200949420 九、發明說明： 【發明所屬之技術領域】 本發明涉及一種具有自動對焦裝置之投影儀及其自動 對焦方法。 ^【先前技術】 ' 自液晶投影儀出現以來’投影儀之性能迅速提高、技 術日新月異（請參見 “Optical system and characteristics of an LCD projector with interleaved pixels using four LCD ❹ projectors ” Takahashi, Y.; Nomura, T.; Sakai, S·; Proceedings of the IEEE, Volume 5, Issue 1, Feb. 1995 Page(s):41-47)。投影儀幾乎佔領了演示領域，同時它亦成 為應用最廣泛之現代教育媒體之一。投影儀不僅於教育領 域獨彳占風頭，而且亦被商務用戶所歡迎。 通常打開投影儀之後’演示者需要進行之步驟係人工 手動調整投影機位置，確保投影顯示晝面之正常，對於經 馨常變換投影儀使用環境之商務用戶而言，這些調節過程相 對繁瑣。而現有之投影儀不能檢測投影儀與投影面之距 離’並且自動調整焦距以確保投影顯示晝面清晰。當投影 機擺放位置與投影平面有一定之角度傾斜，投射之晝面便 產生了失真，為確保晝面之正常顯示’用戶需花大量時間 對晝面進行調節，導致降低了投影演示之效率。 【發明内容】 有鑑於此，有必要提供一種具有自動對焦褽置之投影 儀以及採用上述裝置之自動對焦方法。 200949420 一種投影儀，用於將圖像顯示於投影面上，其包括一 投影透鏡，該投影儀還包括一自動對焦裝置，該自動對焦 裝置包括：一電機、一圖像獲取裝置、一圖像處理系統、 以及一控制器。該電機與該投影透鏡機械連接，用於帶動 該投影透鏡沿著光軸方向移動至複數位置；該圖像獲取裝 置用於獲取該投影透鏡於各個位置對應之該投影面所顯示 之圖像訊號；該圖像處理系統，與該圖像獲取裝置電連接， 用於接收及處理該圖像獲取裝置輸出之各個圖像訊號，並 依據該圖像訊號計算各個圖像清晰度值，並記錄圖像清晰 度值最大時該投影透鏡對應之位置；該控制器分別電連接 至該圖像處理系統與該電機，用於根據該圖像處理系統計 算得到之圖像清晰度值控制該電機帶動該投影透鏡移動至 最大圖像清晰度值所對應之位置。 一種採用上述自動對焦裝置之自動對焦方法，其包括 以下步驟： 確定該投影透鏡之初始位置，該圖像獲取裝置獲取此 時該投影面所顯示之圖像訊號，該圖像處理系統記錄該投 影透鏡於初始位置之圖像清晰度值； 該投影透鏡於該電機之帶動下，沿著光軸移動到複數 對應之位置，該圖像獲取裝置獲取該投影透鏡於複數位置 對應之複數該投影面所顯示之圖像訊號； 該圖像處理系統接收該圖像獲取裝置輸出之複數圖像 訊號，分別計算每個圖像訊號之清晰度值，並記錄圖像清 晰度值最大時該投影透鏡對應之位置； 7 200949420 該控制器控制該電機帶動該投影透鏡移動至最大圖像 清晰度值所對應之位置，從而完成自動對焦。 相較於先前技術，該具有自動對焦裝置之投影儀，首 先藉由電機帶動投影透鏡沿著光轴方向移動到複數對應之 位置，得到每個位置之清晰度值，記錄圖像清晰度值最大 時該投影透鏡對應之位置，然後將投影透鏡從初始位置移 動最大清晰度值所對應之位置，從而完成自動對焦，可省 去人工花大量時間手動調整，並且提高了投影演示之效率。 ®【實施方式】 下面將結合附圖，對本發明實施例作進一步之詳細說 明。 請參閱圖1，本發明實施例提供了一種具有自動對焦裝 置之投影儀100，用於將待顯示圖像顯示於投影面70上。 該投影儀100包括一投影透鏡10，該投影儀100還包括一 自動對焦裝置，該自動對焦裝置包括一圖像獲取裝置30、 ❿一電機40、一圖像處理系統50、以及一控制器60。 該投影透鏡10，安裝於該投影儀100之框體之前表 面，藉由將待顯示圖像之圖像光投影，使待顯示圖像於該 投影面70上顯示。該投影面70可為螢幕、白板及牆面等 其他裝置。 該電機40與該投影透鏡10機械連接，於該控制器60 之控制下帶動該投影透鏡10沿著光軸方向移動至複數位 置。於本實施例中，該電機為一步進馬達。可以理解，該 電機亦可為音圈馬達、超聲波馬達、壓電馬達等。 8 200949420 該圖像獲取裝置30為一個電荷耦合器件（Charge Coupled Device，CCD)攝像機，用於獲取該投影透鏡1〇於 各個位置對應之該投影面70所顯示之圖像訊號。可以理 解’該圖像獲取裝置30亦可為互補金屬氧化物半導體 (Complementary Metal Oxide Semiconductor，CMOS)攝像機 或數位相機或攝像頭等，只要係一種圖像獲取裝置，並且 獲取之圖像訊號係數位形式即可。 ❹ 該圖像處理系統50,與該圖像獲取裝置30電連接，用 於接收及處理該圖像獲取裝置30輸出之各個圖像訊號，並 依據該圖像訊號計算圖像清晰度值，並記錄圖像清晰度值 最大時該投影透鏡10對應之位置。該清晰度值為解析度 值、對比度值或者係模量傳輸函數值（Modulation Transfer Function，簡稱MTF) ’該模量傳輸函數值係對成像品質之 綜合評價值，比單純解析度或者對比度能夠更好反映成像 品質。 ❹ 該控制器60分別電連接至該圖像處理系統50及該電 機40’用於根據該圖像處理系統5〇計算得到之圖像清晰度 值控制該電機40帶動該投影透鏡10移動至最大圖像清晰 度值所對應之位置’從而完成自動對焦。 本發明還提供一種採用上述裝置之自動對焦方法，其 包括以下幾個步驟： 確定該投影透鏡之初始位置，該圖像獲取裝置獲取此 時該投影面所顯示之圖像訊號’該圖像處理系統記錄該投 影透鏡於初始位置之圖像清晰度值； 9 200949420 該投影透鏡於該電機之帶動下，沿著光轴移動到複數 對應之位置，該圖像獲取裝置獲取該投影透鏡於複數位置 對應之複數該投影面所顯示之圖像訊號； 該圖像處理系統接收該圖像獲取裝置輸出之複數圖像 訊號，分別計算每個圖像訊號之清晰度值，並記錄圖像清 晰度值最大時該投影透鏡對應之位置； 該控制器控制該電機帶動該投影透鏡移動至最大圖像 清晰度值所對應之位置，從而完成自動對焦。 相較於先前技術，該具有自動對焦裝置之投影儀100， 首先藉由電機40帶動投影透鏡10沿著光軸方向移動到複 數對應之位置，得到每個位置之清晰度值，記錄圖像清晰 度值最大時該投影透鏡10對應之位置，然後將投影透鏡10 從初始位置移動至最大清晰度值所對應之位置，從而完成 自動對焦，可省去人工花大量時間手動調整，並且提高了 投影演示之效率。 綜上所述，本發明確已符合發明專利之要件，遂依法 提出專利申請。惟，以上所述者僅為本發明之較佳實施方 式，自不能以此限制本案之申請專利範圍。舉凡熟悉本案 技藝之人士援依本發明之精神所作之等效修飾或變化，皆 應涵蓋於以下申請專利範圍内。 【圖式簡單說明】 圖1係本發明實施例提供之具有自動對焦裝置之投影 儀之結構方框圖。 【主要元件符號說明】 200949420 投影儀 100 投影面 70 投影透鏡 10 圖像獲取裝置 30 電機 40 圖像處理系統 50 控制器 60 ❹ 11200949420 IX. Description of the Invention: [Technical Field] The present invention relates to a projector having an autofocus device and an autofocus method thereof. ^ [Prior Art] 'Since the appearance of LCD projectors', the performance of projectors has rapidly increased and the technology has changed rapidly (see "Optical system and characteristics of an LCD projector with interleaved pixels using four LCD ❹ projectors" Takahashi, Y.; Nomura, T.; Sakai, S.; Proceedings of the IEEE, Volume 5, Issue 1, Feb. 1995 Page(s): 41-47). The projector has almost captured the field of presentation and it has become one of the most widely used modern educational media. Projectors are not only in the forefront of education, but also popular with business users. Usually after the projector is turned on, the steps that the presenter needs to perform are manually adjusted manually to ensure that the projection display is normal. These adjustments are quite cumbersome for business users who use the environment to change the projector environment. Existing projectors cannot detect the distance between the projector and the projection surface and automatically adjust the focal length to ensure that the projection display is clear. When the position of the projector is tilted at a certain angle from the projection plane, the projected pupil surface is distorted. To ensure the normal display of the kneading surface, the user needs to spend a lot of time adjusting the kneading surface, which reduces the efficiency of the projection presentation. . SUMMARY OF THE INVENTION In view of the above, it is necessary to provide a projector having an autofocus device and an autofocus method using the above device. 200949420 A projector for displaying an image on a projection surface, comprising a projection lens, the projector further comprising an autofocus device, the autofocus device comprising: a motor, an image acquisition device, an image Processing system, and a controller. The motor is mechanically coupled to the projection lens for driving the projection lens to move to a plurality of positions along the optical axis direction; the image acquisition device is configured to acquire an image signal displayed by the projection lens corresponding to the projection surface at each position The image processing system is electrically connected to the image acquisition device for receiving and processing each image signal output by the image acquisition device, and calculating individual image sharpness values according to the image signal, and recording the image a position corresponding to the projection lens when the sharpness value is maximum; the controller is electrically connected to the image processing system and the motor, respectively, for controlling the motor to drive the image according to the image sharpness value calculated by the image processing system The projection lens moves to the position corresponding to the maximum image sharpness value. An autofocus method using the above autofocus device, comprising the steps of: determining an initial position of the projection lens, the image acquisition device acquiring an image signal displayed by the projection surface at this time, the image processing system recording the projection The image sharpness value of the lens at the initial position; the projection lens is moved along the optical axis to a position corresponding to the plurality of pixels, and the image acquiring device acquires the plurality of projection surfaces corresponding to the plurality of positions of the projection lens The image signal is displayed; the image processing system receives the plurality of image signals output by the image obtaining device, respectively calculates the sharpness value of each image signal, and records the projection lens corresponding to the maximum image sharpness value Position; 7 200949420 The controller controls the motor to move the projection lens to the position corresponding to the maximum image sharpness value, thereby completing the auto focus. Compared with the prior art, the projector with the auto-focus device firstly moves the projection lens along the optical axis direction to the corresponding position by the motor, and obtains the sharpness value of each position, and the recorded image sharpness value is the largest. When the projection lens corresponds to the position, and then the projection lens is moved from the initial position to the position corresponding to the maximum sharpness value, thereby completing the auto focus, the manual manual time adjustment can be omitted, and the efficiency of the projection presentation is improved. ® [Embodiment] Hereinafter, embodiments of the present invention will be further described in detail with reference to the accompanying drawings. Referring to FIG. 1, an embodiment of the present invention provides a projector 100 having an autofocus device for displaying an image to be displayed on a projection surface 70. The projector 100 includes a projection lens 10, and the projector 100 further includes an autofocus device including an image acquisition device 30, a motor 40, an image processing system 50, and a controller 60. . The projection lens 10 is mounted on the front surface of the housing of the projector 100, and the image to be displayed is projected on the projection surface 70 by projecting the image light of the image to be displayed. The projection surface 70 can be other devices such as a screen, a whiteboard, and a wall. The motor 40 is mechanically coupled to the projection lens 10, and the projection lens 10 is moved to a plurality of positions along the optical axis direction under the control of the controller 60. In this embodiment, the motor is a stepping motor. It can be understood that the motor can also be a voice coil motor, an ultrasonic motor, a piezoelectric motor or the like. 8 200949420 The image acquisition device 30 is a charge coupled device (CCD) camera for acquiring an image signal displayed by the projection lens 1 corresponding to the projection surface 70 at each position. It can be understood that the image acquisition device 30 can also be a Complementary Metal Oxide Semiconductor (CMOS) camera or a digital camera or a camera, etc., as long as it is an image acquisition device, and the acquired image signal coefficient bit form Just fine. The image processing system 50 is electrically connected to the image acquisition device 30 for receiving and processing each image signal output by the image acquisition device 30, and calculating an image sharpness value according to the image signal, and The position of the projection lens 10 corresponding to the maximum image sharpness value is recorded. The sharpness value is a resolution value, a contrast value, or a Modulation Transfer Function (MTF). The modulus transfer function value is a comprehensive evaluation value for imaging quality, and can be more than a simple resolution or contrast. Good reflection of image quality. The controller 60 is electrically connected to the image processing system 50 and the motor 40' for controlling the image clarity value calculated by the image processing system 5 to control the motor 40 to move the projection lens 10 to the maximum. The position corresponding to the image sharpness value' completes the autofocus. The present invention also provides an autofocus method using the above apparatus, comprising the steps of: determining an initial position of the projection lens, the image acquisition device acquiring an image signal displayed by the projection surface at this time. The system records the image sharpness value of the projection lens at the initial position; 9 200949420 The projection lens is moved along the optical axis to a corresponding position by the motor, and the image acquiring device acquires the projection lens at a plurality of positions Corresponding to the plurality of image signals displayed on the projection surface; the image processing system receives the plurality of image signals output by the image acquisition device, respectively calculates the sharpness value of each image signal, and records the image sharpness value The position of the projection lens corresponding to the maximum; the controller controls the motor to move the projection lens to a position corresponding to the maximum image sharpness value, thereby completing autofocus. Compared with the prior art, the projector 100 with the auto-focusing device first drives the projection lens 10 along the optical axis direction to the corresponding position by the motor 40, and obtains the sharpness value of each position, and the recorded image is clear. When the degree value is maximum, the position of the projection lens 10 corresponds to the position of the projection lens 10, and then the projection lens 10 is moved from the initial position to the position corresponding to the maximum sharpness value, thereby completing the auto focus, eliminating the manual manual adjustment of a large amount of time, and improving the projection. The efficiency of the presentation. In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the present invention are intended to be included within the scope of the following claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the structure of a projector having an autofocus device according to an embodiment of the present invention. [Main component symbol description] 200949420 Projector 100 Projection surface 70 Projection lens 10 Image acquisition device 30 Motor 40 Image processing system 50 Controller 60 ❹ 11