以下之各實施形態係關於人檢測系統，尤其是關於基於來自檢測空間之紅外線之受光強度而檢測檢測空間中有無人存在的人檢測系統。但，以下說明之各實施形態之人檢測系統僅為本發明之一例，本發明並未限定於以下之人檢測系統。因此，除以下之各實施形態以外，只要於未脫離本發明之技術思想之範圍內，即可根據設計等進行多種變更。 (實施形態1) 參照圖2對本實施形態之人檢測系統10進行說明。 人檢測系統10係檢測例如設定於住宅之起居室等之檢測空間90中有無人91存在。人檢測系統10基於來自檢測空間90之紅外線之受光強度之變化，檢測有無人91存在。即，人檢測系統10係根據人91自檢測空間90外朝檢測空間90內移動、或因檢測空間90內之人91之微小動作產生的紅外線之受光強度之變化，而檢測有無人91存在。此處所言之「微小動作」意指例如人91之呼吸動作引起之身體起伏、及扭身等之人91較小的動作。 人檢測系統10係檢測檢測空間90之狀態為有人狀態與無人狀態之何者。此處所言之「有人狀態」意指於檢測空間90內存在人91之狀態。所謂「無人狀態」意指於檢測空間90內不存在人91之狀態。因此，於在檢測空間90不存在人91之狀態下，人檢測系統10之檢測結果成為「無人狀態」。若人91進入檢測空間90，則人檢測系統10之檢測結果自「無人狀態」變化成「有人狀態」。其後，人91滯留於檢測空間90之期間，人檢測系統10之檢測結果維持「有人狀態」。若人91自檢測空間90退出，則人檢測系統10之檢測結果自「有人狀態」變化成「無人狀態」。 於本實施形態中，作為一例，人檢測系統10之檢測結果係輸出至照明控制系統80(參照圖1)。照明控制系統80具備：照明器具81(參照圖1)，其對檢測空間90進行照明；及控制裝置82(參照圖1)，其控制照明器具81。人檢測系統10之檢測結果係輸入至控制裝置82。控制裝置82係若人檢測系統10之檢測結果為「有人狀態」，則使照明器具81亮燈。另一方面，若人檢測系統10之檢測結果為「無人狀態」，則控制裝置82使照明器具81熄燈。控制裝置82亦可為插入至對照明器具81之供電電路而接通/斷開照明器具81之通電的開關。如此，本實施形態之人檢測系統10係用於根據有無人91存在而自動控制照明器具81的照明控制系統80。藉此，人檢測系統10係若人91進入檢測空間90，則可自動地使照明器具81亮燈。又，人檢測系統10係若人91自檢測空間90退出，則自動地使照明器具81熄燈，藉此可抑制因忘記關照明器具81引起之不必要之電力消耗。 (1)構成 如圖1所示，人檢測系統10具備感測器本體1及檢測電路2。 感測器本體1具有第1受光元件111及第2受光元件112。以下，於不特別區分第1受光元件111與第2受光元件112之情形，將第1受光元件111及第2受光元件112之各者稱為「受光元件11」。受光元件11為熱電元件，且輸出與來自檢測空間90之紅外線之受光強度之變化相應的信號(電性信號)。 感測器本體1具有第1轉換電路121、第1放大電路131及第1A/D (Analog/Digital：類比/數位)轉換器141，作為進行自第1受光元件111輸出之電性信號之信號處理之電路。又，感測器本體1具有第2轉換電路122、第2放大電路132及第2A/D轉換器142，作為進行自第2受光元件112輸出之電性信號之信號處理之電路。感測器本體1將第1A/D轉換器141及第2A/D轉換器142之各者之輸出(電性信號)輸出至檢測電路2。 第1轉換電路121將自第1受光元件111輸出之電性信號自電流信號轉換成電壓信號。第1放大電路131係放大自第1轉換電路121輸出之電壓信號。第1A/D轉換器141係將自第1放大電路131輸出之類比信號(電壓信號)轉換成數位信號。第2轉換電路122、第2放大電路132及第2A/D轉換器142係與第1轉換電路121、第1放大電路131及第1A/D轉換器141同樣之構成，進行自第2受光元件112輸出之電性信號之信號處理。 感測器本體1係與光學系統15(參照圖2)組合使用。光學系統15包含透鏡或鏡面、或該等之組合，而將來自檢測空間90之紅外線聚光至受光元件11。感測器本體1與檢測電路2一起收納於1個框體內。如圖2所示，包含感測器本體1之人檢測系統10例如設置於住宅之起居室之天花板，而自設定於起居室內之檢測空間90接收紅外線。 檢測電路2具有判定部4、乘算部5、積分部6、輸出部7、積分計時器41、待機計時器42、及延遲計時器43。再者，檢測電路2具有第1緩衝器211及第1濾波器部221，作為進行來自第1A/D轉換器141之輸入信號(數位信號)之信號處理的部位。此外，檢測電路2具有第2緩衝器212及第2濾波器部222，作為進行來自第2A/D轉換器142之輸入信號(數位信號)之信號處理的部位。 來自第1A/D轉換器141之輸入信號經由第1緩衝器211輸入至第1濾波器部221。第1濾波器部221使特定頻率成分衰減或放大。來自第2A/D轉換器142之輸入信號經由第2緩衝器212輸入至第2濾波器部222。第2濾波器部222使特定頻率成分衰減或放大。 於本實施形態中，檢測電路2以微電腦等電腦作為主構成。檢測電路2係藉由以微電腦之處理器執行微電腦之記憶體所記錄之程式，而實現上述各部之功能。程式既可預先記錄於記憶體，亦可通過網際網路等電性通信線路提供，亦可記錄於記憶卡等記錄媒體而提供。 第1受光元件111之輸出係經由第1轉換電路121、第1放大電路131、第1A/D轉換器141、第1緩衝器211及第1濾波器部221，輸入至乘算部5。第2受光元件112之輸出係經由第2轉換電路122、第2放大電路132、第2A/D轉換器142、第2緩衝器212及第2濾波器部222，輸入至乘算部5。第1受光元件111與第1轉換電路121、第1放大電路131、第1A/D轉換器141、第1緩衝器211及第1濾波器部221一起構成第1受光部31。第2受光元件112與第2轉換電路122、第2放大電路132、第2A/D轉換器142、第2緩衝器212及第2濾波器部222一起構成第2受光部32。第1受光部31與第2受光部32一起構成受光部3。 即，受光部3(第1受光部31及第2受光部32)具有受光元件11，將與來自檢測空間90之紅外線之受光強度之變化相應的輸出信號V1、V2輸出至乘算部5。對乘算部5分別輸入第1受光部31之輸出信號V1、與第2受光部32之輸出信號V2。再者，關於受光部3之輸出信號V1、V2中之第1受光部31之輸出信號V1，亦直接輸出至判定部4。因此，對於判定部4，經由乘算部5及積分部6輸入第1受光部31及第2受光部32之輸出信號V1、V2，且不經由乘算部5及積分部6而輸入第1受光部31之輸出信號V1。 第1濾波器部221係自第1受光元件111之輸出擷取交流成分。第2濾波器部222自第2受光元件112之輸出擷取交流成分。第1濾波器部221及第2濾波器部222之各者供通過之頻段例如設定為0.3 Hz～1 Hz。該頻段係與人91之微小動作對應之頻段。第1濾波器部221及第2濾波器部222之輸出，即第1受光部31之輸出信號V1及第2受光部32之輸出信號V2係分別成為去除低頻成分(包含直流成分)後之交流信號。 此處，第1濾波器部221較佳使對判定部4直接輸出之輸出信號V1、與輸出至乘算部5之輸出信號V1所通過之頻段(通過頻帶)不同。該情形，對於自第1受光部31輸出至乘算部5之輸出信號V1，第1濾波器部221之通過頻帶如上所述例如為0.3 Hz～1 Hz。另一方面，對於自第1受光部31對判定部4直接輸出之輸出信號V1，第1濾波器部221之通過頻帶為例如以1 Hz附近作為中心頻率之頻段。第1濾波器部221既可就各輸出目的地具有個別之濾波器，亦可根據後述之判定部4之動作模式切換通過頻帶。 乘算部5對第1受光部31之輸出信號V1與第2受光部32之輸出信號V2進行乘算處理。乘算部5將第1受光部31之輸出信號V1之瞬時值、與第2受光部32之輸出信號V2之瞬時值相乘。乘算部5係藉由對第1受光部31之輸出信號V1與第2受光部32之輸出信號V2進行乘算處理，而進行擷取第1受光部31之輸出信號V1與第2受光部32之輸出信號V2之同相成分的同步檢波。 積分部6係對乘算部5之乘算結果進行積分處理。積分部6係具有暫時累積乘算部5之乘算結果的記憶體，而對該記憶體所累積之乘算部5之乘算結果進行積分。積分部6求得最近之積分時間量之乘算結果之積分值。換言之，積分部6係對於以當前為終點之積分時間量之期間(積分對象期間)，求得累計乘算結果之值作為評估值Vi1。即，積分部6執行所謂移動積分。對於積分部6具有之記憶體，藉由累積最近之積分時間量之乘算結果，並按序廢棄舊資料，而更新累積於記憶體之乘算結果。積分部6藉由對累積於記憶體之積分時間量之乘算結果進行積分，而算出最近之積分時間量之乘算結果之積分值(評估值Vi1)。積分時間之長度係根據人檢測系統10之用途等，自例如30秒、60秒、及90秒等適當選擇。作為一例，積分時間為30秒。 判定部4基於受光部3之輸出信號，判定檢測空間90之狀態為於檢測空間90存在人91之「有人狀態」、與於檢測空間90不存在人91之「無人狀態」之何者。 判定部4之動作模式包含進入檢測模式、及滯留檢測模式。進入檢測模式係用以檢測有無人91進入檢測空間90之動作模式。滯留檢測模式係用以檢測人91有無自檢測空間90退出之動作模式。 判定部4於進入檢測模式下，若輸出信號V1之振幅與第1臨限值Vth1(參照圖3)之比較結果滿足第1判定條件，則判定為有人狀態。此處，輸出信號V1係直接輸入至判定部4之第1受光部31之輸出信號V1。於本實施形態中，作為一例，第1判定條件係輸出信號V1之振幅變成第1臨限值Vth1以上。 例如，若因人91進入檢測空間90等，使受光部3中來自檢測空間90之紅外線之受光強度變化，則如圖3所示，於輸出信號V1產生較大之變動。輸出信號V1之振幅與來自輸出信號V1之基準電壓V0之變化量(絕對值)同義。於圖3之例中，輸出信號V1之振幅於時刻t10達到第1臨限值Vth1。因此，判定部4係於時刻t10，判斷為輸出信號V1之振幅與第1臨限值Vth1之比較結果滿足第1判定條件，從而判定為有人狀態。 判定部4於滯留檢測模式下，若根據輸出信號V1、V2求得之值即與檢測空間90中人91之動作相應之評估值Vi1與第2臨限值Vth2(參照圖4B)之比較結果滿足第2判定條件，則判定為無人狀態。此處，評估值Vi1為積分部6之輸出值。即，評估值Vi1係以乘算部5將第1受光部31之輸出信號V1與第2受光部32之輸出信號V2相乘，且以積分部6對乘算結果進行積分之值，即輸出信號V1、V2之積分值。 於本實施形態中，作為一例，第2判定條件係自評估值Vi1變成未達第2臨限值Vth2之時點起至經過特定之延遲時間為止，持續維持評估值Vi1未達第2臨限值Vth2之狀態。具體而言，判定部4係進行評估值Vi1與第2臨限值Vth2之比較，於評估值Vi1未達第2臨限值Vth2之期間，豎立臨時旗標。接著，若以保持豎立臨時旗標之狀態經過延遲時間，則判定部4判定為滿足第2判定條件，而判定為無人狀態。藉此，判定部4即便於評估值Vi1未達第2臨限值Vth2亦不會立即判定為無人狀態，而是將對無人狀態之判定延遲延遲時間，從而實現所謂斷開延遲的功能。 例如，即便人91為靜止之狀態，人91亦因呼吸動作等而產生數mm左右之動作(微小動作)。因此，於在檢測空間90存在人91之情形，於第1受光部31及第2受光部32之輸出信號V1、V2，如例如圖4A所示，包含與人91之動作之大小相應之同相的檢測成分。圖4A所例示之輸出信號V1、V2均未達第1臨限值Vth1。由於第1受光部31與第2受光部32係接收來自同一部位之紅外線，故第1受光部31之輸出信號V1、與第2受光部32之輸出信號V2之各者所含之檢測成分彼此具有相關性。因此，於第1受光部31之輸出信號V1與第2受光部32之輸出信號V2之乘算結果中，同相之檢測成分被加強。此外，在乘算部5之乘算結果之移動積分值中，隨機產生之雜訊成分被減弱。因此，如圖4B所示，包含乘算部5乘算結果之移動積分值之評估值Vi1自積分之開始時點起至經過積分時間之時刻t20之前增加，於時刻t20以後變成大致固定。於圖4B之例中，因評估值Vi1於時刻t20為第2臨限值Vth2以上，故判定部4於時刻t20，判斷為評估值Vi1與第2臨限值Vth2之比較結果不滿足第2判定條件。 又，於本實施形態中，判定部4之動作模式除進入檢測模式及滯留檢測模式外，還包含待機模式。即，判定部4至少有3種動作模式(進入檢測模式、滯留檢測模式及待機模式)。各動作模式之細節於「(2)動作」之欄進行說明。 判定部4自包含進入檢測模式、滯留檢測模式及滯留檢測模式之複數種動作模式中，擇一地選擇動作模式進行動作。因此，不會同時選擇例如進入檢測模式與滯留檢測模式之兩者之動作模式。 判定部4於滯留檢測模式下若判定為無人狀態，則將動作模式自滯留檢測模式切換成進入檢測模式。又，判定部4於進入檢測模式下若判定為有人狀態，則將動作模式自進入檢測模式切換成待機模式。又，於自開始待機模式下之動作之時點起經過特定之待機時間之時點，若輸出信號V1之振幅未達第1臨限值Vth1，則判定部4將動作模式自待機模式切換成滯留檢測模式。進而，判定部4若於滯留檢測模式下輸出信號V1之振幅變成第3臨限值以上，則將動作模式自滯留檢測模式切換成待機模式。於本實施形態中，假定為第3臨限值與第1臨限值Vth1為相同值。惟，第3臨限值亦可為與第1臨限值Vth1不同的值。 藉此，於在檢測空間90不存在人91之狀態下，判定部4基本上以進入檢測模式動作，而檢測有無人91進入檢測空間90。另一方面，於在檢測空間90存在人91之狀態下，判定部4基本上以滯留檢測模式動作，而檢測人91有無自檢測空間90退出。 積分計時器41計數積分時間。積分計時器41係若積分部6開始積分處理，則開始積分時間之計數。於判定部4開始滯留檢測模式下之動作時或結束時重設積分計時器41之計數值。 待機計時器42計數待機時間。待機計時器42係若判定部4開始待機模式下之動作，則開始待機時間之計數。若待機計時器42對待機時間計數結束則重設待機計時器42之計數值。待機時間之長度係根據人檢測系統10之用途等，於例如數秒～10秒左右之範圍內適當設定。作為一例，待機時間為10秒。 延遲計時器43計數延遲時間。延遲計時器43係判定部4於滯留檢測模式下，若判定為評估值Vi1變成未達第2臨限值Vth2，則開始延遲時間之計數。於判定部4開始滯留檢測模式下之動作時或結束時，重設延遲計時器43之計數值。延遲時間之長度係根據人檢測系統10之用途等，自例如30秒、60秒、及90秒等適當選擇。作為一例，延遲時間為30秒。延遲時間之長度較佳為可變且可由使用者任意變更。延遲時間較佳長於待機時間。 然而，乘算部5及積分部6係於判定部4之動作模式處於進入檢測模式之期間、及判定部4之動作模式處於待機模式之期間內，停止動作。即，乘算部5及積分部6僅於判定部4之動作模式處於滯留檢測模式之期間內進行動作。因此，與積分部6連動之積分計時器41係以判定部4以滯留檢測模式開始動作為觸發，開始積分時間之計數。再者，判定部4於積分計時器41結束積分時間計數之前，不進行評估值Vi1與第2臨限值Vth2之比較。若積分計時器41結束積分時間計數，則開始評估值Vi1與第2臨限值Vth2之比較。即，判定部4即便於以滯留檢測模式動作中，於自積分部6開始積分處理之時點至經過積分時間之前，亦不進行評估值Vi1與第2臨限值Vth2之比較。因此，判定部4於動作模式為進入檢測模式或待機模式之期間、及即便為滯留檢測模式積分計時器41結束積分時間計數之前之期間內，不進行評估值Vi1與第2臨限值Vth2之比較。 另一方面，關於輸出信號V1之振幅與第1臨限值Vth1之比較，判定部4無關於動作模式而隨時進行。因此，判定部4於滯留檢測模式下，亦可進行輸出信號V1之振幅與第1臨限值Vth1(第3臨限值)之比較，且若輸出信號V1之振幅變成第1臨限值Vth1以上，則將動作模式自滯留檢測模式切換成待機模式。 輸出部7將判定部4之判定結果作為人檢測系統10之檢測結果，輸出至照明控制系統80。輸出部7將表示判定部4之判定結果之判定信號對人檢測系統10串列輸出。具體而言，輸出部7輸出包含起始位元、判定結果及終止位元之判定信號。判定信號係除「有人狀態」或「無人狀態」之判定結果外，亦可包含例如表示判定部4之動作模式之模式資訊、及輸出信號V1、V2之波形等之資訊。 (2)動作 其次，參照圖5對本實施形態之人檢測系統10之動作進行說明。 圖5係概念性地顯示判定部4之動作之說明圖。於圖5中，第1圓C1表示所謂「無人狀態」之判定部4之判定結果。第2圓C2表示所謂「有人狀態」之判定部4之判定結果。又，於圖5中，虛線箭頭表示基於輸出信號V1之振幅與第1臨限值Vth1之比較結果，判定部4之處理流程。實線箭頭表示基於評估值Vi1與第2臨限值Vth2之比較結果，判定部4之處理流程。 若對人檢測系統10接通電源並啟動人檢測系統10，則判定部4首先以進入檢測模式動作(步驟S1)。此時，判定部4之判定結果為無人狀態，因而步驟S1(進入檢測模式)位於第1圓C1內。 於步驟S1之進入檢測模式下，判定部4進行輸出信號V1之振幅與第1臨限值Vth1之比較。此時，若輸出信號V1之振幅未達第1臨限值Vth1，則判定部4繼續於進入檢測模式下之動作(步驟S2)。另一方面，若輸出信號V1之振幅變成第1臨限值Vth1以上，則判定部4將動作模式自進入檢測模式切換成待機模式(步驟S3)。此時，判定部4之判定結果為有人狀態，因而步驟S4(待機模式)位於第2圓C2內。 於步驟S4之待機模式下，判定部4於待機計時器42結束待機時間計數之時點，進行輸出信號V1之振幅與第1臨限值Vth1之比較。判定部4於待機計時器42結束待機時間計數之時點，若輸出信號V1之振幅未達第1臨限值Vth1，則重設待機計時器42之計數值，將動作模式自待機模式切換成滯留檢測模式(步驟S5)。此時，判定部4之判定結果為有人狀態，因而步驟S6(滯留檢測模式)位於第2圓C2內。另一方面，判定部4於待機計時器42結束待機時間計數之時點，若輸出信號V1之振幅為第1臨限值Vth1以上，則重設待機計時器42之計數值，並繼續待機模式下之動作(步驟S7)。 於步驟S6之滯留檢測模式下，判定部4自積分計時器41結束積分時間計數之時點起，隨時開始評估值Vi1與第2臨限值Vth2之比較。且，判定部4係若評估值Vi1變成第2臨限值Vth2以上，則不重設積分計時器41之計數值，而繼續滯留檢測模式下之動作(步驟S9)。又，判定部4於滯留檢測模式下，亦進行輸出信號V1之振幅與第1臨限值Vth1之比較，且若輸出信號V1之振幅變成第1臨限值Vth1以上，則將動作模式自滯留檢測模式切換成待機模式(步驟S10)。此時，判定部4重設積分計時器41之計數值。 又，於步驟S6之滯留檢測模式下，若評估值Vi1變成未達第2臨限值Vth2，則延遲計時器43開始延遲時間之計數。判定部4於延遲計時器43結束延遲時間之計數之前，繼續滯留檢測模式下之動作。判定部4於延遲計時器43結束延遲時間之計數之時點，若評估值Vi1未達第2臨限值Vth2，則將動作模式自滯留檢測模式切換成進入檢測模式(步驟S8)。此時，判定部4之判定結果為無人狀態，因而步驟S1(進入檢測模式)位於第1圓C1內。又，此時，判定部4重設積分計時器41之計數值及延遲計時器43之計數值。 另一方面，於延遲計時器43計數延遲時間中，若評估值Vi1變成第2臨限值Vth2以上，則判定部4繼續滯留檢測模式下之動作(步驟S9)。此時，判定部4重設積分計時器41之計數值及延遲計時器43之計數值。又，於延遲計時器43計數延遲時間中，若輸出信號V1之振幅變成第1臨限值Vth1以上，則判定部4將動作模式自滯留檢測模式切換成待機模式(步驟S10)。此時，判定部4重設積分計時器41之計數值及延遲計時器43之計數值。 藉由上述動作，判定部4於進入檢測模式下，若輸出信號V1之振幅變成第1臨限值Vth1以上，則判定為有人狀態。且，判定部4若於進入檢測模式下判定為有人狀態，則將動作模式自進入檢測模式切換成待機模式。又，判定部4於自開始待機模式下之動作之時點起經過待機時間之時點，若輸出信號V1之振幅未達第1臨限值Vth1，則將動作模式自待機模式切換成滯留檢測模式。又，判定部4於滯留檢測模式下，若自評估值Vi1變成未達第2臨限值Vth2之時點起至經過特定之延遲時間之前，持續維持評估值Vi1未達第2臨限值Vth2之狀態，則判定為無人狀態。且，判定部4若於滯留檢測模式下判定為無人狀態，則將動作模式自滯留檢測模式切換成進入檢測模式。 若總結以上說明之判定部4之動作，則如表1所示。 [表1]
即，若判定部4之動作模式為進入檢測模式，則判定部4之判定對象為輸出信號V1之振幅。且，判定部4根據輸出信號V1之振幅與第1臨限值Vth1之比較結果，進行步驟S2或步驟S3之處理。判定部4之動作模式為進入檢測模式之期間的判定部4之判定結果係無人狀態。 又，若判定部4之動作模式為待機模式，則判定部4之判定對象為輸出信號V1之振幅。且，判定部4根據輸出信號V1之振幅與第1臨限值Vth1之比較結果，進行步驟S5或步驟S7之處理。判定部4之動作模式為待機模式之期間的判定部4之判定結果係有人狀態。 又，若判定部4之動作模式為滯留檢測模式，則判定部4之判定對象為輸出信號V1之振幅、及評估值Vi1之兩者。且，判定部4根據輸出信號V1之振幅與第1臨限值Vth1之比較結果，進行步驟S10之處理。判定部4根據評估值Vi1與第2臨限值Vth2之比較結果，進行步驟S8或步驟S9之處理。判定部4之動作模式為滯留模式之期間的判定部4之判定結果係有人狀態。 然而，判定部4之處理具有優先度，判定部4優先執行優先度較高的處理。例如於滯留檢測模式下，判定部4將輸出信號V1之振幅及評估值Vi1之兩者作為判定對象，但與輸出信號V1之振幅相應之處理比與評估值Vi1相應之處理優先度高。即，於判定部4以滯留檢測模式動作中，輸出信號V1之振幅變成第1臨限值Vth1以上，且評估值Vi1變成第2臨限值Vth2以上之情形，判定部4執行步驟S10之處理，而非步驟S9之處理。 以下，參照圖6對本實施形態之人檢測系統10之動作之一例進行說明。於圖6之例中，假設於時刻t1，人91進入檢測空間90，於時刻t4，人91自檢測空間90退出之情形。 圖6係將橫軸作為時間軸，自上起依序表示輸出信號V1、第1旗標F1、評估值Vi1、第2旗標F2、及第3旗標F3。第1旗標F1於待機計時器42計數待機時間T1時變成「H」(High：高)，待機計時器42若未計數待機時間T1，就變為「L」(Low：低)。第2旗標F2係表示判定部4之評估值Vi1與第2臨限值Vth2之比較結果的臨時旗標。第2旗標F2係若評估值Vi1未達第2臨限值Vth2則變成「H」(高)，若評估值Vi1為第2臨限值Vth2以上則變成「L」(低)。第3旗標F3表示判定部4之判定結果。第3旗標F3係於判定部4判定為有人狀態時變成「H」(高)，判定部4判定為無人狀態時變成「L」(低)。再者，於圖6中，「M1」表示判定部4之動作模式為進入檢測模式之期間，「M3」表示判定部4之動作模式為待機模式之期間，「M2」表示判定部4之動作模式為滯留檢測模式之期間。又，「Ti1」、「Ti2」、「Ti3」...係表示積分對象期間，即積分部6作為移動積分之對象之期間。 於圖6之例中，關於時刻t1以前之期間，判定部4以進入檢測模式動作，判定部4之判定結果為無人狀態，且第3旗標F3為「L」。於時刻t1，輸出信號V1之振幅變成第1臨限值Vth1以上，因而判定部4判定為有人狀態，第3旗標F3變成「H」。此時，判定部4之動作模式自進入檢測模式切換成待機模式。 於時刻t1～時刻t2之期間內，因判定部4以待機模式動作，故第1旗標F1變成「H」。因於待機計時器42結束待機時間T1計數之時刻t2，輸出信號V1之振幅未達第1臨限值Vth1，故判定部4之動作模式自待機模式切換成滯留檢測模式。此時，第1旗標F1變成「L」。 判定部4自積分計時器41結束積分時間計數之時刻t3起，隨時開始評估值Vi1與第2臨限值Vth2之比較。於時刻t3，積分部6進行以積分對象期間Ti1為對象之積分，並以判定部4比較其結果所得之評估值Vi1與第2臨限值Vth2。於時刻t3，因評估值Vi1未達第2臨限值Vth2，故第2旗標F2變成「H」，且延遲計時器43開始延遲時間T2之計數。其後，於延遲計時器43結束延遲時間T2計數前的時刻t4，因輸出信號V1變動，而評估值Vi1變成第2臨限值Vth2以上，故第2旗標F2變成「L」。 其後，若輸出信號V1無較大變動，則於經過積分時間後之時刻t5，評估值Vi1變成未達第2臨限值Vth2。因此，於時刻t5，第2旗標F2變成「H」，延遲計時器43開始延遲時間T2之計數。其後，若輸出信號V1無較大變動，則於延遲計時器43結束延遲時間T2計數之時刻t6，判定部4判定為無人狀態，第3旗標F3變成「L」。此時，判定部4之動作模式自滯留檢測模式切換成進入檢測模式。 (3)優點 如以上說明，本實施形態之人檢測系統10具備受光部3及判定部4。受光部3具有輸出與來自檢測空間90之紅外線之受光強度之變化相應之信號的受光元件11。判定部4基於受光部3之輸出信號V1、V2，判定檢測空間90之狀態為於檢測空間90存在人91之有人狀態、與於檢測空間90不存在人之無人狀態之何者。判定部4之動作模式包含：進入檢測模式，其檢測有無人91進入檢測空間90；及滯留檢測模式，其檢測人91有無自檢測空間90退出。判定部4於進入檢測模式下，若輸出信號V1之振幅與第1臨限值Vth1之比較結果滿足第1判定條件，則判定為有人狀態。判定部4構成為於滯留檢測模式下，若根據輸出信號V1、V2求得之值即與檢測空間90中人91之動作相應之評估值Vi1與第2臨限值Vth2之比較結果滿足第2判定條件，則判定為無人狀態。 根據上述構成，判定部4之動作模式包含：進入檢測模式，其檢測有無人91進入檢測空間90；及滯留檢測模式，其檢測人91有無自檢測空間90退出。即，判定部4於進入檢測模式下，判定檢測空間90之狀態是否為有人狀態，於滯留檢測模式下，判定檢測空間90之狀態是否為無人狀態。如此，判定部4係以彼此不同之動作模式檢測自無人狀態朝有人狀態之變化、及自有人狀態朝無人狀態之變化。因此，若例如使判定部4之滯留檢測模式比進入檢測模式感度更高，則於滯留檢測模式下不易產生人之微小動作(扭身等)之漏檢測，且於進入檢測模式下可抑制誤檢測的產生。 且，判定部4於進入檢測模式下，基於輸出信號V1之振幅與第1臨限值Vth1之比較結果，判定是否為有人狀態。另一方面，判定部4於滯留檢測模式下，基於根據輸出信號V1、V2求得之值即與檢測空間90中之人91之動作相應之評估值Vi1與第2臨限值Vth2之比較結果，而判定是否為無人狀態。即，於進入檢測模式與滯留檢測模式下，判定部4之判定處理之演算法不同。因此，例如於滯留檢測模式下，藉由應用適於人91之微小動作之檢測的演算法，更不易產生人91之微小動作之漏檢測。 再者，乘算部5及積分部6係於判定部4之動作模式處於進入檢測模式之期間停止動作。因此，可將檢測電路2之消耗電力於進入檢測模式下抑制得比滯留檢測模式低。 又，如本實施形態，評估值Vi1較佳為輸出信號之積分值。但，於本實施形態中，因具有輸出信號V1與輸出信號V2作為「輸出信號」，故評估值Vi1係輸出信號V1、V2之乘算值之積分值。根據該構成，判定部4於滯留檢測模式下，並非基於輸出信號V1、V2之瞬時值，而是基於積分值判定是否存在人91。因此，於例如人91因呼吸而微微動作之情形，亦因該微動作(微小動作)被週期性地重複，而於判定部4中，容易判定存在人91。但，評估值Vi1為輸出信號之積分值的情形對於人檢測系統10並非必須之構成，評估值Vi1只要為根據輸出信號V1、V2求得之值且與檢測空間90中之人91之動作相應之值即可。 又，如本實施形態，第1判定條件較佳為輸出信號V1之振幅變成第1臨限值Vth1以上。根據該構成，判定部4於進入檢測模式下，若輸出信號V1之振幅變成第1臨限值Vth1，則立即判定為有人狀態。因此，例如，可於人91進入檢測空間90之情形立即使照明器具81亮燈。 又，如本實施形態，判定部4較佳構成為若於滯留檢測模式下判定為無人狀態，則將動作模式自滯留檢測模式切換成進入檢測模式。根據該構成，於有人91自檢測空間90內朝檢測空間90外移動之情形，判定部4之動作模式切換成檢測有無人91進入檢測空間90的進入檢測模式。但，判定部4將動作模式自滯留檢測模式自動地切換成進入檢測模式之構成對於人檢測系統10並非必須之構成，可適當省略。 又，如本實施形態，判定部4之動作模式較佳進而包含待機模式。於該情形，判定部4較佳若於進入檢測模式下判定為有人狀態，則將動作模式自進入檢測模式切換成待機模式。再者，判定部4較佳構成為於自開始待機模式下之動作之時點起經過特定之待機時間T1之時點，若輸出信號V1之振幅未達第1臨限值Vth1，則將動作模式自待機模式切換成滯留檢測模式。 根據該構成，於人91自檢測空間90外朝檢測空間90內移動之情形，判定部4之動作模式自動地切換成檢測人91有無自檢測空間90退出之滯留檢測模式。且，判定部4之動作模式自進入檢測模式經過待機模式切換成滯留檢測模式，故而有人91之較大之動作後，不會立即轉換至滯留檢測模式。乘算部5及積分部6係於判定部4之動作模式處於待機模式之期間停止動作。因此，可將檢測電路2之消耗電力於待機模式下抑制為比滯留檢測模式低。但，判定部4將動作模式自進入檢測模式經過待機模式自動地切換成滯留檢測模式之構成對於人檢測系統10並非必須之構成，可適當省略。 該情形，如本實施形態，判定部4較佳構成為若於滯留檢測模式下輸出信號V1之振幅變成第3臨限值(於本實施形態中為第1臨限值Vth1)以上，則將動作模式自滯留檢測模式切換成待機模式。根據該構成，判定部4以滯留檢測模式動作中，於例如產生人91之較大動作(步行等)之情形，判定部4之動作模式自動地切換成待機模式。因此，無論為例如人91僅通過檢測空間90之情形、與人91滯留於檢測空間90後自檢測空間90退出之情形之何者，於人91退出後，判定部4皆自待機模式開始動作。因此，可將人91自檢測空間90退出後，至判定部4判定為無人狀態為止所需之時間的偏差抑制於較小。 又，如本實施形態，第2判定條件較佳為自評估值Vi1未達第2臨限值Vth2之時點起至經過特定之延遲時間T2之前，持續維持評估值Vi1未達第2臨限值Vth2之狀態。根據該構成，判定部4於滯留檢測模式下，即便評估值Vi1變成未達第2臨限值Vth2，亦未立即判定為無人狀態。因此，於例如於檢測空間90存在人91之狀態下，照明器具81不易熄燈。 (4)變化例 圖7係概念性地顯示實施形態1之第1變化例之人檢測系統10之判定部4之動作之說明圖。圖7係與圖5同樣之概念圖，因而省略細節說明。 第1變化例之人檢測系統10係於判定部4不具有將動作模式自滯留檢測模式切換成待機模式之功能之方面，與實施形態1之人檢測系統10不同。於第1變化例中，判定部4之動作模式一旦自待機模式(步驟S4)切換成滯留檢測模式(步驟S6)時，隨後，判定部4之動作模式不會直接切換成待機模式。即，滯留檢測模式下之判定部4之動作係繼續滯留檢測模式下之動作(步驟S9)、或轉換(步驟S8)至進入檢測模式(步驟S1)之任一者。於第1變化例中，若判定部4之動作模式為滯留檢測模式，則無須比較輸出信號V1之振幅與第1臨限值Vth1。 圖8係概念性地顯示實施形態1之第2變化例之人檢測系統10之判定部4之動作之說明圖。圖8係與圖5同樣之概念圖，因而省略細節說明。 第2變化例之人檢測系統10係於判定部4之動作模式不包含待機模式之方面，與實施形態1之人檢測系統10不同。於第2變化例中，判定部4構成為若於進入檢測模式下判定為有人狀態，則將動作模式自進入檢測模式切換成滯留檢測模式。即，判定部4之動作模式係自進入檢測模式(步驟S1)直接切換(步驟S3)成滯留檢測模式(步驟S6)。於第2變化例中，若判定部4之動作模式為滯留檢測模式，則無須比較輸出信號V1之振幅與第1臨限值Vth1。 以下，例舉實施形態1之其他變化例。 人檢測系統10並不限於住宅用，亦可用於例如辦公室、商店、或工廠等非住宅。再者，人檢測系統10並不限於屋內，亦可於屋外使用。 又，人檢測系統10之檢測結果並不限於照明器具之控制，亦可用於例如通風扇、或防盜相機等照明器具以外之電性機器之控制。再者，人檢測系統10之檢測結果並不限於電性機器之控制，亦可用於例如人91之位置之監視等。 又，第1判定條件，即判定部4於進入檢測模式下用以判定為有人狀態之條件係並不限於輸出信號V1之振幅變成第1臨限值Vth1以上的情形。例如，第1判定條件亦可為於特定期間內輸出信號V1之振幅超過第1臨限值Vth1之次數達到規定次數之情形等。再者，判定部4於進入檢測模式下，基於第1受光部31之輸出信號V1、與第2受光部32之輸出信號V2中至少一者之振幅與第1臨限值Vth1之比較結果，判定是否為有人狀態即可。例如，判定部4亦可基於第1受光部31之輸出信號V1及第2受光部32之輸出信號V2之兩者之振幅與第1臨限值Vth1之比較結果，判定是否為有人狀態。或，判定部4亦可基於第2受光部32之輸出信號V2之振幅與第1臨限值Vth1之比較結果，判定是否為有人狀態。 又，第2判定條件，即判定部4於滯留檢測模式下用以判定為無人狀態之條件係並不限於自評估值Vi1變成未達第2臨限值Vth2之時點起至經過延遲時間之前，持續維持評估值Vi1未達第2臨限值Vth2之狀態的情形。例如，第2判定條件亦可為評估值Vi1變成未達第2臨限值Vth2之情形等。即，斷開延遲之功能並非判定部4必須之功能，判定部4亦可於滯留檢測模式下評估值Vi1變成未達第2臨限值Vth2之時點，判定為無人狀態。但，該構成與實施形態1之構成中將延遲時間設定為零之構成相同。 又，判定部4之動作模式亦可與滯留檢測模式另外包含延遲模式，作為用以於判定部4中實現斷開延遲之功能的動作模式。該情形，判定部4係即便於滯留檢測模式下評估值Vi1與第2臨限值Vth2之比較結果滿足第2判定條件，亦未立即判定為無人狀態。即，判定部4係豎立臨時無人旗標，將動作模式自滯留檢測模式切換成延遲模式，並開始延遲時間之計數。延遲模式下之判定部4之動作與實施形態1之人檢測系統10中計數延遲時間時之判定部4之動作相同。 再者，斷開延遲之功能亦可不於判定部4實現，而於判定部4之後段，例如輸出部7中實現。該情形，判定部4於滯留檢測模式下，若評估值Vi1與第2臨限值Vth2之比較結果滿足第2判定條件，則立即判定為無人狀態。輸出部7若接收到判定為無人狀態之判定部4之判定結果，則開始延遲時間之計數。 又，以第1受光部31與第2受光部32接收紅外線之檢測空間90亦可不完全一致，可彼此錯開。該情形，於第1受光部31之輸出信號V1所含之檢測成分、與第2受光部32之輸出信號V2所含之檢測成分有產生相位差的可能性。該情形，乘算部5之乘算結果並不限於始終成為正值，有時亦成為負值。因此，除第2臨限值Vth2外亦可設定負臨限值作為評估值Vi1之比較對象。該情形，判定部4亦可基於評估值Vi1與負臨限值之比較結果，判定是否存在人91。 (實施形態2) 本實施形態之人檢測系統10係受光部3僅具有第1受光部31之方面，與實施形態1之人檢測系統10不同。以下，對與實施形態1同樣之構成附註共通符號且適當省略說明。 判定部4於進入檢測模式下，與實施形態1之人檢測系統10同樣，基於第1受光部31之輸出信號V1之振幅與第1臨限值Vth1之比較結果，判定是否存在人91。另一方面，於滯留檢測模式下，判定部4將第1受光部31之輸出信號V1與參照信號之乘算結果之積分值用作評估值Vi1。即，評估值Vi1係以乘算部5將第1受光部31之輸出信號V1與參照信號相乘，且以積分部6對乘算結果進行積分之值。此處所言之參照信號係例如與人91之微小動作對應之頻率(例如0.3 Hz及0.5 Hz)之正弦波。又，參照信號亦可為將例如第1受光部31之輸出信號V1錯開特定時間量之與第1受光部31之輸出信號V1大致同相位之信號。 如以上所說明，本實施形態之人檢測系統10係即便受光部31僅有第1受光部31，判定部4亦可以進入檢測模式及滯留檢測模式之2種動作模式進行動作。 實施形態2之人檢測系統10之構成可與實施形態1(包含變化例)之構成適當組合。 又，於上述各實施形態(包含變化例)中，振幅及臨限值等2值間之比較時出現之「以上」之描述意指包含2值相等之情形、與2值中的一值超過另一值之情形之兩者。但並不限於此，「以上」亦可與僅包含2值之一值超過另一值的情形之「更大」同義。即，是否包含2值相等之情形，因可依據臨限值等之設定任意變更，故「以上」或「更大」於技術上無差異。同樣，「未達」亦可與「以下」同義。Each of the following embodiments relates to a human detection system, and more particularly to a human detection system that detects presence of a person in a detection space based on the intensity of received infrared light from the detection space. However, the human detecting system of each embodiment described below is only an example of the present invention, and the present invention is not limited to the following human detecting system. Therefore, various modifications may be made depending on the design and the like without departing from the scope of the technical idea of the present invention. (Embodiment 1) A person detecting system 10 of this embodiment will be described with reference to Fig. 2 . The human detecting system 10 detects that there is an unmanned person 91 in the detecting space 90 set in the living room of the house or the like. The human detecting system 10 detects the presence of the unmanned person 91 based on the change in the received light intensity of the infrared rays from the detecting space 90. That is, the human detecting system 10 detects that there is an unmanned person 91 depending on whether the person 91 moves from the outside of the detection space 90 toward the detection space 90 or the intensity of the received light of the infrared rays generated by the minute movement of the person 91 in the detection space 90. The term "minor action" as used herein means, for example, a small movement of a person 91 caused by a breathing action of a person 91, and a body twisting. The human detection system 10 detects which of the state of the detection space 90 is the human state and the unmanned state. The "personal state" as used herein means the state in which the person 91 is present in the detection space 90. The "unmanned state" means the state in which the person 91 does not exist in the detection space 90. Therefore, in the state where the person 91 does not exist in the detection space 90, the detection result of the person detecting system 10 becomes "unmanned state". If the person 91 enters the detection space 90, the detection result of the person detection system 10 changes from "unmanned state" to "personal state". Thereafter, while the person 91 is staying in the detection space 90, the detection result of the human detection system 10 is maintained in the "personal state". If the person 91 exits from the detection space 90, the detection result of the person detection system 10 changes from "personal state" to "unmanned state". In the present embodiment, as an example, the detection result of the human detecting system 10 is output to the illumination control system 80 (see Fig. 1). The lighting control system 80 includes a lighting fixture 81 (see FIG. 1) that illuminates the detection space 90, and a control device 82 (see FIG. 1) that controls the lighting fixture 81. The detection result of the human detection system 10 is input to the control device 82. The control device 82 turns on the lighting fixture 81 if the detection result of the human detecting system 10 is "personal state". On the other hand, if the detection result of the human detecting system 10 is "unmanned state", the control device 82 turns off the lighting fixture 81. The control device 82 may be a switch that is inserted into the power supply circuit of the lighting fixture 81 to turn on/off the energization of the lighting fixture 81. As described above, the human detecting system 10 of the present embodiment is for the lighting control system 80 that automatically controls the lighting fixture 81 based on the presence of the unmanned person 91. Thereby, the person detecting system 10 can automatically turn on the lighting fixture 81 if the person 91 enters the detection space 90. Further, when the person detecting system 10 exits from the detection space 90, the person detecting system 10 automatically turns off the lighting device 81, thereby suppressing unnecessary power consumption caused by forgetting to turn off the lighting device 81. (1) Configuration As shown in FIG. 1, the human detecting system 10 includes a sensor body 1 and a detecting circuit 2. The sensor body 1 has a first light receiving element 111 and a second light receiving element 112. In the case where the first light receiving element 111 and the second light receiving element 112 are not particularly distinguished, each of the first light receiving element 111 and the second light receiving element 112 is referred to as "light receiving element 11". The light receiving element 11 is a thermoelectric element, and outputs a signal (electrical signal) corresponding to a change in the intensity of received infrared light from the detection space 90. The sensor body 1 includes a first conversion circuit 121, a first amplification circuit 131, and a first A/D (Analog/Digital) converter 141 as signals for performing an electrical signal output from the first light receiving element 111. Processing circuit. Further, the sensor body 1 includes a second conversion circuit 122, a second amplification circuit 132, and a second A/D converter 142 as a circuit for performing signal processing of an electrical signal output from the second light receiving element 112. The sensor body 1 outputs an output (electrical signal) of each of the first A/D converter 141 and the second A/D converter 142 to the detection circuit 2. The first conversion circuit 121 converts an electrical signal output from the first light receiving element 111 from a current signal into a voltage signal. The first amplifier circuit 131 amplifies the voltage signal output from the first converter circuit 121. The first A/D converter 141 converts an analog signal (voltage signal) output from the first amplifier circuit 131 into a digital signal. The second conversion circuit 122, the second amplification circuit 132, and the second A/D converter 142 are configured similarly to the first conversion circuit 121, the first amplification circuit 131, and the first A/D converter 141, and are configured from the second light-receiving element. 112 Signal processing of the electrical signal output. The sensor body 1 is used in combination with the optical system 15 (refer to FIG. 2). The optical system 15 includes a lens or a mirror surface, or a combination thereof, and condenses infrared rays from the detection space 90 to the light receiving element 11. The sensor body 1 is housed in one housing together with the detection circuit 2. As shown in FIG. 2, the person detecting system 10 including the sensor body 1 is disposed, for example, on the ceiling of a living room of a house, and receives infrared rays from the detecting space 90 set in the living room. The detection circuit 2 includes a determination unit 4, a multiplication unit 5, an integration unit 6, an output unit 7, an integration timer 41, a standby timer 42, and a delay timer 43. Further, the detection circuit 2 includes a first buffer 211 and a first filter unit 221 as a portion for performing signal processing on an input signal (digital signal) from the first A/D converter 141. Further, the detection circuit 2 includes a second buffer 212 and a second filter unit 222 as a portion for performing signal processing on an input signal (digital signal) from the second A/D converter 142. The input signal from the first A/D converter 141 is input to the first filter unit 221 via the first buffer 211. The first filter unit 221 attenuates or amplifies a specific frequency component. The input signal from the second A/D converter 142 is input to the second filter unit 222 via the second buffer 212. The second filter unit 222 attenuates or amplifies a specific frequency component. In the present embodiment, the detection circuit 2 has a main structure such as a microcomputer such as a microcomputer. The detecting circuit 2 realizes the functions of the above-mentioned parts by executing a program recorded in the memory of the microcomputer by the processor of the microcomputer. The program can be pre-recorded in the memory, or provided via an electronic communication line such as the Internet, or recorded on a recording medium such as a memory card. The output of the first light receiving element 111 is input to the multiplication unit 5 via the first conversion circuit 121, the first amplification circuit 131, the first A/D converter 141, the first buffer 211, and the first filter unit 221. The output of the second light receiving element 112 is input to the multiplication unit 5 via the second conversion circuit 122, the second amplification circuit 132, the second A/D converter 142, the second buffer 212, and the second filter unit 222. The first light receiving element 111 constitutes the first light receiving unit 31 together with the first conversion circuit 121, the first amplification circuit 131, the first A/D converter 141, the first buffer 211, and the first filter unit 221 . The second light receiving element 112 constitutes the second light receiving unit 32 together with the second conversion circuit 122, the second amplification circuit 132, the second A/D converter 142, the second buffer 212, and the second filter unit 222. The first light receiving unit 31 and the second light receiving unit 32 constitute the light receiving unit 3 together. In other words, the light receiving unit 3 (the first light receiving unit 31 and the second light receiving unit 32) has the light receiving element 11 and outputs the output signals V1 and V2 corresponding to the change in the received light intensity of the infrared rays from the detection space 90 to the multiplying unit 5. The multiplication unit 5 inputs the output signal V1 of the first light receiving unit 31 and the output signal V2 of the second light receiving unit 32, respectively. Further, the output signal V1 of the first light receiving unit 31 among the output signals V1 and V2 of the light receiving unit 3 is also directly output to the determination unit 4. Therefore, the determination unit 4 inputs the output signals V1 and V2 of the first light receiving unit 31 and the second light receiving unit 32 via the multiplication unit 5 and the integration unit 6, and inputs the first signal without passing through the multiplication unit 5 and the integration unit 6. The output signal V1 of the light receiving unit 31. The first filter unit 221 extracts an alternating current component from the output of the first light receiving element 111. The second filter unit 222 extracts an alternating current component from the output of the second light receiving element 112. The frequency band through which each of the first filter unit 221 and the second filter unit 222 passes is set to, for example, 0.3 Hz to 1 Hz. This band is the frequency band corresponding to the small movement of the person 91. The output of the first filter unit 221 and the second filter unit 222, that is, the output signal V1 of the first light receiving unit 31 and the output signal V2 of the second light receiving unit 32 are respectively exchanged to remove low frequency components (including DC components). signal. Here, the first filter unit 221 preferably differs between the output signal V1 directly outputted to the determination unit 4 and the frequency band (passing band) through which the output signal V1 output to the multiplication unit 5 passes. In this case, the output band of the first filter unit 221 is outputted from the first light receiving unit 31 to the multiplication unit 5, and the pass band of the first filter unit 221 is, for example, 0.3 Hz to 1 Hz. On the other hand, in the output signal V1 directly output from the first light receiving unit 31 to the determination unit 4, the pass band of the first filter unit 221 is, for example, a frequency band having a center frequency of around 1 Hz. The first filter unit 221 may have an individual filter for each output destination, or may switch the pass band according to an operation mode of the determination unit 4 to be described later. The multiplication unit 5 performs multiplication processing on the output signal V1 of the first light receiving unit 31 and the output signal V2 of the second light receiving unit 32. The multiplying unit 5 multiplies the instantaneous value of the output signal V1 of the first light receiving unit 31 by the instantaneous value of the output signal V2 of the second light receiving unit 32. The multiplication unit 5 performs multiplication processing on the output signal V1 of the first light receiving unit 31 and the output signal V2 of the second light receiving unit 32, and extracts the output signal V1 and the second light receiving unit of the first light receiving unit 31. Synchronous detection of the in-phase component of the output signal V2 of 32. The integration unit 6 performs integration processing on the multiplication result of the multiplication unit 5. The integration unit 6 has a memory that temporarily accumulates the multiplication result of the multiplication unit 5, and integrates the multiplication result of the multiplication unit 5 accumulated in the memory. The integration unit 6 obtains the integral value of the multiplication result of the latest integration time amount. In other words, the integration unit 6 obtains the value of the cumulative multiplication result as the evaluation value Vi1 for the period (integration target period) at which the integration time amount is currently the end point. That is, the integration unit 6 performs so-called motion integration. For the memory of the integration unit 6, the multiplication result accumulated in the memory is updated by accumulating the result of the multiplication of the latest integration time amount and discarding the old data in order. The integration unit 6 integrates the multiplication result of the integration time amount accumulated in the memory, and calculates an integral value (evaluation value Vi1) of the multiplication result of the latest integration time amount. The length of the integration time is appropriately selected from, for example, 30 seconds, 60 seconds, and 90 seconds, depending on the use of the human detecting system 10 or the like. As an example, the integration time is 30 seconds. The determination unit 4 determines based on the output signal of the light receiving unit 3 that the state of the detection space 90 is the "personal state" of the person 91 in the detection space 90 and the "unmanned state" of the person 91 in the detection space 90. The operation mode of the determination unit 4 includes an entry detection mode and a retention detection mode. The entry detection mode is used to detect an action mode in which the unmanned 91 enters the detection space 90. The detention detection mode is used to detect whether the human 91 has an operation mode in which the self-detection space 90 exits. When the determination unit 4 enters the detection mode, if the comparison result of the amplitude of the output signal V1 and the first threshold value Vth1 (see FIG. 3) satisfies the first determination condition, it is determined that the state is a human state. Here, the output signal V1 is directly input to the output signal V1 of the first light receiving unit 31 of the determination unit 4. In the present embodiment, as an example, the amplitude of the first determination condition output signal V1 becomes equal to or greater than the first threshold value Vth1. For example, when the person 91 enters the detection space 90 or the like and changes the received light intensity of the infrared rays from the detection space 90 in the light receiving unit 3, as shown in FIG. 3, a large fluctuation occurs in the output signal V1. The amplitude of the output signal V1 is synonymous with the amount of change (absolute value) of the reference voltage V0 from the output signal V1. In the example of FIG. 3, the amplitude of the output signal V1 reaches the first threshold value Vth1 at time t10. Therefore, the determination unit 4 determines that the comparison result of the amplitude of the output signal V1 and the first threshold value Vth1 satisfies the first determination condition at time t10, and determines that the human state is present. In the retention detection mode, the determination unit 4 compares the evaluation value Vi1 and the second threshold value Vth2 (see FIG. 4B) corresponding to the operation of the person 91 in the detection space 90 based on the output signals V1 and V2. When the second determination condition is satisfied, it is determined to be an unmanned state. Here, the evaluation value Vi1 is the output value of the integration unit 6. In other words, the evaluation value Vi1 multiplies the output signal V1 of the first light receiving unit 31 by the output signal V2 of the second light receiving unit 32 by the multiplying unit 5, and integrates the multiplication result by the integrating unit 6, that is, the output. The integrated value of the signals V1, V2. In the present embodiment, as an example, the second determination condition continues until the evaluation value Vi1 does not reach the second threshold from the time when the evaluation value Vi1 is less than the second threshold value Vth2 until the specific delay time elapses. The value of the value Vth2. Specifically, the determination unit 4 compares the evaluation value Vi1 with the second threshold value Vth2, and erects the temporary flag while the evaluation value Vi1 does not reach the second threshold value Vth2. Then, when the delay time elapses while the erect temporary flag is maintained, the determination unit 4 determines that the second determination condition is satisfied, and determines that the unmanned state is satisfied. As a result, even if the evaluation value Vi1 does not reach the second threshold value Vth2, the determination unit 4 does not immediately determine the unmanned state, but delays the determination of the unmanned state by a delay time, thereby realizing a function of the off-delay. For example, even if the person 91 is in a stationary state, the person 91 generates an operation of about several mm due to a breathing operation or the like (small operation). Therefore, when the person 91 is present in the detection space 90, the output signals V1 and V2 of the first light receiving unit 31 and the second light receiving unit 32 include the same phase as the magnitude of the action of the person 91 as shown, for example, in FIG. 4A. Test component. The output signals V1, V2 illustrated in FIG. 4A do not reach the first threshold value Vth1. Since the first light receiving unit 31 and the second light receiving unit 32 receive infrared rays from the same portion, the detection components included in each of the output signal V1 of the first light receiving unit 31 and the output signal V2 of the second light receiving unit 32 are mutually Relevance. Therefore, in the multiplication result of the output signal V1 of the first light receiving unit 31 and the output signal V2 of the second light receiving unit 32, the detection component of the same phase is strengthened. Further, among the moving integral values of the multiplication results of the multiplying unit 5, the randomly generated noise components are attenuated. Therefore, as shown in FIG. 4B, the evaluation value Vi1 including the movement integral value of the multiplication result by the multiplication unit 5 increases from the start point of the integration to the time t20 after the integration time, and becomes substantially constant after the time t20. In the example of FIG. 4B, since the evaluation value Vi1 is equal to or greater than the second threshold value Vth2 at the time t20, the determination unit 4 determines that the comparison result between the evaluation value Vi1 and the second threshold value Vth2 does not satisfy the second time at time t20. Judging conditions. Further, in the present embodiment, the operation mode of the determination unit 4 includes a standby mode in addition to the detection mode and the retention detection mode. In other words, the determination unit 4 has at least three types of operation modes (incoming detection mode, retention detection mode, and standby mode). The details of each operation mode are described in the column of "(2) Action". The determination unit 4 selectively selects an operation mode to operate from a plurality of operation modes including the entry detection mode, the retention detection mode, and the retention detection mode. Therefore, an operation mode such as both the entry detection mode and the stay detection mode is not simultaneously selected. When the determination unit 4 determines that the state is unmanned in the stay detection mode, the determination unit 4 switches the operation mode from the stay detection mode to the entry detection mode. Further, when the determination unit 4 determines that there is a human state in the entry detection mode, the determination unit 4 switches the operation mode from the entry detection mode to the standby mode. Further, when the amplitude of the output signal V1 does not reach the first threshold value Vth1 at the time when the predetermined standby time elapses from the start of the operation in the standby mode, the determination unit 4 switches the operation mode from the standby mode to the stay detection. mode. Further, when the amplitude of the output signal V1 is equal to or greater than the third threshold value in the stay detection mode, the determination unit 4 switches the operation mode from the stay detection mode to the standby mode. In the present embodiment, it is assumed that the third threshold value and the first threshold value Vth1 are the same value. However, the third threshold value may be a value different from the first threshold value Vth1. Thereby, in a state where the person 91 is not present in the detection space 90, the determination unit 4 basically operates in the entry detection mode, and detects that the unmanned person 91 enters the detection space 90. On the other hand, in a state where the person 91 is present in the detection space 90, the determination unit 4 basically operates in the stay detection mode, and the detection person 91 exits from the detection space 90. The integration timer 41 counts the integration time. The integration timer 41 starts counting of the integration time when the integration unit 6 starts the integration process. The count value of the integration timer 41 is reset when the determination unit 4 starts the operation in the retention detection mode or ends. The standby timer 42 counts the standby time. The standby timer 42 starts the counting of the standby time when the determination unit 4 starts the operation in the standby mode. When the standby timer 42 counts the standby time, the count value of the standby timer 42 is reset. The length of the standby time is appropriately set within a range of, for example, several seconds to 10 seconds, depending on the use of the human detecting system 10 or the like. As an example, the standby time is 10 seconds. The delay timer 43 counts the delay time. The delay timer 43 determines that the delay time is counted when the determination unit 4 determines that the evaluation value Vi1 has not reached the second threshold value Vth2 in the stay detection mode. When the determination unit 4 starts the operation in the stagnant detection mode or ends, the count value of the delay timer 43 is reset. The length of the delay time is appropriately selected from, for example, 30 seconds, 60 seconds, and 90 seconds, depending on the use of the human detecting system 10 or the like. As an example, the delay time is 30 seconds. The length of the delay time is preferably variable and can be arbitrarily changed by the user. The delay time is preferably longer than the standby time. However, the multiplication unit 5 and the integration unit 6 stop the operation while the operation mode of the determination unit 4 is in the entry detection mode and the operation mode of the determination unit 4 is in the standby mode. In other words, the multiplication unit 5 and the integration unit 6 operate only during the period in which the operation mode of the determination unit 4 is in the retention detection mode. Therefore, the integration timer 41 that is interlocked with the integration unit 6 starts the operation of the determination unit 4 in the retention detection mode as a trigger, and starts counting the integration time. Furthermore, the determination unit 4 does not compare the evaluation value Vi1 with the second threshold value Vth2 until the integration timer 41 ends the integration time count. If the integration timer 41 ends the integration time count, the comparison between the evaluation value Vi1 and the second threshold value Vth2 is started. In other words, even when the determination unit 4 operates in the retention detection mode, the comparison between the evaluation value Vi1 and the second threshold value Vth2 is not performed until the integration time is elapsed from the time when the integration unit 6 starts the integration processing. Therefore, the determination unit 4 does not perform the evaluation value Vi1 and the second threshold value Vth2 during the period in which the operation mode is the entry detection mode or the standby mode and even before the accumulation detection mode integration timer 41 ends the integration time count. Comparison. On the other hand, regarding the comparison between the amplitude of the output signal V1 and the first threshold value Vth1, the determination unit 4 does not perform the operation mode at any time. Therefore, in the stay detection mode, the determination unit 4 can also compare the amplitude of the output signal V1 with the first threshold value Vth1 (third threshold value), and if the amplitude of the output signal V1 becomes the first threshold value Vth1 In the above, the operation mode is switched from the stay detection mode to the standby mode. The output unit 7 outputs the determination result of the determination unit 4 to the illumination control system 80 as a detection result of the human detection system 10. The output unit 7 outputs a determination signal indicating the determination result of the determination unit 4 to the human detection system 10 in series. Specifically, the output unit 7 outputs a determination signal including a start bit, a determination result, and a stop bit. The determination signal may include, for example, mode information indicating an operation mode of the determination unit 4, and waveforms of the output signals V1 and V2, in addition to the determination results of the "personal state" or the "unmanned state". (2) Operation Next, the operation of the human detecting system 10 of the present embodiment will be described with reference to Fig. 5 . FIG. 5 is an explanatory diagram conceptually showing the operation of the determination unit 4. In FIG. 5, the first circle C1 indicates the determination result of the determination unit 4 of the "unmanned state". The second circle C2 indicates the determination result of the determination unit 4 of the "personal state". Further, in FIG. 5, a broken line arrow indicates a processing flow of the determination unit 4 based on a comparison result between the amplitude of the output signal V1 and the first threshold value Vth1. The solid arrow indicates the processing flow of the determination unit 4 based on the comparison result between the evaluation value Vi1 and the second threshold value Vth2. When the person detecting system 10 is powered on and the person detecting system 10 is activated, the determining unit 4 first operates in the entry detecting mode (step S1). At this time, since the determination result of the determination unit 4 is the unmanned state, the step S1 (entry detection mode) is located in the first circle C1. In the entry detection mode of step S1, the determination unit 4 compares the amplitude of the output signal V1 with the first threshold value Vth1. At this time, if the amplitude of the output signal V1 does not reach the first threshold value Vth1, the determination unit 4 continues the operation in the entry detection mode (step S2). On the other hand, when the amplitude of the output signal V1 becomes equal to or greater than the first threshold value Vth1, the determination unit 4 switches the operation mode from the entry detection mode to the standby mode (step S3). At this time, since the determination result of the determination unit 4 is the human state, the step S4 (standby mode) is located in the second circle C2. In the standby mode of step S4, the determination unit 4 compares the amplitude of the output signal V1 with the first threshold value Vth1 when the standby timer 42 ends the standby time count. When the standby timer 42 ends the standby time count, the determination unit 4 resets the count value of the standby timer 42 when the amplitude of the output signal V1 does not reach the first threshold value Vth1, and switches the operation mode from the standby mode to the stay detection. Mode (step S5). At this time, since the determination result of the determination unit 4 is the human state, the step S6 (the retention detection mode) is located in the second circle C2. On the other hand, when the standby timer 42 ends the standby time count, the determination unit 4 resets the count value of the standby timer 42 when the amplitude of the output signal V1 is equal to or greater than the first threshold value Vth1, and continues the standby mode. Action (step S7). In the stay detection mode of step S6, the determination unit 4 starts the comparison of the evaluation value Vi1 and the second threshold value Vth2 from the point of time when the integration timer 41 ends the integration time count. In addition, when the evaluation value Vi1 becomes equal to or greater than the second threshold value Vth2, the determination unit 4 does not reset the count value of the integration timer 41, and continues the operation in the stay detection mode (step S9). Further, in the stay detection mode, the determination unit 4 also compares the amplitude of the output signal V1 with the first threshold value Vth1, and if the amplitude of the output signal V1 becomes equal to or greater than the first threshold value Vth1, the operation mode is self-sustained. The detection mode is switched to the standby mode (step S10). At this time, the determination unit 4 resets the count value of the integration timer 41. Further, in the stay detection mode of step S6, if the evaluation value Vi1 becomes less than the second threshold value Vth2, the delay timer 43 starts counting the delay time. The determination unit 4 continues the operation in the stay detection mode until the delay timer 43 ends the counting of the delay time. When the delay timer 43 ends the counting of the delay time, the determination unit 4 switches the operation mode self-stagnation detection mode to the entry detection mode when the evaluation value Vi1 does not reach the second threshold value Vth2 (step S8). At this time, since the determination result of the determination unit 4 is the unmanned state, the step S1 (entry detection mode) is located in the first circle C1. Moreover, at this time, the determination unit 4 resets the count value of the integration timer 41 and the count value of the delay timer 43. On the other hand, when the evaluation value Vi1 becomes equal to or greater than the second threshold value Vth2, the determination unit 4 continues the operation in the stay detection mode (step S9). At this time, the determination unit 4 resets the count value of the integration timer 41 and the count value of the delay timer 43. When the amplitude of the output signal V1 becomes equal to or greater than the first threshold value Vth1, the determination unit 4 switches the operation mode self-suspension detection mode to the standby mode (step S10). At this time, the determination unit 4 resets the count value of the integration timer 41 and the count value of the delay timer 43. When the determination unit 4 enters the detection mode, the determination unit 4 determines that the state of the output signal V1 is equal to or greater than the first threshold value Vth1. When the determination unit 4 determines that the human state is in the entry detection mode, the determination unit 4 switches the operation mode from the entry detection mode to the standby mode. Moreover, the determination unit 4 switches the operation mode from the standby mode to the retention detection mode when the amplitude of the output signal V1 does not reach the first threshold value Vth1 at the time when the standby time elapses from the start of the operation in the standby mode. Further, in the stay detection mode, the determination unit 4 continues to maintain the evaluation value Vi1 less than the second threshold value Vth2 from the time when the evaluation value Vi1 becomes the second threshold value Vth2 until the specific delay time elapses. In the state, it is determined to be in an unattended state. When the determination unit 4 determines that the state is unmanned in the stay detection mode, the determination unit 4 switches the operation mode from the stay detection mode to the entry detection mode. The operation of the determination unit 4 described above is summarized as shown in Table 1. [Table 1] In other words, when the operation mode of the determination unit 4 is the entry detection mode, the determination target of the determination unit 4 is the amplitude of the output signal V1. Further, the determination unit 4 performs the processing of step S2 or step S3 based on the comparison result of the amplitude of the output signal V1 and the first threshold value Vth1. The determination result of the determination unit 4 in the operation mode of the determination unit 4 is the unmanned state. Moreover, when the operation mode of the determination unit 4 is the standby mode, the determination target of the determination unit 4 is the amplitude of the output signal V1. Further, the determination unit 4 performs the processing of step S5 or step S7 based on the comparison result of the amplitude of the output signal V1 and the first threshold value Vth1. The determination result of the determination unit 4 in the operation mode of the determination unit 4 in the standby mode is a human state. When the operation mode of the determination unit 4 is the retention detection mode, the determination target of the determination unit 4 is the amplitude of the output signal V1 and the evaluation value Vi1. Further, the determination unit 4 performs the processing of step S10 based on the comparison result of the amplitude of the output signal V1 and the first threshold value Vth1. The determination unit 4 performs the processing of step S8 or step S9 based on the comparison result between the evaluation value Vi1 and the second threshold value Vth2. The determination result of the determination unit 4 in the period in which the operation mode of the determination unit 4 is the retention mode is a human state. However, the processing of the determination unit 4 has priority, and the determination unit 4 preferentially executes the processing with higher priority. For example, in the stay detection mode, the determination unit 4 determines both the amplitude of the output signal V1 and the evaluation value Vi1 as the determination target, but the processing corresponding to the amplitude of the output signal V1 is higher than the processing priority corresponding to the evaluation value Vi1. In other words, when the determination unit 4 operates in the retention detection mode, the amplitude of the output signal V1 becomes equal to or greater than the first threshold value Vth1, and the evaluation value Vi1 becomes equal to or greater than the second threshold value Vth2, and the determination unit 4 performs the processing of step S10. Instead of the processing of step S9. Hereinafter, an example of the operation of the person detecting system 10 of the present embodiment will be described with reference to Fig. 6 . In the example of Fig. 6, it is assumed that at time t1, the person 91 enters the detection space 90, and at time t4, the person 91 exits from the detection space 90. 6 shows the output signal V1, the first flag F1, the evaluation value Vi1, the second flag F2, and the third flag F3 in order from the top with the horizontal axis as the time axis. When the standby timer 42 counts the standby time T1, the first flag F1 becomes "H" (High: high), and when the standby timer 42 does not count the standby time T1, it becomes "L" (Low: low). The second flag F2 is a temporary flag indicating a comparison result between the evaluation value Vi1 of the determination unit 4 and the second threshold value Vth2. When the evaluation value Vi1 is less than the second threshold value Vth2, the second flag F2 is "H" (high), and when the evaluation value Vi1 is equal to or greater than the second threshold value Vth2, it becomes "L" (low). The third flag F3 indicates the determination result of the determination unit 4. The third flag F3 is "H" (high) when the determination unit 4 determines that there is a human state, and becomes "L" (low) when the determination unit 4 determines that the state is unmanned. In addition, in FIG. 6, "M1" indicates a period in which the operation mode of the determination unit 4 is the entry detection mode, "M3" indicates a period in which the operation mode of the determination unit 4 is the standby mode, and "M2" indicates the operation of the determination unit 4. The mode is the period of the retention detection mode. In addition, "Ti1", "Ti2", and "Ti3" are periods in which the integration target period 6 is the target of the movement integration. In the example of FIG. 6, the determination unit 4 operates in the entry detection mode for the period before time t1, the determination result of the determination unit 4 is the unattended state, and the third flag F3 is "L". At time t1, the amplitude of the output signal V1 becomes equal to or greater than the first threshold value Vth1. Therefore, the determination unit 4 determines that there is a human state, and the third flag F3 becomes "H". At this time, the operation mode of the determination unit 4 is switched from the entry detection mode to the standby mode. In the period from time t1 to time t2, since the determination unit 4 operates in the standby mode, the first flag F1 becomes "H". Since the amplitude of the output signal V1 does not reach the first threshold value Vth1 at the time t2 when the standby timer 42 ends the standby time T1, the operation mode of the determination unit 4 is switched from the standby mode to the stay detection mode. At this time, the first flag F1 becomes "L". The determination unit 4 starts the comparison of the evaluation value Vi1 and the second threshold value Vth2 from the time t3 at which the integration timer 41 ends the integration time count. At time t3, the integration unit 6 performs integration for the integration target period Ti1, and the determination unit 4 compares the result of the evaluation value Vi1 with the second threshold value Vth2. At time t3, since the evaluation value Vi1 does not reach the second threshold value Vth2, the second flag F2 becomes "H", and the delay timer 43 starts counting the delay time T2. Thereafter, at time t4 before the delay timer 43 ends the delay time T2, the output signal V1 fluctuates, and the evaluation value Vi1 becomes equal to or greater than the second threshold value Vth2, so that the second flag F2 becomes "L". Thereafter, if the output signal V1 does not largely change, the evaluation value Vi1 becomes less than the second threshold value Vth2 at time t5 after the integration time elapses. Therefore, at time t5, the second flag F2 becomes "H", and the delay timer 43 starts counting the delay time T2. Then, when the output signal V1 does not largely change, the determination unit 4 determines that the unmanned state is reached at the time t6 when the delay timer 43 ends the delay time T2, and the third flag F3 becomes "L". At this time, the operation mode of the determination unit 4 is switched from the stay detection mode to the entry detection mode. (3) Advantages As described above, the human detecting system 10 of the present embodiment includes the light receiving unit 3 and the determining unit 4. The light receiving unit 3 has a light receiving element 11 that outputs a signal corresponding to a change in the intensity of received infrared light from the detection space 90. The determination unit 4 determines based on the output signals V1 and V2 of the light receiving unit 3 that the state of the detection space 90 is the presence of the human state of the person 91 in the detection space 90 and the absence of the person in the detection space 90. The operation mode of the determination unit 4 includes an entry detection mode that detects that the unmanned person 91 enters the detection space 90, and a retention detection mode in which the detection person 91 exits from the detection space 90. When the determination unit 4 enters the detection mode, if the comparison result of the amplitude of the output signal V1 and the first threshold value Vth1 satisfies the first determination condition, it is determined to be in a human state. The determination unit 4 is configured to satisfy the comparison result between the evaluation value Vi1 and the second threshold value Vth2 corresponding to the operation of the person 91 in the detection space 90, which is obtained based on the output signals V1 and V2 in the retention detection mode. When the condition is determined, it is determined to be in an unattended state. According to the above configuration, the operation mode of the determination unit 4 includes an entry detection mode in which the unmanned person 91 enters the detection space 90, and a retention detection mode in which the detection person 91 exits from the detection space 90. In other words, the determination unit 4 determines whether or not the state of the detection space 90 is a human state in the entry detection mode, and determines whether the state of the detection space 90 is an unmanned state in the retention detection mode. In this way, the determination unit 4 detects a change from the unmanned state to the human state and the change from the human state to the unmanned state in the operation modes different from each other. Therefore, for example, if the retention detection mode of the determination unit 4 is higher than the sensitivity of the entry detection mode, it is difficult to generate a small motion (twisting or the like) of the human in the retention detection mode, and the error can be suppressed in the entry detection mode. The generation of the test. Further, in the entry detection mode, the determination unit 4 determines whether or not the human state is based on the comparison result of the amplitude of the output signal V1 and the first threshold value Vth1. On the other hand, in the stay detection mode, the determination unit 4 compares the evaluation value Vi1 and the second threshold value Vth2 corresponding to the operation of the person 91 in the detection space 90 based on the values obtained by the output signals V1 and V2. And determine whether it is unmanned. That is, in the entry detection mode and the retention detection mode, the algorithm of the determination process of the determination unit 4 is different. Therefore, for example, in the staying detection mode, by applying an algorithm suitable for the detection of the minute motion of the person 91, the leak detection of the minute motion of the person 91 is less likely to occur. Further, the multiplication unit 5 and the integration unit 6 stop the operation while the operation mode of the determination unit 4 is in the entry detection mode. Therefore, the power consumption of the detection circuit 2 can be suppressed to be lower than the retention detection mode in the entry detection mode. Further, as in the present embodiment, the evaluation value Vi1 is preferably an integral value of the output signal. However, in the present embodiment, since the output signal V1 and the output signal V2 are "output signals", the evaluation value Vi1 is an integral value of the multiplied values of the output signals V1, V2. According to this configuration, the determination unit 4 determines whether or not the person 91 is present based on the integral value based on the instantaneous value of the output signals V1 and V2 in the retention detection mode. Therefore, for example, in the case where the person 91 is slightly moved by the breathing, the micro-action (minor movement) is periodically repeated, and the determination unit 4 can easily determine the presence person 91. However, the case where the evaluation value Vi1 is the integral value of the output signal is not essential for the human detecting system 10, and the evaluation value Vi1 is only the value determined based on the output signals V1, V2 and corresponds to the action of the person 91 in the detecting space 90. The value can be. Further, in the first embodiment, it is preferable that the amplitude of the output signal V1 becomes equal to or greater than the first threshold value Vth1. According to this configuration, when the determination unit 4 enters the detection mode and the amplitude of the output signal V1 becomes the first threshold value Vth1, it is immediately determined to be in a human state. Therefore, for example, the lighting fixture 81 can be immediately turned on when the person 91 enters the detection space 90. Further, in the present embodiment, the determination unit 4 is preferably configured to switch the operation mode from the stay detection mode to the entry detection mode if it is determined to be in the unattended state in the stay detection mode. According to this configuration, when the person 91 moves outside the detection space 90 from the detection space 90, the operation mode of the determination unit 4 is switched to the detection detection mode in which the unmanned person 91 enters the detection space 90. However, the configuration in which the determination unit 4 automatically switches the operation mode from the stay detection mode to the entry detection mode is not essential to the human detection system 10, and may be omitted as appropriate. Further, in the present embodiment, the operation mode of the determination unit 4 preferably includes a standby mode. In this case, it is preferable that the determination unit 4 switches the operation mode from the entry detection mode to the standby mode if it is determined to be in the human state in the entry detection mode. Further, the determination unit 4 is preferably configured such that when the predetermined standby time T1 elapses from the time when the operation in the standby mode is started, if the amplitude of the output signal V1 does not reach the first threshold value Vth1, the operation mode is self-operated. The standby mode is switched to the stay detection mode. According to this configuration, when the person 91 moves outside the detection space 90 toward the detection space 90, the operation mode of the determination unit 4 is automatically switched to the presence detection mode in which the detection person 91 exits from the detection space 90. Further, since the operation mode of the determination unit 4 is switched from the entry detection mode to the retention detection mode via the standby mode, the large operation of the human 91 does not immediately shift to the retention detection mode. The multiplication unit 5 and the integration unit 6 stop the operation while the operation mode of the determination unit 4 is in the standby mode. Therefore, the power consumption of the detection circuit 2 can be suppressed to be lower than the stay detection mode in the standby mode. However, the configuration in which the determination unit 4 automatically switches the operation mode from the entry detection mode to the standby mode through the standby mode is not essential to the human detection system 10, and may be omitted as appropriate. In this case, the determination unit 4 is preferably configured such that when the amplitude of the output signal V1 becomes the third threshold (the first threshold value Vth1 in the present embodiment) or more in the retention detection mode, The operation mode is switched from the dead detection mode to the standby mode. According to this configuration, in the case where the determination unit 4 operates in the retention detection mode, for example, when the large operation (walking or the like) of the person 91 is generated, the operation mode of the determination unit 4 is automatically switched to the standby mode. Therefore, the determination unit 4 starts to operate from the standby mode after the person 91 exits, for example, in the case where the person 91 passes only the detection space 90 and the person 91 stays in the detection space 90 and exits from the detection space 90. Therefore, the deviation of the time required for the person 91 to exit from the detection space 90 until the determination unit 4 determines that the unmanned state is determined can be suppressed to be small. Further, in the present embodiment, it is preferable that the second determination condition continues until the evaluation value Vi1 does not reach the second threshold from the time when the evaluation value Vi1 does not reach the second threshold value Vth2 until the specific delay time T2 elapses. The value of the value Vth2. According to this configuration, in the stay detection mode, the determination unit 4 does not immediately determine that the unmanned state is satisfied even if the evaluation value Vi1 does not reach the second threshold value Vth2. Therefore, for example, in a state where the person 91 is present in the detection space 90, the lighting fixture 81 is not easily turned off. (4) Variations FIG. 7 is an explanatory diagram conceptually showing the operation of the determination unit 4 of the human detection system 10 according to the first modification of the first embodiment. Fig. 7 is a conceptual diagram similar to Fig. 5, and thus detailed description is omitted. The person detecting system 10 of the first modification is different from the person detecting system 10 of the first embodiment in that the determining unit 4 does not have a function of switching the operation mode from the staying detection mode to the standby mode. In the first variation, when the operation mode of the determination unit 4 is switched from the standby mode (step S4) to the stay detection mode (step S6), the operation mode of the determination unit 4 is not directly switched to the standby mode. In other words, the operation of the determination unit 4 in the accumulation detection mode is either the operation in the retention detection mode (step S9) or the conversion (step S8) to the entry detection mode (step S1). In the first variation, when the operation mode of the determination unit 4 is the retention detection mode, it is not necessary to compare the amplitude of the output signal V1 with the first threshold value Vth1. FIG. 8 is an explanatory diagram conceptually showing the operation of the determination unit 4 of the human detection system 10 according to the second modification of the first embodiment. Fig. 8 is a conceptual diagram similar to Fig. 5, and thus detailed description is omitted. The human detecting system 10 of the second modification is different from the human detecting system 10 of the first embodiment in that the operation mode of the determining unit 4 does not include the standby mode. In the second variation, the determination unit 4 is configured to switch the operation mode from the entry detection mode to the retention detection mode when it is determined to be in the human state in the entry detection mode. In other words, the operation mode of the determination unit 4 is directly switched (step S3) from the entry detection mode (step S1) to the stay detection mode (step S6). In the second variation, when the operation mode of the determination unit 4 is the retention detection mode, it is not necessary to compare the amplitude of the output signal V1 with the first threshold value Vth1. Hereinafter, other modifications of the first embodiment will be exemplified. The human detection system 10 is not limited to residential use, and can also be used for non-residential homes such as offices, shops, or factories. Furthermore, the human detection system 10 is not limited to the house and can be used outdoors. Further, the detection result of the human detecting system 10 is not limited to the control of the lighting fixture, and may be used for control of an electric device other than a lighting fixture such as a ventilation fan or an anti-theft camera. Furthermore, the detection result of the human detection system 10 is not limited to the control of an electric machine, and may be used, for example, for monitoring the position of the person 91. In addition, the first determination condition, that is, the condition for determining that the human state is determined by the determination unit 4 in the entry detection mode is not limited to the case where the amplitude of the output signal V1 becomes equal to or greater than the first threshold value Vth1. For example, the first determination condition may be a case where the number of times the amplitude of the output signal V1 exceeds the first threshold value Vth1 by a predetermined number of times in a specific period. Further, in the entry detection mode, the determination unit 4 compares the amplitude of at least one of the output signal V1 of the first light receiving unit 31 and the output signal V2 of the second light receiving unit 32 with the first threshold value Vth1. It is only necessary to determine whether it is a human state. For example, the determination unit 4 may determine whether or not the human state is based on the comparison between the amplitude of both the output signal V1 of the first light receiving unit 31 and the output signal V2 of the second light receiving unit 32 and the first threshold value Vth1. Alternatively, the determination unit 4 may determine whether or not the human state is based on the comparison between the amplitude of the output signal V2 of the second light receiving unit 32 and the first threshold value Vth1. Further, the second determination condition, that is, the condition for determining that the unmanned state is determined by the determination unit 4 in the stay detection mode is not limited to the time from when the evaluation value Vi1 becomes the second threshold value Vth2 until the elapse of the delay time. The situation in which the evaluation value Vi1 does not reach the state of the second threshold value Vth2 is continuously maintained. For example, the second determination condition may be a case where the evaluation value Vi1 becomes less than the second threshold value Vth2. In other words, the function of the disconnection delay is not required for the determination unit 4. The determination unit 4 can determine that the evaluation value Vi1 has not reached the second threshold value Vth2 in the stay detection mode, and determines that the state is unmanned. However, this configuration is the same as the configuration in which the delay time is set to zero in the configuration of the first embodiment. Further, the operation mode of the determination unit 4 may include a delay mode in the retention detection mode as an operation mode for realizing the function of the off-delay in the determination unit 4. In this case, the determination unit 4 does not immediately determine that the unmanned state is satisfied even if the comparison result of the evaluation value Vi1 and the second threshold value Vth2 in the retention detection mode satisfies the second determination condition. In other words, the determination unit 4 sets up the temporary unmanned flag, switches the operation mode from the stay detection mode to the delay mode, and starts counting the delay time. The operation of the determination unit 4 in the delay mode is the same as the operation of the determination unit 4 in the case where the delay time is counted in the person detection system 10 of the first embodiment. Further, the function of the disconnection delay may be implemented not in the determination unit 4 but in the subsequent stage of the determination unit 4, for example, in the output unit 7. In this case, when the comparison result of the evaluation value Vi1 and the second threshold value Vth2 satisfies the second determination condition, the determination unit 4 immediately determines that the unmanned state is present. When the output unit 7 receives the determination result of the determination unit 4 that is determined to be in an unattended state, the output unit 7 starts counting the delay time. Further, the detection spaces 90 that receive the infrared rays by the first light receiving unit 31 and the second light receiving unit 32 may not completely match each other, and may be shifted from each other. In this case, there is a possibility that a phase difference is generated between the detection component included in the output signal V1 of the first light receiving unit 31 and the detection component included in the output signal V2 of the second light receiving unit 32. In this case, the multiplication result of the multiplication unit 5 is not limited to always being a positive value, and may be a negative value. Therefore, in addition to the second threshold value Vth2, the negative threshold value can be set as the comparison target of the evaluation value Vi1. In this case, the determination unit 4 may determine whether or not the person 91 exists based on the comparison result between the evaluation value Vi1 and the negative threshold value. (Embodiment 2) The human detecting system 10 of the present embodiment is different from the human detecting system 10 of the first embodiment in that the light receiving unit 3 has only the first light receiving unit 31. In the following, the same components as those in the first embodiment are denoted by the same reference numerals, and their description will be appropriately omitted. In the entry detection mode, the determination unit 4 determines whether or not the person 91 is present based on the comparison result of the amplitude of the output signal V1 of the first light receiving unit 31 and the first threshold value Vth1, similarly to the human detection system 10 of the first embodiment. On the other hand, in the stay detection mode, the determination unit 4 uses the integrated value of the multiplied result of the output signal V1 of the first light receiving unit 31 and the reference signal as the evaluation value Vi1. In other words, the evaluation value Vi1 multiplies the output signal V1 of the first light receiving unit 31 by the multiplying unit 5 by the multiplying unit 5, and integrates the multiplication result by the integrating unit 6. The reference signal referred to herein is, for example, a sine wave of a frequency (for example, 0.3 Hz and 0.5 Hz) corresponding to the minute motion of the person 91. Further, the reference signal may be a signal that is substantially in phase with the output signal V1 of the first light receiving unit 31 by, for example, shifting the output signal V1 of the first light receiving unit 31 by a specific amount of time. As described above, in the human detecting system 10 of the present embodiment, even if the light receiving unit 31 has only the first light receiving unit 31, the determining unit 4 can operate in two operation modes of the detection mode and the retention detection mode. The configuration of the human detecting system 10 of the second embodiment can be combined as appropriate with the configuration of the first embodiment (including the modified example). Further, in the above-described respective embodiments (including the modified examples), the description of "above" in the comparison between the two values such as the amplitude and the threshold value means that the case where the two values are equal and one value of the two values exceeds Two of the other values. However, it is not limited thereto, and "above" may be synonymous with "larger" in a case where only one value of two values exceeds another value. In other words, whether or not the case where the two values are equal is arbitrarily changed according to the setting of the threshold value, etc., so that "above" or "larger" is technically indistinguishable. Similarly, "not reached" can also be synonymous with "below".