JP2004279544A - Line image scanning type picture display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a line image scanning type picture display device which can be realized compactly at low cost and which can display an improved picture by effectively reducing deformation of two-dimensional display picture. <P>SOLUTION: The line image scanning type picture display device is structured to display a two-dimensional picture on a screen by transmitting light from each optical modulation element in an optical modulator 5 as object light by means of an image forming lens 6, by deflecting with a deflector 7 an image forming light flux emitted from the image forming lens system 6, and by scanning the screen while the flux is condensed as a one-dimensional line image on the screen 9 through a scanning lens system 8. Then, in this line image scanning type picture display device, in accordance with uniform gap characteristic in the line image scanning direction caused by the deflector 7 and the scanning lens system 8, the time width of a pixel clock that shows an image signal in the optical modulator is changed by the pixel line unit, thereby compensating the uniform gap characteristic of the line image on the screen to perform the line image scanning. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００７４】

【００７５】
上の表記において、例えば「４．９２Ｅ−０６」は「４．９２×１０^−６」を意味する。以下の実施例においても同様である。
【００７６】
実施例１の走査レンズ系を用い、画像表示面上でＺ方向に±４００ｍｍの走査をしたときの像面湾曲とリニアリティ（等間隔特性に対応する）を図２に示す。走査レンズ系を単レンズとして偏向手段の近くに配置しているにもかかわらず、像面湾曲は幅で０．０３ｍｍ程度で良く補正できている。ここで収差を表示した波長はｅ線（５４６．０７ｎｍ）である。
【００７７】
実施例１では走査レンズ系を単レンズ構成にし、主として像面湾曲を補正しているため、等間隔特性に対応する「リニアリテイ」は補正されていない。
偏向反射面の有効振れ角：±８．２度のときに、偏向反射面から１．４ｍ離れたスクリーン９で±４００ｍｍ（＝幅８００ｍｍ）の走査を行うが、走査の最終部（±４００ｍｍ）で−７．５％のリニアリティが発生している。
【００７８】
この残存リニアリテイ（等間隔特性）は以下のように補正できる。
【００７９】
図１における高周波クロック生成部ＧＳにおいて「画素クロックの８倍の高周波クロック」を生成し、この高周波クロックを分周回路ＢＳで８分周することにより「画素クロック」を生成し、変調回路ＨＴに印加する。
リニアリティが負であることは「中心部に比べて周辺部の走査速度が遅い」ことを意味するので、周辺部にあるブロック（走査域を分割したブロック）の中の画素クロックに、画素クロックの時間幅が正規の時間幅：８／８よりも長い、時間幅：９／８の画素クロックを混在させることにより、リニアリティのマイナス分を補うことができる。
【００８０】
例えば、上記ブロックを構成するライン像（１色のもの）の数が２５である場合、時間幅：８／８をもった画素クロックの数：ｘ、時間幅：９／８の画素クロックの数：ｙとすると、先に説明したように、方程式：
１／（１−７．５％）＝１／（１−０．０７５）＝｛ｘ＋（９ｙ／８）｝／（ｘ＋ｙ）
において、ｘ＋ｙ＝２５とおけば、ｘ＝９、ｙ＝１６となるから、２５個のライン像を順次出力するに際して、出力を決定する画素クロックとして時間幅：８／８ のクロックを９回、時間幅：９／８のクロックを１６回「適当な配列のもとに繰り返す規則（例えば、前半の９回は時間幅：８／８とし、後半の１６回を時間幅：９／８とする）」を用いて発生させることで、−７．５％のリニアリティがもたらす等間隔特性を補正でき、高性能な光走査を達成できる。
【００８１】
リニアリティの変化が図３に示すように走査方向に対称である場合には、走査域を、リニアリティの幅：０．５％毎に分割すると、走査の片側（４００ｍｍ）に対応して１５ブロックに分割でき、ブロック内では予め設定された同一の規則に従い、画素クロックの時間幅を異ならせた画素クロックの数の調整により、当該ブロック内でのリニアリテイの幅を±０．２５％以内に抑えることができるので「画素クロックの時間幅を変化させる規則」が１５規則で済み、これら規則を記憶させるのに必要なメモリ数は少なくてすむ。
【００８２】
実施例２
走査レンズ系はレンズ１枚で構成され、配置関係は実施例１と同じである。
【００８３】
「走査レンズ」
ガルバノミラーとの光軸上の距離：７ｍｍ
光軸上の厚さ：３ｍｍ、
材質の屈折率：ｎｄ＝１．５３０４６
材質のアッベ数：νｄ＝５５．８４
第１面は（式１）で与えられる非円弧形状を光軸の回りに回転させて得られる共軸非球面で、第２面は（式２）で表される湾曲軸トロイダル形状である。
【００８４】
走査レンズ系の各面の形状を特定するデータは以下の通りである。
【００８５】

【００８６】

【００８７】
実施例２に関する像面湾曲とリニアリティを、図２に倣って図４に示す。実施例１と同様、走査レンズ系を単レンズとして偏向手段の近くに配置しているにもかかわらず、像面湾曲は幅で０．０３ｍｍ程度で良く補正できている。
【００８８】
実施例１の場合と同様にして、等間隔特性を良好に補正できる。
【００８９】
実施例３
実施例３は走査レンズ系を２枚のレンズで構成した例である。
【００９０】
配置関係は実施例１と同じである。
「第１レンズ（ガルバノミラー側のレンズ）」
ガルバノミラーとの光軸上の距離：７ｍｍ
光軸上の厚さ：３ｍｍ
材質の屈折率：ｎｄ＝１．５３０４６
材質のアッベ数：νｄ＝５５．８４
「第２レンズ（スクリーン側のレンズ）
第１レンズとの空気間隔：５ｍｍ
光軸上の厚さ：３ｍｍ
材質の屈折率：ｎｄ＝１．５８４１０
材質のアッベ数：νｄ＝３０．４５
第１レンズは「両面とも球面」、第２レンズは「両面とも湾曲軸トロイダル形状」である。
【００９１】
走査レンズ系の各レンズ面形状を特定するデータは以下の通りである。
【００９２】
第１レンズ
第１面
Ｒ（曲率半径） −２４２７．０
第２面
Ｒ（曲率半径） −１１２１．０ 。
【００９３】

【００９４】

【００９５】
実施例３に関する像面湾曲とリニアリティを、図２に倣って図５に示す。実施例１と同様、走査レンズ系を単レンズとして偏向手段の近くに配置しているにもかかわらず像面湾曲は良く補正できている。実施例１の場合と同様にして、等間隔特性を良好に補正できる。
【００９６】
ｅ線（５４６．０７ｍｍ）基準の波長に対する走査長（光軸からの片側）の差（ｍｍ）を示す。
【００９７】

実施例１、２は単レンズ構成のため、走査レンズ系の色収差を補正できないので「波長による走査長の差」が生じている。このような場合は、Ｒ、Ｇ、Ｂのライン像ごとに画素クロックの時間幅の変更を異ならせることにより「ライン像位置の色による差」を低減できる。
【００９８】
実施例３では走査レンズ系の色収差を補正しており、Ｒ、Ｇ、Ｂのライン像の位置に差異がないので、画素クロックの時間幅制御をＲ、Ｇ、Ｂの各色のライン像に対し「共通化された規則」で行うことができる。
【００９９】
図６には光学配置の別例を示す。繁雑を避けるため、混同の虞れが無いと思われるものについては、図１におけると同一の符号を用いた。この例においては、走査レンズ８Ａが上記実施例３のように２枚のレンズで構成され、走査レンズとスクリーン９との間に、走査レンズ系８Ａから画像表示面９へ向う光束の光路を折り曲げる折り返しミラーＭＬが配置されている。
【０１００】
最後に、画素クロックの時間幅の変更につき簡単に説明する。
【０１０１】
上に、実施例１に即して説明した例では、画素クロックは、図１の高周波クロック生成部ＧＳにおいて「画素クロックの８倍の高周波クロック」を生成し、この高周波クロックを分周回路ＢＳで８分周することにより「画素クロック」を生成するのであるが、この場合の具体的な例を、図７、図８を参照して説明する。
【０１０２】
図７は、図１における高周波クロック生成回路ＧＳと分周回路ＢＳを合わせた部分を示している。説明の便宜上、図１における符号とは異なる符号を付した。
【０１０３】
図７において、画素クロック生成回路１０は、（図１の高周波クロック生成回路ＧＳに対応する）高周波クロック生成回路１１、カウンタ１２、比較回路１３及び画素クロック制御回路１４ からなる。
【０１０４】
高周波クロック生成回路１１は、画素クロック：ＰＣＬＫの基準となる高周波クロック：ＶＣＬＫを生成する。カウンタ１２は、高周波クロック：ＶＣＫＬ の立上がりで動作して該クロック：ＶＣＫＬをカウントする。比較回路１２はカウンタ１２のカウント値と「予め設定された値及び外部から与えられる画素クロックの遷移タイミング」として位相シフト量を指示する位相データと比較し、その比較結果にもとづき制御信号：ａ、制御信号：ｂを出力する。
【０１０５】
画素クロック制御回路１３は制御信号：ａ、ｂにもとづき、画素クロック：ＰＣＬＫの立ち上げ・立ち下げのタイミングを制御する。
【０１０６】
「位相データ」は、等間隔特性を補正するために、画素クロックの位相のシフト量を指示するためのデータで、一般に数ビットのデジタル値で与えられ、図示されないメモリに記憶されている。
【０１０７】
画素クロック生成回路１０の動作を図８に即して説明する。
画素クロック：ＰＣＬＫは高周波クロック：ＶＣＬＫの８分周で得られ、標準ではデュティ比：５０％である。図８の（ａ）は、高周波クロック：ＶＣＬＫの８分周に相当するデュティ比：５０％の標準の画素クロック：ＰＣＬＫを生成する様子を、（ｂ）は高周波クロック：ＶＣＬＫの８分周クロックに対して１／８クロック分だけ位相を進めた画素クロック：ＰＣＬＫを生成する様子を、（ｃ）は高周波クロック：ＶＣＬＫの８分周クロックに対して１／８クロックだけ位相を遅らせた画素クロック：ＰＣＬＫクロックを生成する様子を示す。
【０１０８】
前述の説明のように、「画素クロックの時間幅」は、ある画素クロックの立ち上がりから次ぎの画素クロックの立ち上がりに至る時間であり、図８に即しての説明によれば、ある画素クロックに続く画素クロックの位相を±１／８クロック分変化させることにより、画素クロックの時間幅を「１／８クロック分」だけ変化させることができる。
【０１０９】
図８（ａ）においては、位相データとして「７」の値が与えられている。比較回路１３には予め「３」が設定されている。カウンタ１２は高周波クロック：ＶＣＬＫの立上がりで動作しカウントを行う。比較回路１３は、カウンタ１２の値が「３」になったところで制御信号：ａを出力する。
【０１１０】
画素クロック制御回路１４は、制御信号：ａが「Ｈ」になっていることから、クロックのタイミング▲１▼で画素クロック：ＰＣＬＫを「Ｈ」から「Ｌ」に立ち下げる。次いで、比較回路１３は、与えられた位相データ「７」とカウンタ１２のカウント値を比較し、両者が一致したら制御信号：ｂを出力する。図８（ａ）では、カウンタ１２のカウント値が「７」になったところで、比較回路１３が制御信号：ｂを出力する。
【０１１１】
画素クロック制御回路１４は、制御信号：ｂが「Ｈ」になっていることからクロックのタイミング▲２▼で画素クロック：ＰＣＬＫを「Ｌ」から「Ｈ」に立ち上げる。この時、比較回路１３は同時にカウンタ１２をリセットさせ、再び０からカウントを行わせる。
【０１１２】
このようにして、図８（ａ）に示すように、高周波クロック：ＶＣＬＫの８分周に相当するデュティ比：５０ ％の画素クロック：ＰＣＬＫを生成できる。比較回路１３の設定値を変えれば、デュティ比が変化する。
【０１１３】
図８（ｂ）においては、位相データ「８」が与えられている。カウンタ１２は高周波クロック：ＶＣＬＫのカウントを行い、比較回路１３は、カウンタ１２の値が「３」になったところで制御信号：ａを出力する。画素クロック制御回路１４は、制御信号：ａが「Ｈ」になっていることから高周波クロックのタイミング▲１▼で画素クロック：ＰＣＬＫを「Ｈ」から「Ｌ」に立ち下げる。
【０１１４】
次いで、比較回路１３は、カウンタ１２の値が与えられた位相データ「８」と一致したら制御信号：ｂを出力する。画素クロック制御回路１４は、制御信号：ｂが「Ｈ」になっていることから、高周波クロックのタイミング▲２▼で画素クロック：ＰＣＬＫを「Ｌ」から「Ｈ」に立ち上げる。このとき比較回路１３が同時にカウンタ１２をリセットさせ、再び０からカウントを行わせて行く。
【０１１５】
このようにして、図８（ｂ）に示すように、高周波クロック：ＶＣＬＫの８分周クロックに対して「１／８クロック分だけ位相を進ませた画素クロック：ＰＣＬＫ」を生成できる。位相データとして「８」の代わりに「９」を与えておけば、上記位相の進みを画素クロックの２／８だけ進めることができ、これにより、実施例１に即して説明した「画素クロックの時間幅を１０／８」に変化させることができる。
【０１１６】
図８（ｃ）において、位相データ「６」が与えられている。カウンタ１２が画素クロック：ＶＣＬＫのカウントを行い、比較回路１３は、カウンタ１２の値が「３」になったところで制御信号：ａを出力し、画素クロック制御回路１４は制御信号：ａが「Ｈ」になっていることから高周波クロックのタイミング▲１▼で画素クロック：ＰＣＬＫを「Ｈ」から「Ｌ」に立ち下げる。
【０１１７】
次いで、比較回路１３は、カウンタ１２のカウント値が与えられた位相データ「６」と一致したら制御信号：ｂを出力する。画素クロック制御回路１４は、制御信号：ｂが「Ｈ」になっていることから、高周波クロックのタイミング▲２▼で画素クロック：ＰＣＬＫを「Ｌ」から「Ｈ」に立ち上げる。
【０１１８】
この時、同時にカウンタ１２をリセットさせ再び０からカウントを行わせる。このようにして、図８（ｃ）に示すように、高周波クロック：ＶＣＬＫ の８分周クロックに対して１／８クロックだけ位相を遅らせた画素クロック：ＰＣＬＫを生成できる。
【０１１９】
なお、位相データを、画素クロック：ＰＣＬＫの立上がりに同期させて与えると、画素クロック：ＰＣＬＫの位相を高周波クロック：ＶＣＬＫの１クロックごとに変化させることが可能となる。
【０１２０】
【発明の効果】
以上に説明したように、この発明によれば新規なライン像走査型画像表示装置を実現できる。この装置では、走査レンズ系が「主に像面湾曲の補正」を行なえばよいので、走査レンズ系を単レンズあるいは少ない枚数で構成できるため、ライン像走査型画像表示装置をコンパクト且つ低コストで構成できる。
【０１２１】
また、画素クロックの時間幅を画素ライン単位で変更することにより、走査レンズ系で補正できなかった等間隔特性を有効に補正して、良好な２次元画像を表示することができる。
【図面の簡単な説明】
【図１】ライン像走査型画像表示装置の実施の１形態を説明するための図である。
【図２】走査レンズ系の実施例１の像面湾曲と、等間隔特性に対応するリニアリティを示す図である。
【図３】実施例１に関するリニアリティと、これを画素クロックに時間幅の異なる画素の数の調整により調整した後のリニアリティを説明するための図である。
【図４】走査レンズ系の実施例２に関する像面湾曲とリニアリティを示す図である。
【図５】走査レンズ系の実施例３に関する像面湾曲とリニアリティを示す図である。
【図６】ライン像走査型画像表示装置の実施の別形態を説明するための図である。
【図７】画素クロック生成回路を説明するための図である。
【図８】図７の画素クロック生成回路による画素クロックの発生と、画素クロックの時間幅の変更を説明するための図である。
【符号の説明】
１ 照明光学系
３ 半透鏡
６ 結像レンズ系
７ 偏向手段
８ 走査レンズ系
９ 画像表示面の実体をなすスクリーン[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a line image scanning type image display device.
[0002]
[Prior art]
The light from each light modulating element in the “light modulating means having minute light modulating elements arranged one-dimensionally” is transmitted as object light by the image forming lens, and the image forming light flux emitted from this image forming lens system is The image display surface is deflected by a deflecting device in a direction orthogonal to the arrangement direction of the light modulation elements, and the deflected light beam is formed as a one-dimensional line image on the image display surface via a scanning lens system. A “line image scanning type image display device” that scans and displays a two-dimensional image on an image display surface is known (Non-Patent Document 1, Patent Document 1).
[0003]
GLVs (Grating Light Valves), LD arrays and digital micromirror devices have been widely known as light modulation means in which minute light modulation elements are arranged one-dimensionally, and BBLVs (Both End Fixed Beam Light Valve). Is also known (Patent Document 2).
[0004]
Patent Document 3 describes “technology for electrically correcting the constant speed characteristics of optical scanning” in relation to the optical scanning device.
[0005]
In such a line image scanning type image display device, in the scanning of the line image, if the intervals between the line images sequentially projected and formed on the image display surface are not equal, the distortion of the displayed image in the scanning direction occurs. Will happen. In order to avoid such distortion, a “correction function (predetermined distortion) for equalizing the distance between line images” may be given to the scanning lens system. Then, the number of lenses of the scanning lens system is increased (for example, the one described in Patent Document 1 has five scanning lens systems), and the size of the scanning lens system is increased, and thus the size of the image display device is increased. And the cost is likely to increase.
[0006]
[Non-patent document 1]
Calibration of a Scanned Liner GLV Projection System R. W. Corrigan et. al. Silicon Light Machines
[Patent Document 1]
JP-A-2002-131838
[Patent Document 2]
JP-A-2002-214550
[Patent Document 3]
JP-A-14-277788
[0007]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to realize a line image scanning type image display device which can be realized compactly and at low cost and which can effectively reduce the distortion in a two-dimensional display image and display a good image. I do.
[0008]
[Means for Solving the Problems]
According to the line image scanning type image display device of the present invention, "light from each light modulating element in the light modulating means in which minute light modulating elements are arranged one-dimensionally is transmitted as object light by an image forming lens. The imaging light flux emitted from the image lens system is deflected by a deflecting device in a direction orthogonal to the arrangement direction of the light modulation elements, and is formed as a one-dimensional line image on an image display surface via a scanning lens system. A line image scanning type image display device which scans an image display surface and displays a two-dimensional image on the image display surface "has the following features (claim 1).
[0009]
That is, the time width of a pixel clock for displaying an image signal on the light modulating means is changed in pixel line units in accordance with the equidistant characteristics in the line image scanning direction caused by the deflecting means and the scanning lens system. Thus, the line image scanning is performed by correcting the equidistant characteristics of the line images on the image display surface. The “pixel line” is a so-called one-dimensional arrangement of light modulation elements in the light modulation unit.
[0010]
The “line image” is a one-dimensional line image expressed as a modulation state of the light modulating elements arranged in the light modulating means, and is formed on an image display surface via an imaging lens system, a deflecting means, and a scanning lens system. Is formed. Such a line image is scanned on the image display surface in a direction orthogonal to the longitudinal direction of the line image by the deflection of the imaging light beam by the deflecting means.
[0011]
This scanning is performed by displaying "line images sequentially in a flash-like manner at minute time intervals" in the scanning direction, that is, by intermittently forming and displaying images. As described above, one line image is displayed at a time, but when scanning is performed at a high speed, a two-dimensional image is observed as an “afterimage” by an observer.
[0012]
The “image display surface” is substantially a screen or the like.
[0013]
The “pixel clock” is a clock that determines the timing for displaying a sequential line image in scanning of a line image, and is “common to light modulation elements that form one line image”.
[0014]
The time width of the pixel clock is “the time width from the moment when a certain line image is displayed until the moment when the next line image is displayed”.
When the time width of the pixel clock changes, the “interval in the scanning direction” between a certain line image and a line image displayed immediately after this changes.
[0015]
The “equidistant characteristics” means that when a line image is scanned with a fixed time width of a pixel clock, an ideal image height: H and an actual image height: h in an arbitrary line image scanning direction are represented by “｛”. (H−H) / H｝ × 100% ”is ideally 0% over the entire scanning area, but actually varies depending on the position of the line image.
It is the “optical characteristics of the scanning lens system” and the “deflection mode by the deflecting means” that determine the equidistant characteristics. That is, the equidistant characteristics occur due to "due to the deflection means and the scanning lens system".
[0016]
Therefore, if the scanning lens system and the deflecting means are determined, the equidistant characteristics are also determined, and the time width of the pixel clock is controlled in pixel line units so as to correct the thus determined equidistant characteristics. “Distortion in the scanning direction” can be effectively prevented or reduced.
[0017]
The line image scanning type image display device according to claim 1, wherein a predetermined scanning area is set in advance in accordance with the deviation from the equal interval characteristic in the line image scanning direction caused by the deflecting means and the scanning lens system. Is divided into a plurality of blocks, and in each block, the number of pixel clocks whose time widths are changed is adjusted, and the scanning length of each block is adjusted, thereby correcting the equidistant characteristics of the line images on the image display surface. And perform line image scanning "(claim 2).
[0018]
The “scanning area” refers to the total number of line images required to display a two-dimensional image. Assuming that the total number is N, the two-dimensional image displayed on the image display surface is composed of “N line images adjacent to each other”, and an area where these N line images are arranged is a line image. Define the area where scanning will take place.
[0019]
In general, the scanning area is divided into blocks so that the change in the equal-interval characteristic in each block is the same or the same.
[0020]
To supplement the explanation, it is assumed that “a block is composed of n line images”, and if the scanning speed of the line image: v and the time width of the pixel clock: t are both assumed to be constant, the n line images are represented by an image. Although the width is displayed as n · v · t on the display surface, the scanning speed: v is not actually constant because the equidistant characteristics are finite.
[0021]
Therefore, if the average of the scanning speed in this block is “v + Δv”, the n-line image on the image display surface has a display width of n · (v + Δv) t, and the difference from the above n · v · t: n · Δv · t causes distortion of the displayed image.
[0022]
In this case, among the n pixel clocks that display n line images, the number of pixel clocks having a time width: t is m, and the number of pixel clocks having a time width: t + Δt is (nm). The display width of the line image is
m (v + Δv) t + (nm) (t + Δt) (v + Δv)
It becomes.
[0023]
Since higher-order terms are negligible, this equation:
n · t · v + n · Δv · t + n · Δt · v−m · v · Δt
In order for this to be equal to the original display width: n · v · t,
n · v · t = n · t · v + n · Δv · t + n · Δt · v−m · v · Δt
From
m · v · Δt = n (Δv · t + v · Δt)
Should be satisfied.
[0024]
In this equation, n is known as the number of line images included in the block, and t is known as the time width of a reference pixel clock. Further, v and Δv can be known from the equidistant characteristics. Accordingly, by appropriately selecting the amount of change in the time width of the pixel clock: Δt and the number of clocks of the time width: t + Δt: m in the above equation, the display width of the n line images can be changed to the ideal display width: n · It becomes possible to approach or match v · t. Actually, in one block, three or more pixel clocks having “different time widths” such as the time width of the pixel clock: m1 is the clock number of t + Δt1, m2 is the clock number of t + Δt2,. May be included.
[0025]
3. The line image scanning type image display device according to claim 1, wherein the scanning lens system is arranged near the image side of the deflecting means, and corrects the field curvature of the light beam deflected by the deflecting means on the surface to be scanned. The power of the imaging lens system is sufficiently small, and at least one surface is aspherical. "
[0026]
The scanning lens system in the line image scanning type image display device according to the third aspect may be "consisting of three or less lenses, at least one of which is a special toric surface" (claim 4).
[0027]
In the line image scanning type image display device according to any one of claims 1 to 4, the deflecting means may be a "galvano mirror that vibrates the deflecting reflection surface in a single oscillation" (claim 5). In this case, the effective scanning deflection angle of the galvanomirror (the angle area of the deflection angle that affects image display) is θeff, and the maximum deflection angle is θmax.
(1) θeff / θmax> 0.5
Is preferably satisfied (claim 6).
[0028]
7. The line image scanning type image display device according to claim 1, wherein the light modulating means has an illumination optical system and a non-self-luminous light modulating element, and corresponds to a selected signal. Only light is selectively transmitted to the imaging lens system "(claim 7). A GLV or a digital micromirror device can be suitably used as the non-self-luminous light modulation element.
[0029]
In the line image scanning type image display device according to the seventh aspect, a “reflection type BBLV” can be used as a non-self-luminous type light modulation element, and the specular reflection light can be set to correspond to the selected signal. (Claim 8).
[0030]
The light modulating means in the line image scanning type image display device according to any one of claims 1 to 6 can also be "using a self-luminous light modulating element" (claim 9). As such a light modulating means, one in which a semiconductor laser, an LED, or the like is arranged in a one-dimensional manner can be used, and further, a liquid crystal shutter array integrated with a light source can be used.
[0031]
The line image scanning type image display device according to any one of claims 1 to 9, further includes "variable light amount in an image forming light beam according to a scanning position (line image position) on the image display surface". Is preferable (claim 10).
[0032]
The light modulating means in the line image scanning type image display device according to any one of claims 1 to 10, wherein the light modulating means is a "fine light for displaying each of three primary colors: R (red), G (green), and B (blue). The modulating elements may be arranged one-dimensionally for each color and arranged in three rows close to each other (claim 11). In this case, the change of the time width of the pixel clock is referred to as "scanning optical system". (R, G, B) in accordance with the chromatic aberration of the image. "
[0033]
The line image scanning type image display device according to any one of claims 1 to 12 may further include "one or more folding mirrors for folding an optical path of a light beam from the scanning lens system to the image display surface." 13).
[0034]
The line image scanning type image display device described in each of the above claims can be implemented as various display devices such as a projector and a vehicle-mounted navigator.
[0035]
In the line image scanning type image display device of the present invention, by changing the time interval of the pixel clock on a pixel line basis, an equal interval characteristic generated by the deflecting unit and the scanning lens system is changed on the image display surface. The intervals between the respective line images can be made substantially equal intervals, so that “high-performance image display” can be achieved.
[0036]
As described above, since the correction of the equal-interval characteristic is performed by an electrical control method called time width control of the pixel clock, it is not necessary to provide the scanning lens system with a function of highly correcting the equal-interval characteristic. For this reason, the scanning lens system can be configured with a small number of lenses at low cost and compact, and the line image scanning type image display device can be reduced in size, thickness and cost.
[0037]
If the time width of the pixel clock is changed for each line image, the equidistant characteristics can be completely corrected in principle, but if the time width to be changed is stored and controlled for each line image, Since the number of line images for displaying a two-dimensional image is large, the means for controlling the time width of the pixel clock may be complicated or large-scale. Is divided into blocks, and the "introduction of time width change of the same rule in a block" can reduce the number of memories.
[0038]
It is a rational method to divide the size (%) of the equally-spaced characteristic into blocks by equal difference. For example, when the equal-interval characteristic is a maximum of 10%, the quantization error can be reduced to within ± 0.25% when the equal-interval characteristic is divided into “20 blocks with equal difference”, and sufficient performance for practical use is obtained. .
[0039]
If the scanning lens system is arranged near the deflecting means as in claim 3, the size of the scanning lens system can be reduced. By mainly setting the function of the scanning lens system to “the function of correcting the field curvature of the light beam deflected by the deflecting means on the surface to be scanned”, the design of the scanning lens system becomes easy.
[0040]
The scanning lens separates the scanning light beam as it separates from the deflecting means, and the aberration correction becomes easy. However, even if the scanning lens is arranged “in the vicinity of the deflecting means” as in claim 3, it has at least one aspheric surface. Thus, “correction of field curvature” can be sufficiently performed.
[0041]
The magnitude relationship between the power of the imaging lens system: φf and the power of the scanning lens system: φs is as follows.
| Φs | /φf≦0.1
According to such a power distribution, the performance of the imaging lens system can be sufficiently brought out, the chromatic aberration generated in the scanning lens system can be suppressed, the thickness of the scanning lens system can be reduced, and the size can be reduced. The workability can be easily secured.
[0042]
When the scanning lens system is constituted by a single lens, it is preferable that the scanning lens system has a “meniscus shape with the convex surface facing the deflecting means”. With such a lens shape, good correction of the curvature of field can be achieved, and a surface shape close to a plane can be avoided, so that workability is improved.
[0043]
In the scanning lens system, since "the effective area of the lens surface through which the deflected image-forming light beam passes" is rectangular, image display is performed by setting "at least one surface to a special toric surface" as described in claim 4. “Higher-order correction of field curvature” on a surface becomes possible. In particular, in order to correct the chromatic aberration of the scanning lens system and reduce the difference between the R, G, and B pixel positions on the image display surface, in principle, at least “two concave and convex lenses” are necessary. To simultaneously correct the surface curvature and the chromatic aberration, a configuration of two to three lenses is suitable. As described above, when the scanning lens system is composed of “two or more lenses having irregularities”, the Abbe number of convex lenses (average when a plurality of lenses): ν (convex) and the Abbe number of concave lenses: ν (concave) are 10 It is preferable to set the above difference.
[0044]
As the deflecting means, it is possible to use a rotary polygon mirror, a rotary two-sided mirror, or a rotary single-sided mirror widely known in relation to an optical scanning device. You can also.
[0045]
In a general image display, assuming ± 10 degrees as a long side angle of view (angle of view in the scanning direction of a line image) and a maximum scanning angle of ± 15 degrees (= scanning width of 30 degrees), one surface Of the rotary polygon mirror having a deflection angle of 15 degrees has 24 deflection reflection surfaces. In this case, considering the effective width of the deflected imaging light beam, the 24-sided polygon mirror becomes considerably large.
[0046]
Assuming that a small polygon having six deflecting reflection surfaces is used, the maximum scanning angle per one deflecting reflection surface is 120 degrees, so that the effective scanning period ratio (20/120) is approximately 17% and light use efficiency is high. Is low. From this point of view, the galvanometer mirror is suitable as a deflecting means in that the size can be reduced and the amplitude of the angular vibration of the deflecting / reflecting surface can be appropriately set.
[0047]
When a galvanomirror is used as the deflecting means, the deflecting and reflecting surface is generally subjected to sinusoidal oscillation (simple oscillation). Therefore, the deflection angle becomes large under the condition that the effective scanning angle is ± 10 degrees and the maximum scanning angle is ± 15 degrees. The scanning speed becomes slower as "the periphery of the two-dimensional image in the line image scanning direction" becomes smaller, and the interval between the line images becomes gradually smaller in the periphery. Therefore, in such a case, the time width of the pixel clock or the number of pixels having a large time width is increased in the peripheral portion.
[0048]
By setting the effective scanning deflection angle: θeff and the maximum deflection angle: θmax of the galvanomirror of the galvanomirror as the deflecting means to satisfy the above condition (1), the light use efficiency can be set to 50% or more, and image display is performed. Surface brightness can be ensured, and increases in light source power and used power can be suppressed. An appropriate combination of the deflection characteristics of the deflection means and the change of the time width of one clock can improve the light use efficiency.
[0049]
As described in claim 7, a light modulating means having a non-self-luminous light modulating element and an illumination optical system arranged one-dimensionally is used, and "only light corresponding to a selected signal" is used. Is selectively conveyed to the imaging lens system, using a linear light source, a cylindrical reflecting mirror, a cylindrical lens, etc., the illumination light flux can be efficiently condensed on the light modulating means, and a bright line image can be formed. Can be displayed.
[0050]
The color temperature and brightness specifications can be changed by appropriately selecting the light source, and various filters such as infrared cut are inserted between the light source unit and the light modulation element to suppress the temperature rise after the light modulation means. You can also.
[0051]
As described in Patent Document 3, "BBLV" which can be used as a light modulating element passes a beam on a V-shaped base of several tens of μm and changes the state of the beam to "plane when voltage is off" and "V when voltage is on". The light is turned on and off by changing the direction of the reflected light by turning on and off the voltage.However, since the switching frequency is high and the BBLV can be finely formed, this is used as an optical modulation element. By using this, it is possible to reduce the size of the line image scanning type image display device, and since each BBLV is a rectangular mirror, a sharp image can be formed.
[0052]
By setting the regular reflection light (voltage off) by the BBLV so as to “correspond to the selected signal”, light applied to image display can be effectively guided to the image display surface.
[0053]
The light modulating means is a "one-dimensionally arranged self-light emitting type light modulating element" (claim 9), which does not require an illuminating means for condensing and illuminating the light modulating element, and has a simple structure. The line image scanning type image display device can be miniaturized, and cost reduction, miniaturization by fine arrangement, bright display images, and the like can be realized according to the self-luminous light modulation element.
[0054]
In the present invention, as described above, when scanning a line image, the time width of the pixel clock is changed so as to correct the equal interval characteristics. In an extreme case, “brightness unevenness” may occur in the scanning direction of the displayed two-dimensional image. When a galvanomirror is used as the deflecting means, as described above, the closer to the peripheral portion in the scanning direction, the greater the equal-interval characteristic is generated on the “minus side”. Therefore, it is necessary to increase the time width of the pixel clock. The time interval of image irradiation also becomes longer.
[0055]
In such a case, it is possible to reduce or prevent brightness unevenness in a display image by making “the amount of light in the image forming light beam variable according to the scanning position on the image display surface”. .
[0056]
As described in claim 11, by using an element corresponding to the three primary colors: R, G, and B as the light modulation element, a two-dimensional color image can be displayed on the image display surface. The “difference in the imaging position due to chromatic aberration” of the line image of each of the R, G, and B colors can be reduced by “setting the time width of the pixel clock individually for each color”. .
[0057]
Further, as described in claim 13, by having one or more folding mirrors for bending the optical path of the light beam from the scanning lens system to the image display surface, the projection optical path length required for image display is bent, The depth of the line image scanning type image display device can be reduced.
[0058]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments will be described.
In FIG. 1, reference numeral 1 denotes an illumination optical system, reference numeral 3 denotes a semi-transparent mirror, reference numeral 5 denotes a light modulating unit, reference numeral 6 denotes an image forming lens system, reference numeral 7 denotes a deflecting unit, reference numeral 8 denotes a scanning lens system, and reference numeral 9 denotes image display. Each of the screens constitutes a surface entity.
[0059]
The illumination optical system 1 has a linear light source 1A, a reflector 1B, and a condenser lens 2.
The light modulating means 5 is composed of minute light modulating elements of "non-self-luminous type" which are closely arranged in a direction perpendicular to the drawing and are linearly arranged, so that modulation is performed by a modulating signal from the modulating circuit HT. ing.
[0060]
The minute light modulation element is a “reflection type light modulation element BBLV” known from Patent Document 3, and the effective shape of one element (shape capable of changing the direction of reflected light) is 19 μm × 20 μm, and the arrangement pitch of the elements is At 20 μm, 768 elements are linearly arranged, and the array length of the light modulation elements is about 15.36 mm.
[0061]
Such a one-dimensional array of BBLVs is arranged in three rows at intervals of 50 μm, and one row of R, another row of G, and another row of B color filters are integrally joined by a joining method. ing. The arrangement width of the three light modulation element rows is approximately 0.12 mm.
[0062]
The linear light source 1A in the illumination light source 1 is a linear light source such as a halogen bulb, and has a light emission length slightly longer than the “array length of light modulation elements: about 15.36 mm” in the light modulation element 5. The reflector 1B has a cross-sectional shape such as a circular arc or a parabola (a non-circular shape including higher-order terms may be used), and reflects light from the linear light source 1A.
[0063]
The condenser lens 2 is a cylindrical lens having a direction perpendicular to the drawing as a “general line direction of the refraction surface”, and condenses the direct light from the linear light source 1A and the light reflected by the reflector 1B. The one-way condensed light from the cylindrical lens 2 is reflected by the semi-transparent mirror 3 and converges toward the light modulation element 5, and the arrangement width of the three R, G, and B light modulation element rows (= approximately 0) .12 mm).
[0064]
The specularly reflected light from each light modulation element of the light modulation means 5 enters the imaging lens system 6 via the semi-transparent mirror 3. Although the imaging lens system 6 is illustrated as a single lens in the figure, it is actually composed of a plurality of lenses. It is desirable that the imaging lens system 6 be substantially telecentric on the light modulation element 5 side. It is preferable that the imaging lens system 6 be a “behind stop” having a stop after the image forming lens system 6.
[0065]
The light modulating means 5 is disposed almost completely offset from the imaging lens system 6, and the imaging lens system 6 has a focal length of 36 mm and a "39x magnification" on the screen 9 at a conjugate length of 1.5 m. Is enlarged (via the scanning lens system 8). Therefore, the light from the light modulating means 5 having a light modulating element array length of 15.36 mm forms "line images having a length of approximately 600 mm" in the directions perpendicular to the drawing, respectively, for R, G, and B.
[0066]
Since the effective light flux is regulated by the surface of the stop (not shown), the area of the deflecting / reflecting surface can be set small by arranging the deflecting means 7 (the deflecting / reflecting surface) close to the image side of the iris. The deflecting means 7 is a galvanomirror that is driven so that the deflecting / reflecting surface swings at a maximum deflection angle of 15 degrees with sinusoidal vibration.
[0067]
Since the swing of the deflecting reflection surface of the deflecting means 7 is a sine wave oscillation, the incident angle of the deflecting light beam incident on the scanning lens system 8 also changes sinusoidally. Therefore, if "scanning the screen 9 at a constant speed" is to be realized by "achieving the optical characteristics of the scanning lens system 8", the scanning lens system 8 uses the image height h in the scanning direction of the line image and the incident angle: θ, the distance to the image plane: l is
h = l · arcsin (θ)
Must be corrected so as to satisfy the following condition.
[0068]
In this embodiment, as described above, the scanning lens system 8 is mainly provided with a function of field curvature, the correction of the distortion is moderate, and the time width of the pixel clock is controlled for the remaining distortion remaining after the correction. It corresponds with.
[0069]
【Example】
Hereinafter, three specific numerical examples regarding the scanning lens system will be given.
Embodiments 1 and 2 are examples in which the scanning lens system is constituted by one lens as shown in FIG. 1, and Embodiment 3 is an example constituted by two lenses.
[0070]
Example 1
"Scanning lens system (single lens)"
Distance on the optical axis from the galvanometer mirror (distance on the optical axis from the deflecting / reflecting surface of the galvanometer mirror to the entrance lens surface of the scanning lens system): 7 mm
Thickness on optical axis: 3mm
Refractive index of material: nd = 1.53046
Abbe number of material: νd = 55.84
Assuming that coordinate axes: X and Z are defined as shown in FIG. 1 and the Y axis is a direction orthogonal to the drawing, the scanning lens system (single-element configuration) of the first embodiment has a “XZ plane including the optical axis” on both sides. Is a non-circular arc shape, the paraxial radius of curvature: Rz, the higher order coefficient: A ₄ , A ₆ , A ₈ Formulas known as, ...:
X (Z) = Z ² / [Rz + Rz · √ ｛1- (1 + K) Z ² / Rz ² ｝ + A ₄ ・ Z ⁴ + A ₆ ・ Z ⁶ + A ₈ ・ Z ⁸ + A ₁₀ ・ Z ¹⁰ (Equation 1)
Expressed by
[0071]
In addition, the porosity Cy in the “XY plane” has a so-called “curved axis toroidal shape” that changes according to the height Z in the Z direction. Radius of curvature of Y plane: Ry0, higher order coefficient: B ₂ , B ₄ , B ₆ ...
Cy (Z) = 1 / Ry0 + B ₂ ・ Z ² + B ₄ ・ Z ⁴ + B ₆ ・ Z ⁶ + B ₈ ・ Z ⁸ (Equation 2)
Expressed by
[0072]
Data for specifying the shape of each surface of the scanning lens system is as follows.
[0073]

[0074]

[0075]
In the above notation, for example, “4.92E-06” becomes “4.92 × 10 ^-6 Means. The same applies to the following embodiments.
[0076]
FIG. 2 shows the field curvature and linearity (corresponding to the equal-interval characteristic) when the scanning lens system of Example 1 is used to scan ± 400 mm in the Z direction on the image display surface. Even though the scanning lens system is arranged as a single lens near the deflecting means, the field curvature is well corrected with a width of about 0.03 mm. Here, the wavelength indicating the aberration is e-line (546.07 nm).
[0077]
In the first embodiment, since the scanning lens system has a single-lens configuration and mainly corrects curvature of field, “linearity” corresponding to the equidistant characteristics is not corrected.
When the effective deflection angle of the deflecting reflection surface is ± 8.2 degrees, scanning of ± 400 mm (= 800 mm width) is performed on the screen 9 that is 1.4 m away from the deflecting reflection surface, but the final part of the scanning (± 400 mm) , A linearity of -7.5% occurs.
[0078]
This residual linearity (equal interval characteristic) can be corrected as follows.
[0079]
A high-frequency clock generator GS in FIG. 1 generates a “high-frequency clock eight times the pixel clock”, and divides the high-frequency clock by eight by a frequency dividing circuit BS to generate a “pixel clock”. Apply.
Since the negative linearity means that the scanning speed of the peripheral part is lower than that of the central part, the pixel clock in the peripheral block (the block obtained by dividing the scanning area) is added to the pixel clock of the peripheral part. By mixing pixel clocks with a time width longer than the regular time width: 8/8 and a time width: 9/8, it is possible to compensate for the negative linearity.
[0080]
For example, if the number of line images (one color) constituting the block is 25, the number of pixel clocks having a time width of 8/8: x, the number of pixel clocks having a time width of 9/8 : Y, as explained above, the equation:
1 / (1-7.5%) = 1 / (1-0.075) = {x + (9y / 8)} / (x + y)
In this case, if x + y = 25, x = 9 and y = 16. Therefore, when sequentially outputting 25 line images, a clock having a time width of 8/8 is used nine times as a pixel clock for determining the output. A rule of repeating a clock with a time width of 9/8 16 times under an appropriate arrangement (for example, the first 9 times have a time width of 8/8, and the second 16 times have a time width of 9/8. )), It is possible to correct the equidistant characteristics provided by the linearity of -7.5%, and to achieve high-performance optical scanning.
[0081]
If the change in linearity is symmetric in the scanning direction as shown in FIG. 3, the scanning area is divided into linearity widths: 0.5%, and divided into 15 blocks corresponding to one side (400 mm) of scanning. It can be divided, and within a block, the number of pixel clocks with different time widths of the pixel clocks is adjusted according to the same rule set in advance to keep the linearity width within the block within ± 0.25%. Therefore, the "rule for changing the time width of the pixel clock" is only 15 rules, and the number of memories required for storing these rules is small.
[0082]
Example 2
The scanning lens system is composed of one lens, and the arrangement relationship is the same as in the first embodiment.
[0083]
"Scanning lens"
Distance on the optical axis with the galvanometer mirror: 7 mm
Thickness on optical axis: 3 mm,
Refractive index of material: nd = 1.53046
Abbe number of material: νd = 55.84
The first surface is a coaxial aspheric surface obtained by rotating the non-circular arc shape given by (Equation 1) around the optical axis, and the second surface is a curved axis toroidal shape expressed by (Equation 2).
[0084]
Data for specifying the shape of each surface of the scanning lens system is as follows.
[0085]

[0086]

[0087]
FIG. 4 shows the field curvature and the linearity according to the second embodiment, following FIG. As in the first embodiment, the curvature of field is about 0.03 mm in width, which is well corrected even though the scanning lens system is arranged as a single lens near the deflection unit.
[0088]
As in the case of the first embodiment, the equally-spaced characteristics can be favorably corrected.
[0089]
Example 3
Embodiment 3 is an example in which the scanning lens system is constituted by two lenses.
[0090]
The arrangement relationship is the same as in the first embodiment.
"First lens (galvanometer mirror side lens)"
Distance on the optical axis with the galvanometer mirror: 7 mm
Thickness on optical axis: 3mm
Refractive index of material: nd = 1.53046
Abbe number of material: νd = 55.84
"Second lens (screen side lens)
Air gap with the first lens: 5 mm
Thickness on optical axis: 3mm
Refractive index of material: nd = 1.58410
Abbe number of material: νd = 30.45
The first lens has a “spherical shape on both sides”, and the second lens has a “curved axis toroidal shape on both sides”.
[0091]
Data for specifying each lens surface shape of the scanning lens system is as follows.
[0092]
First lens
First side
R (radius of curvature) −2427.0
Second side
R (radius of curvature) -1121.0.
[0093]

[0094]

[0095]
FIG. 5 shows the field curvature and the linearity according to the third embodiment in a manner similar to FIG. As in the first embodiment, the field curvature can be corrected well even though the scanning lens system is arranged as a single lens near the deflection unit. As in the case of the first embodiment, the equally-spaced characteristics can be favorably corrected.
[0096]
The difference (mm) of the scanning length (one side from the optical axis) with respect to the e-line (546.07 mm) reference wavelength is shown.
[0097]

In the first and second embodiments, since the chromatic aberration of the scanning lens system cannot be corrected because of the single-lens configuration, “difference in scanning length due to wavelength” occurs. In such a case, the “difference in color of the line image position” can be reduced by changing the change of the pixel clock time width for each of the R, G, and B line images.
[0098]
In the third embodiment, the chromatic aberration of the scanning lens system is corrected, and there is no difference in the positions of the R, G, and B line images. Therefore, the time width control of the pixel clock is performed for the R, G, and B line images. This can be done with "common rules".
[0099]
FIG. 6 shows another example of the optical arrangement. In order to avoid complication, the same reference numerals as those in FIG. In this example, the scanning lens 8A is composed of two lenses as in the third embodiment, and the optical path of the light beam from the scanning lens system 8A to the image display surface 9 is bent between the scanning lens and the screen 9. A folding mirror ML is provided.
[0100]
Finally, a brief description will be given of a change in the time width of the pixel clock.
[0101]
In the example described above with reference to the first embodiment, the pixel clock generates a “high-frequency clock eight times the pixel clock” in the high-frequency clock generation unit GS in FIG. A “pixel clock” is generated by dividing the frequency by 8 in the above. A specific example in this case will be described with reference to FIGS. 7 and 8.
[0102]
FIG. 7 shows a portion where the high-frequency clock generation circuit GS and the frequency dividing circuit BS in FIG. 1 are combined. For convenience of description, reference numerals different from those in FIG. 1 are given.
[0103]
7, the pixel clock generation circuit 10 includes a high frequency clock generation circuit 11 (corresponding to the high frequency clock generation circuit GS in FIG. 1), a counter 12, a comparison circuit 13, and a pixel clock control circuit 14.
[0104]
The high-frequency clock generation circuit 11 generates a high-frequency clock: VCLK that is a reference of the pixel clock: PCLK. The counter 12 operates at the rising of the high frequency clock: VCKL and counts the clock: VCKL. The comparison circuit 12 compares the count value of the counter 12 with phase data indicating a phase shift amount as a “preset value and a transition timing of an externally supplied pixel clock”, and based on the comparison result, a control signal: a, The control signal b is output.
[0105]
The pixel clock control circuit 13 controls the rising and falling timings of the pixel clock PCLK based on the control signals a and b.
[0106]
“Phase data” is data for instructing a shift amount of a phase of a pixel clock in order to correct an equal interval characteristic, and is generally given as a digital value of several bits, and is stored in a memory (not shown).
[0107]
The operation of the pixel clock generation circuit 10 will be described with reference to FIG.
The pixel clock PCLK is obtained by dividing the high-frequency clock VCLK by eight, and has a duty ratio of 50% as standard. FIG. 8A shows a state in which a standard pixel clock PCLK having a duty ratio: 50% corresponding to a high-frequency clock VCLK divided by 8 is generated, and FIG. 8B shows a state in which a high-frequency clock VCLK divided by 8 is generated. (C) shows a state in which a pixel clock: PCLK whose phase is advanced by 1/8 clock with respect to that of FIG. : Shows how a PCLK clock is generated.
[0108]
As described above, the “time width of the pixel clock” is the time from the rise of a certain pixel clock to the rise of the next pixel clock. According to the description with reference to FIG. By changing the phase of the subsequent pixel clock by ± 「clock, the time width of the pixel clock can be changed by“ １ ／ clock ”.
[0109]
In FIG. 8A, a value of “7” is given as the phase data. “3” is set in the comparison circuit 13 in advance. The counter 12 operates and counts at the rising edge of the high frequency clock: VCLK. The comparison circuit 13 outputs the control signal: a when the value of the counter 12 becomes “3”.
[0110]
Since the control signal: a is “H”, the pixel clock control circuit 14 causes the pixel clock: PCLK to fall from “H” to “L” at the clock timing (1). Next, the comparison circuit 13 compares the given phase data "7" with the count value of the counter 12, and outputs a control signal: b if they match. In FIG. 8A, when the count value of the counter 12 becomes “7”, the comparison circuit 13 outputs a control signal: b.
[0111]
The pixel clock control circuit 14 raises the pixel clock: PCLK from “L” to “H” at the clock timing (2) since the control signal: b is “H”. At this time, the comparison circuit 13 resets the counter 12 at the same time, and starts counting from 0 again.
[0112]
In this way, as shown in FIG. 8A, it is possible to generate a pixel clock: PCLK having a duty ratio: 50% corresponding to the frequency division of the high frequency clock: VCLK by 8. Changing the set value of the comparison circuit 13 changes the duty ratio.
[0113]
In FIG. 8B, phase data “8” is given. The counter 12 counts the high frequency clock: VCLK, and the comparator 13 outputs the control signal: a when the value of the counter 12 becomes “3”. The pixel clock control circuit 14 causes the pixel clock: PCLK to fall from “H” to “L” at the timing (1) of the high frequency clock since the control signal: a is “H”.
[0114]
Next, when the value of the counter 12 matches the given phase data “8”, the comparison circuit 13 outputs a control signal: b. The pixel clock control circuit 14 raises the pixel clock: PCLK from “L” to “H” at the high frequency clock timing (2) since the control signal: b is “H”. At this time, the comparison circuit 13 resets the counter 12 at the same time, and starts counting from 0 again.
[0115]
In this manner, as shown in FIG. 8B, a “pixel clock: PCLK whose phase is advanced by １ ／ clock with respect to the ８ frequency-divided clock of the high frequency clock: VCLK” can be generated. If “9” is given instead of “8” as the phase data, the advance of the phase can be advanced by ／ of the pixel clock, whereby the “pixel clock” described according to the first embodiment can be obtained. Can be changed to 10/8 ”.
[0116]
In FIG. 8C, phase data “6” is given. The counter 12 counts the pixel clock: VCLK, the comparison circuit 13 outputs the control signal: a when the value of the counter 12 becomes “3”, and the pixel clock control circuit 14 sets the control signal: a to “H”. , The pixel clock: PCLK falls from “H” to “L” at the timing (1) of the high-frequency clock.
[0117]
Next, when the count value of the counter 12 matches the given phase data “6”, the comparison circuit 13 outputs a control signal: b. The pixel clock control circuit 14 raises the pixel clock: PCLK from “L” to “H” at the timing (2) of the high frequency clock since the control signal: b is “H”.
[0118]
At this time, the counter 12 is reset at the same time, and counting is started from 0 again. In this way, as shown in FIG. 8C, a pixel clock PCLK whose phase is delayed by 1/8 clock with respect to the high frequency clock VCLK divided by 8 can be generated.
[0119]
When the phase data is given in synchronization with the rise of the pixel clock: PCLK, the phase of the pixel clock: PCLK can be changed every clock of the high frequency clock: VCLK.
[0120]
【The invention's effect】
As described above, according to the present invention, a novel line image scanning type image display device can be realized. In this apparatus, since the scanning lens system only needs to perform "mainly correction of field curvature", the scanning lens system can be configured with a single lens or a small number of lenses, so that the line image scanning type image display device can be made compact and low cost. Can be configured.
[0121]
Further, by changing the time width of the pixel clock for each pixel line, it is possible to effectively correct the equal-interval characteristics that could not be corrected by the scanning lens system, and display a good two-dimensional image.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining an embodiment of a line image scanning type image display device.
FIG. 2 is a diagram illustrating field curvature and linearity corresponding to equidistant characteristics in Example 1 of a scanning lens system.
FIG. 3 is a diagram for explaining linearity according to the first embodiment and linearity after the linearity is adjusted by adjusting the number of pixels having different time widths to a pixel clock.
FIG. 4 is a diagram illustrating field curvature and linearity according to a second embodiment of the scanning lens system.
FIG. 5 is a diagram illustrating field curvature and linearity according to a third embodiment of the scanning lens system.
FIG. 6 is a diagram for explaining another embodiment of the line image scanning type image display device.
FIG. 7 is a diagram for explaining a pixel clock generation circuit.
8 is a diagram for explaining generation of a pixel clock by the pixel clock generation circuit of FIG. 7 and change of the time width of the pixel clock.
[Explanation of symbols]
1 Illumination optical system
3 Semi-transparent mirror
6 Imaging lens system
7 Deflection means
8 Scanning lens system
9 Screen that forms the substance of the image display surface

Claims (13)

Light from each light modulating element in the light modulating means in which minute light modulating elements are arranged one-dimensionally is transmitted as object light by an image forming lens, and an image forming light beam emitted from this image forming lens system is deflected. Means for deflecting light in a direction orthogonal to the arrangement direction of the light modulation elements, and scanning the image display surface while forming a one-dimensional line image on the image display surface via a scanning lens system. A line image scanning type image display device for displaying a two-dimensional image thereon,
By changing the time width of a pixel clock for displaying an image signal on the light modulating unit in units of pixel lines, according to the equal spacing characteristics in the line image scanning direction generated due to the deflecting unit and the scanning lens system, A line image scanning type image display device, wherein line image scanning is performed by correcting an equal interval characteristic of a line image on a display surface. The line image scanning type image display device according to claim 1,
The scanning area is divided into a plurality of predetermined blocks in advance in accordance with the deviation from the uniform spacing characteristic in the line image scanning direction caused by the deflecting means and the scanning lens system, and the time width is changed in each block. The line image scanning is performed by adjusting the scanning length of each block by adjusting the number of pixel clocks to be performed, thereby correcting line-space characteristics of line images on the image display surface. Type image display device. The line image scanning type image display device according to claim 1 or 2,
A scanning lens system is disposed near the image side of the deflecting means, and mainly has a function of correcting the field curvature of the light beam deflected by the deflecting means on the scanned surface,
A line image scanning type image display device, wherein the power of the scanning lens system is sufficiently smaller than the power of the imaging lens system, and at least one surface is aspherical. The line image scanning type image display device according to claim 3,
A line image scanning type image display device, wherein a scanning lens system includes three or less lenses, at least one of which is a special toric surface. A line image scanning type image display device according to any one of claims 1 to 4,
A line image scanning type image display device, wherein the deflecting means is a galvanomirror that oscillates the deflecting reflection surface in a simple manner. The line image scanning type image display device according to claim 5,
The effective scanning deflection angle of the galvanomirror: θeff and the maximum deflection angle: θmax are the conditions:
(1) θeff / θmax> 0.5
A line image scanning type image display device characterized by satisfying the following. A line image scanning type image display device according to any one of claims 1 to 6,
A light modulating means having an illumination optical system and a non-self-luminous light modulating element, wherein only light corresponding to the selected signal is selectively transmitted to the imaging lens system; Type image display device. The line image scanning type image display device according to claim 7,
A non-self-emission type light modulation element is a reflection type BBLV, and a regular reflection light is set so as to correspond to a selected signal. A line image scanning type image display device according to any one of claims 1 to 6,
A line image scanning type image display device, wherein the light modulating means uses a self light emitting type light modulating element. A line image scanning type image display device according to any one of claims 1 to 9,
A line image scanning type image display device, wherein the amount of light in an image forming light beam is variable according to a scanning position on an image display surface. The line image scanning type image display device according to any one of claims 1 to 10,
The light modulating means arranges minute light modulating elements for displaying each of the three primary colors: R (red), G (green), and B (blue) one-dimensionally for each color, and forms three rows close to each other. A line image scanning type image display device characterized by being arranged. The line image scanning type image display device according to claim 11,
A line image scanning type image display device characterized in that the time width of the pixel clock is changed according to the chromatic aberration of the scanning optical system. A line image scanning type image display device according to any one of claims 1 to 12,
A line image scanning type image display device comprising one or more folding mirrors for bending an optical path of a light beam from a scanning lens system to an image display surface.

Images