201220263 六、發明說明： 【發明所屬之技術領域】 本發明係關於影像顯示裝置’特別是有關雷射光的斑 點雜訊（speckle noise)對策。 【先前技術】 在使用雷射光之影像顯示裝置，起因於雷射光固有的 同調性（可干涉性）’被稱爲斑點雜訊（speckle noise ) 的微小斑點狀的閃爍是個問題。爲了減低此斑點雜訊，從 前已有種種手法被提出’其中之一係在專利文獻1揭示著 使用雷射光源的緩和振動的手法。在此手法，使用交互反 覆打開及關閉的矩形脈衝狀之脈衝圖案驅動雷射光源。雷 射光源在驅動電流之升起時機開始緩和振動，其後於打開 期間繼續緩和振動。此打開期間，設定爲與緩和振動收斂 的時間相同，或者比其還要短。亦即，跨打開期間之全區 域’雷射光源的輸出位準會不安定地變動，而使雷射光的 同調性降低，所以減低斑點雜訊。 〔先前技術文獻〕 〔專利文獻〕 〔專利文獻1〕日本特開2001-1 89520號公報 【發明內容】 〔發明所欲解決之課題〕 在前述專利文獻1，某個固定的矩形脈衝的圖案被一 -5- 201220263 律適用’依照此圖案的頻繁切換在所有的階調區域都同樣 地進行。因此，即使在斑點雜訊不是很醒目的低階調區域 (例如關於亮度而言是在比較暗的區域，例如關於顏色而 言是在比較濃的區域），也與高階調區域（例如關於亮度 而言是在比較明亮的區域’例如關於顏色而言是在比較淡 的區域）同樣地頻繁切換，因而招致消耗電力的浪費。 在此，本發明之目的在於使斑點雜訊（speckle noise )更爲減低，謀求耗電量的減低。 〔供解決課題之手段〕 解決相關課題之第1發明，提供具有波形圖案選擇部 與雷射光源，藉由把雷射光投影至投射面，在投射面上顯 示影像的影像顯示裝置。波形圖案選擇部，在應該顯示的 階調未滿閩値的場合，選擇包含至少1個打開期間的第1波 形圖案。此外，波形圖案選擇部，在應該顯示的階調比閾 値更高的場合，選擇打開期間比第1波形圖案更被細分化 的第2波形圖案。雷射光源，使因應於應該顯示的階調的 輸出位準之雷射光，依照藉由波形圖案選擇部選擇的第1 波形圖案或第2波形圖案而射出。 於第1發明，前述第1波形圖案之至少1個打開期間’ 最好比雷射光源固有的緩和振動期間更長。此外，前述第 2波形圖案之打開期間之各個，最好是比雷射光源固有的 緩和振動期間還短。 第2發明，提供具有波形圖案選擇部與雷射光源’藉 -6- 201220263 由把雷射光投影至投射面，在投射面上顯示影像的影像顯 示裝置。波形圖案選擇部，在應該顯示的階調未滿閾値的 場合，於特定的顯示期間，選擇包含根據基準時脈生成的 至少1個打開期間的第1波形圖案。此外，波形圖案選擇部 ，在應該顯示的階調大於閾値的場合，於特定的顯示期間 ，選擇包含根據基準時脈生成的複數打開期間以及複數關 閉期間的第2波形圖案。雷射光源，使因應於應該顯示的 階調的輸出位準之雷射光，依照藉由波形圖案選擇部選擇 的第1波形圖案或第2波形圖案而射出。此處，第1波形圖 案之至少1個打開期間，比雷射光源固有的緩和振動期間 更長。此外，第2波形圖案之打開期間之各個，比雷射光 源固有的緩和振動期間還短。 於第2發明，前述第2波形圖案，最好是藉由反覆複數 次由打開週期及關閉週期所構成的單位週期而構成的。 於第1或第2發明，被供給至前述雷射光源的驅動電流 ，在關閉期間，無關於應該顯示的階調，被設定爲雷射光 源的偏壓電流以下的位準，在打開期間，被設定爲因應於 應該顯示的階調之電流位準。此外，前述閾値，最好於各 個射出波長不同的雷射光之雷射光源，被設定爲不同的値 。在此場合，綠成分之閩値，最好比紅成分的閩値更小》 〔發明之效果〕 根據第1或第2發明，於藉由閩値分割的各階調區域， 藉由使運用在雷射光源的驅動的波形圖案最佳化，可以謀 201220263 求斑點雜訊的減低，同時兼顧耗電量的減低。亦即，應該 顯示的階調在比閾値還高的高階調區域，藉由使用第2波 形圖案，進行比低階調區域的顯示時更多的緩和振動。藉 由雷射光源的緩和振動，使雷射光的同調性降低，所以高 階調區域在顯示時容易變得醒目的斑點雜訊有效地被降低 。另一方面，在應該顯示的階調未滿閾値的低階調區域， 使用第1波形圖案減低打開/關閉的切換頻率，謀求耗電 量的減低。在斑點雜訊不像在高階調區域那樣醒目的低階 調區域，即使減少緩和振動的次數，在畫質上也很少有問 題。 【實施方式】 圖1係相關於本實施型態之雷射投影機的方塊構成圖 。此雷射投影機1，把雷射光源2a〜2C，各種光學元件3〜 5，掃描鏡6，各種驅動/控制單元7〜11構成爲主體。雷 射投影機1，藉由合成紅藍綠各成分之雷射光後投影於螢 幕或牆壁等投射面A，而把因應於影像訊號的彩色影像顯 示於投射面A上。雷射投影機1，利用指向性極高的雷射光 ，所以具有不需要因應於至投射面A的距離之焦點調整的 優異優點， 分別的雷射光源2a〜2c，藉由從雷射驅動器1 1個別供 給的驅動電流而相互獨立地驅動。藉此’如同由雷射光源 2a射出藍成分（B)，由雷射光源2b射出綠成分（G ) ’由 雷射光源2c射出紅成分（R)，射出特定波長的雷射光。 -8- 201220263 分色鏡3、4藉由僅透過特定波長的雷射光，反射其他的光 ，合成由雷射光源2a〜2 c射出的各色成分的雷射光。具體 而言，由雷射光源2a、2b射出的藍成分及綠成分的雷射光 ，於光徑上游側的分色鏡3被合成，而且射出往光徑下游 側的分色鏡4。此射出的合成光，於分色鏡4進而與由雷射 光源2c射出的紅成分的雷射光合成，而作爲目標之最終彩 色光而射出。此射出的彩色光，透過透鏡5入射至掃描鏡6 〇 掃描鏡6，把往自身入射的彩色光，因應於自己的偏 轉角（相位）反射而投射至投射面A上。此掃描鏡6，具有 對應於投射面A的水平方向X及垂直方向Y的二次元的自 由度，藉由對應於此二次元的位移之線循序掃描，於投射 面A上形成影像。此線循序掃描，係藉由在投射面A上之 某條水平線上於一方向上使雷射光點P前進，在次一條水 平線於相反方向上使雷射光點P返回之反覆，而在1圖框內 連續進行。於掃描鏡6，因應於其驅動方式而存在幾種形 式，均可以使用。此形式，使用MEMS (微機電系統， Micro Electro Mechanical Systems)技術者可容易入手， 在謀求裝置全體的小型化、低耗電力化以及處理的高速化 上是有利的。以電磁驅動進行鏡的掃描的場合之動作原理 大致如下。反射雷射光的鏡，中介著相互正交的2個旋轉 軸而被安裝於基板。驅動電流在水平掃描用的線圈上流動 的場合，在與此線圈對應的永久磁石之間產生電磁力，藉 由此電磁力，使被安裝於基板的鏡沿著一方的旋轉軸擺動 -9 - 201220263 (水平掃描）。此外’驅動電流在垂直掃描用的線圈上流 動的場合’在與此線圈對應的另外的永久磁石之間產生電 磁力’藉由此電磁力，使被安裝於基板的鏡沿著另一方的 旋轉軸擺動（垂直掃描）。水平/垂直掃描用的驅動電流 ，具有隨著鏡的尺寸、材料密度、硬度等而特定的固有的 共振頻率，藉由以此共振頻率使鏡二次元地位移，鏡會以 最大的偏轉角連續振動。又，關於電磁驅動型鏡的詳細內 容，揭示於日本特開2009-25832 1號公報，可應需要而參 照》此外，於電磁驅動型掃描鏡之中，也存在著以共振頻 率驅動僅進行水平掃描，而針對垂直掃描則以直流驅動（ 藉由電流的水平控制相位）來進行的形式，將此形式作爲 掃描鏡6使用亦可。 掃描鏡驅動器7，藉由對掃描鏡6供給驅動電流，而驅 動掃描鏡6。伴此，掃描鏡驅動器7，檢測出掃描鏡6之現 在的位置（相位）。此被檢測出的位置資訊，作爲位置檢 測訊號被通知至掃描鏡控制部8。掃描鏡6之位置檢測，例 如可以藉由在連結前述之鏡與基板之間的旋轉軸（二軸） 設扭轉感測器，以扭轉感測器檢測出與鏡的偏轉角連動的 旋轉軸的扭轉角而進行。此外，於掃描鏡6的附近配置受 光元件（光電二極體），藉由以受光元件檢測出與鏡的偏 轉角連動的反射光的位置，而檢測出掃描鏡6的位置亦可 〇 掃描鏡控制部8，以使入射至掃描鏡6的雷射光以特定 的頻率掃描特定的影像區域的方式，來控制掃描鏡6。此 -10- 201220263 控制，係藉由掃描鏡控制部8對掃描鏡驅動器7輸出驅動訊 號而進行的。此外，掃描鏡控制部8，根據來自掃描鏡驅 動器7的位置檢測訊號，產生水平同步訊號HSNC與垂直同 步訊號VSNC，將這些輸出至影像處理部9。來自雷射光源 2a〜2c的雷射光的射出時機，有必要與掃描鏡6的相位控 制進行同步，爲了取得此同步使用水平/垂直同步訊號 HSNC、VSNC。亦即，在本雷射投影機1，掃描鏡6之驅動 成爲主體，根據內部產生的水平/垂直同步訊號H SNC、 VSNC，以與掃描鏡6的驅動同步的方式從動地驅動雷射光 源2 a〜2 c。 影像處理部9，把由外部裝置供給的輸入影像訊號（ 影像資料），藉由從外部裝置供給的同步訊號在規定的時 機，隨時寫入未圖示的圖框緩衝記憶體。此外，影像處理 部9，在由從掃描鏡控制部8所供給的水平/垂直同步訊號 HSNC、VSNC所規定的時機，依序讀出被容納於圖框緩衝 記憶體的影像資料，轉送至雷射控制部1 〇。 雷射控制部10，根據由影像處理部9依序被轉送的影 像資料，於各色成分決定關於分別的畫素之驅動電流Id， 與應適用於此的波形圖案PT。分別的雷射光源2a〜2c，根 據對各色成分設定的驅動電流Id及波形圖案PT，透過雷射 驅動器1 1個別地被控制/驅動。在本實施型態，作爲波形 圖案PT準備2種波形圖案PT1、PT2，因應於應該顯示的階 調的高低，選擇性適用某一方。 此外，雷射控制部1 0根據藉由光檢測器（未圖示）檢 -11 - 201220263 測出的雷射光的射出光量，以使各階調之射出光量安定的 方式，進行驅動電流Id的回饋控制。藉此，即使因雷射光 源2a〜2 c的溫度上升而使光輸出產生變動，也可以有效地 對應此變動。 圖2爲雷射控制部1 〇之方塊構成圖。此雷射控制部1 0 ，具有驅動模式判定電路10a、波形圖案選擇電路10b、驅 動電流選擇電路1 0c。驅動模式判定電路1 0a，根據依序被 轉送之影像資料，於各畫素及各色成分決定雜訊減低模式 以及省電力模式之一。例如由256階調構成的階調資料D， 係由閾値Dth而2分割爲低階調區域（0 $ D < Dth )，與高 階調區域（Dth$DS255)。關於某個畫素之階調資料D 屬於不滿閾値Dth的低階調區域的場合，驅動模式選擇省 電力模式。在省電力模式，比起減低斑點雜訊來說，以減 低消耗電力爲優先。對此，階調資料D屬於閾値Dth以上的 高階調區域的場合，驅動模式選擇雜訊減低模式。在雜訊 減低模式，比起消耗電力來說，以減低斑點雜訊爲優先。 圖3係關於雷射光源2a〜2c的驅動波形之切換邊界的 說明圖。斑點雜訊，在雷射光源2a〜2c的光輸出越大時， 有成線性或非線性增大的傾向。在此，透過實驗或模擬， 把斑點雜訊在畫質上所容許的邊界特定爲容許値，藉由此 容許値來區分應該優先進行斑點雜訊的減低，還是應該優 先減低消耗電力。接著，把對應於此容許値的階調資料D 作爲閩値Dth。 此閩値Dth，亦可在所有的色成分都是同一値，但有 -12- 201220263 鑑於各色成分的階調特性都不同之惡一點，以對各色成分 ，亦即對各波長不同的雷射光設定不同的値爲較佳。例如 ’關於斑點雜訊顯著醒目的綠色成分，以在寬廣的高階調 區域優先採行雜訊減低對策爲較佳，其閾値DGth設定爲最 小。此外，關於斑點雜訊不是那麼醒目的紅色成分，在某 個程度之高階調區域必須要以雜訊減低對策爲優先，但沒 有必要設定像綠色成分那麼寬的階調範圍，所以其閩値 DRth 設定爲比 DGth 更大（〇<DGth<DRth< 255)。進而 ，關於斑點雜訊不太醒目的藍成分，在高階調的極爲限縮 的區域以雜訊減低對策爲優先即已足夠，所以把其閩値 DBth設定爲比DGth，DRth更大。特別是關於藍色成分， 設爲DBth= 25 5，亦即把所有階調區域都分配給省電力模 式亦可。 波形圖案選擇電路l〇b，在藉由驅動模式判定電路10a 選擇省電力模式的場合（未滿閾値Dth之低階調時），選 擇/產生圖4所示的波形圖案PT1。另一方面，波形圖案選 擇電路l〇b，在雜訊減低模式被選擇的場合（閾値Dth以上 之高階調時），選擇/產生該圖所示的波形圖案PT2。這 些波形圖案PT1、PT2，規定藉由點時脈訊號規定的1畫素 之顯示期間的雷射光源2a〜2c之打開/關閉的期間。點時 脈訊號，根據水平/垂直同步訊號HSNC、VSNC在內部產 生。打開/關閉期間，例如使用規定波形圖案PT1、PT2的 最小分解能之特定的基準時脈，藉由計算其變化計時之次 數等，而可以藉由比較單純的電路精度佳地進行設定。201220263 VI. Description of the Invention: [Technical Field of the Invention] The present invention relates to a video display device', particularly a speckle noise countermeasure relating to laser light. [Prior Art] In the image display device using laser light, the homochromaticity (interferability) inherent to the laser light is called a speckle noise, which is a problem of micro-spot-like flicker. In order to reduce this speckle noise, various techniques have been proposed in the past. One of them is disclosed in Patent Document 1 to disclose a method of mitigating vibration using a laser light source. In this method, a laser light source is driven by a rectangular pulse-like pulse pattern that is alternately opened and closed. The laser source begins to moderate the vibration at the moment the drive current rises, and then continues to moderate the vibration during the opening period. During this turn-on, it is set to be the same as or shorter than the time when the vibration is converged. That is, the output level of the laser light source in the entire area spanning the opening period is unstable, and the homology of the laser light is lowered, so that the speckle noise is reduced. [PRIOR ART DOCUMENT] [Patent Document 1] [Patent Document 1] JP-A-2001-1 89520 SUMMARY OF INVENTION [Problem to be Solved by the Invention] In Patent Document 1, a fixed rectangular pulse pattern is A-5-201220263 Law applies 'Frequent switching according to this pattern is performed equally in all tone areas. Therefore, even if the speckle noise is not a very conspicuous low-tone region (for example, in a darker region with respect to brightness, for example, in a relatively rich region with respect to color), it is also associated with a high-tone region (for example, regarding brightness). In other words, in a relatively bright area, for example, in a relatively light area with respect to color, the frequency is frequently switched, thereby incurring waste of power consumption. Here, the object of the present invention is to reduce the speckle noise and to reduce the power consumption. [Means for Solving the Problem] According to a first aspect of the invention, there is provided a video display device having a waveform pattern selecting portion and a laser light source, and projecting a laser beam onto a projection surface to display an image on a projection surface. The waveform pattern selection unit selects the first waveform pattern including at least one open period when the tone to be displayed is not full. Further, when the tone pattern selection portion to be displayed is higher than the threshold 値, the waveform pattern selection unit selects the second waveform pattern whose opening period is more subdivided than the first waveform pattern. The laser light source emits laser light in accordance with the output level of the tone to be displayed, in accordance with the first waveform pattern or the second waveform pattern selected by the waveform pattern selecting portion. In the first invention, at least one of the opening periods of the first wave pattern is preferably longer than a period of the relaxation vibration inherent to the laser light source. Further, it is preferable that each of the opening periods of the second wave pattern is shorter than the period of the relaxation vibration inherent to the laser light source. According to a second aspect of the invention, there is provided an image display device having a waveform pattern selecting portion and a laser light source 'by -6-201220263 for projecting a laser beam onto a projection surface and displaying an image on the projection surface. The waveform pattern selection unit selects a first waveform pattern including at least one open period generated based on the reference clock during a specific display period when the tone to be displayed is less than the threshold 値. Further, when the gradation to be displayed is larger than the threshold ,, the waveform pattern selecting unit selects the second waveform pattern including the complex opening period and the complex closing period generated based on the reference clock during the specific display period. The laser light source emits laser light in accordance with the output level of the tone to be displayed, in accordance with the first waveform pattern or the second waveform pattern selected by the waveform pattern selecting portion. Here, at least one of the opening periods of the first waveform pattern is longer than the period of the relaxation vibration inherent to the laser light source. Further, each of the opening periods of the second waveform pattern is shorter than the period of the relaxation vibration inherent to the laser light source. According to the second aspect of the invention, the second waveform pattern is preferably constituted by repeating a plurality of unit periods including an open period and a close period. In the first or second invention, the drive current supplied to the laser light source is set to a level equal to or lower than the bias current of the laser light source during the off period, regardless of the tone to be displayed. It is set to the current level in response to the tone that should be displayed. Further, it is preferable that the threshold 値 is a laser light source of laser light having different emission wavelengths, and is set to be different 値. In this case, it is preferable that the green component is smaller than the enthalpy of the red component. [Effect of the invention] According to the first or second invention, each of the gradation regions divided by 闽値 is used by The waveform pattern of the driving of the laser light source is optimized, and it is possible to seek reduction of speckle noise in 201220263, and at the same time, reduce the power consumption. That is, the tone to be displayed is in the high-order tone region higher than the threshold ,, and by using the second wave pattern, more moderate vibration is performed than in the display of the low-order tone region. By the gentle vibration of the laser light source, the coherence of the laser light is lowered, so that the high-order tone region is easily and conspicuously reduced in spot noise when displayed. On the other hand, in the low-tone region where the tone to be displayed is less than the threshold ,, the first waveform pattern is used to reduce the switching frequency of the on/off, and the power consumption is reduced. In the low-order tone area where the spot noise is not as prominent as in the high-order tone area, even if the number of times of mitigating vibration is reduced, there is little problem in image quality. [Embodiment] Fig. 1 is a block diagram showing a laser projector relating to the present embodiment. The laser projector 1 has laser light sources 2a to 2C, various optical elements 3 to 5, a scanning mirror 6, and various drive/control units 7 to 11 as main bodies. The laser projector 1 displays a color image corresponding to the image signal on the projection surface A by synthesizing the laser light of the red, blue and green components and projecting it onto the projection surface A such as a screen or a wall. The laser projector 1 utilizes laser light having extremely high directivity, so that there is no need to adjust the focus of the distance to the projection surface A. The respective laser light sources 2a to 2c are provided by the laser driver 1 from the laser driver 1 1 individually driven drive currents are driven independently of each other. Thus, the blue component (B) is emitted from the laser light source 2a, and the green component (G) is emitted from the laser light source 2b. The red component (R) is emitted from the laser light source 2c, and laser light of a specific wavelength is emitted. -8- 201220263 The dichroic mirrors 3 and 4 reflect other laser light by transmitting only the laser light of a specific wavelength, and synthesize the laser light of the respective color components emitted from the laser light sources 2a to 2c. Specifically, the blue component and the green component laser light emitted from the laser light sources 2a and 2b are combined in the dichroic mirror 3 on the upstream side of the optical path, and are emitted to the dichroic mirror 4 on the downstream side of the optical path. The synthesized light emitted by the dichroic mirror 4 is further combined with the laser light of the red component emitted from the laser light source 2c, and is emitted as the final color light of the target. The emitted colored light is incident on the scanning mirror 6 扫描 scanning mirror 6 through the lens 5, and the colored light incident on itself is projected onto the projection surface A in response to reflection of its own deflection angle (phase). The scanning mirror 6 has a degree of freedom corresponding to the quadratic element of the horizontal direction X and the vertical direction Y of the projection surface A, and the image is formed on the projection surface A by sequential scanning corresponding to the displacement of the secondary element. The sequential scanning of the line is performed by moving the laser spot P in one direction on a certain horizontal line on the projection surface A, and returning the laser spot P in the opposite direction on the next horizontal line, and in the frame 1 Continuously inside. The scanning mirror 6 can be used in several forms depending on its driving mode. In this form, it is advantageous to use a MEMS (Micro Electro Mechanical Systems) technology, and it is advantageous to reduce the size of the entire device, reduce power consumption, and speed up processing. The principle of operation in the case of scanning the mirror by electromagnetic driving is as follows. The mirror that reflects the laser light is mounted on the substrate by interposing two mutually orthogonal rotating axes. When the driving current flows on the coil for horizontal scanning, an electromagnetic force is generated between the permanent magnets corresponding to the coil, and the mirror mounted on the substrate is swung along one of the rotating shafts by the electromagnetic force. 201220263 (horizontal scanning). Further, 'when the driving current flows on the coil for vertical scanning', an electromagnetic force is generated between the other permanent magnets corresponding to the coil. By this electromagnetic force, the mirror mounted on the substrate is rotated along the other side. Axis swing (vertical scan). The driving current for horizontal/vertical scanning has a specific resonant frequency specific to the size, material density, hardness, etc. of the mirror. By shifting the mirror element twice at this resonant frequency, the mirror will continue at the maximum deflection angle. vibration. Further, the details of the electromagnetic driving type mirror are disclosed in Japanese Laid-Open Patent Publication No. 2009-25832, and can be referred to as needed. In addition, in the electromagnetic driving type scanning mirror, there is also a horizontal frequency driving to drive only the level. Scanning is performed in the form of DC driving (phase control by current level) for vertical scanning, and this form may be used as the scanning mirror 6. The scanning mirror driver 7 drives the scanning mirror 6 by supplying a driving current to the scanning mirror 6. Accordingly, the scanning mirror driver 7 detects the current position (phase) of the scanning mirror 6. The detected position information is notified to the scanning mirror control unit 8 as a position detection signal. For detecting the position of the scanning mirror 6, for example, a torsion sensor can be provided by connecting a rotating shaft (two axes) between the mirror and the substrate, and the rotating shaft of the rotating shaft that is interlocked with the deflection angle of the mirror can be detected by the torsional sensor. Perform the twist angle. Further, a light-receiving element (photodiode) is disposed in the vicinity of the scanning mirror 6, and the position of the reflected light that is detected by the light-receiving element in conjunction with the deflection angle of the mirror is detected, and the position of the scanning mirror 6 can be detected. The control unit 8 controls the scanning mirror 6 such that the laser light incident on the scanning mirror 6 scans a specific image region at a specific frequency. This -10- 201220263 control is performed by the scanning mirror control unit 8 outputting a driving signal to the scanning mirror driver 7. Further, the scanning mirror control unit 8 generates a horizontal synchronizing signal HSNC and a vertical synchronizing signal VSNC based on the position detecting signal from the scanning mirror driver 7, and outputs these to the image processing unit 9. The timing of the emission of the laser light from the laser light sources 2a to 2c is necessary to synchronize with the phase control of the scanning mirror 6, and the horizontal/vertical synchronization signals HSNC and VSNC are used for the synchronization. That is, in the laser projector 1, the driving of the scanning mirror 6 becomes the main body, and the laser light source is driven in synchronization with the driving of the scanning mirror 6 in accordance with the internally generated horizontal/vertical synchronization signals H SNC, VSNC. 2 a~2 c. The video processing unit 9 writes the input video signal (video data) supplied from the external device to the frame buffer memory (not shown) at a predetermined timing at a predetermined timing. Further, the image processing unit 9 sequentially reads out the image data stored in the frame buffer memory at the timing specified by the horizontal/vertical synchronization signals HSNC and VSNC supplied from the scanning mirror control unit 8, and transfers the image data to the mine. Shooting control unit 1 〇. The laser control unit 10 determines the drive current Id for each pixel and the waveform pattern PT to be applied to the respective color components based on the image data sequentially transferred by the image processing unit 9. The respective laser light sources 2a to 2c are individually controlled/driven by the laser driver 1 1 based on the drive current Id and the waveform pattern PT set for the respective color components. In the present embodiment, two kinds of waveform patterns PT1 and PT2 are prepared as the waveform pattern PT, and one of them is selectively applied depending on the level of the level to be displayed. Further, the laser control unit 10 performs feedback of the drive current Id so that the amount of light emitted from each of the gradations is stabilized based on the amount of light emitted from the laser light detected by the photodetector (not shown) -11 - 201220263 control. Thereby, even if the light output changes due to the temperature rise of the laser light sources 2a to 2c, the fluctuation can be effectively responded to. Fig. 2 is a block diagram showing the structure of the laser control unit 1; The laser control unit 10 includes a drive mode determination circuit 10a, a waveform pattern selection circuit 10b, and a drive current selection circuit 10c. The drive mode determination circuit 10a determines one of the noise reduction mode and the power saving mode for each pixel and each color component based on the image data sequentially transferred. For example, the tone data D composed of 256-order tones is divided into a low-order tone region (0 $ D < Dth ) and a high-order tone region (Dth$DS255) by the threshold 値Dth. When the tone data D of a certain pixel belongs to the low-order tone region of the threshold 値Dth, the drive mode selects the power-saving mode. In the power-saving mode, it is preferred to reduce power consumption compared to reducing speckle noise. In this case, when the tone data D belongs to the high-order tone region of the threshold 値Dth or higher, the drive mode selects the noise reduction mode. In the noise reduction mode, it is preferred to reduce speckle noise compared to power consumption. Fig. 3 is an explanatory view showing switching boundaries of driving waveforms of the laser light sources 2a to 2c. The speckle noise tends to increase linearly or nonlinearly when the light output of the laser light sources 2a to 2c is larger. Here, the boundary allowed by the speckle noise in the image quality is specified as an allowable flaw by experiment or simulation, thereby allowing the chirp to distinguish whether the speckle noise should be preferentially reduced, or whether the power consumption should be reduced first. Next, the gradation data D corresponding to this allowable 値 is taken as 闽値Dth. In this case, Dth can also be the same in all the color components, but there are -12-201220263. In view of the different tone characteristics of each color component, the laser light of different color components, that is, different wavelengths, is different. It is better to set different 値. For example, it is preferable to use a green component that is noticeably striking about speckle noise, and it is preferable to take measures to reduce noise in a wide high-order region, and the threshold 値DGth is set to be the minimum. In addition, the speckle noise is not so striking red component. In a certain high-level tone region, it is necessary to take the noise reduction countermeasure as a priority, but it is not necessary to set a tone range as wide as the green component, so the DRth Set to be larger than DGth (〇<DGth<DRth< 255). Furthermore, it is sufficient that the blue component of the speckle noise is not conspicuous, and it is sufficient to take measures to reduce the noise in the region where the high-order tone is extremely limited. Therefore, the DBth is set to be larger than DGth and DRth. In particular, regarding the blue component, DBth = 25 5 is set, that is, all the tone regions are assigned to the power saving mode. The waveform pattern selection circuit 100b selects/generates the waveform pattern PT1 shown in Fig. 4 when the power-saving mode is selected by the drive mode determination circuit 10a (when the low-order tone is less than the threshold 値Dth). On the other hand, the waveform pattern selection circuit 10b selects/generates the waveform pattern PT2 shown in the figure when the noise reduction mode is selected (when the threshold 値Dth is higher than the high-order tone). These waveform patterns PT1 and PT2 define periods during which the laser light sources 2a to 2c are turned on/off during the display period of one pixel specified by the dot clock signal. The point signal is generated internally based on the horizontal/vertical sync signals HSNC and VSNC. During the on/off period, for example, by using the specific reference clock of the minimum decomposition energy of the predetermined waveform patterns PT1 and PT2, by calculating the number of times of the change timing, etc., it is possible to perform setting by comparing the accuracy of the simple circuit.
S -13- 201220263 在波形圖案PT1，反覆m次（mgl)由比較長的打開 期間，與比較短的關閉時間所構成的單位週期（一例爲m =2 )。分別的打開期間，設定爲比對應於該色成分的雷 射光源固有的緩和振動期間Tf更長。此處，所謂「緩和振 動期間Tf」，是指藉由驅動電流的急遽升起而使雷射光源 開始緩和振動起，直到緩和振動收斂爲止的期間。於波形 圖案PT1設關閉期間的理由，也有次數很少仍然使其產生 緩和振動的意圖，而且有抑制鄰接的畫素間之混色的意思 。因此，隨著場合不同，亦可使1畫素之顯示期間全部爲 打開期間（打開負載=1 〇〇% )。此外，波形圖案PT1，亦 可爲全色成分皆爲共同，但有鑑於各雷射光源2a〜2c緩和 振動期間Tf不同這一點，於各色成分分別準備亦可。 對此，在波形圖案PT2，反覆η次（η > m )由比較短 的打開期間，與比較短的關閉時間所構成的單位週期（一 例爲η = 3 )。在波形圖案ΡΤ2，打開期間比前述波形圖案 ΡΤ 1更被細分化，分別的打開期間，被設定爲小於雷射光 源2a〜2c的緩和振動期間Tf。於波形圖案ΡΤ2設關閉期間 的主要理由，在於細分化打開期間，增加緩和振動的發生 次數。此外，波形圖案PT2，亦可爲全色成分皆爲共同， 但有鑑於各雷射光源2a〜2c緩和振動期間Tf不同這一點， 於各色成分分別準備亦可。 驅動電流選擇電路l〇c，參照依各色成分準備的驅動 電流表，產生/輸出因應於應該顯示的階調資料D之驅動 電流Id。於此驅動電流表，記載著在分別的階調應該設定 -14- 201220263 的電流水平，藉由參照此表，唯一地特定對應於應該顯示 的階調資料D之驅動電流Id。又，在本實施型態’存在著 打開期間的設定不相同的2種類波形圖案PT1、PT2 ’所以 被記載於驅動電流表的電流水平，考慮波形圖案PT1、PT2 的打開期間的長度而設定。實際顯示的階調（亮度）’不 僅由電流水平來決定，也由1畫素之顯示期間之電流水平 與打開期間之積分値來決定。如以上所述地進行’某畫素 之各色成分被特定之驅動電流Id及波形圖案PT，在該畫素 之顯示期間的開始時機，被輸出往雷射驅動器1 1。 雷射驅動器1 1，關於分別的色成分，使用由雷射控制 部10輸出的波形圖案PT調變驅動電流Id，把被調變的驅動 電流輸出至雷射光源2a〜2c。藉此，雷射光源2a〜2c，使 因應於應該顯示的階調的輸出位準之雷射光，依照波形圖 案PT而射出。合成各色成分的射出光之最終的彩色光，被 導至與雷射光的射出同步而被位置控制之掃描鏡6，被投 射至投射面A上的所要的畫素位置。 又，波形圖案選擇電路1 0的機能，不是由雷射控制部 1 〇而由雷射驅動器1 1來擔任亦可。在此場合，雷射控制部 1 〇，替代波形圖案PT，而把驅動模式的指定通知給雷射驅 動器1 1即可。 根據本實施型態，於藉由閾値Dth分割的各階調區域 ’藉由使運用在雷射光源2a〜2c的驅動的波形圖案PT最佳 化’可以謀求斑點雜訊的減低，同時兼顧耗電量的減低。 關於這點’參照圖4同時更詳細說明。某個畫素pi的階調 -15- 201220263 資料D屬於在閾値Dth以上的高階調區域的場合，打開期間 被細分化的波形圖案PT2被選擇，使用此而使驅動電流Id 1 被調變。藉此，被供給至雷射光源2a〜2c的調變驅動電流 的波形（驅動波形），也產生因應於波形圖案PT2之打開 /關閉期間。在打開期間，設定爲相當於因應於應該顯示 的階調資料D的驅動電流Idl之電流水平。另一方面，在關 閉期間，與應該顯示的階調資料D無關，被設定爲雷射光 源2a〜2c的偏壓電流Ith ( LED發光與雷射振盪之邊界値） 以下的電流Ioff (例如爲〇 )。如前所述，波形圖案PT2之 分別的打開期間，設定爲小於緩和振動期間Tf。亦即，於 1畫素之顯示期間，雷射光源2a〜2c之緩和振動斷續地反 覆，而產生比低階調區域之顯示時更多的緩和振動（在本 實施型態爲3次）。藉由雷射光源2a〜2c的緩和振動，使 雷射光的同調性降低（非同調化），所以高階調區域在顯 示時容易變得醒目的斑點雜訊有效地被降低。 另一方面，其他的畫素P2的階調資料D屬於未滿閾値 Dth的低階調區域的場合，打開期間未被細分化的波形圖 案PT1被選擇，使用此而使驅動電流Id2被調變。藉此’調 變驅動電流的波形（驅動波形）也產生因應於波形圖案 PT 1之打開/關閉期間。在打開期間，設定爲相當於因應 於應該顯示的階調資料D的驅動電流Id2之電流水平，在關 閉期間，被強制設定爲偏壓電流Ith以下的電流I〇ff °如前 所述，波形圖案PT2之各個打開期間，被設定爲比緩和振 動期間Tf更長，緩和振動的次數較少（在本實施型態爲2 -16- 201220263 次），無法得到波形圖案PT1那樣的雜訊減低效果。然而 ，打開/關閉的切換頻率比波形圖案PT 1更低，所以可謀 求消耗電力的減低。在斑點雜訊不像在高階調區域那樣醒 目的低階調區域，即使減少緩和振動的次數，在畫質上也 很少有問題。 又，在前述實施型態，說明了以單一的閬値Dth分割 爲2個階調區域的事例，但分割爲更多的階調區域，適用 更多波形圖案PT亦可。圖5係分割爲3個階調區域的場合之 波形圖案的說明圖。在此場合，例如藉由2個閾値 Dthl，Dth2，分割爲低階調區域（0 S D < Dthl )，中階調 區域（DthlSD<Dth2)，與高階調區域（Dth2SDS255 )等3區域。接著，準備適用於分別的階調區域的波形圖 案PT1〜PT3。這些波形圖案PT1〜PT3的打開期間，依照 PT1、PT2、PT3的順序被細分化。如此，藉由適用更多的 波形圖案PT，可以更高的水準來同時實現斑點雜訊的減低 ，與消耗電力的減低。 此外，在前述實施型態，說明了藉由單位週期的反覆 ，而產生波形圖案PT1、PT2之事例。波形圖案PT1、PT2 具有週期性的理由，是因爲容易由基準時脈產生，在電路 設計上有利。亦即，不考慮這一點的話，波形圖案PT 1、 PT2亦可適用沒有週期性者。 此外，在前述之實施型態，閾値D t h可爲固定値，亦 可爲可變値。作爲一例，因應於亮度被調整爲最大階調時 之光輸出位準，把閩値Dth設定爲可變亦可。在此事例， -17- 201220263 最大階調時的光輸出降低的場合，減少閩値Dth，此値增 大的場合增大閾値Dth。此外，作爲另一例，因應於投影 環境的亮度，把閾値Dth設定爲可變亦可。在此事例，攝 影環境的亮度降低的場合，減少閾値Dth，亮度增大的場 合，增大閾値Dth。 此外，在前述實施型態，以1畫素單位適用波形圖案 PT，但亦可如1水平線單位，1區域單位或是1圖框單位， 以特定的畫素群爲單位來適用。在此場合，作爲波形圖案 PT的選擇方法，可以舉出（1)把畫素群的平均階調與閾 値Dth比較之方法，（2)把階調區域分割爲複數個區段， 把階調資料D的出現頻率最高的區段與閩値Dth進行比較的 方法等等。 進而，在前述之實施型態，說明了彩色雷射投影機， 但本發明對於黑白雷射投影機亦可以適用。此外，掃描手 段不限定於掃描鏡’例如代用以例如DMD (數位微鏡裝置 ，Digital Micromirror Device )或 LCOS (矽基液晶， Liquid Crystal on silicon)等公知的手段。此外，有鑑於 本發明的本質’與是否具有掃描手段無關，亦可使用具備 掃描手段的顯示裝置’亦即亦可以是對投射面A灰階顯示1 畫素者。 〔產業上利用可能性〕 如以上所述’本發明係以雷射投影機爲代表，對於藉 由把雷射光投影於投射面，於投射面上階調顯示影像（包 •18· 201220263 含藉由1個畫素構成者）的各種影像顯示裝置，可以廣泛 適用。 【圖式簡單說明】 圖1係雷射投影機之方塊構成圖。 圖2係雷射控制部之方塊構成圖。 圖3係關於雷射光源的驅動波形之切換邊界的說明圖 〇 圖4係驅動模式之訊號波形的說明圖。 圖5係分割爲3個階調區域的場合之波形圖案的說明圖 t主要元件符號說明】 1 :雷射投影機 2a〜2c :雷射光源 3，4 :分色鏡 5 :透鏡 6 :掃描鏡 7 :掃描鏡驅動器 8 :掃描鏡控制部 9 :影像處理部 1 0 :雷射控制部 l〇a :驅動模式判定電路 l〇b :驅動電流選擇電路 -19- 201220263 l〇c :波形圖案選擇電路 1 1 :雷射驅動器 -20S -13- 201220263 In the waveform pattern PT1, the m period (mgl) is repeated for a relatively long period of time, and a unit period consisting of a relatively short off time (an example is m = 2). The respective opening periods are set to be longer than the relaxation vibration period Tf inherent to the laser light source corresponding to the color component. Here, the "moderate vibration period Tf" refers to a period in which the laser light source starts to moderate the vibration by the sudden rise of the drive current until the vibration is relaxed. The reason why the waveform pattern PT1 is turned off is also that the number of times is small, so that the vibration is moderated, and the color mixture between adjacent pixels is suppressed. Therefore, depending on the occasion, the display period of 1 pixel can be made all open (open load = 1 〇〇%). Further, the waveform pattern PT1 may be common to all of the color components. However, in view of the fact that the respective laser light sources 2a to 2c relax the vibration period Tf, they may be prepared for each color component. On the other hand, in the waveform pattern PT2, the n-th (η > m) is reversed by a relatively short opening period and a relatively short closing time (in the case of η = 3). In the waveform pattern ΡΤ2, the opening period is more subdivided than the waveform pattern ΡΤ1, and the respective opening periods are set to be smaller than the relaxation vibration period Tf of the laser light sources 2a to 2c. The main reason for setting the waveform pattern ΡΤ2 to the off period is to increase the number of occurrences of the mitigation vibration during the subdivision opening period. Further, the waveform pattern PT2 may be common to the full-color components. However, in view of the fact that the respective laser light sources 2a to 2c relax the vibration period Tf, they may be prepared for each color component. The drive current selection circuit 10c refers to the drive current table prepared for each color component, and generates/outputs the drive current Id in response to the tone data D to be displayed. Here, the current meter is driven to indicate that the current level of -14 - 201220263 should be set at the respective gradation, and by referring to this table, the drive current Id corresponding to the gradation data D to be displayed is uniquely specified. In the present embodiment, the two types of waveform patterns PT1 and PT2' having different setting periods in the opening period are described in the current level of the driving current meter, and are set in consideration of the lengths of the opening periods of the waveform patterns PT1 and PT2. The actually displayed tone (brightness)' is determined not only by the current level but also by the current level during the display period of one pixel and the integral value of the opening period. As described above, the drive current Id and the waveform pattern PT, which are specific to the respective color components of a certain pixel, are output to the laser driver 11 at the start timing of the display period of the pixel. The laser driver 1 1 modulates the drive current Id using the waveform pattern PT output from the laser control unit 10 with respect to the respective color components, and outputs the modulated drive current to the laser light sources 2a to 2c. Thereby, the laser light sources 2a to 2c emit laser light in accordance with the output level of the tone to be displayed, in accordance with the waveform pattern PT. The final color light of the light emitted by the respective color components is combined and guided to the scanning mirror 6 which is positionally controlled in synchronization with the emission of the laser light, and is projected onto the desired pixel position on the projection surface A. Further, the function of the waveform pattern selection circuit 10 may be performed by the laser driver 1 1 instead of the laser control unit 1 . In this case, the laser control unit 1 通知 may notify the laser driver 1 1 of the designation of the drive mode instead of the waveform pattern PT. According to the present embodiment, the respective gradation regions 'divided by the threshold 値Dth' can optimize the waveform pattern PT of the driving of the laser light sources 2a to 2c to reduce the speckle noise and at the same time consume power The amount is reduced. This point is described in more detail with reference to Fig. 4 at the same time. The tone of a certain pixel pi -15- 201220263 When the data D belongs to the high-order tone region of the threshold 値Dth or more, the waveform pattern PT2 that is subdivided during the opening period is selected, and the drive current Id 1 is modulated by using this. Thereby, the waveform (drive waveform) of the modulation drive current supplied to the laser light sources 2a to 2c is also caused by the opening/closing period of the waveform pattern PT2. During the opening period, it is set to correspond to the current level of the driving current Id1 corresponding to the tone data D which should be displayed. On the other hand, during the off period, regardless of the tone data D to be displayed, the current Ioff (for example, the bias current Ith (the boundary between the LED light and the laser oscillation) of the laser light sources 2a to 2c is set (for example, 〇). As described above, the respective opening periods of the waveform pattern PT2 are set to be smaller than the relaxation vibration period Tf. That is, during the display period of the 1 pixel, the relaxation vibrations of the laser light sources 2a to 2c are intermittently repeated, and more moderate vibrations are generated than in the display of the low-order tone region (3 times in this embodiment). . By the relaxation vibration of the laser light sources 2a to 2c, the coherence of the laser light is reduced (non-coherent), so that the high-order tone region is likely to be conspicuously reduced in the display of the spot noise. On the other hand, when the gradation data D of the other pixels P2 belongs to the low-order tone region which is less than the threshold 値Dth, the waveform pattern PT1 which is not subdivided during the opening period is selected, and the drive current Id2 is modulated by using this. . The waveform (driving waveform) for which the driving current is modulated is also generated in response to the opening/closing period of the waveform pattern PT1. During the on period, it is set to correspond to the current level of the drive current Id2 corresponding to the tone data D to be displayed, and during the off period, the current is forced to be set to be equal to or less than the bias current Ith. The respective opening periods of the pattern PT2 are set to be longer than the relaxation vibration period Tf, and the number of times of vibration relaxation is small (in the present embodiment, it is 2 -16 to 201220263 times), and the noise reduction effect such as the waveform pattern PT1 cannot be obtained. . However, the switching frequency of the on/off is lower than that of the waveform pattern PT 1, so that the power consumption can be reduced. In the low-tone area where the spot noise is not as good as in the high-order area, even if the number of times of mitigating vibration is reduced, there is little problem in image quality. Further, in the above-described embodiment, an example in which a single 阆値Dth is divided into two gradation regions has been described. However, it is also possible to divide into more gradation regions and apply more waveform patterns PT. Fig. 5 is an explanatory diagram of a waveform pattern in the case of dividing into three tone regions. In this case, for example, the two thresholds Dth1 and Dth2 are divided into three regions of a low-order tone region (0 S D < Dthl ), a mid-tone region (DthlSD < Dth2), and a high-order tone region (Dth2SDS255). Next, waveform patterns PT1 to PT3 which are applied to the respective tone regions are prepared. The open periods of these waveform patterns PT1 to PT3 are subdivided in the order of PT1, PT2, and PT3. Thus, by applying more waveform patterns PT, it is possible to simultaneously achieve reduction in speckle noise and reduction in power consumption at a higher level. Further, in the above embodiment, an example in which the waveform patterns PT1, PT2 are generated by the repetition of the unit period has been described. The reason why the waveform patterns PT1 and PT2 have a periodicity is because it is easily generated by the reference clock and is advantageous in circuit design. That is, regardless of this, the waveform patterns PT 1 and PT2 can also be applied without periodicity. Further, in the foregoing embodiment, the threshold 値D t h may be a fixed 値 or a variable 値. As an example, 闽値Dth may be set to be variable in response to the light output level when the brightness is adjusted to the maximum gradation. In this case, when the light output at the maximum gradation of -17-201220263 is lowered, 闽値Dth is reduced, and when the 値 is increased, the threshold 値Dth is increased. Further, as another example, the threshold 値Dth may be set to be variable depending on the brightness of the projection environment. In this case, when the brightness of the shooting environment is lowered, the threshold 値Dth is decreased, and the brightness is increased, and the threshold 値Dth is increased. Further, in the above embodiment, the waveform pattern PT is applied in units of one pixel, but may be applied in units of a specific pixel group as one horizontal line unit, one area unit or one frame unit. In this case, as a method of selecting the waveform pattern PT, (1) a method of comparing the average tonality of the pixel group with the threshold 値Dth, and (2) dividing the tone region into a plurality of segments, the tone is adjusted. The method in which the sector with the highest frequency of occurrence of data D is compared with 闽値Dth, and the like. Further, in the above-described embodiment, a color laser projector has been described, but the present invention is also applicable to a black and white laser projector. Further, the scanning means is not limited to the scanning mirror, for example, a known means such as DMD (Digital Micromirror Device) or LCOS (Liquid Crystal on Silicon). Further, in view of the nature of the present invention, it is also possible to use a display device having a scanning means, irrespective of whether or not there is a scanning means, that is, a pixel can be displayed on the projection plane A gray scale. [Industrial Applicability] As described above, the present invention is represented by a laser projector, and the projection image is displayed on the projection surface by projecting the laser light onto the projection surface (including 18·201220263) Various image display devices composed of one pixel can be widely applied. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram of a laser projector. 2 is a block diagram of a laser control unit. Fig. 3 is an explanatory diagram of a switching boundary of a driving waveform of a laser light source. Fig. 4 is an explanatory diagram of a signal waveform of a driving mode. Fig. 5 is an explanatory diagram of a waveform pattern in the case of dividing into three tone regions. Fig. t Main component symbol description] 1: Laser projector 2a to 2c: Laser light source 3, 4: Dichroic mirror 5: Lens 6: Scanning Mirror 7: Scanning mirror driver 8: Scanning mirror control unit 9: Image processing unit 1 0: Laser control unit 10a: Driving mode determination circuit l〇b: Driving current selection circuit -19-201220263 l〇c: Wave pattern Selection circuit 1 1 : laser driver -20