JP2005001624A - Steering switch - Google Patents

Abstract

To provide a steering switch capable of reducing the number of electric wires for signal output and, in addition, capable of accurately receiving an input.
A load detection switch 30 disposed along a surface of a steering wheel 20 and a plurality of switch portions 40a to 40j provided on a surface of the steering wheel 20 and disposed at a position where the load detection switch 30 is disposed. And a processing unit 7 that receives an input based on a detection signal from the load detection switch 30. The load detection switch 30 has a pair of resistors opposed to each other substantially in parallel. The voltage value at the first voltage detection position of the resistor on one side and the second voltage detection of the resistor on the other side. By detecting the conduction position in the longitudinal direction of the load detection switch based on the voltage value of the position, the input through each of the switch units 40a to 40j is received.
[Selection] Figure 1

Description

【００３７】
のような関係があり、この関係を用いて、操作されているスイッチ素子５を特定することができる。なお、本実施形態では、抵抗体３の他方側端部３ｂをグランドに接続したため、電圧値Ｖ２は０となっている。
【００３８】
例えば、前記式（１）より、Ｖ２＝０として、
【００３９】
【数２】

【００４０】
の関係式が得られ、この関係式を用いて、既知の値Ｖ１及び測定値ＡＤ１，ＡＤ２からＬｘ／Ｌの値（位置算出値）を算出し、その算出値に基づいて操作されているスイッチ素子５を特定するようにしてもよい。
【００４１】
なお、上記式（１），（２）は、一例に過ぎず、既知の値Ｖ１及び測定値ＡＤ１，ＡＤ２を用いてスイッチ素子５を特定可能な関係式としては、種々のものが考えられる。例えば、他の例としては、Ｖ２＝０として、
【００４２】
【数３】

【００４３】
があり、この関係式を用いて、Ｌｘ／（Ｌ−Ｌｘ）の値（位置算出値）を算出し、その算出値に基づいて操作されているスイッチ素子５の位置を特定するようにしてもよい。
【００４４】
また、電圧値Ｖ１，ＡＤ１，ＡＤ２と抵抗値Ｒ１，Ｒ２，Ｒｃとの間には、
【００４５】
【数４】

【００４６】
のような関係がある（なお、式（４）において「＊」は乗算記号である（以下、同様））。このため、電圧値ＡＤ１，ＡＤ２の差に基づいて、スイッチ素子５が安定接触状態となっているか否かを判定することができる。
【００４７】
すなわち、接触抵抗値Ｒｃは、スイッチ素子５への押圧力又は押圧量等に応じて図４のグラフのように変化し、一定値（Ｆｓｔ）以上の押圧力等が与えられると安定接触状態（図４のハッチング領域）となる。そこで、安定接触状態と判断できる接触抵抗値Ｒｃの上限値をＲｃｓｔとし、また、接触抵抗値ＲｃがＲｃｓｔとなるときのＡＤ１−ＡＤ２の値をＶｓｔ（本発明に係る所定の値、第１の基準値）とすると、前記式（４）は、
【００４８】
【数５】

【００４９】
となる。これより、ＡＤ１−ＡＤ２の値が、
【００５０】
【数６】

【００５１】
の関係を満たせば、スイッチ素子５が安定接触状態にあると判断できる。
【００５２】
次に、図５に基づいて、処理部７のスイッチ位置の検出動作について説明する。まずステップＳ１で、電圧値ＡＤ１，ＡＤ２の検出が行われる。続くステップＳ２で、ＡＤ１−ＡＤ２の値がＶｓｔ以下であるか否か、すなわちいずれかのスイッチ素子５が操作されて安定接触状態となっているか否かが判定され、これによっていずれかのスイッチ素子５が操作（オン）されたか否かが判定される。そして、いずれかのスイッチ素子５が操作されたと判断された場合にはステップＳ３に進む一方、いずれのスイッチ素子５も操作されていないと判断された場合にはステップＳ１に戻り、いずれかのスイッチ素子５が操作されるまでステップＳ１，Ｓ２の処理が繰り返される。
【００５３】
ここで、ステップＳ２において、スイッチ素子５の操作が検出されなかった場合には、スイッチ操作なしを示す信号を外部機器に出力するようにしてもよい。
【００５４】
ステップＳ３では、前記式（２）により、検出した電圧値ＡＤ１，ＡＤ２と予め処理部７に登録された既知の電圧値Ｖ１とに基づいて、Ｌｘ／Ｌの値が算出される。
【００５５】
続くステップＳ４では、その算出した位置計算値Ｌｘ／Ｌに基づいて、いずれのスイッチ素子５、即ち、いずれのスイッチ部４０ａ〜４０ｊが操作されたのかが特定され、特定したスイッチ部４０ａ〜４０ｊに対応する信号、或は、特定されたスイッチ部４０ａ〜４０ｊが操作された（オンされた）ことを示す信号が外部機器に出力される。より詳細には、処理部７には、図６に示すようなスイッチ位置判定用テーブルＴ１が予め登録されている。そのテーブルＴ１には、複数のスイッチ素子５に一対一に対応する複数の計算値区間Ｑ１が位置計算値Ｌｘ／Ｌの取り得る値に応じて設定されている。その各計算値区間Ｑ１は、所定の下限値（Ａ１，Ａ２，Ａ３・・・）及び上限値（Ｂ１，Ｂ２，Ｂ３・・・）によって規定されており、電磁ノイズの影響、製造バラツキ等による電圧値ＡＤ１，ＡＤ２のバラツキ等を考慮して誤検出が起こらないように所定の幅を持たせて設定するのが好ましい。なお、各計算値区間Ｑ１は、理論的な計算結果に基づいて設定してもよく、実際に各スイッチ素子５を操作して試験して得られる測定値に基づいて設定してもよい。
【００５６】
そして、ステップＳ３で算出された位置計算値Ｌｘ／Ｌが、その複数の計算値区間Ｑ１のうちのいずれに属するかを判定することにより、いずれのスイッチ素子５（即ち、いずれのスイッチ部４０ａ〜４０ｊ）が操作されたかが判定されるようになっている。
【００５７】
ステップＳ４での処理が終了すると、再びステップＳ１に戻り、ステップＳ１〜Ｓ４が繰り返されることにより、スイッチ素子５の操作検出が行われる。
【００５８】
なお、上述の処理のステップＳ３，Ｓ４では、前記式（２）の関係に基づいてスイッチ位置の検出を行うようにしたが、前記式（２）以外の関係式、例えば前記式（３）を用いてスイッチ位置の検出を行うようにしてもよい。
【００５９】
また、電磁ノイズ、チャタリング等の影響による誤動作を防止するため、ソフト的なフィルタ処理として、ステップＳ１等の電圧値ＡＤ１，ＡＤ２の検出の際には、電圧値ＡＤ１，ＡＤ２の平均化処理を行うようにしてもよく、あるいは、ステップＳ１からステップＳ４にかけてのスイッチ位置検出のための処理を複数回行い、その各回で検出したスイッチ位置が一致した場合に、スイッチ位置の検出結果を確定的なものとして外部機器に出力するようにしてもよい。
【００６０】
以上のように、本実施形態によれば、荷重検出スイッチ３０は、略平行に対向配置された略同一サイズの第１及び第２の抵抗体１，３を有し、その両抵抗体１，３がその長手方向について単位長さ当り略一定の略同一抵抗値を有しているため、いずれかのスイッチ部４０ａ〜４０ｊへの押圧により両抵抗体１，３が互いに接触した際に、第１の電圧検出位置及び第２の電圧検出位置の電圧値に基づいて抵抗体１，３間の導通状況（両抵抗体１，３に印加された電圧の導通位置に対応する分圧等）に基づいて、荷重検出スイッチ３０の長手方向における導通位置を検出し、いずれかの前記スイッチ部４０ａ〜４０ｊを通じた入力を受付けることができる。このため、１つの荷重検出スイッチ３０について複数のスイッチ部４０ａ〜４０ｊの押圧を判別することができ、信号出力用の電線本数を減少させることができる。例えば、本実施の形態では、１０個のスイッチ部４０ａ〜４０ｊを設けた場合であっても、４つの電線を配線するだけでよい。
【００６１】
しかも、上記第１の電圧検出位置及び第２の電圧検出位置の電圧値に基づいて導通位置を検出しているので、抵抗体１，３間の接触抵抗等の影響を排除することができ、正確に入力を受付けることができる。
【００６２】
また、上記スイッチ部４０ａ〜４０ｊを押圧操作することにより、インストルメントパネルの輝度調整や、走行距離計に対する操作、ハザードのオンオフ、音響機器の消音、交通情報の選択、ブザーの音量、音色調整等の操作を運転者が容易に行うことができる。
【００６３】
また、操作されたスイッチ素子５を特定するための所定の位置計算値（例えば、Ｌｘ／Ｌ）を、変数Ｌ，Ｌｘ，Ｖ１，ＡＤ１，ＡＤ２の関係より容易に算出することができる。
【００６４】
さらに、ＡＤ１−ＡＤ２の値がＶｓｔ以下であるか否かを判定することにより、スイッチ素子５が操作されたか否かを高い信頼性で容易に判定することができる。
【００６５】
また、ＡＤ１−ＡＤ２の値に基づいてスイッチ素子５が操作されたと判定された場合にのみ、変数Ｌ，Ｌｘ，Ｖｄ，ＡＤ１，ＡＤ２の関係より、操作されたスイッチ素子５を特定するための所定の位置計算値が算出され、操作されたスイッチ素子５の特定が行われるため、操作が不十分である等の要因によりスイッチ素子５が安定接触状態にない状態で、操作されたスイッチ素子５の特定が行われるのを防止することができ、入力受付の信頼性の向上が図れる。
【００６６】
【発明の効果】
以上のように、この発明の請求項１記載のステアリングスイッチによると、荷重検出スイッチは、略平行に対向配置された略同一サイズの第１及び第２の抵抗体を有し、その両抵抗体がその長手方向について単位長さ当り略一定の略同一抵抗値を有しているため、いずれかのスイッチ部への押圧により両抵抗体が互いに接触した際に、第１の電圧検出位置及び第２の電圧検出位置の電圧値に基づいて抵抗体間の導通状況（両抵抗体に印加された電圧の導通位置に対応する分圧等）に基づいて、荷重検出スイッチの長手方向における導通位置を検出し、いずれかの前記スイッチ部を通じた入力を受付けることができる。このため、１つの荷重検出スイッチについて複数のスイッチ部の押圧を判別することができ、信号出力用の電線本数を減少させることができる。
【００６７】
また、上記第１の電圧検出位置及び第２の電圧検出位置の電圧値に基づいて導通位置を検出しているので、抵抗体間の接触抵抗等の影響を排除することができ、正確に入力を受付けることができる。
【００６８】
また、請求項２記載の発明によれば、ステアリングに設けられたスイッチ部を押圧操作することにより、インストルメントパネルの輝度調整や、走行距離計に対する操作、ハザードのオンオフ、音響機器の消音、交通情報の選択、ブザーの音量、音色調整等を行うことができるため、運転者がそれらの操作を容易に行うことができる。
【００６９】
請求項３記載の発明によれば、各スイッチ部に対応する各位置に、第１及び第２の抵抗体を導通させるためのスイッチ素子が配設されているため、各スイッチ部以外での両抵抗体の導通が防止され、より正確に入力受付を行える。
【図面の簡単な説明】
【図１】ステアリングスイッチを組込んだステアリングホイールを示す図である。
【図２】荷重検出スイッチを模式的に示す図である。
【図３】抵抗体間の導通が生じた際の回路構成を模式的に示す図である。
【図４】操作時の押圧力又は押圧量と抵抗体間の接触抵抗との関係を示すグラフである。
【図５】図２の荷重検出スイッチによる入力受付処理のフローチャートである。
【図６】スイッチ位置判定のためのテーブル構成を示す図である。
【符号の説明】
１，３ 抵抗体
５ スイッチ素子
７ 処理部
２０ ステアリングホイール
２２ ステアリングホイール本体部
２４ ステアリングパッド部
２６ スポーク部
３０ 荷重検出スイッチ
４０ａ〜４０ｊ スイッチ部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steering switch that is incorporated in a steering of a vehicle or the like and controls an in-vehicle electronic device or the like.
[0002]
[Prior art]
As a structure of this type of composite switch, there is one in which a contact-type switch is provided between a spoke part and a spoke part of a steering pad. Conventionally, in this type of steering switch, when a plurality of switches are provided, each switch is connected to an external device using an electric wire separately (see, for example, Patent Document 1).
[0003]
Further, as a steering input device, there is a device in which a piezoelectric sensor is disposed in a steering so that a control target is controlled according to a load applied to the steering by a driver (for example, see Patent Document 2).
[0004]
[Patent Document 1]
JP-A-10-106401 [Patent Document 2]
Japanese Patent Laid-Open No. 2000-228126
[Problems to be solved by the invention]
However, in the structure of the composite switch disclosed in Patent Document 1, a signal output wire is required for each switch. Therefore, the number of switches that can be arranged is limited due to the space for drawing out the wire. It was.
[0006]
Further, the steering input device disclosed in Patent Document 2 adjusts horn sound, audio volume, etc. according to the magnitude of the load on the piezoelectric sensor, or detects the direction of the load by a plurality of piezoelectric sensors. By doing so, the left and right of the blinker and the irradiation direction of the light are controlled, and a plurality of controlled objects are controlled by the magnitude of the load, thereby reducing the number of electric wires drawn from each piezoelectric sensor. Is difficult.
[0007]
Accordingly, an object of the present invention is to provide a steering switch that can reduce the number of electric wires for signal output and, in addition, can accurately accept an input.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is a steering switch incorporated in a steering wheel, a load detection switch disposed along a surface of the steering wheel, and a surface of the steering wheel which includes the load. A plurality of switch portions provided on the position where the detection switch is disposed, and a processing portion for receiving an input based on a detection signal from the load detection switch, wherein the load detection switch is disposed to face each other substantially in parallel. The first and second resistors of substantially the same size that can be directly or indirectly connected to each other, and both the resistors have substantially the same resistance value per unit length in the longitudinal direction, A first constant voltage is applied to one side end of the first resistor, and the other side end is set as a first voltage detection position, and one side end of the second resistor is set. Said Is set as the second voltage detection position so as to be located on the opposite side of the voltage detection position, and the other constant side end is connected to the ground or the second constant voltage lower than the first constant voltage is applied. The processing unit detects the conduction position of the two resistors in the longitudinal direction of the load detection switch based on the voltage values of the first voltage detection position and the second voltage detection position. An input through each of the switch units is accepted.
[0009]
According to a second aspect of the present invention, the switch section includes an instrument panel brightness adjustment switch, an odometer changeover switch and reset switch, a hazard switch, a mute switch for muting sound output from an acoustic device in the vehicle interior, traffic It includes at least one of a switch for selecting traffic information notified by the information notification means and a switch for adjusting at least one of a warning buzzer volume and a tone color.
[0010]
According to a third aspect of the present invention, a switch element for conducting the first and second resistors is provided at each position corresponding to each switch section.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a steering switch according to an embodiment of the present invention will be described.
[0012]
FIG. 1 is a view showing a steering wheel 20 incorporating the present steering switch.
[0013]
This steering wheel 20 is a vehicle steering operation means provided in front of a driver's seat of an automobile or the like.
[0014]
The steering wheel 20 includes a steering wheel main body portion 22, a steering pad portion 24, and a spoke portion 26.
[0015]
The steering wheel main body portion 22 is formed in a substantially annular shape, and a steering pad portion 24 is disposed at a substantially central portion of the steering wheel main body portion 22. The steering wheel main body portion 22 and the steering pad portion 24 are connected and fixed by a plurality of spoke portions 26 disposed therebetween. In the present embodiment, a total of four spoke portions 26 are provided so as to extend obliquely upward and downward on both sides of the steering pad portion 24.
[0016]
A steering switch including a load detection switch 30, a plurality of switch units 40 a to 40 j and a processing unit 7 is incorporated in the steering wheel 20.
[0017]
The load detection switch 30 is formed in a linear shape, and is disposed along the surface of the steering wheel 20. In the present embodiment, the load detection switch 30 is disposed along the outer peripheral surface of the front portion of the steering pad portion 24 so as to be embedded in the outer peripheral surface. In addition, the load detection switch 30 may be disposed along the surface of the center portion of the steering pad portion 24, the surface of the steering wheel main body portion 22, the surface of the spoke portion 26, and the like. The load detection switch 30 will be described in detail later.
[0018]
A plurality of electric wires drawn out from the load detection switch 30 are connected to the processing unit 7 outside the steering wheel 10. And based on the detection signal from the load detection switch 30, the process part 7 receives the input through each switch part 40a-40j.
[0019]
The switch portions 40 a to 40 j are provided on the surface of the steering wheel 20 and on the position where the load detection switch 30 is provided. In the present embodiment, three switch portions 40 a to 40 c and 40 h to 40 j are provided on both sides of the steering pad portion 24, and four switch portions 40 d to 40 g are provided on the steering pad portion 24. .
[0020]
Each of the switch portions 40a to 40j is, for example, slightly protruded or recessed from the peripheral portion thereof, or is formed by forming a ridge or a groove or a printed line at the boundary with the peripheral portion. It has a form and exhibits a distinguishable appearance with respect to its peripheral part.
[0021]
Of the steering wheel main body 22, the steering pad 24, and the spoke 26, at least the surface portion provided with the switch portions 40a to 40j is made of a material that is easily elastically deformed by foamed resin or the like.
[0022]
And when a driver | operator presses each switch part 40a-40j, the load according to the said press is transmitted to the load detection switch 30 via a surface part.
[0023]
In addition, each switch unit 40a includes a brightness adjustment switch on the instrument panel, a changeover switch for switching the content displayed on the odometer to the total mileage and the mileage from when it was reset, its reset switch, and a main hazard switch. Sub-hazard switches provided separately from, for example, a mute switch that mutes the sound output from the acoustic equipment in the passenger compartment when using a mobile phone, traffic information notified by traffic information notification means such as a navigation device or radio, etc. It functions as a switch to select, a buzzer volume for warning such as forgetting to turn off the light, and a switch for adjusting the tone.
[0024]
FIG. 2 is a diagram schematically illustrating the configuration of the load detection switch 30. The load detection switch 30 includes first and second resistors 1 and 3 having substantially the same length L that are opposed to each other substantially in parallel, and a plurality of switches that are electrically connected between the resistors 1 and 3. The processing unit 7 receives the operation via the switch element 5 by determining the conduction state of each switch element 5 based on the input signal.
[0025]
Both resistors 1 and 3 have a form (for example, a linear form) that extends long in one direction, and have substantially the same resistance value that is substantially constant per unit length. One end 1a of the resistor 1 is connected to a power supply circuit (not shown) via a wiring 11, and a predetermined constant voltage V1 (first constant voltage) is applied. The other end 1b of the resistor 1 is set as a first voltage detection position, connected to the processing unit 7 via the wiring 13, and the voltage value AD1 of the other side end 1b is detected by the processing unit 7. The One end 3a of the resistor 3 that is an end in the same direction as the one end 1a of the resistor 1 is set as a second voltage detection position, and is connected to the processing unit 7 via the wiring 15. The processing unit 7 detects the voltage value AD2 at the one end 3a. The other end 3 b of the resistor 3 is connected to the ground via the wiring 17. In the present embodiment, the other end 3b of the resistor 3 is connected to the ground. However, the constant voltage V1 applied to the one end 1a of the resistor 1 is connected to the other end. A low constant voltage (second constant voltage) V2 may be applied.
[0026]
The plurality of switch elements 5 are arranged along the longitudinal direction of the resistors 1 and 3. Each switch element 5 should just be provided in the position corresponding to each said switch part 40a-40j at least. And each switch element 5 is provided so that it may span over both the resistors 1 and 3, and when it is pressed, it makes electrical contact with the resistors 1 and 3, and between the resistors 1 and 3 Are electrically conducted, and are separated from the resistors 1 and 3 as the pressing operation is released. That is, only while the pressing operation is performed on each switch element 5, the portions of the resistors 1 and 3 corresponding to the switch element 5 on which the pressing operation is performed are indirectly connected via the switch element 5. It is supposed to be conductive.
[0027]
Therefore, when none of the switch elements 5 is pressed (not turned on), the resistors 1 and 3 are electrically disconnected. At this time, the voltage value AD1 at the other end 1b of the resistor 1 is equal to the constant voltage V1, and the voltage value AD2 at the one end 3a of the resistor 3 is at the ground level. When any one of the switch elements 5 is pressed, the resistors 1 and 3 are brought into conduction through the switch element 5, and the voltage depends on the position of the pressed switch element 5. The values AD1 and AD2 change.
[0028]
Therefore, in the present embodiment, by installing each switch element 5 at a predetermined position on the resistors 1 and 3, whether or not each switch element 5 is operated based on the change state of the voltage values AD1 and AD2. , And which switch element 5 is operated. For example, the distances from the one end portions 1a, 3a of the resistors 1, 3 of the switch elements 5A, 5B, 5C are set to L1, L2, L3.
[0029]
Here, in the present embodiment, the constant voltage V1 is applied to the one end 1a of the resistor 1, and the other end 3b of the resistor 1 is connected to the ground while the other end 3b of the resistor 3 is connected to the ground. 1b and the voltage values AD1 and AD2 at one end 3a of the resistor 3 are detected, so that when the switch element 5 is operated and the resistors 1 and 3 are conducted through the switch element 5, The partial pressure applied to the portion from one end 1a of the resistor 1 to the switch element 5, the partial pressure applied to the portion of the resistor 3 from the switch element 5 to the other end 3b, etc. , 3 can be accurately grasped without being affected by the contact resistance via the switch element 5.
[0030]
In the present embodiment, when a plurality of switch elements 5 are provided and the switch elements 5 are pressed, the switch elements 5 are electrically connected to the resistors 1 and 3, whereby the resistors 1 and 3 are connected to each other. Although it is configured to conduct indirectly through the switch element 5, as a modification, the switch element 5 is not provided, for example, a pressing operation is applied in a direction to narrow the interval between the resistors 1 and 3, and the pressing is performed. One of the resistors 1 and 3 to which the operation is applied is locally elastically deformed in the direction of approaching the other resistors 1 and 3 and locally contacts the other resistors 1 and 3. You may make it electrically conduct between 3 locally. Also in this case, with the release of the pressing operation, the one resistor 1, 3 automatically returns to its original shape so as to be separated from the other resistor 1, 3, and the continuity between the resistors 1, 3 is established. Is released.
[0031]
However, the switch element 5 is provided at a position corresponding to each of the switch sections 40a to 40j, and in the other portions, for example, the distance between the resistors 1 and 3 is large, and both the resistors 1 and 3 are conducted. In the configuration that has become difficult, the conduction of the resistors 1 and 3 in other portions is prevented, so that more accurate input reception can be performed.
[0032]
The processing unit 7 includes a voltage detection function for detecting the voltage value AD1 at one end 1a of the resistor 1 and the voltage value AD2 at the other end 3b of the resistor 3, and the detected voltage values AD1 and AD2. And a determination processing function for determining the operation state of each switch element 5 and an output function for outputting the determination result to each external device. Various configurations are conceivable as the specific configuration of the processing unit 7. For example, the processing unit 7 may be configured by combining an analog detection element that performs voltage detection, an arithmetic determination element, or the like, or a customized IC is used. You may comprise, and you may comprise using the general purpose microcomputer which has an analog input port which receives the input of a voltage signal.
[0033]
In addition, it is desirable to provide an electromagnetic noise countermeasure circuit and a static electricity countermeasure circuit in the circuit related to the detection of the voltage values AD1 and AD2, depending on the use environment.
[0034]
FIG. 3 is a diagram schematically showing a circuit configuration when conduction between the resistors 1 and 3 occurs. A switch in which the distance from the one end 1a or 3a of the resistors 1 and 3 is at the position Lx. This corresponds to a state where the element 5 is pressed and conduction between the resistors 1 and 3 occurs. In FIG. 3, R1 indicates the resistance value of the portion from the one end 1a, 3a of the resistors 1, 3 to the position of the distance Lx, and R2 indicates the other end from the position of the distance Lx of the resistors 1, 3. 1b and 3b indicate resistance values, and Rc indicates a contact resistance value between the resistors 1 and 3 via the switch element 5. In general, since the input impedance is set to be sufficiently large for the processing unit 7 for detecting the voltage value, the current flowing through the processing unit 7 via the wirings 13 and 15 is ignored in the following discussion.
[0035]
In this conductive state, assuming that the voltage value of the other end 3b of the resistor 3 is V2, as an example, between the variables L, Lx, R1, R2, V1, V2, AD1, AD2,
[0036]
[Expression 1]

[0037]
The switch element 5 being operated can be specified using this relationship. In the present embodiment, the voltage value V2 is 0 because the other end 3b of the resistor 3 is connected to the ground.
[0038]
For example, from the above equation (1), V2 = 0,
[0039]
[Expression 2]

[0040]
Using this relational expression, the Lx / L value (position calculated value) is calculated from the known value V1 and the measured values AD1 and AD2, and the switch operated based on the calculated value The element 5 may be specified.
[0041]
The above formulas (1) and (2) are merely examples, and various relational expressions that can identify the switch element 5 using the known value V1 and the measured values AD1 and AD2 are conceivable. For example, as another example, assuming V2 = 0,
[0042]
[Equation 3]

[0043]
Using this relational expression, the value of Lx / (L−Lx) (calculated position value) is calculated, and the position of the switch element 5 being operated is specified based on the calculated value. Good.
[0044]
In addition, between the voltage values V1, AD1, AD2 and the resistance values R1, R2, Rc,
[0045]
[Expression 4]

[0046]
(Note that “*” in equation (4) is a multiplication symbol (the same applies hereinafter)). Therefore, based on the difference between the voltage values AD1 and AD2, it can be determined whether or not the switch element 5 is in a stable contact state.
[0047]
That is, the contact resistance value Rc changes as shown in the graph of FIG. 4 according to the pressing force or the pressing amount to the switch element 5, and when a pressing force or the like exceeding a certain value (Fst) is applied, the stable contact state ( (Hatching area in FIG. 4). Therefore, the upper limit value of the contact resistance value Rc that can be determined as a stable contact state is Rcst, and the value of AD1-AD2 when the contact resistance value Rc is Rcst is Vst (a predetermined value according to the present invention, the first value (Reference value), the equation (4) is
[0048]
[Equation 5]

[0049]
It becomes. From this, the value of AD1-AD2 is
[0050]
[Formula 6]

[0051]
If the relationship is satisfied, it can be determined that the switch element 5 is in a stable contact state.
[0052]
Next, the switch position detection operation of the processing unit 7 will be described with reference to FIG. First, in step S1, voltage values AD1 and AD2 are detected. In the following step S2, it is determined whether or not the value of AD1-AD2 is equal to or lower than Vst, that is, whether any switch element 5 is operated to be in a stable contact state, and thereby any switch element is determined. It is determined whether or not 5 is operated (turned on). If it is determined that any one of the switch elements 5 has been operated, the process proceeds to step S3. On the other hand, if any switch element 5 has been determined not to be operated, the process returns to step S1 and any switch element 5 is operated. Steps S1 and S2 are repeated until the element 5 is operated.
[0053]
Here, when the operation of the switch element 5 is not detected in step S2, a signal indicating no switch operation may be output to the external device.
[0054]
In step S3, the value of Lx / L is calculated based on the detected voltage values AD1 and AD2 and the known voltage value V1 registered in advance in the processing unit 7 by the equation (2).
[0055]
In subsequent step S4, based on the calculated position calculation value Lx / L, it is specified which switch element 5, that is, which switch unit 40a to 40j is operated, and the specified switch unit 40a to 40j is specified. A corresponding signal or a signal indicating that the specified switch units 40a to 40j are operated (turned on) is output to the external device. More specifically, a switch position determination table T1 as shown in FIG. In the table T1, a plurality of calculated value sections Q1 corresponding to the plurality of switch elements 5 on a one-to-one basis are set according to the values that the position calculated value Lx / L can take. Each calculated value section Q1 is defined by a predetermined lower limit value (A1, A2, A3...) And an upper limit value (B1, B2, B3...), And is due to the influence of electromagnetic noise, manufacturing variations, and the like. It is preferable to set with a predetermined width so that erroneous detection does not occur in consideration of variations in the voltage values AD1 and AD2. Each calculated value section Q1 may be set based on a theoretical calculation result, or may be set based on a measured value obtained by actually operating each switch element 5 and testing it.
[0056]
Then, by determining which of the plurality of calculated value sections Q1 the position calculation value Lx / L calculated in step S3 belongs to, which switch element 5 (that is, which switch unit 40a˜ It is determined whether or not 40j) has been operated.
[0057]
When the process in step S4 ends, the process returns to step S1 again, and steps S1 to S4 are repeated to detect the operation of the switch element 5.
[0058]
In steps S3 and S4 of the above-described process, the switch position is detected based on the relationship of the equation (2). However, a relationship other than the equation (2), for example, the equation (3) It may be used to detect the switch position.
[0059]
Further, in order to prevent malfunctions due to the influence of electromagnetic noise, chattering, etc., the voltage values AD1 and AD2 are averaged when detecting the voltage values AD1 and AD2 in step S1, etc., as a soft filter process. Alternatively, the switch position detection process from step S1 to step S4 is performed a plurality of times, and the switch position detection result is deterministic when the detected switch positions match each time. May be output to an external device.
[0060]
As described above, according to the present embodiment, the load detection switch 30 includes the first and second resistors 1 and 3 having substantially the same size and arranged to face each other substantially in parallel. 3 has substantially the same resistance value per unit length in the longitudinal direction, and therefore when the resistors 1 and 3 are brought into contact with each other by pressing against any one of the switch portions 40a to 40j, the first Based on the voltage values at the first voltage detection position and the second voltage detection position, the conduction state between the resistors 1 and 3 (voltage division corresponding to the conduction position of the voltage applied to both resistors 1 and 3). Based on this, it is possible to detect a conduction position in the longitudinal direction of the load detection switch 30 and accept an input through any one of the switch portions 40a to 40j. For this reason, it is possible to determine the pressing of the plurality of switch portions 40a to 40j for one load detection switch 30, and it is possible to reduce the number of signal output wires. For example, in the present embodiment, even if ten switch units 40a to 40j are provided, only four electric wires need to be wired.
[0061]
Moreover, since the conduction position is detected based on the voltage values of the first voltage detection position and the second voltage detection position, the influence of the contact resistance between the resistors 1 and 3 can be eliminated, The input can be accepted accurately.
[0062]
Also, by pressing the switch sections 40a to 40j, brightness adjustment of the instrument panel, operation on the odometer, hazard on / off, sound equipment mute, traffic information selection, buzzer volume, tone adjustment, etc. The driver can easily perform the operation.
[0063]
In addition, a predetermined position calculation value (for example, Lx / L) for specifying the operated switch element 5 can be easily calculated from the relationship among the variables L, Lx, V1, AD1, and AD2.
[0064]
Furthermore, by determining whether or not the value of AD1-AD2 is equal to or less than Vst, it is possible to easily determine whether or not the switch element 5 has been operated with high reliability.
[0065]
Further, only when it is determined that the switch element 5 has been operated based on the value of AD1-AD2, the predetermined switch element 5 is specified for identifying the operated switch element 5 from the relationship between the variables L, Lx, Vd, AD1, and AD2. Since the calculated position value of the switch element 5 is calculated and the operated switch element 5 is specified, the switch element 5 of the operated switch element 5 is not in a stable contact state due to factors such as insufficient operation. It is possible to prevent identification and improve the reliability of input reception.
[0066]
【The invention's effect】
As described above, according to the steering switch of the first aspect of the present invention, the load detection switch has the first and second resistors having substantially the same size and arranged to face each other substantially in parallel. Have substantially the same resistance value per unit length in the longitudinal direction, so that when the two resistors are brought into contact with each other by pressing against one of the switch portions, the first voltage detection position and the first The conduction position in the longitudinal direction of the load detection switch is determined based on the conduction state between resistors based on the voltage value at the voltage detection position of 2 (voltage division corresponding to the conduction position of the voltage applied to both resistors). Detect and accept input through any of the switch sections. For this reason, it is possible to determine the pressing of the plurality of switch portions for one load detection switch, and it is possible to reduce the number of electric wires for signal output.
[0067]
In addition, since the conduction position is detected based on the voltage values of the first voltage detection position and the second voltage detection position, it is possible to eliminate the influence of contact resistance between the resistors, and to input accurately. Can be accepted.
[0068]
According to the second aspect of the present invention, the brightness of the instrument panel is adjusted, the odometer is operated, the hazard is turned on / off, the sound equipment is silenced, the traffic Since information selection, buzzer volume, tone color adjustment, and the like can be performed, the driver can easily perform these operations.
[0069]
According to the third aspect of the present invention, the switch elements for conducting the first and second resistors are arranged at the positions corresponding to the switch sections. Resistor conduction is prevented and input can be received more accurately.
[Brief description of the drawings]
FIG. 1 is a view showing a steering wheel incorporating a steering switch.
FIG. 2 is a diagram schematically showing a load detection switch.
FIG. 3 is a diagram schematically showing a circuit configuration when conduction between resistors occurs.
FIG. 4 is a graph showing the relationship between the pressing force or pressing amount during operation and the contact resistance between resistors.
FIG. 5 is a flowchart of input acceptance processing by the load detection switch of FIG. 2;
FIG. 6 is a diagram showing a table configuration for switch position determination.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,3 Resistor 5 Switch element 7 Processing part 20 Steering wheel 22 Steering wheel main-body part 24 Steering pad part 26 Spoke part 30 Load detection switch 40a-40j Switch part

Claims (3)

A steering switch built into the steering wheel,
A load detection switch disposed along the steering surface;
A plurality of switch portions provided on the surface of the steering wheel and on the arrangement position of the load detection switch;
A processing unit that receives an input based on a detection signal from the load detection switch,
The load detection switch has first and second resistors of substantially the same size that are arranged opposite to each other in parallel and can be directly or indirectly connected, and both the resistors have a unit length in the longitudinal direction. It has approximately the same resistance value that is approximately constant per hit,
A first constant voltage is applied to one end of the first resistor, and the other end is set as a first voltage detection position.
The second resistor is set as a second voltage detection position so that one end of the second resistor is located on the opposite side of the first voltage detection position, and the other end is connected to the ground or A second constant voltage lower than the first constant voltage is applied;
The processing unit detects the conduction positions of the two resistors in the longitudinal direction of the load detection switch based on the voltage values of the first voltage detection position and the second voltage detection position. A steering switch that accepts input through the switch. The steering switch according to claim 1,
The switch section includes a brightness adjustment switch for an instrument panel, a switch and reset switch for an odometer, a hazard switch, a mute switch for muting sound output from an acoustic device in the passenger compartment, and traffic notified by traffic information notification means. A steering switch including at least one of a switch for selecting information and a switch for adjusting at least one of a warning buzzer volume and a tone. The steering switch according to claim 1 or 2,
A steering switch in which a switch element for conducting the first and second resistors is arranged at each position corresponding to each switch section.

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