201209508 六、發明說明： 【發明所屬之技術領域】 [0001] 本發明涉及一種光學設備及其對焦方法，尤其係關於一 種投影儀及其自動對焦方法。 【先前技術】 [0002] 通常，在不同之投影儀使用環境下進行晝面投影時，需 要不同之鏡頭焦距來獲得最佳畫面投影效果。然而，習 知投影儀等投影光學設備不能自動調節鏡頭焦距以確保 投影顯示晝面之清晰度。因此，使用者打開投影儀進行 畫面投影後，通常需要手動調節投影儀之鏡頭焦距和位 置，以確保投影顯示畫面之清晰度。對於經常變鏡頭焦 距之用戶而言，這種手動調節鏡頭焦距之方式相對不方 便，而且不能保證將鏡頭焦距調節到最佳位置，進而無 法獲得最佳畫面投影效果。 【發明内容】 [0003] 鑒於以上内容，有必要提供一種投影儀及其自動對焦方 法，能夠在投影儀進行畫面投影過程中自動調節鏡頭焦 距至最佳焦距位置，進而獲得最佳畫面投影效果。 [0004] 所述之投影儀包括投射鏡頭、驅動單元、影像攝取單元 及自動對焦單元。該影像攝取單元用於從使用者選定之 投射區域内攝取影像。該自動對焦單元用於在投影儀進 行畫面投影時自動調節投射鏡頭之焦距至最佳焦距位置 。其中，所述之自動對焦單元包括：初始化模組，用於 根據投射鏡頭之變焦範圍設置一個調節鏡頭焦距之步長 值；影像分析模組，用於當投射鏡頭每移動一個步長值 099129204 表單編號A0101 第4頁/共14頁 0992051239-0 201209508 時於投射區朗攝取〜幅影像，並計算每—幅影像之對 比度藉由比對每〜鴨影像之對比度找出對比度最大之 影像’並根據該對tt度最大之影像確定投射鏡頭所對應 之最佳焦距位置’焦矩調節模組，用於藉由驅動單元控 制投射鏡頭在變焦範圍内移動，並將投射鏡頭移動至所 述之最佳焦距位置。 [0005] Ο ❹ 所述之投减之自tir對焦方法包括步驟：（a)根據投射 鏡頭之變焦！&圍$置調節鏡頭焦距之步長值；⑻控制 投射鏡頭在使用者選定之投射區域内投射影像畫面；（c )當投影儀加電開機時籍由驅動單元控制投射鏡頭之焦 距移動到變焦範圍之最近端；藉由影像攝取單元於 投射區域内攝取第一影像，並計算該第一影像之對比度 ;(e)藉由驅動單元控制投射鏡頭向變焦範圍之最遠端 移動一個步長值；（f)藉由影像攝取單元於投射區域内 攝取第一影像並叶算該第二影,像之對比度；（g )判斷 第二影像之對比度是否大於第一影像之封比度；（h)若 第二影像之對比度大於第一影像之對比度，則將第二影 像作為第一影像，並執行步驟（e);及（i)若第二影 像之對比度小於等於第一影像之對比度，則控制驅動單 元將投射鏡頭之焦距回調一個步長值後作為最佳焦距位 置。 [0006] 相較於習知技術，本發明所述之投影儀及其自動對焦方 法能夠在投影儀進行畫面投影過程中自動調節投影儀之 鏡頭焦距至最佳焦距位置，進而獲得最佳畫面之投影效 果。 099129204201209508 VI. Description of the Invention: [Technical Field] [0001] The present invention relates to an optical device and a focusing method thereof, and more particularly to a projector and an autofocus method thereof. [Prior Art] [0002] Generally, when performing facet projection in different projector environments, different lens focal lengths are required to obtain the best picture projection effect. However, conventional projection optics such as projectors do not automatically adjust the lens focal length to ensure the sharpness of the projected display. Therefore, after the user opens the projector for screen projection, it is usually necessary to manually adjust the focal length and position of the projector to ensure the sharpness of the projected display. For users who frequently change the focal length of the lens, this method of manually adjusting the focal length of the lens is relatively inconvenient, and it is not guaranteed to adjust the focal length of the lens to the optimum position, so that the best picture projection effect cannot be obtained. SUMMARY OF THE INVENTION [0003] In view of the above, it is necessary to provide a projector and an autofocus method thereof, which can automatically adjust the lens focal length to the optimal focal length position during the projection of the projector to obtain the best image projection effect. [0004] The projector includes a projection lens, a driving unit, an image capturing unit, and an autofocus unit. The image capture unit is configured to capture images from a projection area selected by a user. This autofocus unit is used to automatically adjust the focal length of the projection lens to the best focus position when the projector is projecting the screen. The autofocus unit includes: an initialization module, configured to adjust a step value of adjusting a focal length of the lens according to a zoom range of the projection lens; and an image analysis module, configured to move each step of the projection lens by a step value of 099129204 No. A0101 Page 4 / 14 pages 0992051239-0 201209508 When the projection area is ingested ~ image, and the contrast of each image is calculated by comparing the contrast of each ~ duck image to find the image with the highest contrast ' and according to Determining the best focal length position corresponding to the projection lens for the image with the largest tt degree, the focus adjustment module for controlling the projection lens to move within the zoom range by the driving unit, and moving the projection lens to the optimal focal length position. [0005] Ο ❹ The self-tir focusing method of the subtraction includes the steps of: (a) according to the zoom of the projection lens! & setting the step length of the lens focal length; (8) controlling the projection lens to project the image in the projection area selected by the user; (c) controlling the focal length of the projection lens to be moved by the driving unit when the projector is powered on The most recent end of the zoom range; the first image is captured by the image capturing unit in the projection area, and the contrast of the first image is calculated; (e) the projection lens is controlled by the driving unit to move to the farthest end of the zoom range by one step a value; (f) taking the first image in the projection area by the image capturing unit and calculating the contrast of the second image, and (g) determining whether the contrast of the second image is greater than the sealing ratio of the first image; h) if the contrast of the second image is greater than the contrast of the first image, the second image is used as the first image, and step (e) is performed; and (i) if the contrast of the second image is less than or equal to the contrast of the first image, Then, the control driving unit adjusts the focal length of the projection lens by one step value as the optimal focal length position. Compared with the prior art, the projector and the autofocus method thereof can automatically adjust the focal length of the projector to the optimal focal length position during the screen projection of the projector, thereby obtaining the best picture. Projection effect. 099129204
表單編號A010I 0992051239-0 201209508 【實施方式】 [〇〇〇7]如圖1所示’係本發明投影儀100較佳實施例之架構圖。 於本實施例中，該投影儀100包括自動對焦單元丨、投射 鏡頭2、驅動單元3、影像攝取單元4、儲存單元5及微處 理器6。該自動對焦單元！用於在投影儀1〇〇進行晝面投影 過程中自動調節投射鏡頭2之焦距至最佳焦距位置，以便 獲得最佳晝面之投影效果。 [0008]所述之投射鏡頭2係指一種鏡頭焦距可變化之變焦鏡頭， 其用於在使用者選定之投射區域内投射畫面。例如，假 設投射鏡頭2之變焦聲面為〇mm至18_，其最近端之焦距 為Omm ’最遠端之焦距為18咖。 [_舰之驅動單元3為—種驅動馬達，其用於控制投射鏡頭 2在變焦範圍内移動位置，進而自動讀投射鏡頭2之焦 距。Form No. A010I 0992051239-0 201209508 [Embodiment] [FIG. 1] FIG. 1 is an architectural diagram of a preferred embodiment of the projector 100 of the present invention. In the present embodiment, the projector 100 includes an autofocus unit 投射, a projection lens 2, a driving unit 3, an image capturing unit 4, a storage unit 5, and a microprocessor 6. The autofocus unit! It is used to automatically adjust the focal length of the projection lens 2 to the best focal length position during the projection of the projector to obtain the best projection effect. [0008] The projection lens 2 refers to a zoom lens with a variable focal length of a lens for projecting a picture in a projection area selected by a user. For example, assume that the zooming surface of the projection lens 2 is 〇mm to 18_, and the focal length of the closest end is Omm'. The farthest focal length is 18 coffee. [_The drive unit 3 of the ship is a drive motor for controlling the projection lens 2 to move the position within the zoom range, thereby automatically reading the focal length of the projection lens 2.
Luuiuj [0011] [0012] 099129204 述之影像攝取單元4為—種__祕之攝像裝置， Γ攝像頭。該影像攝取單元4用於於投射區域内之投影 ㈣取办像，並將該影像潑送給自動對焦單元1進行影 像为析來調節投射鏡頭2之焦距。 =錯存單元5為-種快閃記憶體（_μ 或者為儲存卡等。該儲 固 早兀5用於儲存所需進行投影之 口心狀圖片’例如圓形圖片或正方形圖片等。 所述之自動對焦單元丨包枯 J2„ # 匕括初始化模組、影像分析模組 U及焦距調節模組13。 本發明所稱之模組可為由多個電 件構成之硬體晶片，也可為由一系列計算指令組 表單編號A0101 09921 201209508 • 成之電職歧。於本實施财，所述之触是—種r . 肖被微處理器6所執行並且能夠完定功能之電腦程匕式 段，其儲存在儲存單元5中。 剛⑼述之初始化模組u用於根據投射鏡頭2之變焦範圍設置 每次調卽鏡腳、距之步長值，例如設置每次調節鏡頭焦 距之步長值為2随。該初始化模組u還用於從儲存單元5 内讀取固定形狀n及控制投射鏡頭2在使用者選定 之投射區域内投射賴定形狀n該初始化模組^ ㊄用於在投影儀刚加電-機時藉由躁動單Μ控制投射 鏡頭2之焦距移動到變焦範圍之最近端，例如〇職位置處 [0014]所述之影像分析模組12用於當投射鏡頭2每移動一個步長 值時於投射區域内攝取一幅影像，並計算每一幅影像之 對比度。該影像分析模組〗2還用於藉由比對每一幅影像 .之對比度來找出對比度最大之影像，並將根據對比度最 大之影像確定投射鏡頭2所對應之最佳焦距位置。於本實 Ο 施例中，影像分析模組12藉由計算麥像所有圖元之RGB值 來計箅影像之對比度。例如，在正常室内光線下，當零 色圖元點之亮度RGB值低於50時，人眼就不宜分辨出影像 之黑色圖το點。當所有RGB值不足50之黑色圖元點之數量 占總圖元點中之百分比越多時，則該影像之對比度越高 ，説明此時投射鏡頭2之焦距越好。 [0015] 於本實施例中’當投射鏡頭2之焦距移動到變焦範圍之最 近端時’影像分析模組12藉由影像攝取單元4於投射區域 内攝取第一影像，並計算該第一影像之對比度。當驅動 099129204 表單編號A0101 第7頁/共14頁 0992051239-0 201209508 單元3控制投射鏡頭2之焦距移動一個步長值時，影像分 析模組12藉由影像攝取單元4於投射區域内攝取第二影像 ，並計算該第二影像之對比度。當第二影像之對比度大 於第一影像之對比度時，影像分析模組12將第二影像作 為第一影像儲存在儲存單元5中，當投射鏡頭2移動到下 一個焦距時，將影像攝取單元4所攝取之影像作為第二影 像。 [0016] 所述之焦距調節模組1 3用於藉由驅動單元3控制投射鏡頭 2在變焦範圍内移動，並將投射鏡頭2移動至對比度最大 之影像所對應之最佳焦距位置。於本實施例中，當影像 攝取單元4獲取之第二影像之對比度小於等於第一影像之 對比度時，控制驅動單元3將投射鏡頭2之焦距回調一個 步長值，並將此時之焦距作為最佳焦距。 [0017] 如圖2所示，係本發明投影儀自動對焦方法較佳實施例之 流程圖。於本實施例中，該方法能夠在投影儀100進行畫 面投影過程中自動調節投射鏡頭2之焦距至最佳焦距位置 ，以便獲得最佳畫面之投影效果。 [0018] 步驟S21，初始化模組11根據投射鏡頭2之變焦範圍設置 每次調節鏡頭焦距之步長值，例如設置每次調節鏡頭焦 距之步長值為2mm。所述之變焦範圍係指投射鏡頭2之焦 距可移動範圍，例如，變焦範圍為〇mm至18mm，其最近端 之焦距為0mm，最遠端之焦距為18mm。 [0019] 步驟S22，初始化模組11控制投射鏡頭2在使用者選定之 投射區域内投射一固定形狀之圖片，例如圓形圖片或正 099129204 表單編號A0101 第8頁/共14頁 0992051239-0 201209508 [0020] 方形圖K _ Λ寺。步驟S23，在投影儀100加電開機時，初始 化模、且11藉由驅動單元3控制投射鏡頭2之焦距移動到變 *…範圍之最近端，例如0mm位置處。 S 2 4 ’當投射鏡頭2之焦距移動到變焦範圍之最近端 時景“象分析模組12藉由影像攝取單元4於投射區域内攝 取第—影像’並計算該第一影像之對比度。 [0021] 步驟S2S，& ·、、、距調節模組1 3藉由驅動單元3控制投射鏡頭2 向變焦範圍之最遠端移動一個步長值。步驟S26，影像分 〇 析模組12藉由影像攝取單元4於投射區域内攝取第二影像 ，並計算該第二影像之對比度。 [0022] ^ 0 7 ’影像分析模組12判斷第二影像之對比度是否大 於第一影像之對比度。若第二影像之對比度大於第一影 像之對比度’執行步驟S28。若第二影_之對比度小於等 於第一影像之對比度，執行步驟S29。 [0023] 步驟 ^ 9 ft i . ^ , ΐ ... ’影像分析模組12將第二影像作為第一影像儲存 在儲存單元5中，而後執行步驟S25。步驟S29，焦距調節 模”且13控制驅動單元3將投射鏡頭2之焦距回調一個步長 值’並將此時之焦距作為最佳焦距。 [0024] 於本實施例中’影像分析模組12藉由比對投射鏡頭2在不 同焦距下影像之對比度來找出對比度最大之影像，並將 根據该對比度最大之影像確定投射鏡頭2所對應之最佳焦 距位置。而後焦距調節模組13控制驅動單元3將投射鏡頭 2移動至對比度最大之影像所對應之最佳焦距位置處，進 而使投影儀100獲得最佳畫面之投影效果。 099129204 表單編號A0101 第9頁/共14頁 0992051239-0 201209508 [0025] 以上所述僅為本發明之較佳實施例而已，且已達廣泛之 使用功效，凡其他未脫離本發明所揭示之精神下所完成 之均等變化或修飾，均應包含於下述申請專利範圍内。 【圖式簡單說明】 [0026] 圖1係本發明投影儀較佳實施例之架構圖。 [0027] 圖2係本發明投影儀之自動對焦方法較佳實施例之流程圖 〇 【主要元件符號說明】 [0028] 投影儀100 [0029] 自動對焦單元1 [0030] 初始化模組11 [0031] 影像分析模組12 [0032] 焦距調節模組13 [0033] 投射鏡頭2 [0034] 驅動單元3 [0035] 影像攝取單元4 [0036] 儲存單元5 [0037] 微處理器6 099129204 表單編號A0101 第10頁/共14頁 0992051239-0Luuiuj [0012] The image capturing unit 4 described in 099129204 is an image capturing device of the type __ secret, and a camera. The image capturing unit 4 is used for projecting in the projection area. (4) The image is taken and sent to the autofocus unit 1 to perform image analysis to adjust the focal length of the projection lens 2. = The memory unit 5 is a type of flash memory (_μ or a memory card, etc. The storage box 5 is used to store a mouth-shaped picture that needs to be projected, such as a circular picture or a square picture, etc. The autofocus unit includes an initialization module, an image analysis module U, and a focus adjustment module 13. The module referred to in the present invention may be a hardware chip composed of a plurality of electrical components, or For a series of calculation instruction group form number A0101 09921 201209508 • In this implementation, the touch is a kind of r. Xiao is executed by the microprocessor 6 and can complete the function of the computer program匕The segment is stored in the storage unit 5. The initialization module u described in (9) is used to set the step value of the mirror foot and the distance according to the zoom range of the projection lens 2, for example, to adjust the focal length of the lens each time. The initialization module u is further configured to read the fixed shape n from the storage unit 5 and control the projection lens 2 to project the sizing shape in the projection area selected by the user. By shaking when the projector is just powered on Μ controlling the focal length of the projection lens 2 to move to the nearest end of the zoom range, for example, the image analysis module 12 described in the job position [0014] is used to take in the projection area every time the projection lens 2 moves by one step value. Image, and calculate the contrast of each image. The image analysis module 2 is also used to find the image with the highest contrast by comparing the contrast of each image, and determine the projection lens based on the image with the highest contrast. 2 corresponding optimal focal length position. In the embodiment, the image analysis module 12 calculates the contrast of the image by calculating the RGB values of all the primitives of the wheat image. For example, under normal indoor light, when zero When the luminance RGB value of the color map element is lower than 50, the human eye should not distinguish the black image το point of the image. When the number of black pixel points with less than 50 RGB values is more than the percentage of the total pixel point The higher the contrast of the image, the better the focal length of the projection lens 2. In this embodiment, the image analysis module 12 borrows when the focal length of the projection lens 2 moves to the nearest end of the zoom range. Shadow The ingesting unit 4 takes the first image in the projection area and calculates the contrast of the first image. When driving 099129204 Form No. A0101 Page 7 / 14 pages 0992051239-0 201209508 Unit 3 controls the focal length of the projection lens 2 to move by one step The image analysis module 12 captures the second image in the projection area by the image capturing unit 4, and calculates the contrast of the second image. When the contrast of the second image is greater than the contrast of the first image, the image analysis module 12 storing the second image as the first image in the storage unit 5, and when the projection lens 2 moves to the next focal length, the image captured by the image capturing unit 4 is used as the second image. [0016] The group 13 is used to control the projection lens 2 to move within the zoom range by the driving unit 3, and to move the projection lens 2 to the optimum focal length position corresponding to the image with the highest contrast. In this embodiment, when the contrast of the second image acquired by the image capturing unit 4 is less than or equal to the contrast of the first image, the control driving unit 3 adjusts the focal length of the projection lens 2 by one step value, and uses the focal length at this time as The best focal length. [0017] As shown in FIG. 2, it is a flow chart of a preferred embodiment of the projector autofocus method of the present invention. In the embodiment, the method can automatically adjust the focal length of the projection lens 2 to the optimal focal length position during the screen projection of the projector 100, so as to obtain the best picture projection effect. [0018] Step S21, the initialization module 11 sets the step value of the lens focal length each time according to the zoom range setting of the projection lens 2, for example, setting the step value of the lens focal length for each adjustment to 2 mm. The zoom range refers to the focal range of the projection lens 2, for example, the zoom range is 〇mm to 18mm, the focal length of the nearest end is 0mm, and the focal length of the farthest end is 18mm. [0019] Step S22, the initialization module 11 controls the projection lens 2 to project a fixed shape image in the projection area selected by the user, such as a circular picture or a positive 099129204 form number A0101 page 8 / 14 pages 0992051239-0 201209508 [0020] Square map K _ Λ Temple. In step S23, when the projector 100 is powered on, the initial mode is controlled, and the focal length of the projection lens 2 is controlled by the driving unit 3 to move to the nearest end of the range of ..., for example, 0 mm. S 2 4 ' When the focal length of the projection lens 2 is moved to the nearest end of the zoom range, the image analysis unit 12 captures the first image in the projection area by the image capturing unit 4 and calculates the contrast of the first image. 0021] Step S2S, &, the distance adjustment module 13 controls the projection lens 2 to move a step value to the farthest end of the zoom range by the driving unit 3. In step S26, the image demodulation module 12 borrows The second image is captured by the image capturing unit 4 in the projection area, and the contrast of the second image is calculated. [0022] ^ 0 7 'The image analysis module 12 determines whether the contrast of the second image is greater than the contrast of the first image. The contrast of the second image is greater than the contrast of the first image. [Step S28 is performed. If the contrast of the second image is less than or equal to the contrast of the first image, step S29 is performed. [0023] Step ^ 9 ft i. ^, ... The image analysis module 12 stores the second image as the first image in the storage unit 5, and then performs step S25. In step S29, the focus adjustment mode "13" controls the driving unit 3 to adjust the focal length of the projection lens 2 by one step. The long value 'and the focal length at this time is taken as the best focal length. [0024] In the present embodiment, the image analysis module 12 finds the image with the highest contrast by comparing the contrast of the image of the projection lens 2 at different focal lengths, and determines the corresponding projection lens 2 according to the image with the highest contrast. The best focal length position. The back focus adjustment module 13 controls the driving unit 3 to move the projection lens 2 to the optimal focal length position corresponding to the image with the highest contrast, thereby enabling the projector 100 to obtain the best picture projection effect. 099129204 Form No. A0101 Page 9 of 14 0992051239-0 201209508 [0025] The foregoing is only a preferred embodiment of the present invention and has been used in a wide range of applications, and other features not departing from the spirit of the invention Equivalent changes or modifications made below shall be included in the scope of the following patent application. BRIEF DESCRIPTION OF THE DRAWINGS [0026] FIG. 1 is a block diagram of a preferred embodiment of a projector of the present invention. 2 is a flow chart of a preferred embodiment of the autofocus method of the projector of the present invention. [Main component symbol description] [0028] Projector 100 [0029] Autofocus unit 1 [0030] Initialization module 11 [0031] Image Analysis Module 12 [0032] Focus Adjustment Module 13 [0033] Projection Lens 2 [0034] Drive Unit 3 [0035] Image Capture Unit 4 [0036] Storage Unit 5 [0037] Microprocessor 6 099129204 Form No. A0101 Page 10 of 14 page 0992051239-0