200914799 九、發明說明 【發明所屬之技術領域】 本發明係關於一種對訊號的數量進行計數的計數裝 置、以及使用計數裝置測定干涉波形的數量而求取與測定 對象之距離的干涉型距離計。 【先前技術】 利用因雷射所産生的光的干涉的距離測量因屬於非接 觸測定而不會干擾測定對象，自古以來一直被作爲高精度 的測定方法加以使用。近來，爲了實現裝置的小型化，半 導體雷射係作爲光測量用光源而被加以利用。以其代表例 而言’存在一種採用 FM外差式干涉儀（heterodyne interferometry)者。該者可進行較長距離的測量且精度良 好，但是由於在半導體雷射的外部採用干涉儀，故具有光 學系統較爲複雜的缺點。 相對於此，一種利用雷射的輸出光與來自測定對象的 返回光在半導體雷射內部的干涉（自耦合效應）的測量器 已被提出（參照例如非專利文獻1、非專利文獻2、非專 利文獻3 )。根據如上所示之自耦合型的雷射測量器，由 於內建光電二極體的半導體雷射兼具有發光、干涉、受光 的各功能，故可大幅簡化外部干涉光學系統。因此，感測 器部僅爲半導體雷射與透鏡，與習知技術相比較，較爲小 型。另外，具有距離測定範圍大於三角測量法的特徵。 在第23圖中顯示FP型（Fabry-Perot型）半導體雷 200914799 射的複合共振器模型。在第23圖中，101係半導體雷射， 1 02係半導體結晶的壁開面，1 〇3係光電二極體，1 04係測 定對象。來自測定對象1 0 4的反射光的一部分容易返回到 振盪區域內。返回來的微弱的光與共振器1 0 1內的雷射光 耦合’動作變得不穩定而産生噪音（複合共振器雜訊或返 回光雜訊）。即使相對輸出光的相對返回光量極其微小， 因返回光引起的半導體雷射的特性的變化仍顯著呈現。如 上所示的現象並不限於法布里-伯羅（Fabry-Perot )型 (以下稱爲FP型）半導體雷射，在垂直共振腔面射雷射 (Vertical Cavity Surface Emitting Laser)型（以下稱爲 VCSEL 型）、分佈反饋雷射（Distributed Feedback Laser)型（以下稱爲DFB雷射型）等其他種類的半導體 雷射中也同樣呈現。 若將雷射的振盪波長設爲λ，由接近測定對象1 0 4的 壁開面1 02到測定對象1 04爲止的距離設爲L，則在滿足 以下的共振條件時，返回光和共振器1 0 1內的雷射相互加 強，雷射輸出稍稍增加。 L = ηλ / 2 …（1) 在式（1 )中，η爲整數。該現象係即便在來自測定對 象1 〇4的散射光極其微弱的情況下，亦可因半導體雷射的 共振器101內的表觀反射率增加，而産生放大作用，而足 以充分觀測。 -5- 200914799 在半導體雷射中，由於按照注入電流的大小而放射頻 率不同的雷射光，因此在將振盪頻率進行調變時，不需要 外部調變器，即可藉由注入電流直接進行調變。第24圖 係顯示在按照某個恒定的比例使半導體雷射的振盪波長改 變時的振盪波長和光電二極體1 03的輸出波形的關係圖。 在滿足式（1)所示的L=nX/2時，返回光和共振器101 內的雷射光的相位差變成0° (同相位），返回光和共振器 101內的雷射光最爲相互加強，當ί=ηλ/2+λ/4時， 相位差爲1 8 0 ° (逆相位），返回光和共振器1 〇1內的雷射 光相互最爲相互減弱。由此，如果使半導體雷射的振盪波 長改變，則雷射輸出增強的情形和減弱的情形交替反覆地 出現，若利用設置於共振器1 01的光電二極體1 03檢測此 時的雷射輸出時，如第24圖所示，獲得恒定周期的階梯 狀波形。這樣的波形一般稱爲干涉條紋。 將該階梯狀的波形，亦即干涉條紋中的一個個稱爲模 式跳躍脈衝（mode hop pulse)(以下稱之爲 ΜΗΡ)。 MHP是與模式跳躍（m〇de hopping )現象不同的現象。例 如’在距測定對象104的距離爲L1時，如果MHP的數量 爲10個，則在一半的距離L2時，MHP的數量爲5個。亦 即’在某一定時間使半導體雷射的振盪波長改變時，MHP 的數量與測定距離成正比地改變。因此，如果利用光電二 極體103檢測MHP，並測定MHP的頻率，則可容易進行 距離測量。 (非專利文獻1 )上田正、山田諄、紫藤進，“利用 200914799 半導體雷射的自耦合效應的距離計” ，1 994年度電氣關係 學會東海支部聯合大會演講論文集，1 994年 (非專利文獻2 )山田諄、紫藤進、津田紀生 '上田 正，“利用半導體雷射的自耦合效應的小型距離計的相關 硏究”，愛知工業大學硏究報告，第31號B，p_35至 42 ， 1996 年 (非專利文獻 3) Guido Giuliani，Michele Norgia ’ Silvano Donati and Thierry Bosch， Laser diode selfmixing technique for sensing applications M > JOURNAL OF OPTICS A ： PURE AND APPLIED OPITCS，p.2 83 至 294 ， 2002 年 【發明內容】 (發明所欲解決之課題） 在包含自耦合型之習知的干涉型距離計中，係藉由使 用計數裝置來測定 MHP的數量，或者使用 FFT(Fast Fourier Transform，快速傅立葉變換）來測定 MHP的頻 率，以求取與測定對象的距離。 但是，在使用FFT的距離計中，當雷射的振盪波長 變化相對於時間爲非線性，會有在以F F Τ所計算出的峰値 頻率與原本應求出的ΜΗΡ的平均頻率中產生差異，而使 所測定出的距離產生誤差的問題。 此外，在使用計數裝置的距離計中，例如將擾亂光等 雜訊作爲ΜΗΡ而進行計數或者因欠缺訊號而有無法計數 200914799 的的MHP，而會有在計數裝置所計數的MHP數目中發生 誤差，而使所測定出的距離產生誤差的問題。 其中，如上所示之計數誤差並不限於距離計，在其他 計數裝置中亦同樣會發生。 本發明係爲了解決上述課題而硏發者，其目的在提供 可補正計數誤差的計數裝置及計數方法，且可補正ΜΗΡ 之計數誤差而使距離的測定精度提升的距離計及距離測量 方法。 (解決課題之手段） 本發明係特定的物理量與訊號數量具有線性關係，前 述物理量爲一定時，係對成爲大致單一頻率的前述訊號進 行計數的計數裝置，其係具有：計數手段，對一定計數期 間中的輸入訊號數量進行計數；周期測定手段，在每次被 輸入訊號時，即測定前述計數期間中之前述輸入訊號的周 期；頻率分佈作成手段，由該周期測定手段的測定結果， 作成前述計數期間中之訊號周期的頻率分佈；代表値計算 手段，根據前述頻率分佈，計算前述輸入訊號之周期分佈 的代表値；以及補正値計算手段’根據前述頻率分佈，求 出爲前述代表値之第1預定數倍以下之等級的頻率總和 Ns、及爲前述代表値之第2預定數倍以上之等級的頻率總 和Nw，根據該等頻率Ns及Nw，補正前述計數手段的計 數結果。 此外，本發明之計數裝置之一構成例中，前述代表値 -8 - 200914799 係中位數、眾數、平均値中的任一者。 此外，本發明之計數裝置之一構成例中，前述補正 計算手段係當將前述計數手段的計數結果設爲N時，藉 Ν’ = N + Nw — Ns，求出補正後之計數結果Ν’。 此外，本發明之計數裝置之一構成例中，前述第1 定數爲〇·5，前述第2預定數爲1.5。 此外，本發明之距離計係具有：半導體雷射，對測 對象放射雷射光；雷射驅動器，以使至少包含振盪波長 續單調遞增的期間的第1振盪期間與至少包含振盪波長 續單調遞減的期間的第2振盪期間交替存在的方式使前 半導體雷射進行動作；受光器，將由前述半導體雷射所 射的雷射光與來自前述測定對象的返回光的干涉光轉換 電訊號；計數手段，對該受光器的輸出訊號所包含之因 前述半導體雷射所放射的雷射光與來自前述測定對象的 回光所產生的干涉波形的數量進行計數；周期測定手段 在每次被輸入干涉波形時，即測定對前述干涉波形數量 行計數的前述計數期間中之前述干涉波形的周期；頻率 佈作成手段，由該周期測定手段的測定結果，作成前述 數期間中之干涉波形之周期的頻率分佈；代表値計算 段’根據前述頻率分佈，計算前述干涉波形之周期分佈 代表値；補正値計算手段，根據前述頻率分佈，求出爲 述代表値之第1預定數倍以下之等級的頻率總和Ns、 爲前述代表値之第2預定數倍以上之等級的頻率總 N w ’根據該等頻率N s及N w，補正前述計數手段的計 値 由 預 定 連 連 述 放 成 由 返 進 分 計 手 的 前 及 和 數 -9- 200914799 結果；以及運算手段，根據由該補正値計算手段所補正的 計數結果，求出與前述測定對象的距離。 此外，本發明之距離計係具有：半導體雷射，對測定 對象放射雷射光；雷射驅動器，以使至少包含振邊波長連 續單調遞增的期間的第1振盪期間與至少包含振盪波長連 續單調遞減的期間的第2振盪期間交替存在的方式使前述 半導體雷射進行動作·，檢測手段，檢測包含由前述半導體 雷射所放射的雷射光與來自前述測定對象的返回光因自耦 合效應所產生的干涉波形的電訊號；計數手段，對該檢測 手段的輸出訊號所包含之前述干涉波形的數量進行計數； 周期測定手段，在每次被輸入干涉波形時，即測定對前述 干涉波形數量進行計數的計數期間中之前述干涉波形的周 期；頻率分佈作成手段，由該周期測定手段的測定結果， 作成前述計數期間中之干涉波形之周期的頻率分佈；代表 値計算手段，根據前述頻率分佈，計算前述干涉波形之周 期分佈的代表値；補正値計算手段，根據前述頻率分佈， 求出爲前述代表値之第1預定數倍以下之等級的頻率總和 Ns、及爲前述代表値之第2預定數倍以上之等級的頻率總 和Nw，根據該等頻率Ns及Nw，補正前述計數手段的計 數結果；以及運算手段，根據由該補正値計算手段所補正 的計數結果，求出與前述測定對象的距離。 此外，本發明之距離計之一構成例中，前述檢測手段 係將前述半導體雷射的光輸出轉換成電訊號的受光器。 此外，本發明之距離計之一構成例中，前述檢測手段 -10- 200914799 係用以檢測前述半導體雷射之端子間電壓的電壓檢測手 段。 此外，本發明之距離計之一構成例中，前述代表値係 中位數、眾數、平均値中的任一者。 此外，本發明之距離計之一構成例中，前述補正値計 算手段係當將前述計數手段的計數結果設爲N時’藉由 N ’ = N + N w - N s，求出補正後之計數結果N ’。 此外，本發明之距離計之一構成例中，前述第1預定 數爲0.5，前述第2預定數爲1.5。 此外’本發明之計數方法係具有：計數步驟’對一定 計數期間中的輸入訊號數量進行計數；周期測定步驟’在 每次被輸入訊號時，即測定前述計數期間中之前述輸入訊 號的周期；頻率分佈作成步驟，由該周期測定步驟的測定 結果’作成前述計數期間中之訊號周期的頻率分佈；代表 値計算步驟，根據前述頻率分佈，計算前述輸入訊號之周 期分佈的代表値；以及補正値計算步驟，根據前述頻率分 佈’求出爲前述代表値之第1預定數倍以下之等級的頻率 總和N s、及爲前述代表値之第2預定數倍以上之等級的 頻率總和Nw，根據該等頻率Ns及Nw，補正前述計數步 驟的計數結果。 此外’本發明之距離測量方法係具備有：振盪步驟， 以使至少包含振遢波長連續單調遞增的期間的第1振盪期 間與至少包含振盪波長連續單調遞減的期間的第2振盪期 間交替存在的方式使前述半導體雷射進行動作；檢測步 -11 - 200914799 驟’藉由受光器’將由前述半導體雷射所放射的雷射光與 來自前述測定對象的返回光的干涉光轉換成電訊號；計數 步驟，對在該檢測步騾所獲得的輸出訊號所包含的干涉波 形的數量進行計數；周期測定步驟，在每次被輸入干涉波 形時，即測定對前述干涉波形數量進行計數的計數期間中 之前述干涉波形的周期；頻率分佈作成步驟，由該周期測 定步驟的測定結果，作成前述計數期間中之干涉波形之周 期的頻率分佈：代表値計算步驟，根據前述頻率分佈，計 算前述干涉波形之周期分佈的代表値；補正値計算步驟， 根據前述頻率分佈，求出爲前述代表値之第1預定數倍以 下之等級的頻率總和Ns、及爲前述代表値之第2預定數 倍以上之等級的頻率總和Nw，根據該等頻率Ns及Nw， 補正前述計數步驟的計數結果；以及運算步驟，根據由該 補正値計算步驟所補正的計數結果’求出與前述測定對象 的距離。 此外，本發明之距離測量方法係具備有：振盪步驟， 以使至少包含振盪波長連續單調遞增的期間的第1振盪期 間與至少包含振盪波長連續單調遞減的期間的第2振盪期 間交替存在的方式使前述半導體雷射進行動作；檢測步 驟，檢測包含由前述半導體雷射所放射的雷射光與來自前 述測定對象的返回光因自耦合效應所產生的干涉波形的電 訊號；計數步驟，對在該檢測步驟所獲得的輸出訊號所包 含的前述干涉波形的數量進行計數；周期測定步驟’在每 次被輸入干涉波形時’即測定對前述干涉波形數量進行計 -12- 200914799 數的計數期間中之前述干涉波形的周期；頻率分佈作成步 驟，由該周期測定步驟的測定結果，作成前述計數期間中 之干涉波形之周期的頻率分佈；代表値計算步驟，根據前 述頻率分佈，計算前述干涉波形之周期分佈的代表値；補 正値計算步驟，根據前述頻率分佈，求出爲前述代表値之 第1預定數倍以下之等級的頻率總和Ns、及爲前述代表 値之第2預定數倍以上之等級的頻率總和n w，根據該等 頻率N s及N w，補正前述計數步驟的計數結果；以及運算 步驟，根據由該補正値計算步驟所補正的計數結果，求出 與前述測定對象的距離。 (發明之效果） 藉由本發明，測定計數期間中之輸入訊號的周期，根 據該測定結果作成計數期間中的訊號周期的頻率分佈，根 據該頻率分佈來計算輸入訊號之周期的代表値，根據頻率 分佈’求取爲代表値之第1預定數倍以下之等級的頻率總 和N s、及爲代表値之第2預定數倍以上之等級的頻率總 和Nw ’根據該等頻率Ns和Nw來補正在計數手段的計數 結果’藉此可去除計數時的缺漏或過剩計數的影響，而補 正計數裝置的計數誤差。 此外，在本發明中，測定計數期間中的干涉波形的周 期’根據該測定結果作成計數期間中之干涉波形之周期的 頻率分佈，根據頻率分佈來計算干涉波形之周期的代表 値’根據頻率分佈，求取爲代表値之第1預定數倍以下之 -13- 200914799 等級的頻率總和Ns、及爲代表値之第2預定數倍以上之 等級的頻率總和N w，根據該等頻率n s和N w來補正計數 手段的計數結果’藉此可去除計數時的缺漏或過剩計數的 影響，而補正計數裝置的計數誤差，因此可在使用計數手 段來測定干涉波形的數量而求取與測定對象的距離的距離 計中，使距離的測定精度提升。 【實施方式】 (第1實施形態） 本發明係一種根據在採用波長調變的感測（sensing ) 時射出的波與由對象物反射的波的干涉訊號，來測量距離 的手法。因此，亦可適用於自耦合型以外的光學式干涉 計、光以外的干涉計。若針對採用半導體雷射的自耦合的 情形更加具體說明，當一面由半導體雷射對測定對象照射 雷射光，一面使雷射的振盪波長改變時，在振盪波長從最 小振盪波長變化爲最大振盪波長的期間（或從最大振盪波 長至最小振盪波長變化的期間）中之測定對象的位移係反 映在MHP的數量。因此，可藉由調查使振盪波長改變時 的MHP的數量，來檢測測定對象的狀態。以上爲干涉計 的基本原理。 以下參照圖示，說明本發明的第1實施形態。第1圖 係顯示本發明第1實施形態的距離計的構成的方塊圖。第 1圖的距離計係具有：對測定對象1 2放射雷射光的半導體 雷射1 ;將半導體雷射1的光輸出轉換成電訊號的光電二 -14- 200914799 極體2 ;分別將來自半導體雷射1的光聚光而照射 對象12，並且將來自測定對象12的返回光聚光而 入半導體雷射1的透鏡3;使半導體雷射1交替地 盪波長連續地增加的第1振盪期間和振盪波長連續 的第2振盪期間的雷射驅動器4;將光電二極體2 電流轉換成電壓並進行放大的電流-電壓轉換放大器 電流-電壓轉換放大器5的輸出電壓去除載波的濾 路1 1 ;對濾波器電路1 1的輸出電壓所包含的MHP 進行計數的計數裝置8 ;根據MHP的數量，計算與 象12的距離的運算裝置9;以及顯示運算裝置9的 果的顯示裝置1 0。 以下爲了容易說明，假定在半導體雷射1採用 模式跳躍（mode hopping )現象的類型（VCSEL型 雷射型）。 例如，雷射驅動器4係將關於時間按照恒定的 而反覆增減的三角波驅動電流作爲注入電流而供給 體雷射1。由此，半導體雷射1係以交替反覆第1 間和第2振盪期間的方式被驅動，該第1振盪期間 波長與注入電流的大小成正比以恒定的變化率連 加，該第2振盪期間係振盪波長以恒定的變化率連 少0 第2圖係顯示半導體雷射1的振盪波長之時 圖。在第2圖中，t-Ι表示第（t-Ι )個振盪期間； 第t個振盪期間；t+Ι表示第（t+1 )個振盪期間； 在測定 使其射 反覆振 地減少 的輸出 5 ;由 波器電 的數量 測定對 計算結 不具有 、DFB 變化率 至半導 振盪期 係振盪 續地增 續地減 間變化 t表示 t + 2表 -15- 200914799 示第（t+2)個振盪期間；t+3表示第（t+3)個振擾期 間；t + 4表示第（t + 4 )個振盪期間；λ a表τκ各期間中的 振盪波長的最小値；λ b表示各期間中的振盪波長的最大 値；T表示三角波的周期。在本實施形態中’振盪波長的 最大値λ b及振盪波長的最小値λ a係分別恒爲一定’該 等的差値Xb-ka亦恒爲一定。 由半導體雷射1射出的雷射光係藉由透鏡3予以聚光 而射入測定對象1 2。以測定對象1 2予以反射的光係藉由 透鏡3予以聚光，並射入半導體雷射1。其中’透鏡3的 聚光並非爲必須。光電二極體2係將半導體雷射1的光輸 出轉換成電流。電流-電壓轉換放大器5係將光電二極體2 的輸出電流轉換成電壓並進行放大。 濾波器電路1 1具有從調變波抽出重疊訊號的功能。 第3圖（A )係以模式顯示電流-電壓轉換放大器5的輸出 電壓波形圖，第3圖（B )係以模式顯示濾波器電路1 1的 輸出電壓波形圖。該等圖係表示由相當於光電二極體2之 輸出的第3圖（A )的波形（調變波），去除第2圖的半 導體雷射1的振盪波形（載波），以抽出第3圖（B )的 Μ Η P波形（重疊波）的過程。 計數裝置8係針對濾波器電路η的輸出電壓所包含 之ΜΗΡ的數量，就第1振盪期間t-1、t+1、t + 3與第2振 盪期間t、t + 2、t + 4的各個期間進行計數。第4圖係顯示 計數裝置8之構成之一例的方塊圖。計數裝置8係由：判 定部81、邏輯與運算部（and) 82、計數器83、計數結 -16- 200914799 果補正部84、及記憶部85所構成。電流-電壓轉換放大器 5、濾波器電路1 1、及計數裝置8的判定部8 1、A N D 8 2與 計數器8 3係構成計數手段。 第5圖係顯示計數結果補正部84之構成之1例的方 塊圖。計數結果補正部8 4係由周期測定部8 4 0、頻率分佈 作成部84 1、代表値計算部842、以及補正値計算部843 所構成。 第6圖（A)至第6圖（F)係用以說明計數裝置8的 動作圖，第6圖（A )係以模式顯示濾波器電路1 1之輸出 電壓的波形’亦即MHP的波形的圖，第6圖（B)係顯示 與第6圖（A)相對應的判定部81的輸出的圖，第6圖 (C )係顯示被輸入至計數裝置8的閘極訊號GS的圖， 第6圖（D )係顯示與第6圖（B )相對應之計數器8 3的 計數結果的圖，第6圖（E )係顯示被輸入至計數裝置8 的時鐘訊號CLK的圖’第6圖（F)係顯示與第6圖 (B )相對應之周期測定部8 4 0之測定結果的圖。 首先，計數裝置8的判定部8 1係判定第6圖（A )所 示的濾波器電路11的輸出電壓爲高位準（H)或低位準 (L ) ’輸出如第6圖（B )所示的判定結果。此時，判定 部81係在濾波器電路11的輸出電壓上升至臨限値TH1以 上時’判定爲高位準；濾波器電路1 1的輸出電壓下降至 臨限値TH2 ( TH2 < TH1 )以下時，判定爲低位準，藉此 將濾波器11的輸出進行二値化。 AN D 8 2係輸出判定部8 1的輸出與第6圖（C )所示 -17- 200914799 的閘極訊號GS的邏輯與運算的結果，計數器83係對 AND82的輸出的上升進行計數（第6圖（d))。在此’ 閘極訊號G S係在計數期間（在本實施形態中係第1振遵 期間或第2振盪期間）的起始時上升，在計數期間的結束 時下降的訊號。因此’計數器83係對計數期間中之 AND82的輸出的上升邊緣的數量（亦即MHP之上升邊緣 的數量）進行計數。 另一方面’計數結果補正部8 4的周期測定部8 4 〇係 在每次發生上升邊緣時，即對計數期間中之AND82的輸 出的上升邊緣的周期（亦即MHP的周期）進行測定。此 時’周期測定部840係以第6圖（E )所示之時鐘訊號 CLK的周期爲1個單位，測定MHP的周期。在第6圖 (F )之例中，周期測定部84 〇係依序測定τ α及τ; 作爲MHP的周期。由第6圖（E)、第6圖（F)可知， 周期Τ α、T 〃及T，的大小係分別爲5時鐘、4時鐘、2時 鐘。時鐘訊號CLK的頻率遠大於ΜΗΡ所可取得的最高頻 率。 記憶部8 5係記憶計數器8 3的計數結果及周期測定部 840的測定結果。 在閘極訊號GS下降、計數期間結束之後，計數結果 補正部8 4的頻率分佈作成部8 4 1係根據記憶在記憶部8 5 的測定結果，作生計數期間中之ΜΗΡ的周期的頻率分 佈。 接著，計數結果補正部8 4的代表値計算部8 4 2係根 -18- 200914799 據由頻率分佈作成部8 4 1所作成的頻率分佈’計算M H P 之周期的中位數（median) ° 計數結果補正部8 4的補正値計算部8 4 3係根據頻率 分佈作成部8 4 1所作成的頻率分佈’求取爲周期中位數 T 〇之0.5倍以下的等級的頻率總和N s、及爲周期中位數 T0之1 · 5倍以上的等級的頻率總和N w ’並如下補正計數 器8 3的計數結果。 …（2) N ’ =N + N w-N s 在式（2 )中，N係作爲計數器83之計數結果的MHP 的數量，N ’係補正後的計數結果。 在第7圖中顯示頻率分佈之一例。在第7圖中，Ts係 周期中位數T0的0.5倍的等級値，Tw係周期中位數T0 的1.5倍的等級値。當然第7圖中的等級乃爲MHP的周期 的代表値。其中，在第7圖中爲了簡化記載，省略圖示中 位數T 0與T S之間、及中位數T 0與T w之間的頻率分 佈。 第8圖係用以說明計數器83之計數結果之補正原理 的圖’第8圖（A)係以模式顯示濾波器電路11之輸出電 壓的波形，亦即Μ Η P的波形的圖，第8圖（B )係顯示與 第8圖（Α)相對應之計數器83的計數結果的圖。 原本ΜΗΡ的周期係依與測定對象1 2的距離而異，但 是若與測定對象1 2的距離不變，則μ Η Ρ係以相同的周期 -19- 200914799 出現。但是由於雜訊而會在MHP波形發生缺漏或産生不 應作爲訊號進行計數的波形’而在MHP的數量產生誤 差。 當發生訊號缺漏時，在已發生缺漏的部位的Μ HP的 周期Tw係成爲原本周期的大約2倍。亦即，當MHP的周 期約爲中位數的2倍以上時’係可判斷在訊號中已發生缺 漏。因此，將周期Tw以上之等級的頻率總和Nw視爲訊 號缺漏的次數，並將該Nw加算在計數器8 3的計數結果 N，藉此可補正訊號的缺漏。 此外，在將雜訊進行計數後的部位的MHP的周期T s 係成爲原本周期的大約〇·5倍。亦即，當MHP的周期約爲 中位數的〇. 5倍以下時，係可判斷已過剩計數訊號。因 此，將周期Ts以下之等級的頻率總和Ns視爲過剩計數訊 號的次數，並由計數器83的計數結果N減算該Ns，藉此 可補正誤數的雜訊。 以上爲式（2)所示之計數結果的補正原理。其中， 在本實施形態中，係將Ts設爲周期中位數T0的0 · 5倍， 將Tw設爲中位數T0的1 _ 5倍的値而非中位數T0的2倍 的値，設爲1 .5倍的理由容後陳述。 補正値計算部843係將藉由式（2 )計算所得之補正 後計數結果Ν’輸出至運算裝置9。計數裝置8係按每個第 1振盪期間t-1、t+1、t + 3及每個第2振盪期間t、t + 2、 t + 4進行如以上所示之處理。 接著’運算裝置9係根據藉由計數裝置8測量而得的 -20- 200914799 Μ Η P的數量N ’’求取與測定對象1 2的距離。一定期間中 的Μ Η P的數量係與測定距離成正比。因此，若預先求取 一定計數期間（在本實施形態中的第1振盪期間或第2振 邊期間）中的Μ Η Ρ的數量與距離的關係並預先登記在運 算裝置9的資料庫（未圖示），運算裝置9即可由資料庫 取得與藉由計數裝置8測量而得的μ Η Ρ的數量Ν，相對應 的距離的値，藉此可求取與測定對象1 2的距離。 或者，預先求取表示計數期間中之ΜΗΡ的數量與距 離的關係的數學式並預先設定’運算裝置9係將藉由計數 裝置8測量而得的ΜΗΡ的數量Ν，代入數學式，藉此可計 算出與測定對象1 2的距離。運算裝置9係按每個第1振 盪期間t-1、t+1 ' t + 3及每個第2振盪期間t、t + 2、t + 4進 行如以上所示之處理。 顯不裝置10係即時（real time)顯示藉由運算裝置9 計算所得之與測定對象1 2的距離（位移）。 如以上所示，在本實施形態中，測定計數期間中的 MHP的周期，根據該測定結果作成計數期間中之MHP的 周期的頻率分佈，根據頻率分佈計算MHP的周期的中位 數’根據頻率分佈，求取爲中位數之〇 · 5倍以下的等級的 頻率總和Ns、及爲中位數的1 .5倍以上的等級的頻率總和 N w ’根據該等頻率N s與和N w，補正計數器的計數結 果’藉此可補正MHP的計數誤差，因此可提升距離的測 定精度。 其中，本實施形態中的計數裝置8及運算裝置9係可 -21 - 200914799 藉由例如具備有C P u、記憶裝置、介面的電腦及控制該等 硬體資源的程式來實現。用以使如上所示之電腦動作的程 式係在被記錄在軟性磁碟、CD-ROM、DVD-ROM、記憶卡 等記錄媒體的狀態下予以提供。CPU係將所讀取到的程式 寫入記憶裝置，按照該程式，執行在本實施形態中所說明 的處理。 接著，就使用周期之頻率分佈的中位數作爲Μ HP的 基準周期的理由、及將求取頻率Nw時之周期的臨限値設 爲中位數的1 . 5倍的理由加以說明。 首先，針對由於已誤數雜訊而將MHP的周期分割爲2 的情形的計數結果的補正加以說明。當半導體雷射的振盪 波長變化呈線性時，MHP的周期T係將測量期間Tc除以 MHP的數量N所得的T0爲中心進行常態分佈（第9 圖）。 接著，考慮因雜訊而分割爲2的Μ Η P的周期。過剩 計數雜訊的結果而分割爲2的ΜΗΡ的周期係以隨機的比 例分割爲2，但是分割前的周期爲以Τ0爲中心的常態分 佈’因此成爲相對於0.5T0呈對稱的頻率分佈（第10圖 的a )。 針對包含該雜訊的MHP的周期的頻率分佈，假設 Μ Η P的η %因雜訊而將周期分割爲2時，計算Μ Η P的周期 的平均値及中位數。 所有周期的和1旦爲測量期間T c，並不會改變，但是 當Μ Η Ρ的η %因雜訊而將周期分割爲2時，頻率的積分値 -22- 200914799 會成爲（1 +n〔 ％〕）N，因此MHP的周期的平均値成爲 (1 / ( 1+ η〔 ％〕) ) TO。 另一方面，當忽略以雜訊的分佈而與常態分佈相重疊 的部分時，分割爲2的雜訊累積頻率係成爲中位數與T0 之間的等級所包含的頻率的兩倍，因此，MHP的周期的中 位數係位於第11圖之b的面積爲a的面積的2倍的位 置。 在屬於Microsoft公司之軟體的Excel (註冊商標）中 有可利用由常態分佈的平均値與α σ間之兩側値的內部比 例爲「（ 1 - ( 1-NORMSDIST ( a ) ) x2 ) X1 00〔 ％〕」來 表現的NORMSDIST ()的函數，若利用該函數，可以如 下數式，表示MHP的周期的中位數。 (l-(l-NORMSDIST((中位數-Τ0)/σ))χ2)χ(100-η)/2=η〔 ％〕 …（3) 根據如以上所示，若將標準偏差σ設爲0.02Τ0，而計 算出ΜΗΡ的10%因雜訊而將周期分割爲2時之ΜΗΡ之周 期的平均値Τ0’及中位數Τ0’，如以下所示。 TO7 =(1/(1 + 0.1 ))T0 = 0.91 TO …（4) TO’ = 0.995 T0 · (5) 其中，在此係將平均値、中位數均以TO’表示。計數器値 (頻率的積分値）係成爲1 . 1 N，計數誤差成爲1 0%。 -23- 200914799 在此，考慮在某周期丁』靡被分割爲2之後之2 個周期Τ1、τ2(設爲ΤΘΤ2)所可取得的期間的機率。 假設雜訊是隨機産生，如第1 2圖所不’ Τ2係可以相同的 機率取得〇 < τ 2 s T a / 2的値。同樣地’ Τ 1亦可以相同的 機率取得Τ / 2 $ Τ 1 < T a的値。第1 2圖中的Τ 1所可取^ 的機率分佈的面積與Ϊ2所可取得的機率分佈的面積均爲 1 ° 周期Ta係呈以Τ0爲中心的常態分佈’因此’若將 Ta看作集合，則T2所可取得的機率的頻率分佈係形成爲 與平均値爲0.5T0、標準偏差爲〇.5σ的常態分佈的累積頻 率分佈相同的形狀。 此外，如第1 3圖所示’ Τ1所可取得的機率的頻率分 佈係形成爲將平均値爲0 · 5 Τ 0、標準偏差爲0 · 5 σ的常態分 佈的累積頻率分佈、與平均値爲τ〇、標準偏差爲σ的吊 態分佈的累積頻率分佈相重疊的形狀。在此，τ 1、τ2的 各數量係與周期被分割爲2的Μ Η Ρ的數量η〔 ％〕. Ν相 等。 若可對於因雜訊而使周期被分割爲2的ΜΗΡ的數量η 〔％〕· Ν進行計數，即可使用以下數式，導出ΜΗΡ的數 量Ν。 N = Ν5 - η [ % ] * Ν (6) 如第14圖所示，若可以使具有Tb以下之周期的ΜΗΡ -24- 200914799 的數量Ns與被分割爲2之MHP的數量η〔 ％〕· Ν成爲 相等的方式來設定Tb，即可藉由對於具有Tb以下之周期 的Μ Η P的數量n s進行計數，而間接地對於周期被分割爲 2的ΜΗΡ的數量η〔 ％〕. Ν進行計數。 在第14圖中，當具有Tb以上之周期的ΜΗΡ的周期 Τ2的頻率（第14圖的c)與具有未達Tb之周期的ΜΗΡ 的周期T1的頻率（第μ圖的d)爲相同時’具有Tb以 下之周期的MHP的數量係與T2的數量，亦即周期被分割 爲2的MHP的數量Ns(=n〔％〕. N)成爲相等。亦即’ MHP的數量N係可以如下數式表示。 N = N5 - η [ % ] · Ν = Ν，- Ns …⑺ T 1及T2的頻率形狀係在〇 . 5 T a呈對稱的形狀’因此 將0.5Ta作爲臨限値而進行判斷時，可正確地對周期被分 割爲2的MHP的頻率Ns ( = η〔 ％〕. Ν )進行計數。 接著，藉由對於具有0.5 TO之下之周期的MHP的數 量進行計數，可對周期被分割爲2的 MHP的數量η 〔％〕· Ν的數間接地進行計數，但是並無法根據包含雜 訊的ΜΗΡ的周期的頻率分佈（第1〇圖）來計算出Τ0。若 MHP的母群體如第10圖的頻率分佈所示眾數（mode )愈 與 T0 相等愈爲理想而且母體參數（population parameter )愈大’即可使用眾數作爲TO’。 在此記載使用平均値或中位數T0’所得之MHP的數量 -25- 200914799 η〔 ％〕· Ν的計數。若以T0，=y · ΤΟ表示，代入τ〇,取代 ΤΟ以求出Ns時，比作爲周期被分割爲2之ΜΗΡ的數量 所進行判斷的0.5Τ0’爲小的周期的頻率Ns’係成爲 〔％〕. N (第 1 5 圖）。 若使用平均値或中位數T0’，補正後的計數値Nt係以 下所示。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a counting device for counting the number of signals and an interference type distance meter for determining the distance from a measuring object by measuring the number of interference waveforms using a counting device. [Prior Art] The distance measurement using the interference of the light generated by the laser does not interfere with the measurement target because it is a non-contact measurement, and has been used as a highly accurate measurement method since ancient times. Recently, in order to achieve miniaturization of a device, a semiconductor laser system is utilized as a light source for light measurement. In its representative case, there is a person who uses a heterodyne interferometry. This person can measure long distances with good accuracy, but because of the use of an interferometer outside the semiconductor laser, it has the disadvantage of being complicated by the optical system. On the other hand, a measuring device that uses the laser output light and the return light from the measuring object to interfere with the inside of the semiconductor laser (self-coupling effect) has been proposed (see, for example, Non-Patent Document 1, Non-Patent Document 2, Non-Patent Document) Patent Document 3). According to the self-coupling type laser measuring device as described above, since the semiconductor laser of the built-in photodiode has functions of light emission, interference, and light receiving, the external interference optical system can be greatly simplified. Therefore, the sensor portion is only a semiconductor laser and a lens, and is relatively small compared with the conventional technology. In addition, it has the feature that the distance measurement range is larger than the triangulation method. In Fig. 23, a composite resonator model of the FP type (Fabry-Perot type) semiconductor mine 200914799 is shown. In Fig. 23, a 101-semiconductor laser, a wall-opening surface of a 012-series semiconductor crystal, a 1 〇3-series photodiode, and a 04-series measurement object are shown. A part of the reflected light from the measurement object 104 is easily returned to the oscillation region. The weak light returned and the laser light coupling in the resonator 1 0 1 become unstable and generate noise (composite resonator noise or return light noise). Even if the amount of relative return light relative to the output light is extremely small, the change in the characteristics of the semiconductor laser due to the return light is remarkably exhibited. The phenomenon shown above is not limited to the Fabry-Perot type (hereinafter referred to as FP type) semiconductor laser, and is a vertical cavity cavity type laser (Vertical Cavity Surface Emitting Laser) type (hereinafter referred to as The same is true for other types of semiconductor lasers such as the VCSEL type and the Distributed Feedback Laser type (hereinafter referred to as DFB laser type). When the oscillation wavelength of the laser is λ and the distance from the wall opening surface 102 of the measurement target 104 to the measurement target 104 is L, the return light and the resonator are returned when the following resonance conditions are satisfied. The lasers in 1 0 1 are mutually reinforcing and the laser output is slightly increased. L = ηλ / 2 (1) In the formula (1), η is an integer. In this case, even when the scattered light from the measurement object 1 〇 4 is extremely weak, the apparent reflectance in the resonator 101 of the semiconductor laser is increased to cause amplification, and sufficient observation is sufficient. -5- 200914799 In semiconductor lasers, since laser light of different frequencies is radiated according to the magnitude of the injected current, when the oscillation frequency is modulated, an external modulator is not required, and the current can be directly adjusted by the injection current. change. Fig. 24 is a graph showing the relationship between the oscillation wavelength and the output waveform of the photodiode 103 when the oscillation wavelength of the semiconductor laser is changed at a constant ratio. When L = nX/2 as shown in the formula (1) is satisfied, the phase difference between the returning light and the laser light in the resonator 101 becomes 0 (in-phase), and the returning light and the laser light in the resonator 101 are mutually mutual Reinforce, when ί=ηλ/2+λ/4, the phase difference is 180 ° (reverse phase), and the return light and the laser light in the resonator 1 〇1 mutually weaken each other most. Therefore, if the oscillation wavelength of the semiconductor laser is changed, the situation in which the laser output is enhanced and the case of the attenuation appear alternately and repeatedly. If the photodiode 101 provided in the resonator 101 is used to detect the laser at this time, the laser is detected. At the time of output, as shown in Fig. 24, a stepped waveform of a constant period is obtained. Such waveforms are generally referred to as interference fringes. One of the staircase waveforms, i.e., the interference fringes, is referred to as a mode hop pulse (hereinafter referred to as ΜΗΡ). MHP is a phenomenon different from the phenomenon of mode hopping (m〇de hopping). For example, when the distance from the measurement target 104 is L1, if the number of MHPs is 10, the number of MHPs is five at half the distance L2. That is, when the oscillation wavelength of the semiconductor laser is changed for a certain period of time, the number of MHP changes in proportion to the measured distance. Therefore, if the MHP is detected by the photodiode 103 and the frequency of the MHP is measured, the distance measurement can be easily performed. (Non-Patent Document 1) Ueda Masahiro, Yamada Aya, and Wisteria, "Distance Meter Using Self-Coupling Effect of Semiconductor Radiator in 200914799", Proceedings of the Joint Conference of the East China Sea Branch of the Institute of Electrical Relations, 1994, 1994 (Non-patent) Document 2) Yamada Aya, Wisteria, and Tsuda Kiyoshi 'Ueda Masahiro, "Relevant research on small distance meters using the self-coupling effect of semiconductor lasers", Aichi University of Technology Research Report, No. 31 B, p_35 to 42, 1996 (Non-Patent Document 3) Guido Giuliani, Michele Norgia 'Silvano Donati and Thierry Bosch, Laser diode selfmixing technique for sensing applications M > JOURNAL OF OPTICS A : PURE AND APPLIED OPITCS, p.2 83 to 294, 2002 Disclosure of the Invention (Problems to be Solved by the Invention) In an interference type distance meter including a self-coupling type, the number of MHPs is measured by using a counting device, or FFT (Fast Fourier Transform) is used. The frequency of the MHP is measured to determine the distance from the measurement subject. However, in the distance meter using FFT, when the oscillation wavelength change of the laser is nonlinear with respect to time, there is a difference between the peak 値 frequency calculated by FF Τ and the average frequency of ΜΗΡ which should be obtained originally. And the problem that the measured distance produces an error. Further, in the distance meter using the counting device, for example, the noise such as disturbing light is counted as a defect or the MHP of 200914799 cannot be counted due to the lack of a signal, and there is an error in the number of MHPs counted by the counting device. And the problem that the measured distance produces an error. Among them, the counting error as described above is not limited to the distance meter, and it also occurs in other counting devices. The present invention has been made in order to solve the above problems, and an object of the present invention is to provide a distance measuring device and a counting method capable of correcting a counting error, and which can correct a counting error of ΜΗΡ to improve a distance measurement accuracy and a distance measuring method. (Means for Solving the Problem) The present invention is a counting device in which a specific physical quantity has a linear relationship with the number of signals, and when the physical quantity is constant, a counting device that counts the signal that becomes a substantially single frequency has a counting means and a certain counting The number of input signals in the period is counted; the period measuring means measures the period of the input signal in the counting period every time the signal is input; the frequency distribution forming means, and the measurement result of the period measuring means is used to create the foregoing The frequency distribution of the signal period in the counting period; representing the 値 calculating means, calculating the representative 値 of the periodic distribution of the input signal according to the frequency distribution; and calculating the 値 calculating means according to the frequency distribution to obtain the representative 前述1 is a frequency sum Ns of a predetermined number of times or less and a frequency sum Nw of a level which is a second predetermined number or more of the representative 値, and the counting result of the counting means is corrected based on the frequencies Ns and Nw. Further, in one configuration example of the counting device of the present invention, the aforementioned representative 値 -8 - 200914799 is any one of a median, a mode, and an average 。. Further, in a configuration example of the counting device of the present invention, when the counting result of the counting means is N, the correction result means 求出' = N + Nw - Ns, and the corrected counting result 求出 ' . Further, in a configuration example of the counting device of the present invention, the first predetermined number is 〇·5, and the second predetermined number is 1.5. Further, the distance meter of the present invention has a semiconductor laser that radiates laser light to the object to be measured, and a laser driver that monotonically decreases the first oscillation period and at least the oscillation wavelength including at least the oscillation wavelength continuously increasing. The front semiconductor laser is operated alternately in the second oscillation period of the period; the light receiver converts the interference light from the laser light emitted by the semiconductor laser and the return light from the measurement target into an electric signal; The output signal of the photodetector includes the number of interference waveforms generated by the laser light emitted by the semiconductor laser and the return light from the measurement target; the period measuring means is input each time the interference waveform is input, that is, Measuring a period of the interference waveform in the counting period in which the number of the interference waveforms is counted; a frequency distribution forming means, and a frequency distribution of a period of the interference waveform in the plurality of periods during the measurement period of the period measuring means; Calculating the segment 'calculates the circumference of the aforementioned interference waveform based on the aforementioned frequency distribution The distribution representative means, based on the frequency distribution, the frequency sum Ns of the level which is the first predetermined number of times or less of the representative 値, and the frequency of the second predetermined number or more of the representative 値. N w 'According to the frequencies N s and N w , the calculation of the counting means by the predetermined connection is performed by the pre-reporting hand and the number of the -9-200914799; and the calculation means The result of the correction corrected by the calculation means is corrected, and the distance from the measurement target is obtained. Further, the distance meter of the present invention includes: a semiconductor laser that radiates laser light to a measurement target; and a laser driver that continuously monotonically decreases the first oscillation period and at least the oscillation wavelength including at least the period in which the oscillation wavelength continuously increases monotonically. The semiconductor oscillation is performed in such a manner that the second oscillation period alternates, and the detection means detects that the laser beam emitted from the semiconductor laser and the return light from the measurement target are self-coupling effects. An electrical signal of the interference waveform; the counting means counts the number of the interference waveforms included in the output signal of the detecting means; and the period measuring means counts the number of the interference waveforms each time the interference waveform is input a period of the interference waveform in the counting period; a frequency distribution forming means for generating a frequency distribution of a period of the interference waveform in the counting period by the measurement result of the period measuring means; and representing the 値 calculating means, calculating the foregoing based on the frequency distribution Representative of the periodic distribution of the interference waveform The correction 値 calculation means obtains, based on the frequency distribution, a frequency sum Ns of a level equal to or less than a first predetermined number of times of the representative 値, and a frequency sum Nw of a level of a second predetermined number or more of the representative 値, The counting result of the counting means is corrected based on the frequencies Ns and Nw, and the calculating means obtains the distance from the measurement target based on the counting result corrected by the correction calculating means. Further, in a configuration example of the distance meter of the present invention, the detecting means is a light receiver for converting the light output of the semiconductor laser into an electric signal. Further, in a configuration example of the distance meter of the present invention, the detecting means -10-200914799 is a voltage detecting means for detecting the voltage between the terminals of the semiconductor laser. Further, in one configuration example of the distance meter of the present invention, the aforementioned representative system is any one of a median, a mode, and an average value. Further, in a configuration example of the distance meter according to the present invention, the correction correction means is configured to determine the correction result by N' = N + N w - N s when the count result of the counting means is N. Count the result N '. Further, in a configuration example of the distance meter of the present invention, the first predetermined number is 0.5, and the second predetermined number is 1.5. In addition, the counting method of the present invention has a counting step of counting the number of input signals in a certain counting period, and a period measuring step 'measuring the period of the aforementioned input signal in the counting period every time the signal is input; a frequency distribution forming step of: generating a frequency distribution of the signal period in the counting period by the measurement result of the period measuring step; representing a 値 calculating step of calculating a representative 周期 of the periodic distribution of the input signal according to the frequency distribution; and correcting 値a calculation step of obtaining a frequency sum N s of a level equal to or less than a first predetermined number of times of the representative 値 and a frequency sum Nw of a level of a second predetermined number or more of the representative 値 based on the frequency distribution ‘ The equal frequency Ns and Nw correct the counting result of the aforementioned counting step. Further, the distance measuring method of the present invention includes an oscillating step of alternately causing a first oscillation period including at least a period in which the oscillation wavelength continuously increases monotonically and a second oscillation period in which the oscillation wavelength is continuously monotonically decreasing. The operation of the semiconductor laser is performed; detecting step -11 - 200914799 "converting the interference light of the laser light emitted by the semiconductor laser and the return light from the measuring object into an electric signal by a light receiver"; Counting the number of interference waveforms included in the output signal obtained at the detection step; the period measuring step, each time the interference waveform is input, that is, the aforementioned counting period in which the number of the interference waveforms is counted is measured a period of the interference waveform; a frequency distribution forming step of generating a frequency distribution of the period of the interference waveform in the counting period from the measurement result of the period measuring step: representing a 値 calculating step of calculating a periodic distribution of the interference waveform based on the frequency distribution Representation 补; correction 値 calculation step, according to the former The frequency distribution is obtained as a frequency sum Ns of a level equal to or less than a first predetermined number of times of the representative 値, and a frequency sum Nw of a level equal to or greater than a second predetermined number of times of the representative 値, based on the frequencies Ns and Nw And correcting the counting result of the counting step; and calculating the distance from the measurement target based on the counting result corrected by the correction calculating step. Further, the distance measuring method of the present invention includes an oscillating step of alternately presenting a first oscillation period including at least a period in which the oscillation wavelength continuously monotonically increases, and a second oscillation period including a period in which the oscillation wavelength continuously monotonically decreases. The semiconductor laser is operated; the detecting step detects an electrical signal including an interference waveform generated by the self-coupling effect of the laser light emitted by the semiconductor laser and the return light from the measurement target; and the counting step The number of the aforementioned interference waveforms included in the output signal obtained by the detecting step is counted; the period measuring step 'when the interference waveform is input each time' is measured in the counting period of the number of the interference waveforms -12-200914799 a period of the interference waveform; a frequency distribution forming step of generating a frequency distribution of a period of the interference waveform in the counting period by the measurement result of the period measuring step; representing a 値 calculating step of calculating a period of the interference waveform based on the frequency distribution Representation of distribution a step of obtaining, based on the frequency distribution, a frequency sum Ns of a level equal to or less than a first predetermined number of times of the representative 値, and a frequency sum nw of a level of a second predetermined number or more of the representative 値, according to the frequencies N s and N w are used to correct the counting result of the counting step, and the calculation step is to obtain the distance from the measurement target based on the counting result corrected by the correction 値 calculating step. (Effect of the Invention) According to the present invention, the period of the input signal in the counting period is measured, the frequency distribution of the signal period in the counting period is generated based on the measurement result, and the representative of the period of the input signal is calculated based on the frequency distribution, according to the frequency The distribution 'requires a sum of frequencies N s representing a level equal to or less than the first predetermined number of times 値, and a frequency sum Nw of a level representing a second predetermined number or more of 値', based on the frequencies Ns and Nw The counting result of the counting means 'by this, the influence of the missing or excess count at the time of counting can be removed, and the counting error of the counting means can be corrected. Further, in the present invention, the period of the interference waveform in the counting period is measured. The frequency distribution of the period of the interference waveform in the counting period is calculated based on the measurement result, and the representative of the period of the interference waveform is calculated based on the frequency distribution. And obtaining the frequency sum Ns of the -13-200914799 level representing the first predetermined number of times less than the first predetermined number of times, and the frequency sum Nw of the level representing the second predetermined number of times or more of the 値, according to the frequencies ns and N w is used to correct the counting result of the counting means. Thus, the influence of the missing or excessive counting at the time of counting can be removed, and the counting error of the counting device can be corrected. Therefore, the number of interference waveforms can be measured by using the counting means to determine the target to be measured. The distance measurement of the distance increases the accuracy of the distance measurement. [Embodiment] (First Embodiment) The present invention is a method for measuring a distance based on an interference signal of a wave emitted by sensing when wavelength modulation is applied and a wave reflected by an object. Therefore, it can be applied to an optical interferometer other than the self-coupling type or an interferometer other than light. More specifically, for the case of self-coupling using a semiconductor laser, when the laser beam is irradiated to the measuring object by a semiconductor laser, and the oscillation wavelength of the laser is changed, the oscillation wavelength is changed from the minimum oscillation wavelength to the maximum oscillation wavelength. The displacement of the measurement object in the period (or the period from the maximum oscillation wavelength to the minimum oscillation wavelength) is reflected in the number of MHPs. Therefore, the state of the measurement target can be detected by investigating the number of MHPs at which the oscillation wavelength is changed. The above is the basic principle of the interferometer. Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing the configuration of a distance meter according to a first embodiment of the present invention. The distance meter of Fig. 1 includes a semiconductor laser 1 that emits laser light to the measurement target 12, and a photodiode II-14-200914799 of the semiconductor laser 1 to be converted into an electric signal; The light of the laser 1 is condensed to illuminate the object 12, and the return light from the measurement target 12 is condensed into the lens 3 of the semiconductor laser 1; the first oscillation period in which the semiconductor laser 1 is alternately increased in wavelength continuously a laser driver 4 during a second oscillation period in which the oscillation wavelength is continuous; a current-voltage conversion amplifier that converts the photodiode 2 current into a voltage and amplifies the output voltage of the current-voltage conversion amplifier 5 to remove the carrier filter 1 1 A counting device 8 that counts the MHP included in the output voltage of the filter circuit 1; an arithmetic device 9 that calculates the distance from the image 12 based on the number of MHPs; and a display device 10 that displays the fruit of the arithmetic device 9. Hereinafter, for the sake of easy explanation, it is assumed that the type of mode hopping phenomenon (VCSEL type laser type) is employed in the semiconductor laser 1. For example, the laser driver 4 supplies the body laser 1 as an injection current with a triangular wave drive current which is repeatedly increased or decreased with respect to time. Thereby, the semiconductor laser 1 is driven to alternately repeat the first and second oscillation periods, and the wavelength of the first oscillation period is proportional to the magnitude of the injection current and is continuously increased at a constant rate of change. The oscillation wavelength is continuously reduced by a constant rate of change. FIG. 2 is a timing chart showing the oscillation wavelength of the semiconductor laser 1. In Fig. 2, t-Ι represents the (t-Ι)th oscillation period; the tth oscillation period; t+Ι represents the (t+1)th oscillation period; Output 5; the number of waves is determined by the number of waves, the DFB rate of change to the semi-inductive period is oscillating, and the change is t. t + 2 Table -15- 200914799 shows (t+2 ) an oscillation period; t+3 represents the (t+3)th oscillation period; t + 4 represents the (t + 4)th oscillation period; λ a represents the minimum oscillation wavelength of each period of τκ; λ b Indicates the maximum 値 of the oscillation wavelength in each period; T represents the period of the triangular wave. In the present embodiment, the maximum 値λ b of the oscillation wavelength and the minimum 値λ a of the oscillation wavelength are always constant, and the difference 値Xb-ka is also constant. The laser light emitted from the semiconductor laser 1 is condensed by the lens 3 and incident on the measurement object 12. The light reflected by the measuring object 12 is condensed by the lens 3 and incident on the semiconductor laser 1. Among them, the condensing of the lens 3 is not essential. The photodiode 2 converts the light output of the semiconductor laser 1 into a current. The current-voltage conversion amplifier 5 converts the output current of the photodiode 2 into a voltage and amplifies it. The filter circuit 11 has a function of extracting overlapping signals from the modulated waves. Fig. 3(A) shows the output voltage waveform diagram of the current-voltage conversion amplifier 5 in a mode, and Fig. 3(B) shows the output voltage waveform diagram of the mode display filter circuit 1 in a mode. These figures show the waveform (modulated wave) of Fig. 3 (A) corresponding to the output of the photodiode 2, and the oscillation waveform (carrier) of the semiconductor laser 1 of Fig. 2 is removed to extract the third. Figure (B) shows the process of the Η P waveform (overlapping wave). The counting device 8 is the number of 包含 included in the output voltage of the filter circuit η, and the first oscillation period t-1, t+1, t + 3 and the second oscillation period t, t + 2, t + 4 Counting is performed for each period. Fig. 4 is a block diagram showing an example of the configuration of the counting device 8. The counting device 8 is composed of a determination unit 81, a logical AND operation unit (and) 82, a counter 83, a counter knot -16-200914799, a correction unit 84, and a storage unit 85. The current-voltage conversion amplifier 5, the filter circuit 1 and the determination units 8 1 and A N D 8 2 of the counter device 8 and the counter 8 3 constitute a counting means. Fig. 5 is a block diagram showing an example of the configuration of the count result correcting unit 84. The count result correcting unit 84 is composed of a period measuring unit 840, a frequency distribution creating unit 841, a representative unit calculating unit 842, and a correction unit calculating unit 843. 6(A) to 6(F) are diagrams for explaining the operation of the counting device 8, and Fig. 6(A) shows the waveform of the output voltage of the filter circuit 11 in a mode, that is, the waveform of the MHP. 6(B) is a diagram showing the output of the determination unit 81 corresponding to FIG. 6(A), and FIG. 6(C) is a diagram showing the gate signal GS input to the counting device 8. Fig. 6(D) shows a graph of the count result of the counter 8 3 corresponding to Fig. 6(B), and Fig. 6(E) shows a graph of the clock signal CLK input to the counter device 8. Fig. 6(F) is a view showing the measurement results of the period measuring unit 840 corresponding to Fig. 6(B). First, the determination unit 8 1 of the counting device 8 determines that the output voltage of the filter circuit 11 shown in Fig. 6(A) is at a high level (H) or a low level (L) 'output as shown in Fig. 6(B). The judgment result shown. At this time, the determination unit 81 determines that the output voltage of the filter circuit 11 is high when the output voltage of the filter circuit 11 rises above the threshold 値 TH1; the output voltage of the filter circuit 11 falls to the threshold 値 TH2 (TH2) When <TH1) is below, it is determined to be a low level, whereby the output of the filter 11 is binarized. The result of the logical AND operation of the output of the AN D 8 2 output determination unit 8 1 and the gate signal GS of -17-200914799 shown in Fig. 6 (C), the counter 83 counts the rise of the output of the AND 82 (the 6 (d)). Here, the gate signal G S is a signal that rises at the start of the counting period (in the present embodiment, the first oscillation period or the second oscillation period), and falls at the end of the counting period. Therefore, the counter 83 counts the number of rising edges of the output of the AND 82 in the counting period (i.e., the number of rising edges of the MHP). On the other hand, the period measuring unit 84 of the counting result correcting unit 84 measures the period of the rising edge of the output of the AND 82 (i.e., the period of the MHP) every time the rising edge occurs. At this time, the period measuring unit 840 measures the period of the MHP by using the period of the clock signal CLK shown in Fig. 6(E) as one unit. In the example of Fig. 6(F), the period measuring unit 84 sequentially measures τ α and τ as the period of the MHP. As can be seen from Fig. 6(E) and Fig. 6(F), the periods Τα, T 〃 and T are 5 clocks, 4 clocks, and 2 clocks, respectively. The frequency of the clock signal CLK is much greater than the highest frequency that can be achieved. The memory unit 805 is the result of counting the memory counter 8.3 and the measurement result of the period measuring unit 840. After the gate signal GS is lowered and the counting period is completed, the frequency distribution creating unit 804 of the counting result correcting unit 84 is based on the measurement result stored in the memory unit 85, and the frequency distribution of the period in the period of the counting period is set. . Next, the representative result calculation unit 8 4 of the count result correcting unit 8 4 is rooted -18- 200914799. The median of the period of the MHP is calculated based on the frequency distribution made by the frequency distribution creating unit 8 4 1 (median) The correction/calculation unit 804 of the result correcting unit 8 4 obtains the frequency sum N s of the level which is equal to or less than 0.5 times the period median T 根据 based on the frequency distribution 'made by the frequency distribution creating unit 841 1 ', and The frequency sum N w ' of the level of the cycle median T0 of 1 · 5 times or more is corrected as follows by the counter 8 3 . (2) N ′ = N + N w-N s In the equation (2), N is the number of MHPs which are counted as the counter 83, and N' is the count result after correction. An example of the frequency distribution is shown in Fig. 7. In Fig. 7, the level 値 of the Ts period is 0.5 times the median T0, and the level of the Tw period is 1.5 times the median T0. Of course, the level in Figure 7 is representative of the period of the MHP. Here, in Fig. 7, in order to simplify the description, the frequency distribution between the median T 0 and T S and the median T 0 and T w in the figure is omitted. Fig. 8 is a diagram for explaining the principle of correction of the count result of the counter 83. Fig. 8(A) is a diagram showing the waveform of the output voltage of the filter circuit 11 in the mode, that is, the waveform of Μ Η P, 8th. Fig. (B) is a diagram showing the count result of the counter 83 corresponding to Fig. 8 (Α). The period of the original 而 varies depending on the distance from the measurement target 12, but if the distance from the measurement target 12 is constant, the μ Η 出现 appears in the same cycle -19-200914799. However, due to noise, there is a gap in the MHP waveform or a waveform that does not count as a signal, and an error occurs in the number of MHPs. When a signal leak occurs, the period Tw of the helium HP at the portion where the leak has occurred is about twice as large as the original period. That is, when the period of the MHP is about twice the median, it is judged that a defect has occurred in the signal. Therefore, the frequency sum Nw of the level above the period Tw is regarded as the number of times the signal is missing, and the Nw is added to the count result N of the counter 8 3, whereby the missing signal can be corrected. Further, the period T s of the MHP at the portion where the noise is counted is approximately 〇·5 times the original period. That is, when the period of the MHP is about 5. 5 times or less of the median, the excess count signal can be judged. Therefore, the frequency total value Ns of the level below the period Ts is regarded as the number of times of the excess count signal, and the Ns is subtracted from the count result N of the counter 83, whereby the erroneous noise can be corrected. The above is the correction principle of the counting result shown in the formula (2). In the present embodiment, Ts is set to 0. 5 times the period median T0, and Tw is set to 1 _ 5 times the median T0 instead of twice the median T0. , set the reason for 1.5 times to make a statement. The correction correction calculation unit 843 outputs the corrected post-count result Ν' calculated by the equation (2) to the arithmetic unit 9. The counting means 8 performs the processing as described above for each of the first oscillation periods t-1, t+1, t + 3 and each of the second oscillation periods t, t + 2, t + 4. Next, the arithmetic unit 9 obtains the distance from the measurement target 12 based on the number N ’ of -20-200914799 Μ Η P measured by the counting device 8. The number of Μ Η P in a certain period is proportional to the measured distance. Therefore, the relationship between the number of Μ Ρ and the distance in the predetermined counting period (the first oscillation period or the second vibration period in the present embodiment) is determined in advance and registered in the database of the arithmetic unit 9 in advance (not As shown in the figure, the arithmetic unit 9 can obtain the distance from the measurement target 12 by obtaining the number of μ Η 测量 measured by the counting device 8 from the database. Alternatively, a mathematical expression indicating the relationship between the number of enthalpies in the counting period and the distance is obtained in advance, and the arithmetic unit 9 presets the number ΜΗΡ of the enthalpy measured by the counting device 8 into a mathematical expression. The distance from the measurement object 12 is calculated. The arithmetic unit 9 performs the processing as described above for each of the first oscillation periods t-1 and t+1 't + 3 and for each of the second oscillation periods t, t + 2, and t + 4. The display device 10 displays the distance (displacement) from the measurement target 12 calculated by the arithmetic unit 9 in real time. As described above, in the present embodiment, the period of the MHP in the counting period is measured, the frequency distribution of the period of the MHP in the counting period is calculated based on the measurement result, and the median of the period of the MHP is calculated based on the frequency distribution. Distribution, which is obtained as the sum of the frequencies of the median 〇·5 times or less, and the sum of the frequencies of the ranks of the median of 1.5 times or more, N w 'based on the frequencies N s and N w By correcting the count result of the counter 'by this, the count error of the MHP can be corrected, so that the measurement accuracy of the distance can be improved. The counting device 8 and the computing device 9 in the present embodiment can be realized by, for example, a computer having a CPU, a memory device, an interface, and a program for controlling the hardware resources. The program for operating the computer as described above is provided in a state of being recorded on a recording medium such as a flexible disk, a CD-ROM, a DVD-ROM, or a memory card. The CPU writes the read program to the memory device, and executes the processing described in the embodiment in accordance with the program. Next, the reason why the median of the frequency distribution of the period is used as the reference period of ΜHP and the threshold 周期 of the period when the frequency Nw is obtained is set to 1.5 times the median. First, the correction of the counting result in the case where the period of the MHP is divided into two due to the erroneous noise is explained. When the oscillation wavelength of the semiconductor laser changes linearly, the period T of the MHP is a normal distribution centering on the T0 obtained by dividing the measurement period Tc by the number N of MHPs (Fig. 9). Next, consider the period of Μ Η P divided into 2 by noise. The period of the ΜΗΡ which is divided into two by the result of the excess count noise is divided into two at a random ratio, but the period before the division is a normal distribution centered on Τ0, and thus becomes a frequency distribution symmetric with respect to 0.5T0 (the first Figure 10 a). For the frequency distribution of the period of the MHP containing the noise, assuming that η % of Μ Η P divides the period into 2 due to noise, the average 値 and median of the period of Μ Η P are calculated. The period T c of all periods and 1 denier is not changed, but when η % of Μ Ρ 分割 divides the period into 2 due to noise, the integral of frequency 値-22- 200914799 becomes (1 + n [%]) N, so the average 値 of the period of MHP becomes (1 / (1 + η [%])) TO. On the other hand, when the portion overlapping with the normal distribution is ignored by the distribution of the noise, the noise accumulation frequency divided into 2 becomes twice the frequency included in the level between the median and T0, and therefore, The median of the period of the MHP is located at a position twice the area of the area a of the b of Fig. 11 . In Excel (registered trademark) belonging to the software of Microsoft Corporation, the internal ratio of the two sides between the average 値 and α σ of the normal distribution is "( 1 - ( 1-NORMSDIST ( a ) ) x2 ) X1 00 The function of NORMSDIST() expressed by [%]", using this function, can represent the median of the period of the MHP as follows. (l-(l-NORMSDIST((median-Τ0)/σ))χ2)χ(100-η)/2=η[%] (3) According to the above, if the standard deviation σ is set For 0.02 Τ 0, the average 値Τ0' and the median Τ0' of the period after dividing the period into 2 by the noise of 10% of ΜΗΡ are calculated as shown below. TO7 = (1/(1 + 0.1 )) T0 = 0.91 TO ... (4) TO' = 0.995 T0 · (5) where, the average 値 and median are expressed by TO'. The counter 値 (integral 频率 of the frequency) becomes 1.1 N, and the count error becomes 10%. -23- 200914799 Here, the probability of a period that can be acquired in two cycles Τ1 and τ2 (set to ΤΘΤ2) after a certain period of time is divided into two is considered. Assume that the noise is randomly generated, as shown in Figure 12. The Τ2 system can be obtained with the same probability. < τ 2 s T a / 2 値. Similarly, Τ 1 can also obtain Τ / 2 $ Τ 1 with the same probability. <T a 値. The area of the probability distribution of Τ 1 in Fig. 1 and the probability distribution of Ϊ2 are both 1 °. The period Ta is a normal distribution centered on Τ0. Therefore, if Ta is regarded as a set Then, the frequency distribution of the probability that T2 can obtain is formed into the same shape as the cumulative frequency distribution of the normal distribution having an average 値 of 0.5 T0 and a standard deviation of 〇.5 σ. In addition, the frequency distribution of the probability that Τ1 can be obtained as shown in Fig. 1 is formed as a cumulative frequency distribution and average 将 of a normal distribution with an average 値 of 0 · 5 Τ 0 and a standard deviation of 0 · 5 σ. The shape in which the cumulative frequency distribution of the suspension state of τ〇 and the standard deviation is σ overlaps. Here, the respective numbers of τ 1 and τ 2 are equal to the number η [ % ] Ν of the Μ Η 周期 whose period is divided into two. If the number η [%]· Ν of the ΜΗΡ whose period is divided into 2 by the noise is counted, the following equation can be used to derive the Ν quantity Ν. N = Ν5 - η [ % ] * Ν (6) As shown in Fig. 14, if the number of ΜΗΡ -24- 200914799 having a period of Tb or less and the number of MHPs divided into 2 η [%] can be made Ν Ν 相等 相等 相等 相等 , 相等 相等 设定 设定 设定 设定 设定 相等 相等 相等 相等 相等 相等 相等 相等 相等 相等 相等 相等 相等 T T T T T T T T T T T T T T T T T T T T T T T T T T count. In Fig. 14, when the frequency of the period Τ2 of ΜΗΡ having a period of Tb or more (c of Fig. 14) is the same as the frequency of the period T1 of ΜΗΡ having a period of not reaching Tb (d of the μ map) The number of MHPs having a period of Tb or less is equal to the number of T2, that is, the number Ns (=n[%].N) of the MHP whose period is divided into two. That is, the number N of 'MHPs' can be expressed by the following equation. N = N5 - η [ % ] · Ν = Ν, - Ns (7) The frequency shape of T 1 and T2 is in the shape of 〇. 5 T a is symmetrical. Therefore, when 0.5Ta is used as a threshold, it can be judged. The frequency Ns (= η [ % ]. Ν ) of the MHP whose period is divided into 2 is correctly counted. Then, by counting the number of MHPs having a period of 0.5 TO or less, the number of η [%]· M of the MHP whose period is divided into 2 can be indirectly counted, but the noise cannot be included. The frequency distribution of the chirp period (Fig. 1) is used to calculate Τ0. If the MHP female population is as shown in the frequency distribution in Fig. 10, the more the mode is equal to T0, the more ideal and the larger the population parameter is, the more the population can be used as TO'. Here, the count of the number of MHPs obtained using the average 値 or the median T0' -25 - 200914799 η [ %]· Ν is described. When T0, =y · ΤΟ is substituted, τ 代 is substituted, and ΤΟ is used instead of ΤΟ to obtain Ns. The frequency Ns ′ of 0.5 Τ 0′ which is determined by dividing the number of cycles into 2 is a small frequency Ns′ [%]. N (Fig. 1 5). If the average 値 or median T0' is used, the corrected 値Nt is shown below.
Nt = N，- Ns，=(1 + η〔 ％〕）N - yn〔 ％〕N =(1 + (1 - y)η〔 ％〕）N = N + (1 - y)η〔 ％〕N ...(8) 其中，作爲補正後誤差的（1 -y ) n〔％〕N係第1 6圖的e 的部分的頻率。 在此，就使用平均値或中位數το’的計數器83的計數 結果的補正例進行說明。 若將標準偏差設爲（7=0.021'0，且]^11?的10%因雜訊 而使周期分割爲2時（計數結果爲10%的誤差），由於 MHP的周期的平均値 T0’爲 0.91T0，中位數 T0,爲 0.9949T0，因此使用平均値T0’時的y爲〇·91，使用中位 數丁0’的y爲0.9949，補正後的計數結果Ν’係如以下所示 予以計算。 N，=(1 + 0.1(1 - 0_91))N = 1.009Ν ·· (9) Ν’ =( 1 + 〇· 1 (1 - 0_995))N = 1 .0005 Ν ".(10) -26- 200914799 數式（9)係表示使用平均値το’時的補正後的rf*數結 果N，，數式（10 )係表示使用中位數το’時的補正後的計 數結果N，。使用平均値T 0 ’時的計數結果N ’的誤差爲 0.9%，使用中位數T0’時的計數結果Ν’的誤差爲0.05%。 接著，若將標準偏差設爲σ =〇.〇5 Τ0 ’且ΜΗΡ的20% 因雜訊而使周期分割爲2時（計數結果爲20%的誤差）’ 由於MHP的周期的平均値T0’爲0.83T0，中位數T0’爲 0.9682T0，因此使用平均値T0’時的y爲〇.83’使用中位 數T 0 ’的y爲〇 _ 9 6 8，補正後的計數結果N ’係如以下所示 予以計算。 N5 =(1 + 0.2(1 - 0.83))N = 1.034N ···(") N，=( 1 + 0.2( 1 - 0.96 8))N = 1.0064N ··· (1 2) 數式（1 1 )係表示使用平均値το ’時的補正後的計數 結果N’，數式（12)係表示使用中位數T0’時的補正後的 計數結果Ν’。使用平均値T0’時的計數結果Ν’的誤差爲 3.4%，使用中位數Τ0’時的計數結果Ν’的誤差爲0.64%。 由以上可知，若使用ΜΗΡ的周期的中位數來補正計 數結果Ν，可減小補正後的計數結果Ν ’的誤差。 接著說明在ΜΗΡ波形產生缺漏時的計數結果的補 正。由於ΜΗΡ的強度較小而在計數時產生缺漏時之ΜΗΡ 的周期係由於原本的ΜΗΡ的周期係以Τ0爲中心的常態分 佈，因此成爲平均値爲2T0，標準偏差2 σ的常態分佈 -27- 200914799 (第17圖中的f)。假設缺漏m〔 ％〕的ΜΗΡ，因該缺漏 而成爲 2倍的 ΜΗΡ的周期的頻率爲Nw ( =m〔 ％〕 · N )。此外，因計數時的的缺漏而減少後之大約T 0之周期 的頻率爲第1 7圖所示的g，第1 7圖的h所示的頻率減小 份爲2Nw ( =2m〔 ％〕）。因此，在計數時沒有發生ΜΗΡ 缺漏時之原本ΜΗΡ的數量Ν’係可以下式表示。 Ν5 = N + m [ % ] =N + Nw ".(13) 接著，考慮在對用以補正計數結果的Nw進行計數時 之周期的臨限値。在此，假設爲因計數時的缺漏而使周期 成爲2倍的MHP的周期的頻率Nw中因雜訊而分割爲2的 情形。缺漏的Μ Η P中被分割爲2的Μ Η P的周期的頻率爲 N w ’（ = m · ρ〔 ％〕 · N )。再次分割爲2的Μ Η P的周期 的頻率分佈係如第1 8圖所示。當將視爲N w的周期的臨 限値設爲1 ·5Τ0時，周期爲0.5 Τ0以下之ΜΗΡ的周期的頻 率爲 0.5Nw，（=0.5p〔％〕 · Nw )，周期爲 0.5T0 至 1.5T0之MHP的周期的頻率爲Nw，（=p〔％〕.Nw)， 周期爲1.5T0以上之MHP的周期的頻率爲〇.5Nw，（ = 0 · 5 ρ〔 ％〕· Nw )。 因此，所有MHP的周期的頻率分佈成爲如第丨9圖所 示，若將Ns的臨限値設爲0.5T0，將Nw的臨限値設爲 1.5T0，計數結果N係可以下式表示。 -28 - 200914799 N = (N ’ - 2 N w) + (N w - N w，）+ 2 N w，= N，_ N w + N w， ··· ( 14 ) 由數式（1 4 )予以補正的結果如以下所示，可知計算 出計數時未發生MHP之缺漏之情形下之原本的MHP的數 量N，。 N - 0.5Nw’ +(0.5Nw’ +(Nw - Nw，）） =(N - Nw + Nw’）+ (0_5Nw，+(Nw - Nw，））Nt = N, - Ns, = (1 + η [ %]) N - yn [ % ] N = (1 + (1 - y) η [ %]) N = N + (1 - y) η [ %] N (8) where (1 - y ) n [%] N is the frequency of the portion of e in the sixth graph. Here, a description will be given of a correction example of the count result of the counter 83 using the average 値 or the median το'. If the standard deviation is set to (7=0.021'0, and ]11% of 10% due to noise, the period is divided into 2 (counting result is 10% error), due to the average 値T0' of the period of MHP It is 0.91T0, the median T0 is 0.9949T0, so the y when using the average 値T0' is 〇·91, and the y using the median □0' is 0.9949, and the result of the correction is as follows. The calculation is given. N,=(1 + 0.1(1 - 0_91))N = 1.009Ν ·· (9) Ν' =( 1 + 〇· 1 (1 - 0_995))N = 1.0005 Ν ". (10) -26- 200914799 Equation (9) indicates the result of the corrected rf* number N when the average 値το' is used, and the equation (10) indicates the corrected count when the median το' is used. The result is N. The error of the count result N' when using the average 値T 0 ' is 0.9%, and the error of the count result Ν ' when the median T0' is used is 0.05%. Next, if the standard deviation is set to σ = 〇.〇5 Τ0 'and 20% of ΜΗΡ is divided into 2 due to noise (counting result is 20% error)' Since the average 値T0' of the MHP period is 0.83T0, the median T0' is 0.9682T0, so use the average 値T The y at 0' is 〇.83' The y using the median T 0 ' is 〇 _ 9 6 8. The result of the correction after N ' is calculated as shown below. N5 = (1 + 0.2 (1 - 0.83))N = 1.034N ···(") N,=( 1 + 0.2( 1 - 0.96 8))N = 1.0064N ··· (1 2) The expression (1 1 ) indicates the average 値Το 'The count result after correction is N', and the formula (12) indicates the result of the correction after the median T0' is used. The error of the count result Ν' when using the average 値T0' is 3.4. %, the error of the count result Ν' when using the median Τ0' is 0.64%. From the above, if the median period of the ΜΗΡ period is used to correct the count result Ν, the count result after correction can be reduced Ν ' Next, the correction of the counting result when the ΜΗΡ waveform is missing is explained. The period of ΜΗΡ when the ΜΗΡ is weak and the 缺 is missing at the time of counting is because the original ΜΗΡ period is a normal distribution centered on Τ0. The normal distribution is 2T0, the standard deviation 2 σ is normal distribution -27- 200914799 (f in Figure 17). Suppose the missing m [%] Ρ, the frequency of the period of the ΜΗΡ which is doubled due to the omission is Nw (=m[%]·N). Further, the frequency of the period of about T 0 which is reduced by the leak at the time of counting is the first 7 g shown in the figure, the frequency-reduced portion shown by h in Fig. 7 is 2Nw (= 2m [%]). Therefore, the number of original flaws when no defects occur at the time of counting can be expressed by the following formula. Ν5 = N + m [ % ] = N + Nw " (13) Next, consider the threshold 周期 of the period when Nw for counting the count result is counted. Here, it is assumed that the frequency Nw of the period of the MHP in which the period is doubled due to the omission at the time of counting is divided into two by noise. The frequency of the period of Μ Η P divided into 2 in the missing Μ Η P is N w '( = m · ρ[ %] · N ). The frequency distribution of the period of Μ Η P divided again into 2 is as shown in Fig. 18. When the threshold 周期 of the period regarded as N w is set to 1 · 5 Τ 0, the frequency of the period of the period of 0.5 Τ 0 or less is 0.5 Nw, (= 0.5p [%] · Nw ), and the period is 0.5T0 to The frequency of the period of the MHP of 1.5T0 is Nw, (=p[%].Nw), and the frequency of the period of the MHP with a period of 1.5T0 or more is 〇.5Nw, (= 0 · 5 ρ [ %] · Nw ). Therefore, the frequency distribution of all MHP periods is as shown in Fig. 9. If the threshold N of Ns is set to 0.5T0, the threshold N of Nw is set to 1.5T0, and the count result N can be expressed by the following equation. -28 - 200914799 N = (N ' - 2 N w) + (N w - N w,) + 2 N w,= N,_ N w + N w, ··· ( 14 ) From the formula (1 4 The result of the correction is as follows. It can be seen that the number N of the original MHPs in the case where the missing MHP did not occur at the time of counting was calculated. N - 0.5Nw' + (0.5Nw' + (Nw - Nw,)) = (N - Nw + Nw') + (0_5Nw, +(Nw - Nw,))
=N …（15) 由以上可知，若將求取頻率Nw之周期的臨限値設爲 中位數的1 · 5倍’即可補正g十數結果n。其中，與因雜訊 而將MHP的周期分割爲2的情形相同地，由於取代το而 使用中位數來進行補正，因此發生同樣的誤差。 在以上說明中’係分別說明過剩計數雜訊的結果使 MHP的周期分割爲2的情形、及因計數時的缺漏而使 MHP的周期成爲2倍的情形，惟該等情形獨立發生，因此 若將該等情形表現爲1個頻率分佈，即如第2 0圖所示。 若將Ns的臨限値設爲〇.5 το，將Nw的臨限値設爲 1 · 5 T 0，計數結果N即可以下式表示。 …（1 6) N =(N’ - 2Nw - Ns) + (Nw - Nw，）+ 2Nw，+ 2Ns =N’ — Nw + Nw，+ Ns -29- 200914799 由數式（1 6 )予以補正的結果如以下所示’可 出計數時未發生缺漏或過剩計數之情形下之原# E 的數量N ’ ° N - {〇.5Nw’ + Ns} + {0.5Nw’ +(Nw - Nw’）} ={N - Nw + Nw’ + Ns} · {0.5Nw’ + Ns} + {0.5Nw’ +(Nw - Nw’）} =N， (第2實施形態） 接著說明本發明之第2實施形態。在第1實 中，係使用中位數作爲MHP的周期的代表値來補 結果，但是亦可使用眾數作爲周期的代表値。 例如因低頻之雜訊成分的影響，使得MHP的 頻率分佈由第21圖所示之原本的分佈j偏移而變 21圖之分佈k所示時，MHP周期的中位數亦由原 T0偏移成爲Td。若在如上所示之情形下使用中位I 補正計數結果，補正後的計數結果的誤差會變大。 因此，若考慮到如上所示因雜訊成分所造成的 佈偏移的影響時，係使用眾數作爲周期的代表値。 言，計數結果補正部8 4的代表値計算部8 4 2若根 分佈作成部84 1所作成的頻率分佈，來計算MHP 的眾數即可。計數結果補正部84的補正値計算部 使用眾數來取代中位數T0，進行與第1實施形態=N (15) From the above, it can be seen that the g-th order result n can be corrected by setting the threshold 周期 of the period of the obtained frequency Nw to 1·5 times the median. However, similarly to the case where the period of the MHP is divided into two due to noise, the median is used instead of τ, and the same error occurs. In the above description, the case where the result of the excess count noise is described is that the period of the MHP is divided into two, and the period of the MHP is doubled due to the omission at the time of counting, but these cases occur independently. These cases are expressed as one frequency distribution, as shown in Fig. 20. If the threshold of Ns is set to 〇.5 το, the threshold of Nw is set to 1 · 5 T 0, and the result of counting N can be expressed by the following formula. ...(1 6) N =(N' - 2Nw - Ns) + (Nw - Nw,)+ 2Nw, + 2Ns =N' — Nw + Nw,+ Ns -29- 200914799 Corrected by the formula (1 6 ) The result is as follows: 'The number of original # E in the case where no missing or excessive count occurs when counting. N ' ° N - {〇.5Nw' + Ns} + {0.5Nw' +(Nw - Nw' )}={N - Nw + Nw' + Ns} · {0.5Nw' + Ns} + {0.5Nw' + (Nw - Nw')} = N, (Second Embodiment) Next, the second aspect of the present invention will be described. Implementation form. In the first example, the median is used as a representative of the period of the MHP to compensate for the result, but the mode can also be used as the representative of the period. For example, due to the influence of the low-frequency noise component, the frequency distribution of the MHP is shifted from the original distribution j shown in FIG. 21 to the distribution k of the figure 21, and the median of the MHP period is also offset from the original T0. Move to Td. If the median I is used to correct the count result in the above situation, the error of the count result after correction becomes large. Therefore, when considering the influence of the cloth offset caused by the noise component as described above, the mode is used as the representative of the period. In other words, the representative of the count result correcting unit 804, the calculation unit 804 calculates the frequency distribution of the MHP, and calculates the mode of the MHP. The correction 値 calculation unit of the count result correcting unit 84 uses the mode instead of the median T0 to perform the first embodiment.
知計算 g MHP 17 ) 施形態 正計數 周期的 成如第 本的値 (Td來 頻率分 具體而 據頻率 的周期 843若 相同的 -30- 200914799 處理即可。 此外，如使用數式（8 )至數式（1 2 )加以說明所 示’與使用中位數T 0的情形相比較，補正後的計數結果 的誤差會變大，但是亦可使用平均値來作爲周期的代表 値。此時，代表値計算部8 4 2若計算Μ Η P的周期的平均 値即可。 其中’在第1、第2實施形態中係就本發明的計數裝 置適用於距離計的情形加以說明，惟並非侷限於此，本發 明之計數裝置亦可適用於其他領域。本發明的計數裝置爲 有效時，作爲計數對象的訊號數量係與特定的物理量（在 第1、第2實施形態中爲距離）具有線性關係，若該物理 量爲一定時，訊號即成爲大致單一頻率。 此外，即使訊號非爲單一頻率，如同與計數期間相比 較，作爲計數對象的特定的物理量以十分低的頻率，例如 1 / 1 0以下的頻率振動的對象物的速度所示周期分佈的擴 展爲較小時’亦可作爲大致單一頻率，本發明的計數裝置 即爲有效。 此外，在第1、第2實施形態中，係針對ΜΗΡ的缺漏 的補正，藉由1個缺漏，使ΜΗΡ的周期成爲原本周期大 約2倍的情形加以說明’但是在連續發生2個以上之缺漏 的情形亦適用本發明。Μ HP連續缺漏2個時，係視爲中位 數的3倍的周期的MHP係3個MHP成爲1個者。此時， 求取爲周期的中位數的大約3倍以上之等級的頻率，若該 頻率設爲2倍’即可補正MHP的缺漏。若將如上所示的 -31 - 200914799 思考方式一般化’即可使用下式來取代數式（2 ) N，= N + N w 1 + N w2 + N w3 + …-Ns ... (18)Knowing the calculation of g MHP 17) The form of the positive counting period is as the first 値 (Td is frequency specific and according to the frequency period 843, the same -30-200914799 can be processed. In addition, if using the formula (8) As shown in the equation (1 2 ), the error of the count result after correction becomes larger than the case where the median T 0 is used, but the average 値 can also be used as the representative of the period 値. The representative 値 calculation unit 804 calculates the average 値 of the period of Μ Η P. In the first and second embodiments, the case where the counting device of the present invention is applied to the distance meter is described, but In addition, the counting device of the present invention is also applicable to other fields. When the counting device of the present invention is effective, the number of signals to be counted has a specific physical quantity (distance in the first and second embodiments). A linear relationship, if the physical quantity is constant, the signal becomes a substantially single frequency. Further, even if the signal is not a single frequency, as compared with the counting period, the specific physical quantity as the counting object is At a very low frequency, for example, when the velocity of the object vibrating at a frequency of 1 / 10 or less is small, the expansion of the periodic distribution is small, and the counting device of the present invention can be used as a substantially single frequency. 1. In the second embodiment, the correction of the defect of the flaw is described by the fact that the period of the flaw is approximately twice as large as the original period by one leak, but the case where two or more leaks occur continuously is also applicable. According to the present invention, when two consecutive HP defects are present, three MHPs of the MHP system having a period of three times the median are one. In this case, the median of the cycle is approximately three times or more. The frequency of the level, if the frequency is set to 2 times, can correct the missing of the MHP. If the above-mentioned -31 - 200914799 thinking mode is generalized, you can use the following formula to replace the formula (2) N, = N + N w 1 + N w2 + N w3 + ...-Ns ... (18)
Nw 1係爲周期之中位數之1 · 5倍以上之等級的頻率總 和，Nw2係爲周期之中位數之2 · 5倍以上之等級的頻率總 和，Nw 3係爲周期之中位數之大約3.5倍以上之等級的頻 率總和。 其中，在將第1、第2實施形態應用於除了自耦合型 之外的距離計時，係將以測定對象1 2所反射的半導體雷 射1的光，藉由例如分束器（beam splitter )等與入射至 測定對象12的入射光分離，而以光電二極體2予以檢 測。如此一來，在自耦合型以外的距離計中，亦可獲得與 第1、第2實施形態相同的效果。 (第3實施形態） 在第1、第2實施形態中，從作爲受光器的光電二極 體的輸出訊號中抽取MHP波形，但是亦可在不使用光電 二極體的情形下抽取MHP波形。第22圖係顯示作爲本發 明之第3實施例之距離計之構成的方塊圖，關於與第！圖 相同的構成係標註相同的元件符號。本實施形態的距離計 係使用電壓檢測電路1 3來代替第1實施形態之光電二極 體2和電流-電壓轉換放大器5。 電壓檢測電路1 3係檢測並放大半導體雷射1的端子 -32- 200914799 間的電壓’亦即陽極_陰極間電壓。因由半導體雷射1所 發射的雷射光與來自測定對象12的返回光而產生干涉 時，在半導體雷射1的端子間電壓係呈現Μ Η P波形。因 此，可由半導體雷射1的端子間電壓抽出ΜΗΡ波形。 與第1實施形態相同地’濾波器電路1 1係具有由調 變波抽出重疊訊號的功能’由電壓檢測電路13的輸出電 壓抽出Μ Η Ρ波形。 半導體雷射1、雷射驅動器4、計數裝置8、運算裝置 9及顯示裝置1 〇的動作係與第1實施形態相同。 如此一來，在本實施形態中’係可在不使用光電二極 體的情形下抽出Μ Η Ρ波形，與第1實施形態相比’可刪 減距離計的零件，並可減少距離計的成本。 其中，在第1、第2實施形態的情形下’不僅自耦合 型，亦可適用於自耦合型以外的距離計’而本實施形態之 適用對象僅爲自耦合型。 (產業上利用可能性） 本發明係可適用於對於訊號數量進行計數的計數裝 置、使用計數裝置來測定干涉波形的數量而求取與測定對 象之距離的平涉型距離計。 【圖式簡單說明】 第1圖係顯示作爲本發明第1實施形態之距離計之構 成的方塊圖。 -33- 200914799 第2圖係顯示本發明第丨實施形態中之半導體雷射的 振盪波長的時間變化的一例圖。 第3圖係以模式顯示本發明第丨實施形態之電流-電 壓轉換放大器的輸出電壓波形及濾波器電路的輸出電壓波 形的圖。 第4圖係顯示本發明第1實施形態中之計數裝置之構 成之一例的方塊圖。 第5圖係顯示第4圖的計數裝置中之計數結果補正部 之構成之一例的方塊圖。 第6圖係用以說明第4圖之計數裝置的動作圖。 第7圖係顯示本發明第1實施形態中之周期之頻率分 佈之一例圖。 第8圖係用以說明本發明第1實施形態中之計數器之 計數結果之補正原理的說明圖。 第9圖係顯示模式跳躍脈衝之周期的頻率分佈圖。 第1 〇圖係顯示包含雜訊的模式跳躍脈衝之周期的頻 率分佈圖。 第u圖係顯示包含雜訊的模式跳躍脈衝之周期之中 位數的圖。 第1 2圖係顯示周期經分割爲2之模式跳躍脈衝之周 期的頻率分佈圖。 第1 3圖係顯示周期經分割爲2之模式跳躍脈衝之周 期的頻率分佈圖。 第1 4圖係顯示周期經分割爲2之模式跳躍脈衝之周 -34- 200914799 期的頻率分佈圖。 第1 5圖係顯示周期經分割爲2之模式跳躍脈衝之周 期的頻率分佈圖。 第1 6圖係顯示計數器値補正後的誤差的圖。 第1 7圖係顯示形成爲2倍之周期的模式跳躍脈衝的 周期的頻率分佈圖。 第1 8圖係顯示在計數時所缺漏的模式跳躍脈衝中經 分割爲2之模式跳躍脈衝之周期的頻率分佈圖。 第1 9圖係顯示在計數時所缺漏的模式跳躍脈衝中經 分割爲2之模式跳躍脈衝之周期的頻率分佈圖。 第20圖係顯示在計數時同時發生缺漏與過剩計數時 之模式跳躍脈衝之周期的頻率分佈圖。 第2 1圖係用以說明本發明第1實施形態中在補正後 的計數結果發生誤差之例圖。 第2 2圖係顯示作爲本發明第3實施形態之距離計之 構成的方塊圖。 第2 3圖係顯示習知之雷射測量器中之半導體雷射之 複合共振模型圖。 第24圖係顯示半導體雷射的振盪波長與內建光電二 極體的輸出波形的關係圖。 【主要元件符號說明】 1 :半導體雷射 2 :光電二極體 -35- 200914799 3 :透鏡 4 :雷射驅動器 5 :電流-電壓轉換放大器 8 :計數裝置 9 :運算裝置 1 〇 :顯示裝置 1 1 :濾波器電路 1 2 :測定對象 1 3 :電壓檢測電路 8 1 :判定部 82 :邏輯與運算部（AND ) 8 3 :計數器 84 :計數結果補正部 8 5 :記憶部 1 0 1 :半導體雷射 102 :半導體結晶的壁開面 1 03 :光電二極體 104 :測定對象 840 :周期測定部 8 4 1 :頻率分佈作成部 8 4 2 :代表値計算部 843 :補正値計算部 -36-Nw 1 is the sum of the frequencies of the level of 1 · 5 times or more of the median period, Nw2 is the sum of the frequencies of the level of 2 · 5 times the median of the period, and Nw 3 is the median of the period The sum of the frequencies of the order of about 3.5 times or more. In the first embodiment, the first and second embodiments are applied to the distance measurement other than the self-coupling type, and the light of the semiconductor laser 1 reflected by the measurement target 12 is used, for example, by a beam splitter. The light is incident on the incident light 12, and is detected by the photodiode 2. As a result, in the distance meter other than the self-coupling type, the same effects as those of the first and second embodiments can be obtained. (Third Embodiment) In the first and second embodiments, the MHP waveform is extracted from the output signal of the photodiode as the photoreceiver, but the MHP waveform can be extracted without using the photodiode. Fig. 22 is a block diagram showing the configuration of a distance meter as a third embodiment of the present invention, relating to the first! The same components are denoted by the same component symbols. In the distance meter of the present embodiment, the voltage detecting circuit 13 is used instead of the photodiode 2 and the current-voltage converting amplifier 5 of the first embodiment. The voltage detecting circuit 13 detects and amplifies the voltage between the terminals -32 - 200914799 of the semiconductor laser 1 ', that is, the anode-cathode voltage. When the laser light emitted from the semiconductor laser 1 and the return light from the measurement target 12 interfere with each other, the voltage between the terminals of the semiconductor laser 1 exhibits a Η P waveform. Therefore, the chirp waveform can be extracted by the voltage between the terminals of the semiconductor laser 1. Similarly to the first embodiment, the filter circuit 11 has a function of extracting the superimposed signal by the modulated wave, and the waveform of the voltage is detected by the output voltage of the voltage detecting circuit 13. The operation of the semiconductor laser 1, the laser driver 4, the counter device 8, the arithmetic unit 9, and the display device 1 is the same as that of the first embodiment. In this way, in the present embodiment, the waveform of the Μ Ρ can be extracted without using the photodiode, and the parts of the distance meter can be deleted as compared with the first embodiment, and the distance meter can be reduced. cost. In the case of the first and second embodiments, it is not only a self-coupling type but also a distance meter other than the self-coupling type, and the application target of the present embodiment is only a self-coupling type. (Industrial Applicability) The present invention is applicable to a counting device that counts the number of signals, and a flat type distance meter that measures the distance from the measuring object by using the counting device to measure the number of interference waveforms. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram showing the configuration of a distance meter according to a first embodiment of the present invention. -33- 200914799 Fig. 2 is a view showing an example of temporal changes in the oscillation wavelength of the semiconductor laser in the embodiment of the present invention. Fig. 3 is a view showing, in a mode, an output voltage waveform of a current-voltage conversion amplifier according to a third embodiment of the present invention and an output voltage waveform of the filter circuit. Fig. 4 is a block diagram showing an example of the configuration of the counting device in the first embodiment of the present invention. Fig. 5 is a block diagram showing an example of a configuration of a counting result correcting unit in the counting device of Fig. 4. Fig. 6 is a view for explaining the operation of the counting device of Fig. 4. Fig. 7 is a view showing an example of the frequency distribution of the period in the first embodiment of the present invention. Fig. 8 is an explanatory view for explaining the principle of correction of the counting result of the counter in the first embodiment of the present invention. Figure 9 is a graph showing the frequency distribution of the period of the mode skip pulse. The first graph shows the frequency distribution of the period of the pattern skip pulse containing noise. Figure u is a graph showing the median period of the pattern skip pulse containing noise. Fig. 12 is a graph showing the frequency distribution of the period of the mode skip pulse divided into two by the period. Fig. 13 shows a frequency distribution diagram of the period of the mode skip pulse divided into two by the period. Figure 14 shows the frequency distribution of the period -34- 200914799 period of the mode skip pulse divided into 2 cycles. Fig. 15 shows a frequency distribution diagram of the period of the mode skip pulse divided into two by the period. Figure 16 shows a plot of the error after the counter 値 is corrected. Fig. 17 is a graph showing the frequency distribution of the period of the mode skip pulse formed in a period of twice the period. Fig. 18 is a frequency distribution diagram showing the period of the mode skip pulse divided into 2 in the mode skip pulse which is missing at the time of counting. Fig. 19 is a frequency distribution diagram showing the period of the mode skip pulse divided into 2 in the mode skip pulse which is missing at the time of counting. Fig. 20 is a graph showing the frequency distribution of the period of the mode skip pulse when both the missing and the excess count occur at the time of counting. Fig. 2 is a view for explaining an example of an error in the counting result after correction in the first embodiment of the present invention. Fig. 2 is a block diagram showing the configuration of a distance meter according to a third embodiment of the present invention. Fig. 2 is a diagram showing a composite resonance model of a semiconductor laser in a conventional laser measuring device. Fig. 24 is a graph showing the relationship between the oscillation wavelength of the semiconductor laser and the output waveform of the built-in photodiode. [Description of main component symbols] 1 : Semiconductor laser 2 : Photodiode - 35 - 200914799 3 : Lens 4 : Laser driver 5 : Current-voltage conversion amplifier 8 : Counting device 9 : Operation device 1 显示 : Display device 1 1 : Filter circuit 1 2 : Measurement target 1 3 : Voltage detection circuit 8 1 : Determination unit 82 : Logic AND operation unit (AND ) 8 3 : Counter 84 : Counting result correction unit 8 5 : Memory unit 1 0 1 : Semiconductor Laser 102 : Wall opening surface of semiconductor crystal 1 03 : Photodiode 104 : Measurement target 840 : Period measuring unit 8 4 1 : Frequency distribution creating unit 8 4 2 : Representative 値 calculating unit 843 : Correcting 値 calculating unit - 36 -