201239439 六、發明說明： 【發明所屬之技術領域】 本發明是有關於-種自動對焦袭置，且特別是有關於 一種用於影像擷取裝置的自動對焦裳置。 【先前技術】 圖1繪不為-種習知之影像掏取襄置的内部架構圖。 請參照圖卜習知的影像摘取裝置100包括接物鏡1〇2、主 衫像鏡104、景>像感測器1〇6、影像處理單元1〇8、位置解 碼單元no、音圈馬達驅動單元112和音圈馬達114。主影 像鏡104位於接物鏡1〇2和影像感測器1〇6之間。其中， 影像感測ϋ 106會影像處理單元⑽。糾，位置解 碼單元110 _影像處理單元⑽和音圈馬達驅動單元 112 ’而音圈馬達鶴單元⑴則祕音圈馬達m 裝置⑽内，音圈馬達114是用來調整接物鏡呢 的位置。 影像擷取裝置觸可以透過接物鏡m接收 光。當環境光透過接物鏡102 _像擷取二 、擷取時’環境光會被接物鏡102轉成平行光122。而 主影像鏡104，然後被距焦到影像咖 ΙΜ二;1!後Γ感測器106會輸出-影像感測利 一 NF，、、。衫像處理單元108進行處理。 承上述，當一物體13〇出現在預設範圍内時，影像處 201239439 理單元10 8會透過影像感測資訊IMGJNF而計算出關於該 物體130的影像資料1^1(}一〇八丁八1(：時，影像處理單元'1〇^ 會從關於該物體130的影像資料，而判斷物體13〇是否位 於影像操取裝置1GG的焦點上。若是影像處理單元1〇8判 斷物體130並未在影像掏取褒^ 1〇〇的焦點上時，則會發 出-位置碼PGS_CX)DE給位置解碼單元11G進行解碼，並 且=位置解碼單元11G輸出—控龍號cs給音圈馬達驅 動單元112此時’曰圈馬達驅動單元I】〗就會依據控制 sfu虎cs而控制音圈馬達114調整接物鏡1〇2的位置，以 使其焦點能夠位於物體130所在的位置。 由於在習知的影像擷取裳置中，是由影像處理單元依 據所獲得之影像的清晰度’來控鄉像#|取裝置中的自動 對焦功能。然而’在高解析度相機内，影像處理單元所處 理的資料量非常鼓，因此可能會拉長自麟焦的時間。 【發明内容】 因此，本發明一種影像擷取裝置的自動對焦裝置，可 以使影像擷取裝置具備較快的自動對焦速度。 另外’本發明還提供一種自動對焦的方法，可 自動對焦的時間。 本發明提供-種影像擷取裝置的自動對焦褒置，包括 私、’、接物鏡、透鏡組、控制模组和致動器^光源可以發 另该測光’哺物賴會將_光投賴—預設範圍。 接物鏡也會接收由偵測光被一物體反射時所產生的 6 201239439 一反射偵測光。透鏡組則是配置在光源和接物鏡之間，以 引導偵測光以及被接物鏡所接收之反射偵測光前進的方 向。控制模組配置在反射偵測光受透鏡組所引導前進的路 徑上，以依據反射偵測光而產生一控制訊號給致動器，使 得致動器依據控制訊號而決定接物鏡的位置，使得接物鏡 的焦點位於物體的位置。 在本發明之一實施例中，控制模組包括偵測光感測器 和控制器。偵測光感測器配置在反射偵測光之平行光受透 鏡組所引導前進的路徑上，以依據反射偵測光之平行光截 面的形狀而輸出一反射偵測光資訊給控制器。藉此，控制 器就會依據反射偵測光資訊而輸出控制訊號給致動器。其 中，偵測光感測器可以是2*2陣列感測器。 從另一觀點來看，本發明提供一種自動變焦的方法， 適用於一影像操取裝置，其用來擷取一預設範圍内的影 像。本發明所提供的方法包括向預設範圍投射一偵測光。 當偵測光被預設範圍内的一物體反射而產生一反射偵測光 時，擷取此反射偵測光。藉此，本發明就會依據所擷取到 反射偵測光的截面形狀，而調整影像擷取裝置的焦點定於 物體所在的位置。 在本發明之一實施例中，依據所擷取到反射偵測光之 截面形狀來調整影像擷取裝置之焦點位置的步驟，包括當 被操取到反射偵測光的截面形狀接近正圓時，則維持影像 擷取裝置之焦點的位置不變。另外，當被擷取到反射偵測 光的截海形狀為橢圓形，且水平軸較縱軸長時，則將影像 擷取裝置的焦點向後移。相對地，當被擷取到反射偵測光 201239439 為橢圓形，且縱軸較水平軸長時，則將影像操 取在置的焦點向前移。 由於本發明會向預設範圍投射一偵測光，並且依據反 门偵測先賴_絲蚊影像齡裝置之紐的位置， 此本發明可以進行自動定焦的時間較短。 為讓本發明之上述和其他目的、特徵和優點能更明顯 下文特舉較佳實施例，並配合所附圖式，作詳細說 明如下。 ' 【實施方式】 =不為依照本發明之一較佳實施例的一種影像摘 =裝置之自動對焦裝置的示意圖。請參照圖2，本實施例 中^像練裝置細，例如是__相機，其可以___預 中的影像。在本實施例中，影像擷取襄置2〇〇包括 =勿=〇2、透鏡組204、主影像鏡2〇6、影像感測器· 理單元2Π)。其中’透鏡组204配置在接物鏡2〇2 和衫像鏡206之間，而影像感測器2〇8則配置旦 鏡襲之後。另外，影像處理單元⑽則轉接影像感二器 2Uo 0 接物鏡202可以導入-光資訊，例如：環境光肛及/ 或擷取-物體25G之影像資訊，並且將其轉換成平行光。 接著，環境光EL的平行光會人射透鏡組酬，並被透鏡組 2〇4引導至主影像鏡206。接著，主影像鏡2〇6會將環境光 虹的平行光聚焦到影像感測器施上。此時，影像感· 8 201239439 208就會輸出影像感測資訊img_jnF給影像處理單元2i〇 進行處理。藉此’影像處理單元21G就會依據影像感測資 訊IMG_INF而輸出一影像資料IMG一DATA。然而，在本 實施例中，影像擷取裝置200的自動對焦作業並非由影像 處理單元210所處理。 請繼續參照圖2，在影像擷取裝置200中，還包括光 源212、致動器214和控制模組216。在本實施例中，透鏡 組204是配置在光源212和接物鏡202之間。其中，光源 212例如是雷射二極體。另外，致動器214會耦接控制模 組216，並且致動器214可以調整接物鏡2〇2的位置，而 進行自動對焦作業。 光源212會發出偵測光DL，例如是雷射光，並且此 偵測光DL的波長較佳為不可見光的波長，但本發明並不 限制。此偵測光DL會入射透鏡組204 ’並且被引導入射接 物鏡202，以透過接物鏡202投射到預設範圍中。當物體 250出現在預設範圍内時，偵測光dl會被物體250反射， 而產生反射偵測光DL，。此反射偵測光DL，也會被接物鏡 202所掏取’並且轉換成平行光。接著，反射偵測光dl， 的平行光會入射透鏡組204,而被引導前進至控制模組 216。因此，控制模組216會依據反射偵測光dl，而輸出控 制訊號CS給致動器214。此時，致動器214就會依據控制 訊號CS來決定接物鏡202的位置。在本實施例中，致動 器214可以是音圈馬達。 透鏡組204包括準直透鏡222、分光鏡224和226、 以及感測器鏡228。準直透鏡222是配置在光源212和分201239439 VI. Description of the Invention: [Technical Field] The present invention relates to an autofocus attack, and more particularly to an autofocus skirt for an image capture device. [Prior Art] FIG. 1 depicts an internal architecture diagram of a conventional image capturing device. Please refer to the conventional image capturing device 100 including the objective lens 1 2, the main image mirror 104, the scene image sensor 1〇6, the image processing unit 1〇8, the position decoding unit no, the voice coil motor driver. Unit 112 and voice coil motor 114. The primary image mirror 104 is located between the objective lens 1〇2 and the image sensor 1〇6. The image sensing unit 106 is an image processing unit (10). Correction, position decoding unit 110_image processing unit (10) and voice coil motor driving unit 112' and voice coil motor unit (1) in the voice coil motor m device (10), the voice coil motor 114 is used to adjust the position of the objective lens. The image capturing device can receive light through the objective lens m. When ambient light is transmitted through the objective lens 102, such as capturing and capturing, the ambient light is converted into parallel light 122 by the objective lens 102. The main image mirror 104 is then defocused to the image coffee café; 1! The Γ sensor 106 outputs - image sensing NF, , , . The shirt image processing unit 108 performs processing. According to the above, when an object 13〇 appears within a preset range, the image unit 201239439 unit 10 8 calculates the image data about the object 130 through the image sensing information IMGJNF 1^1(} 1 (:, the image processing unit '1〇^ will judge whether the object 13〇 is located at the focus of the image manipulation device 1GG from the image data about the object 130. If the image processing unit 1〇8 determines that the object 130 is not When the image captures the focus of the frame, the position decoder PGS_DE is issued to decode the position decoding unit 11G, and the position decoding unit 11G outputs the control number cs to the voice coil motor drive unit 112. At this time, the '曰 motor drive unit I】 controls the voice coil motor 114 to adjust the position of the objective lens 1〇2 according to the control sfu tiger cs so that the focus can be located at the position where the object 130 is located. In the image capture unit, the image processing unit controls the autofocus function in the home image based on the sharpness of the obtained image. However, in the high resolution camera, the image processing unit processes the image. Non-data volume The present invention is an autofocus device for an image capture device that can provide an image capture device with a faster autofocus speed. A method of autofocusing is also provided, which can automatically focus the time. The present invention provides an autofocus device for an image capturing device, including a private, ', an objective lens, a lens group, a control module, and an actuator. Sending the other metering 'Feeding will rely on _ light to rely on the preset range. The objective lens will also receive the 6 201239439-reflected detection light generated by the reflected light reflected by an object. The lens group is configured in Between the light source and the objective lens, the direction of the detection light and the reflection received by the object to be detected is detected. The control module is disposed on the path of the reflected detection light guided by the lens group to reflect the reflection. The light metering generates a control signal to the actuator, so that the actuator determines the position of the objective lens according to the control signal, so that the focus of the objective lens is at the position of the object. In an embodiment, the control module includes a detection light sensor and a controller. The detection light sensor is disposed on a path in which the parallel light of the reflected detection light is guided by the lens group to detect the light according to the reflection. The shape of the parallel light section is outputted to output a reflection detection light information to the controller, whereby the controller outputs a control signal to the actuator according to the reflected detection light information, wherein the detection light sensor can be 2 *2 Array Sensor. From another point of view, the present invention provides an automatic zoom method for an image manipulation device for capturing images within a predetermined range. The method includes: projecting a detection light to a preset range. When the detection light is reflected by an object in a preset range to generate a reflection detection light, the reflection detection light is captured. Therefore, according to the cross-sectional shape of the reflected detection light, the focus of the image capturing device is adjusted to the position of the object. In an embodiment of the invention, the step of adjusting the focus position of the image capturing device according to the cross-sectional shape of the reflected detection light is taken, including when the cross-sectional shape of the reflected detection light is close to a perfect circle. , the position of the focus of the image capturing device is maintained unchanged. In addition, when the shape of the intercepted sea to which the reflected light is captured is elliptical and the horizontal axis is longer than the vertical axis, the focus of the image capturing device is shifted backward. In contrast, when the reflected detection light 201239439 is elliptical and the vertical axis is longer than the horizontal axis, the image is moved forward at the focus of the image. Since the present invention projects a detection light to a preset range, and according to the position of the back door to detect the position of the device, the present invention can perform automatic focusing for a short period of time. The above and other objects, features and advantages of the present invention will become more apparent from [Embodiment] = A schematic diagram of an autofocus device of an image pickup device in accordance with a preferred embodiment of the present invention. Referring to Fig. 2, in the embodiment, the image processing device is thin, such as a __ camera, which can ___ pre-image. In this embodiment, the image capturing device 2 includes = do not 〇 2, the lens group 204, the main image mirror 2 〇 6, and the image sensor unit 2). Wherein the lens group 204 is disposed between the objective lens 2〇2 and the shirt mirror 206, and the image sensor 2〇8 is disposed after the mirror. In addition, the image processing unit (10) relays the image sensor 2Uo 0. The objective lens 202 can introduce image information such as ambient light anus and/or capture object 25G image information and convert it into parallel light. Then, the parallel light of the ambient light EL is incident on the lens, and is guided to the main image mirror 206 by the lens group 2〇4. Next, the main image mirror 2〇6 will focus the ambient light parallel light onto the image sensor. At this time, the image sensor 8 201239439 208 outputs the image sensing information img_jnF to the image processing unit 2i. Thereby, the image processing unit 21G outputs an image data IMG_DATA in accordance with the image sensing information IMG_INF. However, in the present embodiment, the autofocus operation of the image capture device 200 is not processed by the image processing unit 210. Referring to FIG. 2, the image capturing device 200 further includes a light source 212, an actuator 214, and a control module 216. In the present embodiment, the lens group 204 is disposed between the light source 212 and the objective lens 202. The light source 212 is, for example, a laser diode. In addition, the actuator 214 is coupled to the control module 216, and the actuator 214 can adjust the position of the objective lens 2〇2 to perform an autofocus operation. The light source 212 emits detection light DL, such as laser light, and the wavelength of the detection light DL is preferably a wavelength of invisible light, but the invention is not limited thereto. This detection light DL is incident on the lens group 204' and is guided to the incident lens 202 to be projected through the objective lens 202 into a predetermined range. When the object 250 appears within the preset range, the detected light d1 is reflected by the object 250, and the reflected light DL is generated. This reflected light DL is also captured by the objective lens 202 and converted into parallel light. Then, the parallel light reflecting the detection light dl is incident on the lens group 204 and guided to the control module 216. Therefore, the control module 216 outputs the control signal CS to the actuator 214 according to the reflected light dl. At this time, the actuator 214 determines the position of the objective lens 202 based on the control signal CS. In the present embodiment, the actuator 214 may be a voice coil motor. The lens group 204 includes a collimating lens 222, beam splitters 224 and 226, and a sensor mirror 228. The collimating lens 222 is disposed at the light source 212 and the minute
S 9 201239439 光鏡224之間，而分光鏡224則是配置在分光鏡226和接 物鏡202之間。另外，感測器鏡228則配置在分光鏡226 -和控制模組216之間。 當偵測光DL入射透鏡組204時，會被準直透鏡222 放大成平行光，並且被引導至分光鏡224。接著，分光鏡 224會將偵測光DL的至少部分引導至接物鏡2〇2，以透過 接物鏡202投射至預設範圍内。另一方面，當反射偵測光 DL’的平行光入射透鏡組2〇4時，.反射偵測光DL，的至少部 分會經過分光鏡224而到達分光鏡226。同樣地，分光鏡 226則會將通過分光鏡224之反射偵測光dL，的至少部分引 導至感測器鏡228。此時，感測器鏡228就會將被分光鏡 226引導來的反射偵測光DL，的部份聚焦到控制模組216 上。 類似地，環境光EL的平行光在透鏡組204中的行進 路徑大致上與反射偵測光DL，的行進路徑相同。不同的 是，經過分光鏡224之環境光EL·的平行光至少部分，還 會穿透分光鏡226而到達主影像鏡206，並且透過主影像 鏡206到達影像感測器208。 另一方面，控制模組216包括偵測光感測器232和控 制器234。其中，偵測光感測器232可以配置在感測器鏡 228的焦點上，並且輕接控制器234。另外，控制器234 則搞接致動器214。當反射偵測光DL’之平行光的部分被感 測器鏡228聚焦後’會入射至偵測光感測器232。接著， 4貞測光感測器232會依據入射的反射偵測光dl’而產生一 反射偵測光資訊DL’_INF給控制器234。此時，控制器234 201239439 就會依據反射偵測光資訊DL’_INF而輸出控制訊號CS給 致動器214。 圖3繪示為依照本發a月之一較佳實施例的一種偵測光 感應器232為2*2陣列感應器的示意圖。請參照圖3，本 實施例之偵測光感應器232包括感應區域302、304、306 和 308。 圖4A到圖4C繪示為依照本發明之一較佳實施例的一 種反射偵測光DL’投射到偵測光感測器232上的示意圖。 請合併參照圖2以及圖4A到圖4C，當物體250正好在影 像擷取裝置200的焦點上，更正確地說是接物鏡2〇2的焦 點上時，反射偵測光DL’的截面形狀就如圖4A所繪示，大 致上接近一正圓。此時，感應區域302、304、300和308 所感應到反射偵測光DL’的面積大致上相同。因此，控制 器234不會發出控制訊號Cs給致動器214 ,以使接物鏡 202的位置不變。 若是反射偵測光DL，的截面形狀為橢圓形，並且水平 軸較縱軸長，就如圖4B所繪示，則代表物體25〇離影像 擷取裝置200太近。此時，控制器234就會依據偵測光資 訊DL’—INF’而輸出對應的控制訊號邙給致動器214。接 著，致動器214會依據控制訊號cs調整接物鏡2〇2的位 置，而使其焦點向前移，也就是往影像擷取裝置2〇〇的位 置移動’直到接物鏡202的焦點大致上落於物體25〇的所 在位置。 、相對地，若是反射_光DL，的截面形狀為擴圓形， 並且縱軸較水·長’就如圖4C崎示，職表物體 201239439 l 離影像擷取裝置200太遠。此時’控制器234就會輸出對 應的控制訊號CS給致動器214，並且致動器214也會依據 控制訊號CS調整接物鏡202的位置，而使其焦點向後移， 也就是往影像擷取裝置200所在位置相反的方向移動，直 到接物鏡202的焦點大致上落於物體250的所在位置。 圖5繪示為依照本發明之一較佳實施例的一種自動對 焦方法的步驟流程圖，適用於一影像擷取裝置。請參照圖 5 ’首先如步驟S502所述’向影像擷取裝置擷取影像的預 設範圍投射一偵測光。當偵測光被物體反射而產生反射偵 測光時’則擷取此反射偵測光，就如步驟S504所述。藉此， 就可以進行步驟S510，就是依照被擷取之反射偵測光的截 面來決定影像擷取裝置之焦點的位置。 更詳細地來看步驟S510，當掘取到反射偵測光後，可 以如步驟S512所述，判斷反射偵測光的截面形狀是接近正 圓或是橢圓。若是反射债測光的截面大致接近正圓時，則 進行步驟S514，就是維持影像擷取裝置目前的焦點位置。 相對地，若是反射偵測光的截面形狀大致是接近搞圓時， 則如步驟S516所述’判斷反射彳貞測光的截面是水平軸較長 或是縱轴較長。 若是截面大致上接近橢圓的反射/[貞測光之截面是水 平軸長於縱軸，代表可能是物體離影像擷取裝置較近，則 進行步驟S518，就是將影像擷取裝置的焦點向前移，直到 影像擷取裝置的焦點大致上位於物體的位置上。另外，若 是截面大致上接近橢圓的反射偵測光截面是縱軸長於水平 軸，代表可能是物體離影像擷取裝置較遠。因此，本實施 12 201239439 驟S520 ’就是將影像擷取裝置的焦點向後移， 衫像掏取襄置的焦點大致上位於物體的位置上。 T上所述，由於本發明是投射1測光_ 【點t:據反射偵測光的截面形狀來決定糊取裝置 …、、 因此本發明可以縮點自動對焦的作業時間。 雖然本發明已以較佳實施例揭露如上，然其並非用以 =明，習此技藝者，在不脫離本發= ^幸巳圍内可作些許之更動與潤飾，因此本發明之保 fc圍當視後附之巾料利範讀界定者為準。 … 【圖式簡單說明】 圖1繪示為一種習知之影像擷取裝置的内部架構圖。 ，2,為依照本發明之—較佳實施例的—種影 取裝置之自動對焦裝置的示意圖。 圖3繪不為依照本發明之一較佳實施例的一種偵測光 感應器為2*2陣列感應器的示意圖。 圖4 A到圖4 C繪示為依照本發明之一較佳實施例的— 禮反射偵測光投射到圖3之偵測光感測器上的示意圖。 圖5繪示為依照本發明之一較佳實施例的一種自動對 焦方法的步驟流程圖。 【主要元件符號說明】. 100、200 :影像梅取震置 13 201239439 102 ' 202 102、202 :接物鏡 104、206 :主影像鏡 106、208 :影像感測器 108、210 :影像處理單元 110 :位置解碼單元 112 :音圈馬達驅動單元 114 :音圈馬達 122 :平行光 130、250 :物體 204 :透鏡組 212 :光源 216 :控制模組 222 :準直透鏡 224、226 :分光鏡 228 :感測器鏡 302、304、306、308 :感應區域 CS :控制訊號 DL :偵測光 DL’ ：反射偵測光 DL’_INF :反射偵測光資訊 EL :環境光 IMG_DΑΤΑ :影像資料 IMG_INF :影像感測資訊 POS—CODE :位置碼 S502、S504、S510、S512、S514、S516、S518、S520 ： 201239439 自動對焦之方法的步驟流程 15S 9 201239439 between the mirrors 224, and the beam splitter 224 is disposed between the beam splitter 226 and the objective lens 202. In addition, the sensor mirror 228 is disposed between the beam splitter 226 - and the control module 216. When the detection light DL is incident on the lens group 204, it is amplified by the collimator lens 222 into parallel light and guided to the beam splitter 224. Next, the beam splitter 224 guides at least a portion of the detection light DL to the objective lens 2〇2 to be projected through the objective lens 202 to a predetermined range. On the other hand, when the parallel light of the reflected light DL' is incident on the lens group 2〇4, at least a portion of the reflected light DL passes through the beam splitter 224 to reach the beam splitter 226. Similarly, the beam splitter 226 directs at least a portion of the reflected light dL that passes through the beam splitter 224 to the sensor mirror 228. At this time, the sensor mirror 228 focuses the portion of the reflected detection light DL guided by the beam splitter 226 onto the control module 216. Similarly, the traveling path of the parallel light of the ambient light EL in the lens group 204 is substantially the same as the traveling path of the reflected detecting light DL. The difference is that the parallel light passing through the ambient light EL of the beam splitter 224 at least partially passes through the beam splitter 226 to reach the main image mirror 206 and through the main image mirror 206 to the image sensor 208. On the other hand, the control module 216 includes a detection photo sensor 232 and a controller 234. The detection light sensor 232 can be disposed at the focus of the sensor mirror 228 and lightly connected to the controller 234. In addition, the controller 234 engages the actuator 214. When the portion of the parallel light of the reflected light DL' is focused by the sensor mirror 228, it is incident on the detecting light sensor 232. Then, the photometric sensor 232 generates a reflected detection light information DL'_INF to the controller 234 according to the incident reflected light dl'. At this time, the controller 234 201239439 outputs the control signal CS to the actuator 214 according to the reflected detection light information DL'_INF. FIG. 3 is a schematic diagram of a detection light sensor 232 being a 2*2 array sensor according to a preferred embodiment of the present invention. Referring to FIG. 3, the detection light sensor 232 of the present embodiment includes sensing regions 302, 304, 306, and 308. 4A-4C are schematic diagrams showing a reflection detection light DL' projected onto the detection light sensor 232 according to a preferred embodiment of the present invention. Referring to FIG. 2 and FIG. 4A to FIG. 4C together, when the object 250 is at the focus of the image capturing device 200, more specifically, at the focus of the objective lens 2〇2, the cross-sectional shape of the reflected detecting light DL' is combined. As shown in Figure 4A, it is substantially close to a perfect circle. At this time, the areas of the reflection detecting light DL' sensed by the sensing regions 302, 304, 300, and 308 are substantially the same. Therefore, the controller 234 does not issue the control signal Cs to the actuator 214 to keep the position of the objective lens 202 unchanged. If the reflection detecting light DL has an elliptical cross-sectional shape and the horizontal axis is longer than the vertical axis, as shown in Fig. 4B, it means that the object 25 is too close to the image capturing device 200. At this time, the controller 234 outputs a corresponding control signal to the actuator 214 according to the detected optical information DL'_INF'. Then, the actuator 214 adjusts the position of the objective lens 2〇2 according to the control signal cs, and moves the focus forward, that is, moves to the position of the image capturing device 2〇〇 until the focus of the objective lens 202 is substantially It falls on the 25th position of the object. In contrast, if the reflection_light DL has a cross-sectional shape that is rounded and the vertical axis is longer than the water, the surface is shown in Fig. 4C, and the object 201231439 is too far from the image capturing device 200. At this time, the controller 234 outputs a corresponding control signal CS to the actuator 214, and the actuator 214 also adjusts the position of the objective lens 202 according to the control signal CS to shift the focus backward, that is, to the image. The position of the device 200 is moved in the opposite direction until the focus of the objective lens 202 is substantially at the position of the object 250. FIG. 5 is a flow chart showing the steps of an automatic focusing method according to a preferred embodiment of the present invention, which is applicable to an image capturing device. Referring to FIG. 5', first, as described in step S502, a detection light is projected onto the preset range of the image captured by the image capturing device. When the detected light is reflected by the object to generate the reflected detection light, the reflected detection light is captured, as described in step S504. Thereby, step S510 can be performed to determine the position of the focus of the image capturing device according to the cross-section of the reflected light detected. Looking at the step S510 in more detail, after the reflected detection light is drilled, it can be determined that the cross-sectional shape of the reflected detection light is close to a perfect circle or an ellipse as described in step S512. If the cross section of the reflected debt metering is substantially close to a perfect circle, then step S514 is performed to maintain the current focus position of the image capturing device. On the other hand, if the cross-sectional shape of the reflected detection light is substantially close to the circle, the cross-section of the reflected pupil measurement is determined to be longer in the horizontal axis or longer in the vertical axis as described in step S516. If the cross section is substantially close to the ellipse/[the cross section of the photometry is that the horizontal axis is longer than the vertical axis, which means that the object may be closer to the image capturing device, then step S518 is performed to move the focus of the image capturing device forward. Until the focus of the image capture device is substantially at the position of the object. In addition, if the cross section of the reflected detection light having a section substantially close to an ellipse is longer than the horizontal axis, it may mean that the object is far from the image capturing device. Therefore, in the present embodiment 12 201239439 step S520 ', the focus of the image capturing device is moved backward, and the focus of the shirt image capturing device is substantially at the position of the object. As described above, since the present invention is to project 1 metering _ [point t: the stripping device is determined according to the cross-sectional shape of the reflected light, so that the present invention can be used for the autofocus operation time. Although the present invention has been disclosed in the above preferred embodiments, it is not intended to be used by the skilled person, and the present invention may be modified and retouched without departing from the present invention. The definition of the towel that is attached to the poster will be subject to the definition. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the internal structure of a conventional image capturing device. 2 is a schematic diagram of an autofocus device of an image capture device in accordance with a preferred embodiment of the present invention. 3 is a schematic diagram showing a 2*2 array sensor in which the detecting light sensor is not in accordance with a preferred embodiment of the present invention. 4A through 4C are schematic diagrams showing the reflection of the reflected light reflected onto the detecting light sensor of FIG. 3 in accordance with a preferred embodiment of the present invention. FIG. 5 is a flow chart showing the steps of an automatic focus method in accordance with a preferred embodiment of the present invention. [Main component symbol description]. 100, 200: image capture device 13 201239439 102 '202 102, 202: objective lens 104, 206: main image mirror 106, 208: image sensor 108, 210: image processing unit 110 Positioning decoding unit 112: voice coil motor driving unit 114: voice coil motor 122: parallel light 130, 250: object 204: lens group 212: light source 216: control module 222: collimating lens 224, 226: beam splitter 228: Sensor mirrors 302, 304, 306, 308: sensing area CS: control signal DL: detecting light DL': reflected detecting light DL'_INF: reflected detecting light information EL: ambient light IMG_DΑΤΑ: image data IMG_INF: image Sensing information POS_CODE: position code S502, S504, S510, S512, S514, S516, S518, S520: 201239439 Steps of the method of autofocusing Flow 15