1283952 i式本學式時，請揭示最能齡發明特徵的化 九、發明說明： _ 【發明所屬之技術領域】 ，本發明係有關一種雷射掃描裝置，尤指一種利用一簡 諧性運動之微機電擺動式反射鏡（臓⑽心吻 mirror )來操控雷射光束之投射方向，並藉一 F_Sin θ線 ⑩性掃描鏡片以針對擺動式反射鏡隨時間成正弦關係的角度 變化f作出修正’而達成雷射掃描裝置所要求之線性掃描 效果，並增進掃描效率者。 【先前技術】 目七雷射光束印表機LBP ( Laser Beam Printer )之應 用技術中’已包括有美國US 5,128, 795、US 5,162, 938、 us 5, 329, 399、US 5, 710, 654、US 5, 757, 533、US 5,619,362、US 5,721, 631、US 5, 553,729、US 5’Ul，219、US 5,995，131、US 6,724,509，及日本 440908、日本5—4558〇等多件專利，其中，所使用之雷 射掃描裂置LSU ( Laser Scanning Unit )模組大都是利用 向速疑轉之多面鏡（polygon mirror )以操控雷射光束 之婦篇動作（laser beam scanning )，其係利用一半導體 發出雷射光束（laser beam )，該雷射光束經一準直 鐘( v c〇Uimat〇r )，再經過一光圈（aperture )而形成平 行光束’平行光束再經過一柱面鏡（cylindrical lens) ’而該柱面鏡主要作用係使前述平行光束在副掃描 ^1283952 ^ 方向（sub scanning direct i on ) Y轴上之寬度能沿著主掃 、 描方向（main scanning direction ) X轴之平行方向聚焦 而形成一線狀成像（line image )，再投射至一高速旋轉 之多面鏡（polygonal mirror )上；該多面鏡上均勻連續 ^ 佈設有多面反射鏡，其恰位於或接近於上述線狀成像 (line image )之焦點位置；而藉多面鏡控制雷射光束之 • 投射方向，當連續之複數反射鏡在高速旋轉時可將射至一 反射鏡上之雷射光束沿著主掃描方向（X軸）之平行方向 • 以同一轉角速度（angular velocity )偏斜反射至一F- 0 線性掃描鏡片上；而該F- 0鏡片係設置於多面鏡旁侧，可 為單件式鏡片結構（single-element scanning lens )或為 兩件式鏡片結構（如US 5, 995,131之專利圖所示），而藉 F- Θ鏡片主要是使經由多面鏡上反射鏡反射而射入F- θ鏡 片之雷射光束能聚焦成一楕圓形光點並投射在一光接收面 (photoreceptor drum，即成像面）上，並達成線性掃描 (scanning linearity)之要求；然，習用雷射掃描裝置 _ LSU在使用上會有下列問題·· (1)、該旋轉式多面鏡（polygon mirr〇r )之製作 難度高且價格不低，相對增加LSU之製作成本。 (2 )、該多面鏡須具高度旋轉（如40000轉/分） 功能，精密度要求又高，致一般多面鏡上反射面之鏡面γ • 轴寬度極薄，使習用LSU中均須增設一柱面鏡 (cylindrical lens )以使雷射光束經過該柱面鏡能聚焦 成一線（Y轴上成一點）而再投射在多面鏡之反射鏡上， 致增加構件及組裝作業流程。 3 ‘1283952 (3 )、習用多面鏡須离 分），致旋轉嚷音相對提高，^轉（如4()_轉/ i# ^ B* PI ^ ^4, 且多面鏡從啟動至工作轉 速須耗費較長％間’增加開機 (4 )、習用LSU之_姓4待時間 Ά褒結構中，投射至多面鏡反射 鏡之雷射光束中心軸並非“ ，上 ^ 對夕面鏡之中心轉軸，致在設1283952 i-style, please reveal the characteristics of the most inventive invention. 9. Description of the invention: _ [Technical field of invention] The present invention relates to a laser scanning device, in particular to a simple harmonic motion. The microelectromechanical oscillating mirror (臓(10) mitre mirror) is used to manipulate the projection direction of the laser beam, and an F_Sin θ line 10 scanning lens is used to correct the angle change f of the oscillating mirror in a sinusoidal relationship with time. 'And achieve the linear scanning effect required by the laser scanning device, and improve the scanning efficiency. [Prior Art] In the application technology of the LBP (Laser Beam Printer), the US has included US 5,128, 795, US 5,162, 938, us 5, 329, 399, US 5, 710, 654. US 5, 757, 533, US 5, 619, 362, US 5, 721, 631, US 5, 553, 729, US 5'Ul, 219, US 5,995, 131, US 6, 724, 509, and Japanese 440908, Japan 5-4558, and the like, Among them, the laser scanning unit (LSU) used in the laser scanning unit is mostly used to manipulate the beam beam of the laser beam by using a polygon mirror. A semiconductor emits a laser beam that passes through a collimating clock (vc〇Uimat〇r) and then passes through an aperture to form a parallel beam. The parallel beam passes through a cylindrical mirror (cylindrical) Lens) 'The main effect of the cylindrical mirror is to make the width of the parallel beam in the sub-scanning direction of the sub-scanning direction on the Y-axis along the X-axis of the main scanning direction. Focusing in parallel to form a line a line image is projected onto a high-speed rotating polygon mirror; the polygon mirror is uniformly and continuously provided with a polygon mirror which is located at or near the focus of the above line image. Position; and the polygon mirror controls the projection direction of the laser beam, and when the continuous plurality of mirrors rotate at a high speed, the laser beam incident on a mirror can be parallel along the main scanning direction (X-axis). Deflection to an F- 0 linear scanning lens at the same angular velocity; and the F-0 lens is placed beside the polygon mirror, which can be a single-element scanning lens or It is a two-piece lens structure (as shown in the patent of US 5,995,131), and the F- Θ lens is mainly used to make the laser beam reflected by the mirror on the polygon mirror and incident on the F- θ lens can be focused into a single beam. The circular spot is projected onto a light receiving surface (photographing surface) and meets the requirements of linear scanning (scanning linearity); however, the conventional laser scanning device _ LSU has the following questions in use. (1) The production of the rotary polygon mirror (polygon mirr〇r) is difficult and the price is not low, which increases the production cost of the LSU. (2) The polygon mirror must have a high degree of rotation (such as 40,000 rpm), and the precision requirements are high. The mirror surface of the reflecting surface of the general polygon mirror is γ. The width of the shaft is extremely thin, so that one of the conventional LSUs must be added. A cylindrical lens is used to cause the laser beam to be focused into a line (a point on the Y-axis) through the cylindrical mirror and then projected onto the mirror of the polygon mirror, thereby increasing the component and assembly process. 3 '1283952 (3), the conventional polygon mirror must be separated), the rotation of the voice is relatively increased, ^ turn (such as 4 () _ turn / i # ^ B * PI ^ ^ 4, and the polygon mirror from start to work speed It takes a long time to increase the start-up (4), the LSU's last name, and the center axis of the laser beam projected onto the polygon mirror is not ", the center axis of the upper mirror In the design
計相配合之F- 0鏡片時，箔π 0士 L 相。· , 為冋時考慮多面鏡之離轴偏差問 通（—η)，相對增加Μ鏡片之設計及製作上麻 煩0 【發明内容】 本發明主要目的乃在於提供-種雷射掃描裝置 (LSU)，其係利用-微機電擺動式反射鏡以取代習用旋 轉式多面絲難雷射光束_ ( laserbeajn scamung)，並利用-F—細0線性掃描鏡片以取代習用 F (9線|±掃描鏡片，而該F—如0鏡片係針對擺動式反射 鏡隨時間成正弦關係的角度變化量作修正，使雷射光束在 成像面上作等速率的掃描；藉此，半導體雷射射出之雷射 光束先^準直鏡形成平行光束，再射至微機電擺動式反射 鏡，再藉經該反射鏡之簡諧式擺動使雷射光束反射至 F—Sin Θ鏡片，再藉該F-Sin 0鏡片對入射雷射光束隨時 間成正弦關係的角度變化量之修正效果，使雷射光束投射 在成像面上作等速率掃描，而達成雷射掃描裝置所要求之 線性掃描效果，並增進掃描效率者。 本發明再一要目的乃在於提供一種雷射掃描裝置，其 係針對微機電擺動式反射鏡以簡諧運動方式反射雷射光束 4 1283952 間距呈現隨時間增加而遞減的非等 速轉描現象’而特別設計—F_sin 0線性掃描鏡片，使 該F-Sm^鏡片可對隨時間成正弦關係的角度變化量作修 正’使微機電簡諧運動反射鏡在成像面上光點間距由原來 隨時間增加__料速特描現象，修正為等速率掃 描’使雷射光束投射在成像面上作等速铸描，而達成雷 射掃描裝置所要求之線性掃描效果。When the F- 0 lens is matched, the foil is π 0 L phase. · In view of the off-axis deviation of the polygon mirror (-η), it is relatively troublesome to design and manufacture the lens. [Invention] The main purpose of the present invention is to provide a laser scanning device (LSU). , which uses a micro-electromechanical oscillating mirror to replace the conventional rotating multi-faced ray laser _ ( laserbeajn scamung), and uses the -F-fine 0 linear scanning lens to replace the conventional F (9-line | ± scanning lens, The F-like lens is corrected for the angular variation of the oscillating mirror in a sinusoidal relationship with time, so that the laser beam is scanned at an equal rate on the imaging surface; thereby, the laser beam emitted by the semiconductor laser is emitted. First, the collimating mirror forms a parallel beam, which is then incident on the microelectromechanical oscillating mirror, and then the harmonic beam is reflected by the mirror to reflect the laser beam to the F-Sin Θ lens, and then the F-Sin 0 lens is used. The correction effect of the angle change of the incident laser beam in a sinusoidal relationship with time, so that the laser beam is projected on the imaging surface for equal-rate scanning, and the linear scanning effect required by the laser scanning device is achieved, and the scanning efficiency is improved. A further object of the present invention is to provide a laser scanning device which is directed to a microelectromechanical oscillating mirror which reflects a laser beam in a simple harmonic motion manner. The distance between the laser beam 4 1283952 and the non-equal speed scanning phenomenon which decreases with time increases. Specially designed—F_sin 0 linear scanning lens, so that the F-Sm^ lens can correct the angular variation of the sinusoidal relationship with time', so that the spot spacing of the microelectromechanical harmonic motion mirror on the imaging surface is from the original time. Increasing the __ material speed special tracing phenomenon, corrected to equal-rate scanning 'casts the laser beam onto the imaging surface for constant velocity casting, and achieves the linear scanning effect required by the laser scanning device.
本發明又要目的乃在於提供一種雷射掃描裝置，其 中該雷射光束中心轴係正對該微機電反射鏡之機械中心 (即反射鏡之擺動中心），藉以消除習用者多面鏡之離轴 偏差（deviation)，而可簡化F-Sin (9鏡片之設計及製 作0 本發明另一要目的乃在於提供一種雷射掃描裝置，其 中該雷射掃描裝置（LSU )之模組中，在該準直鏡及該微 機電擺動式反射鏡之間可隨需要而設置或不設置一柱面鏡 (cylindrical lens )，藉以簡化雷射掃描裝置之構件及 組裝作業流程。 【實施方式】 為使本發明更加明確詳實，茲舉一較佳實施例並配合 下列圖示，將本發明之結構及其技術特徵詳述如後： 參考圖1、2、3、4所示，本發明雷射掃描裝置 (LSU，Laser Scanning Unit ) 1，主要包括一半導體雷 射10、一準直鏡11、一微機電擺動式反射鏡（MEMS oscillatory mirror) 12、及一 F-Sin 0 鏡片 13，而其特徵 5 ^ 1283952 在於：利用該微機電擺動式反射鏡12以取代習用旋轉式多 面鏡（polygon mirror )，使半導體雷射10所發出之雷射 光束可經過準直鏡11以形成平行光束，而平行光束可以不 必再經過一柱面鏡（cylindrical lens )，而可直接投射 ' 至微機電擺動式反射鏡（MEMS oscillatory mirror ) 12 . 上，而微機電擺動式反射鏡（MEMS oscillatory mirror ) 22係在某一擺動幅度下進行簡諧運動，藉以控制該入射雷 射光束之反射方向，使雷射光束反射至位於旁侧之F-Sin 馨 β鏡片13，再經由F-Sin 0鏡片13折射而投射至成像面 (Image I>lane)14上，達成一雷射掃描裝置所要求之線性掃 描（scanning linearity)功效。 又針對該微機電擺動式反射鏡（腿US oscillatory mirror ) 12之簡諧運動（harmonic motion )方式，本發明 特別利用一重新設計之F-Sin 0鏡片13，以達成線性掃描 (scanning linearity)之要求；玆針對該 F—Sin 0 鏡片 13 之技徵特徵及作用功效，以及其與原有1?一0鏡片之間的不 _ 同處說明如下： 一般傳統的雷射掃描裝置（LSU)是採用旋轉式多面鏡 (Polygon Minror)以等角速率旋轉來完成雷射光束在感光 - 鼓上作掃描的動作；此時雷射光束由旋轉式多面鏡反射的 角度滿足下式： Θ (t) = ωΗ ,其中ω為Polygon Mirr〇r的旋轉角速 率.........E(l) 、 6 1283952 2圖5 (A) 、6 (A)所示，由於多面鏡為等角速率旋 軏，即ω為常數，故反射角度0正比於時間t;換言之， 在相同的時間間隔下，反射角度0隨時間的變化量也是相 同的。被反射的雷射光束經由鏡片聚焦於成像面（Image lane)l4處，此時光點在γ方向的仇置γ，滿足下式： Y〜Lp * Tmi( 0 (t))，其中Lp為多面鏡之反射鏡面到成 像面的距離.........e(2)Another object of the present invention is to provide a laser scanning device in which the central axis of the laser beam is directly opposite to the mechanical center of the microelectromechanical mirror (ie, the center of oscillation of the mirror), thereby eliminating the off-axis of the conventional polygon mirror. Deviation, which simplifies F-Sin (9 lens design and fabrication 0. Another object of the invention is to provide a laser scanning device in which the laser scanning device (LSU) is in the module A cylindrical lens may or may not be provided between the collimating mirror and the microelectromechanical oscillating mirror to simplify the components of the laser scanning device and the assembly operation flow. The invention will be more clearly described in detail, and the structure and technical features of the present invention will be described in detail as follows with reference to the following drawings: Referring to Figures 1, 2, 3 and 4, the laser scanning device of the present invention is shown. (LSU, Laser Scanning Unit) 1, mainly comprising a semiconductor laser 10, a collimating mirror 11, a MEMS oscillatory mirror 12, and an F-Sin 0 lens 13, and its feature 5 ^ 1 283952 is to use the microelectromechanical oscillating mirror 12 to replace the conventional rotary polygon mirror, so that the laser beam emitted by the semiconductor laser 10 can pass through the collimating mirror 11 to form a parallel beam, and the parallel beam can be It does not have to go through a cylindrical lens, but can directly project 'to the MEMS oscillatory mirror 12', while the MEMS oscillatory mirror 22 is in a certain A simple harmonic motion is performed under the swing amplitude to control the reflection direction of the incident laser beam, so that the laser beam is reflected to the F-Sin ββ lens 13 located on the side, and then refracted by the F-Sin 0 lens 13 to project to the imaging On the surface (Image I>lane) 14, the linear scanning effect required by a laser scanning device is achieved. The harmonic motion of the micro-electromechanical oscillating mirror (leg US oscillatory mirror) 12 is also applied. In this way, the present invention particularly utilizes a redesigned F-Sin 0 lens 13 to achieve the requirements of linear scanning (scanning linearity); for the F-Sin 0 mirror The features and functions of the film 13 and its non-identical relationship with the original 1-0 lens are as follows: The conventional conventional laser scanning device (LSU) uses a rotating polygon mirror (Polygon Minror). Rotating at a constant angular rate to complete the scanning of the laser beam on the photosensitive drum; at this time, the angle of the laser beam reflected by the rotating polygon mirror satisfies the following equation: Θ (t) = ωΗ , where ω is Polygon Mirr〇 The angular rate of rotation of r.........E(l), 6 1283952 2Fig. 5 (A), 6 (A), since the polygon mirror is an isometric rate of rotation, that is, ω is a constant, Therefore, the reflection angle 0 is proportional to the time t; in other words, at the same time interval, the amount of change of the reflection angle 0 with time is also the same. The reflected laser beam is focused by the lens on the image plane l4, and the spot is gamma in the γ direction, which satisfies the following formula: Y~Lp*Tmi( 0 (t)), where Lp is multifaceted The distance from the mirror surface of the mirror to the imaging surface.........e(2)
如圖6 ( A )中虛線所示，在成像面的光點軌跡隨時間增 且光點與下一個光點間的間距也隨之漸增，即在成像 面上光點的速率為非等速且漸增的，而此現象在LSU中是 气的，此時該鏡片除了聚焦的功能外，尚需有修正光 二非等速運動的功能，使光點的軌跡是等速率的，使修正 後之先點位置Y，滿足下式： Y’ = F * 0(t)，其中F為該鏡片的焦距.........E(3) 如圖6 ( A )中實線所示，相同的時間間隔對應相同的反 ，角度的變化量，由E(3)式便可知對應到的光點位置γ，為 等間距的變化，故稱此種同時具有修正光點大小與修正其 轨跡為等速的特殊鏡片為F-0鏡片；又如圖7 ( A )所 示’在光學設計上，此鏡片是要刻意的產生一，，負畸變 (Negative Distortion or Barrel Distortion)，’，即將原來的 光束路徑（Original Beam Path )經由F- 0鏡片向列印中心 (Printing Center )彎折，而被鏡片彎折的光束與原來的 7 1283952 光束在成像面14上的位置差量，如圖6 ( A )所示之dl、 d2、d3，由中心向外漸增。 而本發明係利用一微機電擺動式反射鏡（MEMS osci 1 latory mirror) 12以取代多面鏡（Polygon Mirror)，而微機電擺動式反射鏡12的運動模式是簡諧運 動（Harmonic Motion)，與旋轉式多面鏡不同，即雷射光束 經擺動式反射鏡反射後的反射角度0與時間t的關係為： Θ (t) = Gs * Sin(27rf * t ) .........E(3) 其中：f為微機電反射鏡12的掃描頻率； <9s為光束經微機電反射鏡後，單邊最大的掃描角度； 如圖5 (B)所示，在相同的時間間隔下，所對應的反射 角度的變化量並不相同且為遞減，係一與時間成正弦函數 (Sinusoidal)的關係；微機電擺動式反射鏡來回擺動一次 為一完整的周期，圖5 (B)所示僅為四分之一周期，此 時即達到最大的反射角度6» s。 ’ 如圖6 ( B )所示，同理可得光點的位置γ，亦滿足 E(2)，並將e(4)代入E(2)可得： 彳 Y = Lm* Tan [ 0s * Sin(2 7rf * t ) ]..........g(5) 其中’ Lm為反射鏡面到成像面14的距離 =式可得’在成像面上光點與下一個光點的間距隨時 曰 1曰加而遞減，即在成像面14上光點的速率為非等速且遞 1283952 減的’而此現象與旋轉式多面鏡（p〇lyg〇n Mirror )的情 況相反’因此須加入一特殊鏡片來修正此現象，使其在成 像面上作等速率的掃描；由於此鏡片是針對隨時間成正弦 關係的角度變化量作修正，而有別用於旋轉式多面鏡所使 用的鏡片，故稱其為F-Sin 0鏡片13 ;而在光學設計 上’此F-Sin 0鏡片13是要刻意產生一”正畸變 (Positive Distortion or Pincushion Distortion)，，，即將原 來的光束路徑經由F-Sin 0鏡片向列印終端（Printing _ End )彎折，如圖6 ( b )所示，而被F-Sin 0鏡片13彎 折的光束與原來的光束在成像面上的位置差量（即dl，、 d2’ 、d3’），由中心向外漸增。 再參考圖7 (A) 、 （B)，其分別為旋轉式多面鏡 (Polygon Mirror )與微機電擺動式反射鏡（MEMS oscillatory mirror)之雷射掃描裝置（LSU )的光學設 計’其中，光學系統中的鏡片，包括F-θ鏡片及F-Sin β ’都有修正光點位置的功能，使其在成像面上的掃描速 ⑩ 率為等速率，即相同的時間間隔下，光點與下一光點的間 距為相等的。 再參考圖8 (A) 、 （β)，其分別為旋轉式多面鏡 — 與微機電擺動式反射鏡之雷射掃描裝置（LSU )所使用的 F-6>鏡片與F-Sin (9鏡片在畸變（Distorti〇n)的光學特 性，圖8 ( Δ )是表示一”負畸變’’的光學特性，圖8 (B )則是一 M正畸變’，的光學特性。 由上所述，可知本發明利用一微機電擺動式反射鏡12 及一 F-Sin 0鏡片13組成一雷射掃描裝置（LSU )，已與 9 1283952 習知利用一旋轉式多面鏡（Polygon Mirror )及一F-0鏡 片組成之雷射掃描裝置（LSU )完全不同。 本發明至少可達成下列優點： (1 )、在雷射掃描裝置（LSU )模組中不一定須要 设置一柱面鏡（cylindrical lens )，可使F-Sin 0鏡片 之光學没汁將更堅固（more r〇bust )且更高公差 (higher tolerance )。 (2)、雷射光束中心轴與微機電擺動式反射鏡之機 械中心不再有習用多面鏡（P〇lyg〇n fflirr〇r )之離轴偏差 問題（deviation)，因此在設計F-Sin 0鏡片時，可只考 慮對稱性光學區域（symmetric optical field )，而可簡 化F-Sin 0鏡片之設計及製作。 (3 )、微機電擺動式反射鏡之簡諧運動（harmonic motion )啟動後可馬上達成工作轉速，幾乎沒有待機時 間，而且可具較高運轉速度，甚至比多面鏡馬達 (polygon瓜otor )使用氣式轴承馬達（air-bearing motor )還高，故微機電擺動式反射鏡微機電反射鏡之掃 幅效率較佳。 (4 )、微機電擺動式反射鏡之簡譜運動（harmonic motion)係在某一定擺動幅度下之正反向擺動，使掃描方 向（scanning direction)可雙向來回進行，致同一運轉速 度之下，微機電擺動式反射鏡之雙向掃幅速度可兩倍於多 面鏡之單尚婦幅速度’相對增進掃幅效率。 综上所述，本發明的確能藉由上述所揭露之結構達到 所預期之功效’且本發明申請前未見於刊物亦未公開使 ^ 1283952 用，誠已符合專利之新穎、進步等要件。 惟’上述所揭之圖式及說明，僅為本發明之實施例而 已’非為限定本發明之實施例；大凡熟悉該項技藝之人 士 ’其所依本發明之特徵範疇，所作之其它等效變化或修 飾’皆應涵盖在以下本案之申請專利範圍内。 . 【圖式簡單說明】 圖1:係本發明雷射掃描裝置模組之立體示意圖。 籲 圖2 :係圖1光學路徑之上視示意圖。 圖3 :係圖1光學路徑之一侧視示意圖。（圖2之垂直向 視圖）。 圖4 ··係本發明微機電擺動式反射鏡（MEMS mirror) —實 施例立體不意圖。 圖5(A)、（B):分別係旋轉式多面鏡（polygon mirror)及與微機電擺動式反射鏡（MEMSmirror)反射後 的反射角度(9與時間t的關係圖。 圖6 ( A )、（ B ):分別係旋轉式多面鏡及與微機電擺 動式反射鏡之掃描光點軌跡圖。 圖7 (A) 、 （B):分別係旋轉式多面鏡及微機電擺動 式反射鏡之光學設計（lay0Ut )示意圖。 ’ 圖8 ( A )、（ B ):分別係旋轉式多面鏡與微機電擺動 - 式反射鏡之雷射掃描裝置所使用的F-0鏡片與F-Sin0鏡 片在畸變（Distortion)的光學特性示意圖。 【主要元件符號說明】 11 1283952 I 雷射掃描裝置（LSU，Laser Scanning Unit ) 10 半導體雷射 II 準直鏡 12 微機電擺動式反射鏡（MEMS oscillatory mirror ) 13 F-Sin0 鏡片 14 成像面As shown by the dotted line in Fig. 6 (A), the trajectory of the spot on the imaging surface increases with time and the distance between the spot and the next spot increases, that is, the velocity of the spot on the imaging surface is non-equal. Speed and increasing, and this phenomenon is gas in the LSU. In addition to the focusing function, the lens needs to have the function of correcting the light non-equal motion, so that the trajectory of the light spot is equal rate, so that the correction After the first point position Y, the following formula is satisfied: Y' = F * 0(t), where F is the focal length of the lens... E(3) as shown in Fig. 6 (A) As shown, the same time interval corresponds to the same inverse, the amount of change in the angle, and the position γ of the corresponding spot is known by the equation E(3), which is an equidistant change, so it is said that this has both the corrected spot size and Correct the special lens whose trajectory is constant velocity to F-0 lens; as shown in Figure 7 (A) 'In optical design, this lens is to deliberately produce a negative distortion (Negative Distortion or Barrel Distortion) , ', the original beam path (Original Beam Path) is bent through the F- 0 lens to the Printing Center, and is bent by the lens The beam and beam position 71283952 original difference on the imaging surface 14, FIG. 6 (A) dl as shown in the, d2, d3, increasing outwardly from the center. The present invention utilizes a MEMS osci 1 latory mirror 12 instead of a Polygon Mirror, and the motion mode of the microelectromechanical oscillating mirror 12 is Harmonic Motion, and The rotary polygon mirror is different, that is, the relationship between the reflection angle 0 of the laser beam reflected by the oscillating mirror and the time t is: Θ (t) = Gs * Sin(27rf * t ) ......... E(3) where: f is the scanning frequency of the microelectromechanical mirror 12; <9s is the maximum scanning angle of the single side after the beam passes through the microelectromechanical mirror; as shown in Fig. 5(B), at the same time interval Next, the corresponding change angle of the reflection angle is not the same and is decreasing, which is a sinusoidal relationship with time; the microelectromechanical oscillating mirror swings back and forth once for a complete cycle, Figure 5 (B) Only a quarter cycle is shown, at which point the maximum reflection angle of 6» s is reached. As shown in Fig. 6 (B), the position γ of the light spot can also satisfy E(2), and the substitution of e(4) into E(2) can be obtained: 彳Y = Lm* Tan [ 0s * Sin(2 7rf * t ) ]..........g(5) where 'Lm is the distance from the mirror surface to the imaging surface 14= can be obtained' on the imaging surface and the next spot The spacing of the dots is increased and decreased at any time, that is, the velocity of the spot on the imaging surface 14 is non-equal and the difference is 1283952. This phenomenon is opposite to that of the rotating polygon mirror (p〇lyg〇n Mirror). Therefore, a special lens must be added to correct this phenomenon so that it can be scanned at an equal rate on the imaging surface; since the lens is corrected for the amount of angular change in sinusoidal relationship with time, it is used for rotary polygon mirrors. The lens used, so it is called F-Sin 0 lens 13; and in the optical design 'this F-Sin 0 lens 13 is to deliberately produce a "Positive Distortion or Pincushion Distortion", that is, the original The beam path is bent toward the printing terminal (Printing_End) via the F-Sin 0 lens, as shown in Fig. 6(b), and the beam is bent by the F-Sin 0 lens 13 The position difference of the beam on the imaging plane (ie, dl, d2', d3') increases gradually from the center. Referring to Figure 7 (A), (B), respectively, the rotating polygon mirror (Polygon Mirror) ) Optical design of a laser scanning device (LSU) with a MEMS oscillatory mirror, in which lenses in the optical system, including F-θ lenses and F-Sin β 'have corrected spot positions The function is to make the scanning speed 10 on the imaging plane the same rate, that is, the spacing between the light spot and the next light spot is equal at the same time interval. Referring again to Figure 8 (A), (β), They are a rotating polygon mirror - the F-6 of the laser scanning device (LSU) used with the microelectromechanical oscillating mirror, and the optical characteristics of the lens and the F-Sin (9 lens in the distortion). 8 ( Δ ) is an optical characteristic indicating a "negative distortion", and FIG. 8 (B ) is an optical characteristic of an M orthodontic '. From the above, it is understood that the present invention utilizes a microelectromechanical oscillating mirror. 12 and an F-Sin 0 lens 13 constitute a laser scanning device (LSU), which has been conventionally utilized with 9 1283952 The laser scanning device (LSU) consisting of a rotating polygon mirror (Polygon Mirror) and an F-0 lens is completely different. The present invention can at least achieve the following advantages: (1) not in the laser scanning device (LSU) module It is necessary to provide a cylindrical lens to make the optical immersion of the F-Sin 0 lens more robust (more r〇bust) and higher tolerance. (2) The center of the laser beam and the mechanical center of the microelectromechanical oscillating mirror no longer have the off-axis deviation problem of the conventional polygon mirror (P〇lyg〇n fflirr〇r), so the F-Sin is designed. In the case of 0 lenses, only the symmetric optical field can be considered, and the design and fabrication of the F-Sin 0 lens can be simplified. (3) The harmonic motion of the micro-electromechanical oscillating mirror can reach the working speed immediately after starting, almost no standby time, and it can have higher running speed, even more than the polygon mirror motor (polygon meto) The air-bearing motor is also high, so the micro-electromechanical oscillating mirror microelectromechanical mirror has better sweeping efficiency. (4) The harmonic motion of the microelectromechanical oscillating mirror is a forward and reverse oscillating motion under a certain oscillating amplitude, so that the scanning direction can be performed in both directions, resulting in the same operating speed, micro The two-way sweeping speed of the electromechanical oscillating mirror can be twice as high as that of the polygon mirror. In summary, the present invention can achieve the desired effect by the above-disclosed structure, and the present invention has not been disclosed in the publication and has not been disclosed to use 12,839,952, and has met the novelty, progress and the like of the patent. The drawings and the descriptions of the present invention are merely exemplary embodiments of the present invention, and are not intended to limit the embodiments of the present invention; Depending on the scope of the patent application in this case, the effect changes or modifications shall be covered. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a laser scanning device module of the present invention. Figure 2: A top view of the optical path of Figure 1. Figure 3 is a side elevational view of one of the optical paths of Figure 1. (The vertical view of Figure 2). Fig. 4 is a perspective view of a microelectromechanical oscillating mirror (MEMS mirror) of the present invention. Fig. 5 (A) and (B) are diagrams showing the relationship between the reflection angle (9 and time t) of a polygon mirror and a microelectromechanical oscillating mirror (Fig. 6 (A)). (B): Scanning spot trajectory diagrams of a rotating polygon mirror and a microelectromechanical oscillating mirror, respectively. Figure 7 (A), (B): Rotary polygon mirror and microelectromechanical oscillating mirror Schematic diagram of optical design (lay0Ut). 'Fig. 8 (A), (B): F-0 lens and F-Sin0 lens used in the laser scanning device of the rotary polygon mirror and the MEMS oscillating mirror respectively Schematic diagram of the optical characteristics of Distortion. [Main component symbol description] 11 1283952 I Laser Scanning Unit (LSU) 10 Semiconductor Laser II Collimating Mirror 12 MEMS oscillatory mirror 13 F-Sin0 lens 14 imaging surface