200823589 九、發明說明： 【發明所屬之技術領域】 本發明係有關於一種投影機，特別是指一種自動聚焦 投影機及其自動聚焦方法。 【先前技術】 投影機作爲一種影像投射放大裝置，廣泛應用於教 學、培訓、會議等場合。投影機主要根據輸入之影像訊號， 利用液晶單元或者DMD(Digital Micromirror Device，數位 微反射器）微晶片等，將光源發出之照明光調變成顯示影像 之影像光，然後藉由光學透鏡系統，將影像光放大投射到 螢幕上，以方便教學、培訓、會議等場合作演示之用。 習知投影機，用戶常需要根據其擺放位置，調整其光 學透鏡系統的焦距和聚焦位置，以使投射到螢幕上的影像 獲得較佳之清晰度。投影機聚焦調整方法大致包括手動調 •焦法與自動調焦法。然而手動調焦法存在操作複雜、耗時 等缺失。尤其對於吊頂式投影機，由於其通過支架和連杆 固定於天花板上，在實際操作中，用戶無法手動調節光學 透鏡系統之焦距和聚焦位置。 投影機自動調焦法通常又可分爲測距法和像檢測法兩 種。一種典型之紅外線測距法，其投影機通過向螢幕發射 紅外線，並接收從螢幕反射之光線，通過獲得紅外線發射 到接收之傳播時間，並計算投影機和螢幕之距離，再基於 此投射距離驅動光學透鏡系統調整焦距和聚焦位置，以獲 7 200823589 得清晰的投影影像。採用此種方法之紅外線裝置雖然結構 簡單，然一般投影機之投射距離爲2〜6米左右，且紅外線 之傳播速度（空氣介質中約300 ’ 〇〇〇千米/秒）較快，一般 計時器很難達到10-8秒數量級之檢測精度，因而用此種方 法來調節光學透鏡系統的焦距存在調節精度不高之缺點。 另外紅外線易於被物體吸收，有時出現漏檢現象，故實際 應用中難以獲得理想之光學聚焦。 一種典型之對比度像檢測法採用類似相機産品使用的 自動聚焦（AF，Auto Focus)測距元件。其首先向螢幕投 射出預設之測試圖樣，通過自動聚焦元件擷取此預設之測 試圖樣，並基於對比度、亮度等影像參數即時地對榻取之 圖樣進行處理’與内部已設置之影像參數指標值進行比 對’判斷聚焦是否準確’進而給出控制信號驅動光學透鏡 糸統調整採用此種方法存在之問題為，在接近 狀態下’隨著焦距移動，對比度、亮度影像參 故，其通常要多次採集預定測試圖樣進行 二數比對’因而-般需要耗#較長之時間進行自動聚焦調 【發明内容】 的 有鑒於此，有必要提供一 自動聚焦投影機。 種調節精度高且調整時間短 此外，還有必要提供一 一種自動聚焦投影機， 種投影機之自動聚焦方法。 使輸入影像訊號經光學透鏡系 8 200823589 、'先♦焦投射到螢幕上。包括一輸出模組和一資料處理模 組，所述輸出模組用於將影像投射到螢幕上，所述資料處 理模组用於5十异投景夕機和螢幕間之距離，並基於此距離值 =整輸出模組。其還包括-超音波發射接收模組，所述超 音波發射接收模組包括超音波發生單元，調變解調變變模 組、’計時單元，所述超音波發生單元用於産生超音波訊號， 所述調，解調變變模組用於調變解調變變超音波訊號，所 鲁述计時早疋用於計算超音波從發射到接收之傳播時間，並 將時間訊號傳輸給資料處理模組。 一種投影機之自動聚焦方法，包括如下步驟： 超音波發生單元產生超音波訊號，調變單元調變超音 f訊，’超音波發射接收模組發射、接收超音波，解調變 =^變接收之超音波訊號，計時單元計算超音波從發 間；資料處理模組計算投影機到榮幕之投射 二輸出农相匹配的變焦參數訊號和聚焦位置參數訊 2輪“組㈣變域鏡和聚线鏡 值和聚焦位置參數值。 Li焦參數 與習知技㈣比’料相同之投射 超音波的傳播速度快約…的數量 条件下’測量超音波之傳播時間比 播時間獲得之精確度要高；此外，.外:線：傳 音波=二=確定的對應關係，所以通過超 与播夕ώ * 射距離值後，即可對應進行投 動聚焦調整，相對對比度像檢㈣需㈣進行自 9 200823589 動聚焦調整而言，有利於縮短自動聚焦之調整時間。 【實施方式】 以下藉由具體實施例配合所附圖式之詳細說明，當更 易瞭解本發明之目的、技術内容、特點及其所達成之功效。 如圖1所示，投影機100包括依次電性連接之超音波 發射接收模組300、資料處理模組400及輸出模組500。超 音波發射接收模組300用於發射和接收超音波，並計算超 _ 音波從發射到接收之傳播時間Δί。資料處理模組400用於 根據傳播時間△(，由公式Δ5 = ν·Δί/2計算投影機100和螢幕 200之間之投射距離As，並給出與當前投射距離As最相匹 配之變焦參數值和聚焦參數值。輸出模組500用於根據接 收之變焦參數值和聚焦參數值將調變影像光清晰地投射到 螢幕200上。以下將參照附圖2、附圖3、附圖4對超音波 發射接收模組300、資料處理模組400和輸出模組500之 馨較佳實施方式予以詳細描述。 如圖2所示，超音波發射接收模組300主要包括超音 波發生單元310、調變單元320、發射放大單元330、發射 轉換單元340、接收轉換單元350、接收放大單元360、解 調變單元370、檢波單元380及計時單元390。超音波發生 單元310用於發射超音波訊號和計時驅動訊號。調變單元 320和解調變單元370分別用於根據不同之訊號調變模式 調變和解調變超音波訊號。發射放大單元330和接收放大 單元360都用於將訊號進行無失真放大。發射轉換單元340 200823589 和接收轉換單元350分>別用於將電訊號轉換成超音波和將 超音波轉換成電訊號。檢波單元380用於檢測具有特定頻 率或者振幅之訊號。計時單元390用於計算超音波發射到 接收之傳播時間。其中，發射轉換單元340具有一轉換元 件（圖未示），其較佳的以壓電陶兗等材料製成。 在超音波發射接收模組300發射超音波時，超音波發 生單元310同步産生一超音波訊號S 311和一計時驅動訊 號S312。其中，超音波訊號S311之振動頻率較佳的爲40 響千赫茲。計時單元390接收計時驅動訊號S312後開始計 時，並設定開始計時的時刻爲[。調變單元320較佳地以 幅度調變（AM，Amplitude Modulation)模式工作，其接收 到超音波訊號S311後，産生一低頻調頻信號（該低頻調 頻信號可爲20赫茲），將此低頻調頻信號疊加到超音波訊 號S311上，從而得到周期間隔爲0.05秒而以40千赫茲的 頻率振蕩的調變信號S321。發射放大單元330接收調變信 馨號S321並將其放大，輸出驅動訊號S331給發射轉換單元 340。發射轉換單元340在驅動訊號S331之作用下，利用 壓電陶瓷之壓電共振現象（即驅動訊號之工作頻率等於壓 電陶瓷之固有振動頻率時，輸出最大的機械波訊號）産生 向螢幕200發射的超音波W341。有關超音波發射接收模 組300接收從螢幕200反射回來之超音波過程如下所述。 在超音波發射接收模組300接收從螢幕200反射回來 之超音波W351時，接收轉換單元350利用壓電陶瓷的逆 壓電效應將超音波W351轉換成周期間隔爲0.05秒而以40 11 200823589 千赫茲之頻率振蕩之超音波訊號S351。接收放大單元360 接收超音波訊號S351，將其放大，以補償超音波在入射、 反射過程中被衰減之超音波能量，並輸出放大信號S361 給解調變單元370。解調變單元370之解調變模式和調變 單元320之調變模式相對應，其較佳的爲幅度解調變（AD， Amplitude Demodulation)工作模式。其從周期間隔爲0.05 秒而以40千赫茲之頻率振蕩之放大訊號S361中解調變出 40千赫茲之超音波訊號S371，並將超音波訊號S371輸出 ® 給檢波單元380。檢波單元380較佳地以頻率檢測方式工 作，其對特徵頻率爲40千赫茲之訊號作出回應，並輸出觸 發訊號S381給計時單元390。計時單元390接收到此觸發 訊號S381即停止計時，並輸出時間訊號S391給資料處理 模組400。設停止計時之時刻爲ί2，則時間訊號S391中包 含之傳播時間為。 在圖2所示之超音波發射接收模組300之實施方式 馨中，超音波訊號的調變和解調變功能分別由兩個單元（即 調變單元320和解調變單元370)來達成。因爲解調變的 工作模式和調變模式相對應，所以也可以另一實施方式， 以一獨立之調變解調變模組替換兩個單元達成調變解調變 功能。 如圖2所示，本實施方式揭示之接收放大單元360進 一步可使期具備濾波功能，或者在接收放大單元360的前 面進一步配置一濾波單元（圖未示），該濾波單元電性連接 於接收轉換單元350和接收放大單元360之間，以進一步 12 200823589 濾除可能由外界聲源産生之干擾訊號。 如圖3所示，資料處理模組400包括與匯流排460電 性連接之距離測量單元410、ROM存儲單元420、RAM存 儲單元430、控制單元440及比較單元450。距離测量單元 410用於根據接收之時間訊號△/，依照公式Δ5 = ν·Δί/2,計 算投影機當前之投射距離As*。其中超音波傳播速度ν可根 據實際環境測量得之數值在距離測量單元430中預先予以 設定。ROM存儲單元420用於存儲與投射距離相對應之焦 胃距參數表和聚焦位置參數表。RAM存儲單元430用於存儲 資料處理程式。控制單元440用於控制程式之執行和資料 在匯流排460上之傳遞。比較單元450用於比較得出與當 前投射距離最相匹配之變焦參數值和聚焦位置參數值。其 中，ROM存儲單元420進一步包括變焦參數單元421和聚 焦參數單元422，分別用於存儲與不同之投射距離相對應 之焦距參數表和聚焦位置參數表。因投影機與螢幕之投射 0距離確定後，投影鏡頭之變焦透鏡和聚焦透鏡即分別對應 有一最佳的工作焦距/和一最佳的聚焦位置X，其中/和X 的數值可由透鏡成像公式計算而得。 資料處理模組400開始處理資料時，控制單元440即 調用RAM存儲單元中之資料處理程式並順序執行。首先， 距離測量單元410接收從超音波發射接收模組300輸出之 時間訊號S391，執行乘法運算，計算得到距離值Λ?，並産 生包含該距離值的距離訊號S411。在控制單元440之控制 下，距離訊號S411被傳遞到資料匯流排460上。然後， 13 200823589 變焦參數單元421中的變焦參數表和聚焦參數單元422中 的聚焦參數表逐一被讀取並傳遞到資料匯流排460上。接 著，比較單元450從資料匯流排460上讀取距離訊號S411 和變焦參數訊號S421、聚焦位置參數訊號3422，逐一從 參數表中比較出與當前投射距離值最相匹配之焦距值和聚 焦位置值，並將變焦參數訊號S451和聚焦參數訊號S452 傳給輸出模組500。 _ 如圖4所示，輸出模組500包括驅動模組510和光學 透鏡系統520。驅動模組510通過變焦電機512和聚焦電 機513連接並控制光學透鏡系統520。驅動模組510進一 步包括電機驅動電路511、變焦電機5Ί2及聚焦電機513 (較佳的可爲步進電機，步進電機按照載入其上之電壓或 者電流轉動一定的步進值）。其中，電機驅動電路511分別 和變焦電機512和聚焦電機513電性連接，電機驅動電路 511用於控制變焦電機512和聚焦電機513之作動。變焦 _電機512和聚焦電機513分別用於改變變焦透鏡521的焦 距值和聚焦透鏡522的聚焦位置值。光學透鏡系統520進 —步包括變焦透鏡521、聚焦透鏡522和光軸523，其中變 焦透鏡521之作用是改變透鏡521自身之焦距值而不改變 透鏡沿光軸523的位置，聚焦透鏡522的作用是使透鏡522 沿光軸523作前後移動改變焦點之位置而不改變透鏡522 自身之焦距值。 輸出模組500之工作原理如下：電機驅動電路510接收 資料處理模組400輸出之變焦參數信號S451和聚焦參數 200823589 信號S452，分別輸出變焦控制信號S511、聚焦控制信號 S512給變焦電機512和聚焦電機513。變焦電機512按照 驅動訊號S511之大小轉動特定的步進數值，並使變焦透 鏡521改變自身的焦距，取得最佳的焦距值/。聚焦電機 513按照控制信號S512的大小轉動一定的步進數值，並帶 動聚焦透鏡522，使其沿光轴523前後移動到最佳聚焦位 置Z。由此即達成投影機之自動調節功能，並使經光學透 鏡系統520投射到螢幕200上之影像達到較佳之清晰度。 — 如圖4所示，光學透鏡系統520可在變焦透鏡521和 聚焦透鏡522基礎上設置若干光學鏡片（圖未示）。變焦透 鏡521和聚焦透鏡522及光學鏡片之組合提供合適之光學 放大倍率，使得光學透鏡系統520具備多倍光學變焦功 能，因而用戶在近距離、遠距離觀看時，均可獲得更佳之 影像清晰度。 圖5A所示爲本發明投影機自動聚焦方法一較佳實施 馨方式之流程圖。投影機自動聚焦方法之工作原理如下： 步驟910，投影機開始工作後，首先判斷投影機100 當前之聚焦是否正確，如果聚焦正確，則整個流程轉向結 束，如果聚焦不正確，則將進行自動聚焦調整。 步驟920，投影機聚焦不正確，進行自動聚焦調整。 由超音波發射接收模組300向螢幕200發射超音波，並接 收從螢幕200發射之超音波，有關發射接收超音波之方法 將在下面作詳細描述。 步驟930，計時單元390在聲波發射接收模組300發 15 200823589 出超音波時開始計時，接收到超音波時停止計時，由此計 算出超音波從發射到接收之傳播時間以。 步驟940，資料處理模組400接收從超音波發射接收 模組300傳遞來的時間訊號Δί，由距離測量單元430，利 用公式Δ5 = ν·Δί/2,執行乘法運算，得出投影機100與螢幕 200的投射距離。 步驟950，通過比較單元460，將實際測量之投射距離 &與存儲在ROM單元440中之變焦參數表和聚焦參數表 ® 中之數值逐一進行比較，輸出與當前投射距離最相匹配之 變焦參數值和聚焦位置參數值。 步驟960,輸出模組500,接收從資料處理模組傳遞來 之變焦參數值和聚焦位置參數值。電機驅動電路驅動變焦 電機320和聚焦電機330,使變焦透鏡3403調整到最佳焦 距值/，聚焦透鏡調整到最佳聚焦位置Z，達成對投影機 之自動聚焦，流程結束。 φ 承上所述，如圖5B所示，步驟502中之發射接收超 音波之方法進一步包括如下步驟。 步驟921，超音波發生單元310産生超音波訊號。 步驟922，調變單元320將超音波訊號調變成調變信 號。 步驟923，發射放大單元330對調變信號進行放大。 步驟924，發射轉換單元340根據放大之調變信號向 螢幕200發射超音波。 步驟925，接收轉換單元350接收從螢幕200反射回 16 200823589' 來之超音波，將超音波轉換成電訊號。 放大步驟926，接收放大單元36〇對轉換後之電信號進行 從放大後之電信號中解調 步驟927，解調變單元370 變出超音波訊號。 、如圖5B所示，本實施方式揭示之發射接收超音波方 法之步驟926中。可梯接你备4*〇〇-：^ 、 使接收放大早兀進一步具備濾波功BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projector, and more particularly to an autofocus projector and an autofocus method thereof. [Prior Art] As a kind of image projection and amplification device, the projector is widely used in teaching, training, conferences and other occasions. The projector mainly adjusts the illumination light emitted by the light source into the image light of the display image according to the input image signal, using a liquid crystal unit or a DMD (Digital Micromirror Device) microchip, etc., and then by the optical lens system, The image light is magnified and projected onto the screen to facilitate collaborative presentations such as teaching, training, and conferences. Conventional projectors, where users often need to adjust the focal length and focus position of their optical lens system based on their placement to achieve better clarity of the image projected onto the screen. The projector focus adjustment method generally includes manual focus adjustment and automatic focus adjustment. However, the manual focus method has the disadvantages of complicated operation and time consuming. Especially for ceiling-mounted projectors, since they are fixed to the ceiling by brackets and connecting rods, in practice, the user cannot manually adjust the focal length and focus position of the optical lens system. The projector autofocus method is usually divided into two methods: ranging method and image detection method. A typical infrared ranging method, in which the projector emits infrared rays to the screen and receives the light reflected from the screen, obtains the propagation time of the infrared emission to the reception, calculates the distance between the projector and the screen, and drives based on the projection distance. The optical lens system adjusts the focus and focus position to obtain a clear projected image of 7 200823589. Although the infrared device using the method has a simple structure, the projection distance of the projector is generally about 2 to 6 meters, and the propagation speed of the infrared rays (about 300 '〇〇〇 km/sec in the air medium) is fast, and the timing is generally It is difficult to achieve the detection accuracy of the order of 10-8 seconds, and thus the method of adjusting the focal length of the optical lens system has the disadvantage that the adjustment precision is not high. In addition, infrared rays are easily absorbed by objects, and sometimes leak detection occurs, so that it is difficult to obtain an ideal optical focus in practical applications. A typical contrast image detection method uses an AF (Auto Focus) ranging component similar to that used in camera products. Firstly, the preset test pattern is projected onto the screen, and the preset test pattern is captured by the auto-focusing component, and the pattern of the couch is processed on the basis of the image parameters such as contrast and brightness, and the image parameters set internally are set. The index value is compared to 'determine whether the focus is accurate' and then the control signal is driven to drive the optical lens. The problem is that the method has the problem that in the close state, as the focal length moves, the contrast and brightness images are changed, which is usually It is necessary to provide a self-focusing projector in order to collect a predetermined test pattern a plurality of times for a plurality of comparisons. Therefore, it takes a long time to perform automatic focus adjustment. High adjustment accuracy and short adjustment time In addition, it is also necessary to provide an autofocus projector, an autofocus method for the projector. The input image signal is projected onto the screen through the optical lens system 8 200823589. The utility model comprises an output module and a data processing module, wherein the output module is used for projecting an image onto a screen, and the data processing module is used for the distance between the screen and the screen, and based on the Distance value = integer output module. The method further includes an ultrasonic transmitting and receiving module, wherein the ultrasonic transmitting and receiving module comprises an ultrasonic generating unit, a modulated demodulation and transforming module, and a timing unit, wherein the ultrasonic generating unit is configured to generate an ultrasonic signal. The modulation and demodulation transformer module is used for modulating the demodulation and transforming the ultrasonic signal, and the timing is used to calculate the propagation time of the ultrasonic wave from the transmission to the reception, and transmitting the time signal to the data. Processing module. An automatic focusing method for a projector includes the following steps: an ultrasonic generating unit generates an ultrasonic signal, a modulation unit modulates an ultrasonic super-acoustic signal, and a 'sound wave transmitting and receiving module transmits and receives ultrasonic waves, and the demodulation becomes variable. Receiving the ultrasonic signal, the timing unit calculates the ultrasonic wave from the hair; the data processing module calculates the projection of the projector to the screen of the glory; the output of the matching zoom parameter signal and the focus position parameter of the agricultural phase 2 rounds "group (four) variable domain mirror and Convergence mirror value and focus position parameter value. Li focus parameter and conventional technique (4) The accuracy of measuring the propagation time of ultrasonic wave is better than the broadcast time under the condition that the propagation speed of the projected ultrasonic wave is the same as that of the material. To be high; in addition, the outer: line: the sound wave = two = the corresponding relationship, so through the super and the broadcast ώ * shoot distance value, you can correspondingly carry out the focus adjustment, relative contrast image inspection (four) need (four) In the case of the dynamic focus adjustment of 9 200823589, it is advantageous to shorten the adjustment time of the auto focus. [Embodiment] Hereinafter, it is easier to use the detailed description of the drawings with specific embodiments. The purpose of the present invention is to understand the purpose, technical content, features and functions achieved by the present invention. As shown in FIG. 1 , the projector 100 includes an ultrasonic transmitting and receiving module 300, a data processing module 400 and an output module 500 which are electrically connected in sequence. The ultrasonic transmitting and receiving module 300 is configured to transmit and receive ultrasonic waves, and calculate a propagation time Δί of the super_sonic wave from transmission to reception. The data processing module 400 is configured to use the propagation time Δ (by the formula Δ5 = ν·Δί /2 calculates the projection distance As between the projector 100 and the screen 200, and gives a zoom parameter value and a focus parameter value that best match the current projection distance As. The output module 500 is configured to receive the zoom parameter value and focus according to the received projection distance. The parameter value clearly reflects the modulated image light onto the screen 200. The following will refer to FIG. 2, FIG. 3, and FIG. 4 for the ultrasonic emission receiving module 300, the data processing module 400, and the output module 500. The preferred embodiment is described in detail. As shown in FIG. 2, the ultrasonic transmitting and receiving module 300 mainly includes an ultrasonic generating unit 310, a modulation unit 320, a transmitting and amplifying unit 330, a transmitting and converting unit 340, and receiving and transmitting. The switching unit 350, the receiving and amplifying unit 360, the demodulating and transforming unit 370, the detecting unit 380 and the timing unit 390. The ultrasonic generating unit 310 is configured to transmit the ultrasonic signal and the timing driving signal. The modulation unit 320 and the demodulation unit 370 are respectively used. The ultrasonic signal is modulated and demodulated according to different signal modulation modes. Both the transmission amplifying unit 330 and the receiving amplifying unit 360 are used for amplitude-free amplification of the signal. The transmission conversion unit 340 200823589 and the receiving conversion unit 350 are different. For converting electrical signals into ultrasonic waves and converting ultrasonic waves into electrical signals. The detecting unit 380 is configured to detect signals having a specific frequency or amplitude. The timing unit 390 is configured to calculate the propagation time of the ultrasonic waves transmitted to the receiving. The emission conversion unit 340 has a conversion element (not shown), which is preferably made of a material such as piezoelectric ceramics. When the ultrasonic transmitting and receiving module 300 transmits the ultrasonic wave, the ultrasonic generating unit 310 synchronously generates an ultrasonic signal S 311 and a timing driving signal S312. Among them, the ultrasonic signal S311 preferably has a vibration frequency of 40 kHz. The timing unit 390 starts counting after receiving the timing driving signal S312, and sets the timing to start counting to [. The modulation unit 320 preferably operates in an AM (Amplitude Modulation) mode, and after receiving the ultrasonic signal S311, generates a low frequency FM signal (the low frequency FM signal can be 20 Hz), and the low frequency FM signal is generated. Superimposed on the ultrasonic signal S311, a modulated signal S321 having a period of 0.05 second and oscillating at a frequency of 40 kHz is obtained. The transmission amplifying unit 330 receives the modulation signal S321 and amplifies it, and outputs a driving signal S331 to the transmission converting unit 340. The emission conversion unit 340 generates the piezoelectric resonance phenomenon of the piezoelectric ceramic under the action of the driving signal S331 (that is, when the operating frequency of the driving signal is equal to the natural vibration frequency of the piezoelectric ceramic, the maximum mechanical wave signal is output), and the emission is generated to the screen 200. Ultrasonic W341. The ultrasonic process associated with the ultrasonic transmitting and receiving module 300 receiving the reflection from the screen 200 is as follows. When the ultrasonic transmitting and receiving module 300 receives the ultrasonic wave W351 reflected from the screen 200, the receiving conversion unit 350 converts the ultrasonic wave W351 into a periodic interval of 0.05 seconds by using the inverse piezoelectric effect of the piezoelectric ceramic to 40 11 200823589 thousand. The ultrasonic signal of the Hertz frequency oscillates S351. The receiving amplification unit 360 receives the ultrasonic signal S351, amplifies it to compensate the ultrasonic energy that the ultrasonic wave is attenuated during the incident and reflection, and outputs the amplified signal S361 to the demodulation unit 370. The demodulation mode of the demodulation unit 370 corresponds to the modulation mode of the modulation unit 320, which is preferably an AD (Amplitude Demodulation) mode of operation. The ultrasonic signal S371 which is 40 kHz is demodulated from the amplification signal S361 which is oscillated at a frequency of 40 kHz with a period of 0.05 second, and the ultrasonic signal S371 is output to the detection unit 380. The detecting unit 380 preferably operates in a frequency detecting manner, which responds to a signal having a characteristic frequency of 40 kHz and outputs a trigger signal S381 to the timing unit 390. The timing unit 390 stops the timing when receiving the trigger signal S381, and outputs the time signal S391 to the data processing module 400. When the timing of stopping the timing is ί2, the propagation time included in the time signal S391 is. In the embodiment of the ultrasonic transmitting and receiving module 300 shown in Fig. 2, the modulation and demodulation function of the ultrasonic signal is achieved by two units (i.e., the modulation unit 320 and the demodulation unit 370). Since the demodulation operation mode and the modulation mode correspond to each other, another embodiment can be used to replace the two units with a separate modulation and demodulation module to achieve the modulation and demodulation function. As shown in FIG. 2, the receiving and amplifying unit 360 disclosed in this embodiment may further have a filtering function, or a filtering unit (not shown) may be further disposed in front of the receiving and amplifying unit 360, and the filtering unit is electrically connected to the receiving unit. Between the converting unit 350 and the receiving amplifying unit 360, further 12 200823589 filters out interference signals that may be generated by an external sound source. As shown in FIG. 3, the data processing module 400 includes a distance measuring unit 410, a ROM storage unit 420, a RAM storage unit 430, a control unit 440, and a comparison unit 450 that are electrically connected to the bus bar 460. The distance measuring unit 410 is configured to calculate the current projection distance As* of the projector according to the received time signal Δ/ according to the formula Δ5 = ν·Δί/2. The ultrasonic propagation velocity ν can be previously set in the distance measuring unit 430 based on the value measured by the actual environment. The ROM storage unit 420 is for storing a focus parameter table and a focus position parameter table corresponding to the projection distance. The RAM storage unit 430 is used to store a data processing program. Control unit 440 is used to control the execution of the program and the transfer of material on bus 460. The comparison unit 450 is for comparing the zoom parameter value and the focus position parameter value that best match the current projection distance. The ROM storage unit 420 further includes a zoom parameter unit 421 and a focus parameter unit 422 for storing a focus parameter table and a focus position parameter table corresponding to different projection distances, respectively. After the projection distance between the projector and the screen is determined, the zoom lens and the focus lens of the projection lens respectively have an optimal working focal length / and an optimal focus position X, wherein the values of / and X can be calculated by the lens imaging formula. And got it. When the data processing module 400 starts processing data, the control unit 440 calls the data processing program in the RAM storage unit and executes them sequentially. First, the distance measuring unit 410 receives the time signal S391 outputted from the ultrasonic transmitting and receiving module 300, performs a multiplication operation, calculates a distance value Λ?, and generates a distance signal S411 including the distance value. Under the control of the control unit 440, the distance signal S411 is delivered to the data bus 460. Then, 13 200823589 The zoom parameter table in the zoom parameter unit 421 and the focus parameter table in the focus parameter unit 422 are read one by one and transferred to the data bus 460. Next, the comparing unit 450 reads the distance signal S411, the zoom parameter signal S421, and the focus position parameter signal 3422 from the data bus 460, and compares the focal length value and the focus position value that match the current projection distance value one by one from the parameter table. And the zoom parameter signal S451 and the focus parameter signal S452 are transmitted to the output module 500. As shown in FIG. 4, the output module 500 includes a drive module 510 and an optical lens system 520. The drive module 510 is coupled to and controls the optical lens system 520 via a zoom motor 512 and a focus motor 513. The drive module 510 further includes a motor drive circuit 511, a zoom motor 5Ί2, and a focus motor 513 (preferably a stepper motor that rotates a certain step according to the voltage or current loaded thereon). The motor driving circuit 511 is electrically connected to the zoom motor 512 and the focus motor 513, respectively, and the motor driving circuit 511 is used to control the operations of the zoom motor 512 and the focus motor 513. The zoom_motor 512 and the focus motor 513 are used to change the focus value of the zoom lens 521 and the focus position value of the focus lens 522, respectively. The optical lens system 520 further includes a zoom lens 521, a focus lens 522, and an optical axis 523. The function of the zoom lens 521 is to change the focal length value of the lens 521 itself without changing the position of the lens along the optical axis 523. The function of the focus lens 522 is The lens 522 is moved back and forth along the optical axis 523 to change the position of the focus without changing the focal length value of the lens 522 itself. The working principle of the output module 500 is as follows: the motor driving circuit 510 receives the zoom parameter signal S451 and the focus parameter 200823589 signal S452 output by the data processing module 400, and outputs a zoom control signal S511 and a focus control signal S512 to the zoom motor 512 and the focus motor, respectively. 513. The zoom motor 512 rotates a specific step value in accordance with the size of the drive signal S511, and causes the zoom lens 521 to change its focal length to obtain an optimum focal length value /. The focus motor 513 is rotated by a certain step value in accordance with the magnitude of the control signal S512, and drives the focus lens 522 to move back and forth along the optical axis 523 to the optimum focus position Z. Thereby, the automatic adjustment function of the projector is achieved, and the image projected onto the screen 200 via the optical lens system 520 achieves better definition. As shown in FIG. 4, the optical lens system 520 may be provided with a plurality of optical lenses (not shown) based on the zoom lens 521 and the focus lens 522. The combination of the zoom lens 521 and the focus lens 522 and the optical lens provides suitable optical magnification, so that the optical lens system 520 has multiple optical zoom functions, so that the user can obtain better image sharpness when viewed at close range and at a distance. . Fig. 5A is a flow chart showing a preferred embodiment of the automatic focusing method of the projector of the present invention. The working principle of the projector autofocus method is as follows: Step 910, after the projector starts working, first determine whether the current focus of the projector 100 is correct. If the focus is correct, the whole process is turned to the end, and if the focus is not correct, the auto focus will be performed. Adjustment. In step 920, the projector is not in focus and the auto focus adjustment is performed. The ultrasonic transmitting and receiving module 300 transmits ultrasonic waves to the screen 200 and receives ultrasonic waves transmitted from the screen 200. A method for transmitting and receiving ultrasonic waves will be described in detail below. In step 930, the timing unit 390 starts counting when the acoustic wave transmitting and receiving module 300 sends out an ultrasonic wave, and stops counting when receiving the ultrasonic wave, thereby calculating the propagation time of the ultrasonic wave from transmission to reception. Step 940, the data processing module 400 receives the time signal Δί transmitted from the ultrasonic wave transmitting and receiving module 300, and the distance measuring unit 430 performs a multiplication operation by using the formula Δ5 = ν·Δί/2 to obtain the projector 100 and The projection distance of the screen 200. Step 950, by comparing unit 460, comparing the actual measured projection distance & with the values in the zoom parameter table and the focus parameter table® stored in the ROM unit 440, and outputting the zoom parameter that most closely matches the current projection distance. Value and focus position parameter values. Step 960, the output module 500 receives the zoom parameter value and the focus position parameter value transmitted from the data processing module. The motor drive circuit drives the zoom motor 320 and the focus motor 330 to adjust the zoom lens 3403 to the optimum focus value /, and the focus lens is adjusted to the optimum focus position Z to achieve automatic focusing of the projector, and the flow ends. As shown in Fig. 5B, the method of transmitting and receiving the ultrasonic wave in step 502 further includes the following steps. In step 921, the ultrasonic generating unit 310 generates an ultrasonic signal. In step 922, the modulation unit 320 adjusts the ultrasonic signal into a modulation signal. In step 923, the transmission amplifying unit 330 amplifies the modulated signal. In step 924, the transmission conversion unit 340 transmits an ultrasonic wave to the screen 200 according to the amplified modulation signal. Step 925, the receiving conversion unit 350 receives the ultrasonic wave reflected from the screen 200 back to 16 200823589', and converts the ultrasonic wave into an electrical signal. In an amplification step 926, the receiving amplification unit 36 解调 demodulates the converted electrical signal from the amplified electrical signal. Step 927, the demodulation unit 370 outputs the ultrasonic signal. As shown in FIG. 5B, the present embodiment discloses a step 926 of transmitting and receiving an ultrasonic method. You can step up your backup 4*〇〇-:^, so that the receiving amplification will be further improved.
月匕濾除外界聲源可能產生之干擾訊號，或者可在步驟 =前增設-個步驟，該步驟主要利請波單元濾 聲源可能産生之干擾信號。 、、者f本發明揭示之自動聚焦投影機和投影機自動聚焦方 法貝施方式中，因爲超音波之傳播速度相對紅外線之傳播 速^要k，藉由超音波發射接收模組1〇〇發射接收超音波 測里傳播時間，以提高自動調節之精度。接著資料處理模 組4〇〇叶异得到投影機1〇〇和螢幕2〇〇間之投射距離，比 _較出與當前之投射距離最相匹配之變焦參數值和聚焦參數 值。然後由輸出模組500調整光學透鏡系統52〇相應透鏡 之焦距值和聚焦位置值，通過輸出模組5⑽投射到螢幕2〇〇 j之影像即可獲得較佳之清晰度。因投影機之投射距離與 變焦參數和聚焦參數有確定之對應關係，所以通過超音波 測里出投影機當前之投射距離值後，即可對應進行投影機 之自動聚焦調整，相對於紅外線測距法需反復擷取測試圖 樣而言，有利於節約調整時間。 综上所述，本發明符合發明專利要件，爰依法提出專 17 200823589 利申請。惟，以上所述者僅為本發明之較佳實施例，舉凡 熟悉本案技藝之人士，在援依本案創作精神所作之等效修 飾或變化，皆應包含於以下之申請專利範圍内。 » 【圖式簡單說明】 圖1爲本發明一較佳實施方式揭示之自動聚焦投影機 的整體功能模組圖。 圖2爲圖1所示之超音波發射接收模組的具體功能模 春組連接圖。 圖3爲圖1所示之資料處理模組之具體功能模組連接 圖。 圖4爲圖1所示之輸出模組之具體功能模組連接圖。 圖5A爲本發明一較佳實施方式揭示之投影機自動聚 焦方法流程圖。 圖5B爲圖5A所示之發射接收超音波步驟之進一步方 φ法流程圖。 【主要元件符號說明】 投影機 100 變焦參數單元 421 螢幕 200 聚焦參數單元 422 超音波發射接收模組300 RAM存儲單元 430 資料處理模組 400 控制單元 440 超音波發生單元 310 比較單元 450 調變單元 320 匯流排 460 18 200823589 發射放大單元 330 驅動電路 510 發射轉換單元 340 電機驅動電路 511 接收轉換單元 350 變焦電機 512 接收放大單元 360 聚焦電機 513 解調變單元 370 光學透鏡系統 520 檢波單元 380 變焦透鏡 521 計時單元 390 聚焦透鏡 522 距離測量單元 410 光轴 523 ROM存儲單元 420 投影機自動聚焦方法步驟 S91(l· ^S960 發射接收超音波步驟 S921〜S927 19The 匕 匕 filter can generate interference signals from the sound source, or you can add a step before step = 1. This step mainly helps the wave unit to filter the interference signal that may be generated by the sound source. The autofocus projector and the autofocus method of the projector disclosed in the present invention, because the propagation speed of the ultrasonic wave is relatively fast with respect to the infrared ray propagation speed, and is transmitted by the ultrasonic wave transmitting and receiving module 1 Receive the ultrasonic propagation time to improve the accuracy of automatic adjustment. Then, the data processing module 4 obtains the projection distance between the projector 1 and the screen 2, and compares the zoom parameter value and the focus parameter value which match the current projection distance. Then, the output module 500 adjusts the focal length value and the focus position value of the corresponding lens of the optical lens system 52, and the image is projected to the screen 2〇〇 by the output module 5 (10) to obtain better definition. Since the projection distance of the projector has a certain correspondence with the zoom parameter and the focus parameter, the projector can automatically adjust the focus of the projector after the current projection distance value of the projector is extracted by the ultrasonic wave measurement, relative to the infrared distance measurement. The method needs to repeatedly capture the test pattern, which is beneficial to save adjustment time. In summary, the present invention complies with the requirements of the invention patent, and the application for the application of the 2008 200823589 patent. However, the above description is only a preferred embodiment of the present invention, and those who are familiar with the art of the present invention should be included in the following patent claims within the scope of the following claims. Brief Description of the Drawings Fig. 1 is a block diagram showing the overall function of an autofocus projector disclosed in a preferred embodiment of the present invention. 2 is a connection diagram of a specific function module of the ultrasonic transmitting and receiving module shown in FIG. 1. FIG. 3 is a connection diagram of specific functional modules of the data processing module shown in FIG. 1. 4 is a connection diagram of specific functional modules of the output module shown in FIG. 1. FIG. 5A is a flow chart of a method for automatically focusing a projector according to a preferred embodiment of the present invention. Fig. 5B is a flow chart showing the further φ method of the step of transmitting and receiving ultrasonic waves shown in Fig. 5A. [Main component symbol description] Projector 100 Zoom parameter unit 421 Screen 200 Focus parameter unit 422 Ultrasonic wave transmitting and receiving module 300 RAM storage unit 430 Data processing module 400 Control unit 440 Ultrasonic wave generating unit 310 Comparison unit 450 Modulation unit 320 Bus 460 18 200823589 Transmit Amplification Unit 330 Drive Circuit 510 Transmit Conversion Unit 340 Motor Drive Circuit 511 Receive Conversion Unit 350 Zoom Motor 512 Receive Amplification Unit 360 Focus Motor 513 Demodulation Transform Unit 370 Optical Lens System 520 Detection Unit 380 Zoom Lens 521 Timing Unit 390 Focusing lens 522 Distance measuring unit 410 Optical axis 523 ROM storage unit 420 Projector autofocus method Step S91 (l·^S960 Transmit and receive ultrasonic steps S921~S927 19