れる電流Ｉは、インピーダンスが極めて高い操作者や操作者１０８と基準ノード１０６間をも流れるので、微小値であり、各検出電極１０３ａ、〜１０３ｄに流れる信号電流Ｉａ、〜Ｉｄは、更にその微少電流Ｉが分流されたものなので、電流検出回路１０５によりその値を正確に検出することが困難であった。 However, in the conventional capacitive touch panel 100 exemplified in Patent Document 1, the current I that flows through the input operation body 110 close to the input operation surface is an operator or operator 108 with a very high impedance and the reference node 106. Since the signal currents Ia and Id flowing through the detection electrodes 103a and 103d are further shunted, the current detection circuit 105 accurately determines the value. It was difficult to detect.

また、入力操作が行われていない状態であっても、透明導電層１０２はＡＣ電源１０６から出力される交流電圧の電位で変動しているので、その表面から放射電磁波が放射され、放射電流が流れることによって電流検出回路１０５では、常時一定量の待機電流Ｉａ’、〜Ｉｄ’を検出している。従って、信号電流Ｉａ、〜Ｉｄは、電流検出回路１０５で実際に検出した電流値と、この待機電流Ｉａ’、〜Ｉｄ’との差分から求める必要があり、入力操作体を接近させる入力操作自体や入力操作位置の検出精度が低下する原因となっていた。 Even when the input operation is not performed, the transparent conductive layer 102 fluctuates with the potential of the AC voltage output from the AC power source 106, so that radiated electromagnetic waves are radiated from the surface, and the radiated current is reduced. By flowing, the current detection circuit 105 always detects a certain amount of standby currents Ia ′ and ˜Id ′. Therefore, the signal currents Ia and ˜Id need to be obtained from the difference between the current value actually detected by the current detection circuit 105 and the standby currents Ia ′ and ˜Id ′. Or the input operation position detection accuracy is reduced.

更に、各検出電極１０３ａ、〜１０３ｄを介して透明導電層１０２に交流電圧を印加するので、入力操作体が接近することにより各検出電極１０３ａ、〜１０３ｄに重畳して現れる信号電圧を検出することが困難であり、電流検出回路１０５により、信号電流Ｉａ、〜Ｉｄを検出している。しかしながら、電流値自体の検出は困難であり、信号電流Ｉａ、〜Ｉｄは、マイコンなどによる（１）式や（２）式を用いた演算処理にも不向きであるので、電流検出回路１０５では、結局、内部抵抗に信号電流Ｉａ、〜Ｉｄを流して、信号電流Ｉａ、〜Ｉｄを内部抵抗の両端の電圧に変換する複雑な構成とする必要があった。 Further, since an AC voltage is applied to the transparent conductive layer 102 via the detection electrodes 103a and 103d, the signal voltage appearing superimposed on the detection electrodes 103a and 103d when the input operation body approaches is detected. The current detection circuit 105 detects the signal currents Ia and ˜Id. However, it is difficult to detect the current value itself, and the signal currents Ia and ~ Id are unsuitable for arithmetic processing using the formulas (1) and (2) by a microcomputer or the like. Eventually, the signal currents Ia and ˜Id were passed through the internal resistors, and the signal currents Ia and ˜Id had to be converted into voltages at both ends of the internal resistors.

本発明は、このような従来の問題点を考慮してなされたものであり、入力操作自体や入力操作位置の検出精度が高い静電容量式タッチパネルを提供することを目的とする。 The present invention has been made in consideration of such conventional problems, and an object of the present invention is to provide a capacitive touch panel with high detection accuracy of the input operation itself and the input operation position.

また、電流検出回路を用いない簡単な構成で、入力操作位置が検出できる静電容量式タッチパネルを提供することを目的とする。 It is another object of the present invention to provide a capacitive touch panel that can detect an input operation position with a simple configuration that does not use a current detection circuit.

上述の目的を達成するため、請求項１の静電容量式タッチパネルは、入力操作面に、単位長さあたりの抵抗値が一定の均一導電層と均一導電層を覆う絶縁保護層が積層された絶縁性基板と、均一導電層の周囲の互いに離間する位置で均一導電層に接続された複数の検出電極と、固有周波数ｆの固有発振信号を出力し、均一導電層の電位を固有周波数ｆで振動させる信号出力回路と、基準ノードに対する各検出電極の電圧から、各検出電極に現れる固有発振信号の信号電圧を検出する信号検出回路とを備え、入力操作面へ入力操作体を接近させる入力操作の入力操作位置を、各検出電極について検出した固有発振信号の信号電圧と、各検出電極の均一導電層への接続位置とから検出する静電容量式タッチパネルであって、一方を接地若しくは定電位とした低圧基準電源線と高圧基準電源線を配線した基準電源回路と、基準電源回路の低圧基準電源線と高圧基準電源線間に直流電圧を出力する直流電源と、低圧振動電源線と高圧振動電源線を配線した振動電源回路と、低圧基準電源線と低圧振動電源線間に接続され、固有周波数ｆの固有発振信号で低圧基準電源線と低圧振動電源線間の電圧を変動させる第１インダクタと、高圧基準電源線と高圧振動電源線間に接続され、固有周波数ｆの固有発振信号で高圧基準電源線と高圧振動電源線間の電圧を変動させる第２インダクタと、を更に備え、全ての検出電極と基準ノードを、低圧振動電源線又は高圧振動電源線に接続するとともに、信号出力回路と信号検出回路を振動電源回路に接続し、第１インダクタと第２インダクタを介した直流電源の出力で駆動し、信号出力回路から出力される固有発振信号を、キャパシタを介して基準電源回路の低圧基準電源線と高圧基準電源線へ出力し、各検出電極が接続する均一導電層と信号検出回路の基準ノードの電位を固有周波数ｆで振動させることを特徴とする。 In order to achieve the above object, the capacitive touch panel according to claim 1 has a uniform conductive layer having a constant resistance value per unit length and an insulating protective layer covering the uniform conductive layer on the input operation surface. An insulating substrate, a plurality of detection electrodes connected to the uniform conductive layer at positions around the uniform conductive layer, and a natural oscillation signal having a natural frequency f are output, and the potential of the uniform conductive layer is set at the natural frequency f. A signal output circuit that vibrates and a signal detection circuit that detects a signal voltage of a specific oscillation signal that appears at each detection electrode from the voltage of each detection electrode with respect to a reference node, and an input operation that causes the input operation body to approach the input operation surface The capacitive touch panel detects the input operation position from the signal voltage of the natural oscillation signal detected for each detection electrode and the connection position of each detection electrode to the uniform conductive layer, one of which is grounded or fixed. A low-voltage reference power supply line and a high-voltage reference power supply line, a DC power supply that outputs a DC voltage between the low-voltage reference power supply line and the high-voltage reference power supply line, a low-voltage vibration power supply line, and a high-voltage A vibration power circuit in which a vibration power line is wired, and a first connected to a low-voltage reference power line and a low-voltage vibration power line and fluctuating a voltage between the low-voltage reference power line and the low-voltage vibration power line by a natural oscillation signal having a natural frequency f. An inductor, and a second inductor connected between the high-voltage reference power line and the high-voltage vibration power line, and changing a voltage between the high-voltage reference power line and the high-voltage vibration power line with a natural oscillation signal having a natural frequency f. The detection electrode and the reference node are connected to the low-voltage vibration power supply line or the high-voltage vibration power supply line, the signal output circuit and the signal detection circuit are connected to the vibration power supply circuit, and the direct current is passed through the first inductor and the second inductor. A uniform conductive layer that is driven by the output of the source and outputs a natural oscillation signal output from the signal output circuit to the low-voltage reference power supply line and the high-voltage reference power supply line of the reference power supply circuit via a capacitor, and to which each detection electrode is connected The potential of the reference node of the signal detection circuit is oscillated at the natural frequency f.

基準電源回路と振動電源回路は、第１インダクタと第２インダクタを介して接続するので、固有発振信号を基準電源回路へ出力すると、基準電源回路と振動電源回路間の電圧は、固有発振信号の固有周波数ｆで相対的に変動する。基準電源回路の低圧基準電源線と高圧基準電源線の一方は、接地若しくは定電位であるので、基準電源回路の電位は安定し、振動電源回路の電位が固有周波数ｆで変動する。従って、入力操作体が接近しない待機状態では、低圧振動電源線又は高圧振動電源線に接続する全ての検出電極と基準ノード間も等電位若しくは定電圧で固有周波数ｆで振動し、信号検出回路で検出する各検出電極の電圧に、固有周波数ｆの固有発振信号は現れない。一方、接地若しくは定電位にある入力操作体が、固有周波数ｆで振動する均一導電層に接近すると、基準ノードの電位に対し相対的に入力操作体が固有周波数ｆで振動するので、各検出電極に固有周波数ｆの固有発振信号が現れる。固有発振信号は、入力操作位置と各検出電極間の距離に応じて減衰するので、各検出電極に現れる固有周波数ｆの固有発振信号の信号電圧と各検出電極の配置位置から入力操作の入力操作位置が検出される。 Reference power supply circuit and the vibration power supply circuit, since the connection via the first inductor and the second inductor, and outputs to the reference power supply circuit specific oscillation signal, a voltage between the reference power supply circuit and the vibration power supply circuit, the inherent oscillation signal It fluctuates relatively at the natural frequency f. Since one of the low-voltage reference power supply line and the high-voltage reference power supply line of the reference power supply circuit is grounded or at a constant potential, the potential of the reference power supply circuit is stable and the potential of the vibration power supply circuit varies at the natural frequency f. Therefore, in a standby state where the input operation body does not approach, all the detection electrodes connected to the low-voltage vibration power supply line or the high-voltage vibration power supply line and the reference node vibrate at the natural frequency f with the same potential or constant voltage, and the signal detection circuit The natural oscillation signal having the natural frequency f does not appear in the voltage of each detection electrode to be detected. On the other hand, when the input operating body at the ground or constant potential approaches the uniform conductive layer that vibrates at the natural frequency f, the input operating body vibrates at the natural frequency f relative to the potential of the reference node. A natural oscillation signal having a natural frequency f appears in FIG. Since the natural oscillation signal is attenuated according to the distance between the input operation position and each detection electrode, the input operation of the input operation is determined from the signal voltage of the natural oscillation signal having the natural frequency f appearing on each detection electrode and the arrangement position of each detection electrode. The position is detected.

請求項２の静電容量式タッチパネルは、基準電源回路と振動電源回路間の第１インダクタと第２インダクタの合成インダクタンスをＬ／２、信号出力回路と基準電源回路の低圧側電源線間及び信号出力回路と基準電源回路の高圧側電源線間にそれぞれ介在されるキャパシタの合成キャパシタンスを２Ｃとしたときに、固有発振信号の固有周波数ｆを、
ｆ＝１／［２π（ＬＣ）^１／２］
とすることを特徴とする。 The capacitive touch panel according to claim 2, wherein the combined inductance of the first inductor and the second inductor between the reference power supply circuit and the vibration power supply circuit is L / 2, the signal output circuit and the low-voltage side power supply line of the reference power supply circuit, and the signal When the combined capacitance of the capacitors interposed between the output circuit and the high-voltage power supply line of the reference power supply circuit is 2C, the natural frequency f of the natural oscillation signal is
f = 1 / [2π (LC) ^1/2 ]
It is characterized by.

基準電源回路と振動電源回路間の第１インダクタ及び第２インダクタと、信号出力回路と基準電源回路間のキャパシタは、直列に接続され、固有周波数ｆが１／［２π（ＬＣ）^１／２］の固有発振信号が流れると、直列共振し、固有発振信号の電圧Ｖｉに対して振動する振動電源回路の電圧Ｖｏは、理論上無限大となる。従って、振動電源回路に接続する均一導電層の電位を拡大させて振動させることができ、相対的に入力操作体側に発生する固有発振信号の電流値が微小であっても、検出電極に現れる固有発振信号の信号電圧を検出容易なレベルに拡大させることができる。 The first inductor and the second inductor between the reference power supply circuit and the vibration power supply circuit, and the capacitor between the signal output circuit and the reference power supply circuit are connected in series, and the natural frequency f is 1 / [2π (LC) ^1/2 ]. When the natural oscillation signal flows, the voltage Vo of the vibration power supply circuit that resonates in series and vibrates with respect to the voltage Vi of the natural oscillation signal is theoretically infinite. Accordingly, the potential of the uniform conductive layer connected to the vibration power supply circuit can be expanded and vibrated, and even if the current value of the characteristic oscillation signal generated on the input operation body side is relatively small, the characteristic signal appearing on the detection electrode is displayed. The signal voltage of the oscillation signal can be expanded to a level where detection is easy.

請求項３の静電容量式タッチパネルは、信号出力回路は、振動電源回路に接続して直流電源の出力で駆動するマイクロプロセッサで構成され、マイクロプロセッサを動作させるクロックの周波数ｆｃｋを分周若しくは倍周して固有周波数ｆの固有発振信号を出力することを特徴とする。 According to another aspect of the present invention, the signal output circuit is composed of a microprocessor connected to the vibration power supply circuit and driven by the output of the DC power supply, and the frequency fck of the clock for operating the microprocessor is divided or multiplied. It circulates and outputs the natural oscillation signal of the natural frequency f.

マイクロプロセッサを動作させるクロックの周波数ｆｃｋを分周若しくは倍周して固有周波数ｆの固有発振信号とするので、マイクロプロセッサに簡単な分周回路若しくは倍周回路を加えるだけで、信号出力回路を兼ねて固有発振信号を出力できる。 Since the frequency fck of the clock for operating the microprocessor is divided or multiplied to generate a natural oscillation signal of the natural frequency f, it can also serve as a signal output circuit by adding a simple frequency divider or frequency multiplier to the microprocessor. Can output a natural oscillation signal.

また、マイクロプロセッサにより、固有発振信号の固有周波数ｆや振幅を調整できる。 Further, the natural frequency f and amplitude of the natural oscillation signal can be adjusted by the microprocessor.

請求項１の発明によれば、入力操作面側の均一導電層を固有周波数ｆで振動させて、相対的に入力操作体に固有周波数ｆの固有発振信号を発生させるので、操作者の入力操作体側で、固有周波数ｆの固有発振信号を出力する信号出力回路を用意する必要がない。 According to the first aspect of the present invention, the uniform conductive layer on the input operation surface side is vibrated at the natural frequency f, and the input operation body relatively generates the natural oscillation signal of the natural frequency f. It is not necessary to prepare a signal output circuit that outputs a natural oscillation signal having a natural frequency f on the body side.

入力操作の待機状態では、各検出電極と信号検出回路の基準ノード間の電位が定電圧に保たれるので、入力操作体が均一導電層に接近して各検出電極に現れる固有発振信号の信号電圧を、信号検出回路により、固有周波数ｆで振動する電圧から検出できる。従って、複雑構成の電流検出回路を用いて検出電極に流れる信号電流から信号電圧に変換する必要がない。 In the standby state of the input operation, the potential between each detection electrode and the reference node of the signal detection circuit is maintained at a constant voltage, so that the input operation body approaches the uniform conductive layer and the signal of the natural oscillation signal that appears on each detection electrode The voltage can be detected from the voltage oscillating at the natural frequency f by the signal detection circuit. Therefore, it is not necessary to convert a signal current flowing through the detection electrode into a signal voltage using a current detection circuit having a complicated configuration.

また、入力操作体が入力操作面に接近しない状態で、信号検出回路で検出する各検出電極の電圧に、固有周波数ｆの固有発振信号は現れないので、入力操作体が接近して、各検出電極の電圧に現れる固有周波数ｆの固有発振信号の信号電圧を精度良く検出できる。 In addition, since the natural oscillation signal of the natural frequency f does not appear in the voltage of each detection electrode detected by the signal detection circuit in a state where the input operation body does not approach the input operation surface, the input operation body approaches each detection. The signal voltage of the natural oscillation signal having the natural frequency f appearing in the electrode voltage can be detected with high accuracy.

また、直流電源が接続する基準電源回路と検出電極が接続する振動電源回路とを、絶縁型ＤＣ−ＤＣコンバータなどの高価な絶縁部品を用いずに分離して、振動電源回路を独立に電圧変動させることができる。 In addition, the reference power supply circuit to which the DC power supply is connected and the vibration power supply circuit to which the detection electrode is connected are separated without using expensive insulating parts such as an insulated DC-DC converter, and the voltage fluctuation of the vibration power supply circuit is independently performed. Can be made.

請求項２の発明によれば、固有発振信号が操作者と絶縁保護層を流れ、相対的に入力操作体に現れる固有発振信号の電流値が微小であっても、固有周波数ｆを調整して、検出電極に現れる固有発振信号の信号電圧を精度良く検出可能な電圧に調整できる。 According to the invention of claim 2, even if the natural oscillation signal flows through the insulating protective layer with the operator and the current value of the natural oscillation signal that appears in the input operation body is relatively small, the natural frequency f is adjusted. The signal voltage of the natural oscillation signal appearing on the detection electrode can be adjusted to a voltage that can be accurately detected.

請求項３の発明によれば、固有周波数ｆの固有発振信号をマイクロプロセッサを動作させるクロックから生成することができ、信号出力回路をマイクロプロセッサと別に設ける必要がない。 According to the invention of claim 3, the natural oscillation signal having the natural frequency f can be generated from the clock for operating the microprocessor, and there is no need to provide a signal output circuit separately from the microprocessor.

また、使用環境やインダクタ、キャパシタの回路定数に応じて調整する固有発振信号の固有周波数ｆや振幅を、マイクロプロセッサから容易に行うことができる。 In addition, the natural frequency f and amplitude of the natural oscillation signal adjusted according to the use environment and the circuit constants of the inductor and capacitor can be easily obtained from the microprocessor.

本発明の一実施の形態に係る静電容量式タッチパネル１を示すブロック図である。1 is a block diagram showing a capacitive touch panel 1 according to an embodiment of the present invention. 静電容量式タッチパネル１の電源回路の等価回路図である。3 is an equivalent circuit diagram of a power supply circuit of the capacitive touch panel 1. FIG. 静電容量式タッチパネル１の縦断面図である。1 is a longitudinal sectional view of a capacitive touch panel 1. FIG. 静電容量式タッチパネル１の平面図である。1 is a plan view of a capacitive touch panel 1. FIG. 従来の静電容量式タッチパネル１００の等価回路図である。FIG. 6 is an equivalent circuit diagram of a conventional capacitive touch panel 100.

以下、本発明の一実施の形態に係る静電容量式タッチパネル（以下、タッチパネルという）１を、図１乃至図４を用いて説明する。タッチパネル１は、図１に示すように、タッチパネル１を構成する主要回路部品が２種類の非振動側回路基板２と振動側回路基板３に分けて搭載されている。 Hereinafter, a capacitive touch panel (hereinafter referred to as a touch panel) 1 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4. As shown in FIG. 1, the touch panel 1 includes main circuit components constituting the touch panel 1 divided into two types of a non-vibration side circuit board 2 and a vibration side circuit board 3.

非振動回路基板２には、接地電位とした低圧基準電源線ＧＮＤと高圧基準電源線ＶＣＣとからなる基準電源回路４が配線され、低圧基準電源線ＧＮＤと高圧基準電源線ＶＣＣ間に直流電圧Ｖｃｃを印加するＤＣ電源５が接続されている。これにより、非振動回路基板２に搭載されるインターフェース回路６等の各回路部品を基準電源回路４に接続し、ＤＣ電源５の出力電圧Ｖｃｃにより駆動させている。 The non-vibration circuit board 2 is provided with a reference power supply circuit 4 including a low-voltage reference power supply line GND and a high-voltage reference power supply line VCC that are set to the ground potential, and a DC voltage Vcc between the low-voltage reference power supply line GND and the high-voltage reference power supply line VCC. Is connected to a DC power source 5. Thereby, each circuit component such as the interface circuit 6 mounted on the non-vibration circuit board 2 is connected to the reference power supply circuit 4 and driven by the output voltage Vcc of the DC power supply 5.

また、振動側回路基板３には、低圧振動電源線ＳＧＮＤと高圧振動電源線ＳＶＣＣとからなる振動電源回路７が配線されている。低圧振動電源線ＳＧＮＤは低圧基準電源線ＧＮＤと、高圧振動電源線ＳＶＣＣは高圧基準電源線ＶＣＣと、それぞれコイル８、９を介して接続している。コイル８とコイル９は、ここでは、同一のインダクタンスＬのコイル８、９を用いている。これにより、図１に示すように、基準電源回路４の低圧基準電源線ＧＮＤと高圧基準電源線ＶＣＣへ、固有周波数ｆの固有発振信号ＳＧを同期させて出力すると、基準電源回路４の低圧基準電源線ＧＮＤが接地されて安定した電位にあるので、振動電源回路７の低圧振動電源線ＳＧＮＤと高圧振動電源線ＳＶＣＣの電位が、同期して固有周波数ｆで変動し、両者間の電圧は、基準電源回路４と同じ直流出力電圧Ｖｃｃとなる。 Further, the vibration side circuit board 3 is provided with a vibration power circuit 7 including a low voltage vibration power line SGND and a high voltage vibration power line SVCC. The low-voltage vibration power supply line SGND is connected to the low-voltage reference power supply line GND, and the high-voltage vibration power supply line SVCC is connected to the high-voltage reference power supply line VCC via the coils 8 and 9, respectively. Here, the coils 8 and 9 are the coils 8 and 9 having the same inductance L. As a result, as shown in FIG. 1, when the natural oscillation signal SG having the natural frequency f is synchronized and output to the low voltage reference power supply line GND and the high voltage reference power supply line VCC of the reference power supply circuit 4, the low voltage reference of the reference power supply circuit 4 is output. Since the power supply line GND is grounded and at a stable potential, the potentials of the low-voltage vibration power supply line SGND and the high-voltage vibration power supply line SVCC of the vibration power supply circuit 7 fluctuate synchronously with the natural frequency f. The DC output voltage Vcc is the same as that of the reference power supply circuit 4.

振動電源回路７が配線された振動側回路基板３には、図１に示す４種類の検出電極Ｅ１Ｅ２、Ｅ３、Ｅ４が、振動電源回路７の低圧振動電源線ＳＧＮＤと高圧振動電源線ＳＶＣＣのいずれかの、ここでは高圧振動電源線ＳＶＣＣに接続している。 On the vibration side circuit board 3 to which the vibration power supply circuit 7 is wired, four types of detection electrodes E1E2, E3, and E4 shown in FIG. 1 are connected to either the low-voltage vibration power supply line SGND or the high-voltage vibration power supply line SVCC of the vibration power supply circuit 7. Here, it is connected to the high-voltage vibration power supply line SVCC.

４種類の検出電極Ｅ１Ｅ２、Ｅ３、Ｅ４は、図３、図４に示すように、矩形状絶縁性基板１１の入力操作面となる表面全体に形成された均一導電層２１の４隅にそれぞれ接続し、均一導電層２１を高圧振動電源線ＳＶＣＣの電位としている。矩形状絶縁性基板１１は、上述の振動側回路基板３の一部であっても良いが、ここでは、振動側回路基板３と別に設けている。均一導電層２１は、絶縁性基板１１の表面に１０乃至均一の厚みの薄膜として形成され、絶縁性基板１１の表面に沿った単位長さあたりの抵抗値を一定としている。均一導電層２１の更に表面全体は、均一導電層２１が変形したり損傷してその抵抗値が変化しないように、絶縁保護層２２により覆われている。 The four types of detection electrodes E1E2, E3, and E4 are respectively connected to the four corners of the uniform conductive layer 21 formed on the entire surface serving as the input operation surface of the rectangular insulating substrate 11, as shown in FIGS. The uniform conductive layer 21 is set to the potential of the high-voltage vibration power supply line SVCC. The rectangular insulating substrate 11 may be a part of the vibration side circuit board 3 described above, but is provided separately from the vibration side circuit board 3 here. The uniform conductive layer 21 is formed on the surface of the insulating substrate 11 as a thin film having a thickness of 10 to uniform, and the resistance value per unit length along the surface of the insulating substrate 11 is constant. The entire surface of the uniform conductive layer 21 is covered with an insulating protective layer 22 so that the uniform conductive layer 21 is not deformed or damaged and its resistance value does not change.

このように構成されたタッチパネル１を液晶表示素子等の表示装置上に配置して、タッチパネル１を通して表示装置の表示が目視できるように、絶縁性基板１１、検出電極Ｅ、均一導電層２１及び絶縁保護層２２は、透明材料で形成される。 The touch panel 1 configured as described above is arranged on a display device such as a liquid crystal display element so that the display of the display device can be visually observed through the touch panel 1, the insulating substrate 11, the detection electrode E, the uniform conductive layer 21, and the insulation. The protective layer 22 is made of a transparent material.

振動側回路基板３には、更に、アナログマルチプレクサ１２、信号検出回路１３、Ａ／Ｄコンバータ１４、信号出力回路を兼ねたＭＰＵ（マイクロプロセッサユニット）１０及び発振回路１５の各回路素子が搭載され、いずれも振動電源回路７の低圧振動電源線ＳＧＮＤと高圧振動電源線ＳＶＣＣに接続し、ＤＣ電源５から出力電圧Ｖｃｃを受けて動作している。また、信号検出回路１３で各検出電極Ｅの電圧を比較する基準ノードも、振動電源回路７の低圧振動電源線ＳＧＮＤと高圧振動電源線ＳＶＣＣのいずれかの、ここでは高圧振動電源線ＳＶＣＣに接続している。 The vibration side circuit board 3 further includes circuit elements of an analog multiplexer 12, a signal detection circuit 13, an A / D converter 14, an MPU (microprocessor unit) 10 that also serves as a signal output circuit, and an oscillation circuit 15. Both are connected to the low-voltage vibration power supply line SGND and the high-voltage vibration power supply line SVCC of the vibration power supply circuit 7 and operate by receiving the output voltage Vcc from the DC power supply 5. The reference node for comparing the voltage of each detection electrode E in the signal detection circuit 13 is also connected to either the low-voltage vibration power line SGND or the high-voltage vibration power line SVCC of the vibration power circuit 7, here the high-voltage vibration power line SVCC. doing.

各検出電極Ｅ１、Ｅ２、Ｅ３、Ｅ４は、アナログマルチプレクサ１２の４種類の入力に接続し、アナログマルチプレクサ１２は、ＭＰＵ１０からの切り替え制御により、一定の走査周期で各検出電極Ｅ１、Ｅ２、Ｅ３、Ｅ４を図示しない増幅回路を介して信号検出回路１３へ切り換え接続する。 Each detection electrode E1, E2, E3, E4 is connected to four types of inputs of the analog multiplexer 12, and the analog multiplexer 12 is controlled by switching from the MPU 10 so that each detection electrode E1, E2, E3, E4 is switched and connected to the signal detection circuit 13 through an amplifier circuit (not shown).

信号検出回路１３は、固有発振信号ＳＧの固有周波数ｆを中心とする周波数帯域の信号を通過させることにより、直流信号等の低周波成分とコモンモードノイズ等の高周波ノイズをカットするバンドパスフィルタと、バンドパスフィルタから出力される固有発振信号ＳＧの基準ノードに対する信号電圧を検出するオペアンプを利用した積分回路とからなっている。 The signal detection circuit 13 is a band-pass filter that cuts low-frequency components such as DC signals and high-frequency noise such as common mode noise by passing a signal in a frequency band centered on the natural frequency f of the natural oscillation signal SG. And an integrating circuit using an operational amplifier for detecting a signal voltage with respect to a reference node of the natural oscillation signal SG output from the band pass filter.

バンドパスフィルタの出力は、プルアップ抵抗によりプルアップされると共に、低圧振動電源線ＳＧＮＤの方向を順方向とするダイオードでクランプされ、積分回路を構成するオペアンプの反転入力端子に接続している。これにより、バンドパスフィルタから出力される固有発振信号ＳＧは、オペアンプの反転入力端子に入力される。一方、オペアンプの非反転入力端子の基準電位も、反転入力端子のクランプした電位に一致させている。これにより、オペアンプの出力電圧は、経過時間とともに、固有発振信号ＳＧの振幅（信号電圧）に比例して上昇するので、積分回路のリセット時から一定時間経過後のオペアンプの出力電圧を、固有発振信号ＳＧの振幅を拡大させた信号電圧として検出できる。 The output of the band-pass filter is pulled up by a pull-up resistor and clamped by a diode whose forward direction is the direction of the low-voltage oscillation power supply line SGND, and is connected to the inverting input terminal of the operational amplifier constituting the integrating circuit. Thus, inherent oscillation signal SG outputted from the band-pass filter is input to the inverting input terminal of the operational amplifier. On the other hand, the reference potential of the non-inverting input terminal of the operational amplifier is also matched with the clamped potential of the inverting input terminal. As a result, the output voltage of the operational amplifier rises with the elapsed time in proportion to the amplitude (signal voltage) of the natural oscillation signal SG. It can be detected as a signal voltage obtained by expanding the amplitude of the signal SG.

信号検出回路１３が検出した固有発振信号ＳＧの信号電圧は、ＭＰＵ１０において演算処理を実行するために、Ａ／Ｄコンバータ１４で、固有周波数ｆの少なくとも２倍以上の周波数でサンプリングされ、量子化データとしてＭＰＵ１０へ出力される。 The signal voltage of the natural oscillation signal SG detected by the signal detection circuit 13 is sampled at a frequency at least twice the natural frequency f by the A / D converter 14 in order to execute arithmetic processing in the MPU 10, and the quantized data Is output to the MPU 10.

Ａ／Ｄコンバータ１４から出力される量子化データは、その時にアナログマルチプレクサ１２が選択接続した検出電極Ｅに現れる固有発振信号ＳＧの信号電圧を二値化して表すので、ＭＰＵ１０では、一走査周期にＡ／Ｄコンバータ１４から出力された各検出電極Ｅ１、Ｅ２、Ｅ３、Ｅ４に現れる信号電圧の総和を所定の閾値と比較し、所定の閾値以上である場合に、入力操作体である操作者の指２０が入力操作面に接近して固有発振信号ＳＧが検出電極Ｅに現れたものとして、入力操作と判定する。 Since the quantized data output from the A / D converter 14 represents the signal voltage of the natural oscillation signal SG that appears at the detection electrode E selectively connected by the analog multiplexer 12 at that time, the MPU 10 displays it in one scanning cycle. The sum of signal voltages appearing at the detection electrodes E1, E2, E3, and E4 output from the A / D converter 14 is compared with a predetermined threshold value. As the finger 20 approaches the input operation surface and the natural oscillation signal SG appears on the detection electrode E, the input operation is determined.

また、入力操作と判定した後は、一走査周期に入力された各検出電極Ｅ１、Ｅ２、Ｅ３、Ｅ４に現れる個々の信号電圧を比較し、後述する方法で、指２０が接近する入力操作面上の入力操作位置（ｘ，ｙ）を検出する。ＭＰＵ１０で検出した入力操作位置（ｘ，ｙ）を含む入力操作データは、直流が絶縁された信号線１６を介して、非振動回路基板２に搭載されるインターフェース回路６に出力され、インターフェース回路６からＵＳＢ通信、Ｉ^２Ｃ通信等で入力操作データを利用する上位機器に出力される。 In addition, after the input operation is determined, the individual signal voltages appearing on the detection electrodes E1, E2, E3, and E4 input in one scanning cycle are compared, and the input operation surface on which the finger 20 approaches is compared by a method described later. The upper input operation position (x, y) is detected. Input operation data including the input operation position (x, y) detected by the MPU 10 is output to the interface circuit 6 mounted on the non-vibration circuit board 2 via the signal line 16 in which the direct current is insulated. To the host device that uses the input operation data by USB communication, I ² C communication, or the like.

発振回路１５は、固定周波数ｆｃｋのクロックＣＫを、アナログマルチプレクサ１２、信号検出回路１３、Ａ／Ｄコンバータ１４、ＭＰＵ１０へ出力し、これらの回路による上述した一連の動作の同期をとっている。 The oscillation circuit 15 outputs a clock CK having a fixed frequency fck to the analog multiplexer 12, the signal detection circuit 13, the A / D converter 14, and the MPU 10, and synchronizes the series of operations described above by these circuits.

ＭＰＵ１０は、固有発振信号ＳＧの固有周波数ｆを基準電源回路４の低圧基準電源線ＧＮＤと高圧基準電源線ＶＣＣへ出力する信号出力回路としても作用し、ここでは、ＭＰＵ１０から、有周波数ｆが１８７ｋＨｚ、振幅（ピーク間の電圧Ｖｐ−ｐ）が５Ｖの固有発振信号ＳＧが出力される。固有発振信号ＳＧの固有周波数ｆは、発振回路１５から入力されるクロックＣＫの周波数ｆｃｋを分周若しくは倍周し、また、振幅（信号電圧）は、低圧振動電源線ＳＧＮＤと高圧振動電源線ＳＶＣＣ間の電圧Ｖｃｃを昇圧若しくは降圧して、任意に調整することができる。 The MPU 10 also functions as a signal output circuit that outputs the natural frequency f of the natural oscillation signal SG to the low-voltage reference power supply line GND and the high-voltage reference power supply line VCC of the reference power supply circuit 4. Here, the MPF 10 has a frequency f of 187 kHz. The natural oscillation signal SG having an amplitude (voltage Vp-p between peaks Vp-p) of 5 V is output. The natural frequency f of the natural oscillation signal SG is obtained by dividing or multiplying the frequency fck of the clock CK input from the oscillation circuit 15, and the amplitude (signal voltage) is the low-voltage vibration power supply line SGND and the high-voltage vibration power supply line SVCC. The voltage Vcc between them can be arbitrarily adjusted by increasing or decreasing the voltage Vcc.

固有発振信号ＳＧを出力するＭＰＵ１０の出力は、二股に分岐しそれぞれコンデンサ１７、１８を介して基準電源回路４の低圧基準電源線ＧＮＤと高圧基準電源線ＶＣＣに接続している。コンデンサ１７とコンデンサ１８は、電源線の直流電圧を遮断する目的で介在させるので、それぞれのキャパシタンスは任意であるが、ここでは、同一のキャパシタンスＣのコンデンサ１７、１８を用いている。 The output of the MPU 10 that outputs the natural oscillation signal SG is bifurcated and connected to the low-voltage reference power supply line GND and the high-voltage reference power supply line VCC of the reference power supply circuit 4 through capacitors 17 and 18, respectively. Since the capacitor 17 and the capacitor 18 are interposed for the purpose of blocking the DC voltage of the power supply line, the respective capacitances are arbitrary, but here, the capacitors 17 and 18 having the same capacitance C are used.

固有周波数ｆの固有発振信号ＳＧが基準電源回路４と振動電源回路７に流れる場合に、低圧基準電源線ＧＮＤと高圧基準電源線ＶＣＣ間及び低圧振動電源線ＳＧＮＤと高圧振動電源線ＳＶＣＣ間が近接して配線され、固有周波数ｆの帯域でこれらの電源線間は短絡しているとすれば、図１の基準電源回路４と振動電源回路７は、図２の等価回路図で示される。 When the natural oscillation signal SG having the natural frequency f flows in the reference power supply circuit 4 and the vibration power supply circuit 7, the low voltage reference power supply line GND and the high voltage reference power supply line VCC and the low voltage vibration power supply line SGND and the high voltage vibration power supply line SVCC are close to each other. If the power supply lines are short-circuited in the band of the natural frequency f, the reference power supply circuit 4 and the vibration power supply circuit 7 of FIG. 1 are shown in the equivalent circuit diagram of FIG.

図２に示すように、ＭＰＵ１０の出力と基準電源回路４間には、並列にキャパシタンスＣのコンデンサ１７、１８が接続されているので、その合成キャパシタンスは、２Ｃであり、また、基準電源回路４と振動電源回路７間に並列に接続されるコイル８、９の合成インダクタンスは、Ｌ／２となる。これらのキャパシタとインダクタは、固有周波数ｆの固有発振信号ＳＧが流れる閉回路において直列に接続され、固有発振信号ＳＧの振幅（レベル）をＶｉ、コイル８、９両端の基準電源回路４と振動電源回路７間の電圧をＶｏ、２πｆで表される角速度をω（ｒａｄ／ｓｅｃ）とすれば、
Ｖｏ＝［ω^２ＬＣ／（ω^２ＬＣ−１）］Ｖｉ・・・（３）式
で表される。
ここで、図２に示す回路は、ω^２ＬＣ＝１で直列共振し、そのときの周波数ｆ_０は、
ｆ_０＝１／［２π（ＬＣ）^１／２］・・・（４）式
となる。 As shown in FIG. 2, since capacitors 17 and 18 having a capacitance C are connected in parallel between the output of the MPU 10 and the reference power supply circuit 4, the combined capacitance is 2C, and the reference power supply circuit 4 And the combined inductance of the coils 8 and 9 connected in parallel between the vibration power supply circuit 7 is L / 2. These capacitors and inductors are connected in series in a closed circuit through which the natural oscillation signal SG having the natural frequency f flows. The amplitude (level) of the natural oscillation signal SG is Vi, the reference power supply circuit 4 at both ends of the coils 8 and 9 and the vibration power supply. If the voltage between the circuits 7 is Vo, and the angular velocity represented by 2πf is ω (rad / sec),
Vo = [ω ² LC / (ω ² LC-1)] Vi expressed by the equation (3).
Here, the circuit shown in FIG. 2 resonates in series at ω ² LC = 1, and the frequency f _{0 at} that time is
f ₀ = 1 / [2π (LC) ^1/2 ] (4).

つまり、（４）式関係から得られる共振周波数ｆ_０を、固有発振信号ＳＧの固有周波数ｆとすれば、固有発振信号ＳＧの信号電圧に対して、（３）式から理論上振動電源回路７の電位が無限大で振動し、振動電源回路７に接続する検出電極Ｅと均一導電層２１の電位も無限大に振動させることができる。その結果、絶縁保護層２２を介した均一導電層２１と指２０との間の静電容量が微小で、入力操作者と振動電源回路７間のインピーダンスが極めて高くても、検出電極Ｅと指２０間に現れる信号電圧を理論上無限大まで任意に拡大することができるので、検出電極Ｅに現れる固有発振信号ＳＧの信号電圧を、信号検出回路１４により検出可能なレベルまで引き上げることができる。 That is, if the resonance frequency f ₀ obtained from the relationship of the equation (4) is the natural frequency f of the natural oscillation signal SG, the vibration power supply circuit 7 is theoretically obtained from the equation (3) with respect to the signal voltage of the natural oscillation signal SG. And the potential of the detection electrode E connected to the vibration power supply circuit 7 and the uniform conductive layer 21 can be vibrated infinitely. As a result, even if the capacitance between the uniform conductive layer 21 and the finger 20 through the insulating protective layer 22 is very small and the impedance between the input operator and the vibration power supply circuit 7 is extremely high, the detection electrode E and the finger Since the signal voltage appearing between 20 can theoretically be arbitrarily increased to infinity, the signal voltage of the natural oscillation signal SG appearing at the detection electrode E can be raised to a level detectable by the signal detection circuit 14.

例えば、図１に示すタッチパネル１において、コイル８、９のインダクタンスが２２０μＨ、コンデンサ１７、１８のキャパシタンスが３３０ｐＦであるとして、固有発振信号ＳＧの振幅（Ｖｐ−ｐ）が５Ｖで固有周波数ｆが１８７ｋＨｚをＭＰＵ１０から出力すると、振動電源回路７と振動電源回路７に接続する検出電極Ｅは、４倍の２０Ｖの振幅（Ｖｐ−ｐ）で振動することが実測された。 For example, in the touch panel 1 shown in FIG. 1, assuming that the inductances of the coils 8 and 9 are 220 μH and the capacitances of the capacitors 17 and 18 are 330 pF, the amplitude (Vp−p) of the natural oscillation signal SG is 5 V and the natural frequency f is 187 kHz. Is output from the MPU 10, and it was actually measured that the vibration power supply circuit 7 and the detection electrode E connected to the vibration power supply circuit 7 vibrate with an amplitude (Vp-p) of 20V that is four times.

実際のタッチパネル１では、基準電源回路４と振動電源回路７のインダクタンス、浮遊容量などの影響から、（４）式から得る周波数ｆ_０で共振せず、また、基準電源回路４と振動電源回路７に固有発振信号ＳＧが流れる際のエネルギーロス等により、振動電源回路７は、固有発振信号ＳＧのレベルに対して有限倍率に拡大された振幅で電位が振動する。一方、操作者の指２０を介して大電流の固有発振信号ＳＧを流すことはできないので、固有発振信号ＳＧの固有周波数ｆを共振周波数ｆ_０から外したり、ＭＰＵ１０から出力する固有発振信号ＳＧの振幅を調整し、検出電極Ｅに現れる信号電圧の上限を、入力操作位置（ｘ，ｙ）を確実に検出できる信号電圧の範囲内としている。 The actual touch panel 1 does not resonate at the frequency f ₀ obtained from the equation (4) due to the influence of the inductance, stray capacitance, etc. of the reference power supply circuit 4 and the vibration power supply circuit 7, and the reference power supply circuit 4 and the vibration power supply circuit 7 Due to the energy loss or the like when the natural oscillation signal SG flows in the oscillation power supply circuit 7, the potential vibrates with the amplitude expanded to a finite magnification with respect to the level of the natural oscillation signal SG. On the other hand, it is impossible to flow a specific oscillation signal SG of a large current through the operator's finger 20, or remove the natural frequency f of the natural oscillation signal SG from the resonance frequency f _0, the inherent oscillation signal SG outputted from the MPU10 The amplitude is adjusted, and the upper limit of the signal voltage appearing at the detection electrode E is set within the signal voltage range in which the input operation position (x, y) can be reliably detected.

このように構成されたタッチパネル１により、指２０の入力操作位置を検出する動作を以下に説明する。入力操作が行われない待機状態で、均一導電層２１に接続する検出電極Ｅは、その電位が固有周波数ｆで振動するが、信号検出回路１４も等電位差で共に固有周波数ｆで振動するので、信号検出回路１４のバンドパスフィルタを通過する信号はない。積分回路を構成するオペアンプの一対の入力も共に、低圧振動電源線ＳＧＮＤに接続する基準ノードに対してダイオードの順電圧Ｖｆを加えた等電位となっているので、オペアンプの出力電圧は所定期間後も上昇せず、固有発振信号ＳＧの信号電圧は検出されない。従って、一走査周期に信号検出回路１４から出力される信号電圧の総和も所定の閾値未満であり、入力操作が行われていないと判定される。 An operation for detecting the input operation position of the finger 20 by the touch panel 1 configured as described above will be described below. In the standby state where no input operation is performed, the detection electrode E connected to the uniform conductive layer 21 vibrates at the natural frequency f, but the signal detection circuit 14 also vibrates at the natural frequency f due to an equipotential difference. There is no signal passing through the band-pass filter of the signal detection circuit 14. Since both the pair of inputs of the operational amplifier constituting the integrating circuit are equipotentials obtained by adding the forward voltage Vf of the diode to the reference node connected to the low-voltage oscillation power supply line SGND, the output voltage of the operational amplifier is a predetermined period later. And the signal voltage of the natural oscillation signal SG is not detected. Therefore, the sum of the signal voltages output from the signal detection circuit 14 in one scanning cycle is also less than the predetermined threshold value, and it is determined that no input operation is performed.

入力操作により入力操作面の均一導電層２１に指２０が接近すると、全ての検出電極Ｅが高圧振動電源線ＳＶＣＣに接続することにより、均一導電層２１の電位が固有周波数ｆで振動するのに対し、足下などの一部が接地している操作者の指２０の電位は定電位であるので、図３に示すように、指２０が接近する均一導電層２１の位置（入力操作位置）から絶縁保護層２２を介して指２０へ固有周波数ｆの固有発振信号ＳＧが出力される。これを、固有周波数ｆで振動する信号回路側回路基板３の各素子からみれば、指２０から出力される固有周波数ｆの固有発振信号が均一導電層２１の入力操作位置（ｘ，ｙ）に入力されたものとして現れ、振動電源回路７で駆動する信号検出回路１３において、各検出電極Ｅに現れる固有周波数ｆの固有発振信号ＳＧが検出される。従って、一走査周期に信号検出回路１４から出力される信号電圧の総和が所定の閾値以上となった場合に、入力操作が行われたと判定し、次にその入力操作位置（ｘ，ｙ）を検出する。 When the finger 20 approaches the uniform conductive layer 21 on the input operation surface by the input operation, all the detection electrodes E are connected to the high-voltage vibration power supply line SVCC, so that the potential of the uniform conductive layer 21 vibrates at the natural frequency f. On the other hand, since the potential of the finger 20 of the operator whose part such as the foot is grounded is a constant potential, as shown in FIG. 3, from the position (input operation position) of the uniform conductive layer 21 where the finger 20 approaches. A natural oscillation signal SG having a natural frequency f is output to the finger 20 through the insulating protective layer 22. If this is seen from each element of the signal circuit side circuit board 3 that vibrates at the natural frequency f, the natural oscillation signal of the natural frequency f output from the finger 20 is input to the input operation position (x, y) of the uniform conductive layer 21. In the signal detection circuit 13 that appears as input and is driven by the vibration power supply circuit 7, the natural oscillation signal SG of the natural frequency f that appears at each detection electrode E is detected. Accordingly, when the sum of the signal voltages output from the signal detection circuit 14 in one scanning cycle is equal to or greater than a predetermined threshold value, it is determined that an input operation has been performed, and then the input operation position (x, y) is determined. To detect.

各検出電極Ｅに現れる固有発振信号ＳＧの信号電圧は、各検出電極Ｅ１、Ｅ２、Ｅ３、Ｅ４から入力操作位置（ｘ，ｙ）までの距離に依存する。すなわち、各検出電極Ｅに現れる固有発振信号ＳＧの信号電圧は、各検出電極Ｅと基準ノード間の内部抵抗ｒ０と各検出電極Ｅと入力操作位置（ｘ，ｙ）間の抵抗値ｒの和に反比例し、図４に示す各検出電極Ｅ１、Ｅ２、Ｅ３、Ｅ４から入力操作位置（ｘ，ｙ）までの均一導電層２１の抵抗値ｒ１、ｒ２、ｒ３、ｒ４は、その間の距離Ｌにほぼ比例するので、一走査周期にＭＰＵ１０に入力された各検出電極Ｅ１、Ｅ２、Ｅ３、Ｅ４の信号電圧から、入力操作面の４隅の各検出電Ｅ１、Ｅ２、Ｅ３、Ｅ４から入力操作位置（ｘ，ｙ）までの距離Ｌを算出し、指２０が接近する入力操作面上の入力操作位置（ｘ，ｙ）を検出する。 The signal voltage of the natural oscillation signal SG appearing on each detection electrode E depends on the distance from each detection electrode E1, E2, E3, E4 to the input operation position (x, y). That is, the signal voltage of the natural oscillation signal SG appearing at each detection electrode E is the sum of the internal resistance r0 between each detection electrode E and the reference node and the resistance value r between each detection electrode E and the input operation position (x, y). The resistance values r1, r2, r3, r4 of the uniform conductive layer 21 from the detection electrodes E1, E2, E3, E4 to the input operation position (x, y) shown in FIG. Since it is almost proportional, the input operation position from each of the detection electrodes E1, E2, E3, E4 at the four corners of the input operation surface from the signal voltage of each detection electrode E1, E2, E3, E4 input to the MPU 10 in one scanning period. The distance L to (x, y) is calculated, and the input operation position (x, y) on the input operation surface where the finger 20 approaches is detected.

上述の実施の形態では、４つの検出電極Ｅ１、Ｅ２、Ｅ３、Ｅ４を入力操作面の４隅に配置しているが、その数や配置位置は上述の例限らず、例えば、直線上の入力操作位置を検出する場合には、直線方向に沿って一対の検出電極Ｅを配置すればよい。 In the above-described embodiment, the four detection electrodes E1, E2, E3, and E4 are arranged at the four corners of the input operation surface. However, the number and arrangement position are not limited to the above-described example, and for example, input on a straight line In the case of detecting the operation position, a pair of detection electrodes E may be arranged along the linear direction.

また、ＰＭＵ１０に兼ねた信号出力回路は、振動電源回路７に接続して駆動するものであれば、振動側回路基板３にＭＰＵ１０と別に搭載するものであってもよい。 The signal output circuit that also serves as the PMU 10 may be mounted separately from the MPU 10 on the vibration side circuit board 3 as long as it is connected to and driven by the vibration power supply circuit 7.

また、入力操作体２０は、操作者が入力操作を行う指２０で説明したが、操作者が握る専用入力ペンなど操作者と別の操作体であってもよい。 Further, the input operation body 20 has been described with the finger 20 on which the operator performs an input operation. However, the input operation body 20 may be an operation body different from the operator, such as a dedicated input pen held by the operator.

また、低圧基準電源線ＧＮＤを接地させて基準電源回路４を定電位としたが、定電位とする手段は、この方法に限らず、低圧基準電源線ＧＮＤと高圧基準電源線ＶＣＣを入力操作者の指２０や入力操作体に対して一定の電位に保たれれば、その方法は任意である。 Further, although the low-voltage reference power line GND is grounded and the reference power supply circuit 4 is set to a constant potential, the means for setting the constant potential is not limited to this method, and the low-voltage reference power line GND and the high-voltage reference power line VCC are input operators. As long as the finger 20 and the input operating body are kept at a constant potential, the method is arbitrary.

本発明は、絶縁保護層を介して非接触で入力操作体の入力操作位置を検出する静電容量式タッチパネルに適している。 The present invention is suitable for a capacitive touch panel that detects an input operation position of an input operation body in a non-contact manner through an insulating protective layer.

１静電容量式タッチパネル
４基準電源回路
５直流電源（ＤＣ電源）
７振動電源回路
８第１インダクタ
９第２インダクタ
１０信号出力回路（ＭＰＵ）
１１絶縁性基板
１３信号検出回路
１７キャパシタ
１８キャパシタ
２０入力操作体（指）
２１均一導電層
２２絶縁保護層
Ｅ検出電極
ＧＮＤ低圧基準電源線
ＶＣＣ高圧基準電源線
ＳＧＮＤ低圧振動電源線
ＳＶＣＣ高圧振動電源線 1 Capacitive touch panel 4 Reference power supply circuit 5 DC power supply (DC power supply)
7 Vibration Power Supply Circuit 8 First Inductor 9 Second Inductor 10 Signal Output Circuit (MPU)
11 Insulating substrate 13 Signal detection circuit 17 Capacitor 18 Capacitor 20 Input operation body (finger)
21 Uniform conductive layer 22 Insulation protective layer E Detection electrode GND Low voltage reference power line VCC High voltage reference power line SGND Low voltage vibration power line SVCC High voltage vibration power line

Claims

An insulating substrate in which a uniform conductive layer having a constant resistance value per unit length and an insulating protective layer covering the uniform conductive layer are laminated on the input operation surface;
A plurality of detection electrodes connected to the uniform conductive layer at positions apart from each other around the uniform conductive layer;
A signal output circuit that outputs a natural oscillation signal having a natural frequency f and vibrates the potential of the uniform conductive layer at the natural frequency f;
A signal detection circuit for detecting the signal voltage of the natural oscillation signal appearing on each detection electrode from the voltage of each detection electrode relative to the reference node;
Capacitance for detecting the input operation position of the input operation for bringing the input operation body close to the input operation surface from the signal voltage of the natural oscillation signal detected for each detection electrode and the connection position of each detection electrode to the uniform conductive layer Type touch panel,
A low-voltage reference power line with one side grounded or at a constant potential and a reference power supply circuit wired with a high-voltage reference power line;
A DC power supply that outputs a DC voltage between the low-voltage reference power supply line and the high-voltage reference power supply line of the reference power supply circuit;
A vibration power supply circuit in which a low-voltage vibration power supply line and a high-voltage vibration power supply line are wired;
A first inductor connected between the low-voltage reference power line and the low-voltage vibration power line and changing a voltage between the low-voltage reference power line and the low-voltage vibration power line with a natural oscillation signal having a natural frequency f ;
A second inductor connected between the high-voltage reference power line and the high-voltage vibration power line, and changing a voltage between the high-voltage reference power line and the high-voltage vibration power line with a natural oscillation signal having a natural frequency f ;
All the detection electrodes and the reference node are connected to the low-voltage vibration power supply line or the high-voltage vibration power supply line, and the signal output circuit and the signal detection circuit are connected to the vibration power supply circuit, and the DC power source is connected via the first inductor and the second inductor. Drive with
The characteristic oscillation signal output from the signal output circuit is output to the low-voltage reference power line and the high-voltage reference power line of the reference power supply circuit through the capacitor, and the uniform conductive layer connected to each detection electrode and the reference node of the signal detection circuit A capacitive touch panel that vibrates an electric potential at a natural frequency f.

The combined inductance of the first inductor and the second inductor between the reference power supply circuit and the vibration power supply circuit is L / 2, between the signal output circuit and the low voltage side power supply line of the reference power supply circuit, and between the signal output circuit and the high voltage side power supply line of the reference power supply circuit When the combined capacitance of the capacitors interposed between them is 2C, the natural frequency f of the natural oscillation signal is
f = 1 / [2π (LC) ^1/2 ]
The capacitive touch panel according to claim 1, wherein:

The signal output circuit is composed of a microprocessor connected to the vibration power supply circuit and driven by the output of the DC power supply,
3. The capacitive touch panel according to claim 1, wherein the frequency fck of a clock for operating the microprocessor is divided or multiplied to output a natural oscillation signal having a natural frequency f.