JP2669253B2 - Image sensor - Google Patents
Image sensorInfo
- Publication number
- JP2669253B2 JP2669253B2 JP4078459A JP7845992A JP2669253B2 JP 2669253 B2 JP2669253 B2 JP 2669253B2 JP 4078459 A JP4078459 A JP 4078459A JP 7845992 A JP7845992 A JP 7845992A JP 2669253 B2 JP2669253 B2 JP 2669253B2
- Authority
- JP
- Japan
- Prior art keywords
- liquid crystal
- layer
- electrodes
- substrates
- incident light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000004973 liquid crystal related substance Substances 0.000 claims description 55
- 239000000758 substrate Substances 0.000 claims description 22
- 230000003287 optical effect Effects 0.000 claims description 14
- 238000003384 imaging method Methods 0.000 claims description 12
- 229910021417 amorphous silicon Inorganic materials 0.000 claims description 7
- 239000011159 matrix material Substances 0.000 claims description 3
- 230000001678 irradiating effect Effects 0.000 claims description 2
- 239000000463 material Substances 0.000 description 9
- 230000005684 electric field Effects 0.000 description 6
- 230000035945 sensitivity Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- 125000006850 spacer group Chemical group 0.000 description 3
- 230000003595 spectral effect Effects 0.000 description 3
- WUPHOULIZUERAE-UHFFFAOYSA-N 3-(oxolan-2-yl)propanoic acid Chemical compound OC(=O)CCC1CCCO1 WUPHOULIZUERAE-UHFFFAOYSA-N 0.000 description 2
- MARUHZGHZWCEQU-UHFFFAOYSA-N 5-phenyl-2h-tetrazole Chemical compound C1=CC=CC=C1C1=NNN=N1 MARUHZGHZWCEQU-UHFFFAOYSA-N 0.000 description 2
- 239000004988 Nematic liquid crystal Substances 0.000 description 2
- 229910052980 cadmium sulfide Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- ZUOUZKKEUPVFJK-UHFFFAOYSA-N diphenyl Chemical compound C1=CC=CC=C1C1=CC=CC=C1 ZUOUZKKEUPVFJK-UHFFFAOYSA-N 0.000 description 2
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 2
- 239000011669 selenium Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- YJTKZCDBKVTVBY-UHFFFAOYSA-N 1,3-Diphenylbenzene Chemical group C1=CC=CC=C1C1=CC=CC(C=2C=CC=CC=2)=C1 YJTKZCDBKVTVBY-UHFFFAOYSA-N 0.000 description 1
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- CZPWVGJYEJSRLH-UHFFFAOYSA-N Pyrimidine Chemical compound C1=CN=CN=C1 CZPWVGJYEJSRLH-UHFFFAOYSA-N 0.000 description 1
- -1 Schiff Chemical group 0.000 description 1
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 1
- 239000004990 Smectic liquid crystal Substances 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 125000000751 azo group Chemical group [*]N=N[*] 0.000 description 1
- 125000005337 azoxy group Chemical group [N+]([O-])(=N*)* 0.000 description 1
- 235000010290 biphenyl Nutrition 0.000 description 1
- 239000004305 biphenyl Substances 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- UHYPYGJEEGLRJD-UHFFFAOYSA-N cadmium(2+);selenium(2-) Chemical compound [Se-2].[Cd+2] UHYPYGJEEGLRJD-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 125000001153 fluoro group Chemical group F* 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910003437 indium oxide Inorganic materials 0.000 description 1
- PJXISJQVUVHSOJ-UHFFFAOYSA-N indium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[In+3].[In+3] PJXISJQVUVHSOJ-UHFFFAOYSA-N 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- GGYFMLJDMAMTAB-UHFFFAOYSA-N selanylidenelead Chemical compound [Pb]=[Se] GGYFMLJDMAMTAB-UHFFFAOYSA-N 0.000 description 1
- 229910052711 selenium Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 1
- 229910001887 tin oxide Inorganic materials 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
Landscapes
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
- Transforming Light Signals Into Electric Signals (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、被写体の光学像を入力
とし、テレビジョンの走査の原理により時系列の電気信
号に変換して出力する撮像素子に係り、特に、入射光に
より液晶分子の配向制御を実現し、かつ、対向する電極
間の液晶分子の誘電率異方性によるインピーダンス変化
を電気信号として出力する撮像素子に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device which receives an optical image of an object and converts it into a time-series electric signal according to the principle of television scanning and outputs the electric signal. The present invention relates to an imaging device that realizes alignment control and outputs an impedance change due to dielectric anisotropy of liquid crystal molecules between opposing electrodes as an electric signal.
【０００２】[0002]
【従来の技術】撮像素子には撮像管と固体撮像素子とが
あり、これら撮像素子の機能としては、光電変換（書き
込み），蓄積，走査（読み出し）からなる。撮像素子に
入射された入射光は光電変換され、撮像管においては蓄
積ターゲットと呼ばれる高抵抗材料面に、固体撮像素子
においては相互に分離された微小容量アレーに、入射光
学像に対応した信号電荷像として蓄積される。そして、
像の最小構成単位である画素の電荷量が走査方式に従っ
て順次読み出され、出力信号電流となる。2. Description of the Related Art Image pickup devices include an image pickup tube and a solid-state image pickup device. The functions of these image pickup devices include photoelectric conversion (writing), accumulation, and scanning (reading). Incident light incident on the image pickup device is photoelectrically converted, and in the image pickup tube, a high-resistance material surface called a storage target, and in a solid-state image pickup device, a microcapacitor array separated from each other, a signal charge corresponding to an incident optical image. It is stored as an image. And
The charge amount of the pixel, which is the minimum constituent unit of the image, is sequentially read out according to the scanning method, and becomes an output signal current.
【０００３】撮像管においては、走査と読み出しは集束
した電子ビームを偏向して行う。また、固体撮像素子に
おいては、画素は構造的に１つずつ分離独立しており、
走査信号発生器を用いて各画素を順次通電放電させるＸ
Ｙアドレス方式と、固体内で電荷を順次転送して取り出
す電荷転送方式とが代表的である。従って、このように
して撮像素子から取り出される各画素の情報を再生処理
すると、入射光学像を任意の場所で可視化することがで
きる。In an image pickup tube, scanning and reading are performed by deflecting a focused electron beam. In the solid-state imaging device, pixels are structurally separated and independent one by one,
X for sequentially energizing and discharging each pixel using a scanning signal generator
A Y address method and a charge transfer method in which charges are sequentially transferred and extracted in a solid are representative. Therefore, when the information of each pixel extracted from the image sensor is reproduced in this way, the incident optical image can be visualized at an arbitrary position.
【０００４】[0004]
【発明が解決しようとする課題】しかしながら、上述し
た従来の撮像素子においては、大きさ，重量，消費電力
等の運用性に問題があり、さらに、高価である等の経済
性に問題がある。そこで本発明は、光により液晶分子の
配向状態を変化させて得られるインピーダンスの変化を
出力信号として取り出す撮像素子の構造を提案し、もっ
て前記した従来の撮像素子の問題点を解決することを目
的として創作された。However, the above-mentioned conventional imaging device has problems in operability such as size, weight, and power consumption, and also has problems in economics such as high cost. Therefore, the present invention proposes a structure of an image pickup device that extracts a change in impedance obtained by changing the alignment state of liquid crystal molecules by light as an output signal, and thus solves the above-mentioned problems of the conventional image pickup device. Was created as.
【０００５】[0005]
【課題を解決するための手段】本発明は、上述した従来
の技術の課題を解決するため、(1) 複数の電極が形成さ
れた１対の基板を、前記電極がマトリクス状に交差する
よう対向させて画素を形成し、前記１対の基板間に液晶
層を挟装すると共に、少なくとも一方の前記基板の前記
液晶層側に、入射される光強度で比抵抗が変化する光導
電体層を積層形成してなり、前記電極に低周波の交流電
圧を印加すると共に被写体からの入射光を照射させるこ
とにより、前記液晶層の液晶分子を再配列させて光学像
を書き込み、前記低周波の交流電圧に重畳して高周波の
交流電圧を印加することにより、前記液晶分子の誘電率
異方性によるインピーダンス変化を電気信号として取り
出して前記書き込んだ光学像を読み出すことを特徴とす
る撮像素子を提供し、(2) 前記入射される光強度で比抵
抗が変化する光導電体層は、アモルファスシリコン（ａ
−Ｓｉ：Ｈ）であることを特徴とする(1) 記載の撮像素
子を提供するものである。In order to solve the above-mentioned problems of the prior art, the present invention provides (1) a pair of substrates on which a plurality of electrodes are formed so that the electrodes intersect in a matrix. A pixel is formed so as to face the substrate, a liquid crystal layer is sandwiched between the pair of substrates, and a photoconductor layer whose specific resistance changes with the intensity of incident light is provided on at least one of the substrates on the side of the liquid crystal layer. By applying a low-frequency AC voltage to the electrodes and irradiating incident light from a subject, the liquid crystal molecules of the liquid crystal layer are rearranged to write an optical image, and the low-frequency An imaging element is provided in which a high-frequency AC voltage is applied in superimposition on an AC voltage, whereby an impedance change due to dielectric anisotropy of the liquid crystal molecules is taken out as an electric signal and the written optical image is read. Shi (2) The photoconductor layer whose specific resistance changes with the incident light intensity is made of amorphous silicon (a
-Si: H) is provided.
【０００６】[0006]
【作用】入射光が基板を透過して光導電体層に照射され
ると、その入射光強度に応じて光導電体層はその比抵抗
が変化する。電極がマトリクス状に交差した画素に印加
される電界は、光導電体層の比抵抗に応じて変化し、予
め一定の配向状態にあった液晶分子がその配向状態を変
化させる。入射光が強い部分では光導電体層の比抵抗が
大きく低下するため液晶層に大きな電界が印加し、入射
光が弱い部分では液晶層にわずかな電界しか印加しない
ので、入射光強度に対応して液晶分子が配向状態を変え
る。液晶分子は分子長軸方向の誘電率と分子短軸方向の
誘電率が異なる異方性を有するので、液晶分子の配向状
態で対向する電極間の電気容量、即ちインピーダンスは
著しく変化する。そこで、電極を順次走査すれば、各画
素の対向する電極間のインピーダンス変化を時系列の出
力信号として取り出すことができる。When the incident light passes through the substrate and irradiates the photoconductor layer, the specific resistance of the photoconductor layer changes according to the intensity of the incident light. The electric field applied to the pixels where the electrodes intersect in a matrix changes according to the specific resistance of the photoconductor layer, and the liquid crystal molecules in a predetermined alignment state change the alignment state. Since the specific resistance of the photoconductor layer is greatly reduced in the portion where the incident light is strong, a large electric field is applied to the liquid crystal layer, and in the portion where the incident light is weak, only a small electric field is applied to the liquid crystal layer. The liquid crystal molecules change the alignment state. Since the liquid crystal molecules have different anisotropy in which the dielectric constant in the molecular major axis direction and the dielectric constant in the molecular minor axis direction are different, the electric capacitance, that is, the impedance, between the opposed electrodes in the state of alignment of the liquid crystal molecules is significantly changed. Therefore, by sequentially scanning the electrodes, a change in impedance between the opposing electrodes of each pixel can be extracted as a time-series output signal.
【０００７】[0007]
【実施例】以下、本発明の撮像素子について、添付図面
を参照して説明する。図１は本発明の撮像素子の一実施
例を模式的に示した断面図、図２は本発明の撮像素子の
一実施例を模式的に示した分解斜視図、図３は本発明の
撮像素子の動作原理を模式的に示した断面図、図４は本
発明の撮像素子の一実施例の分光感度特性を示す図であ
る。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an image pickup device according to the present invention. FIG. 1 is a cross-sectional view schematically showing one embodiment of the image sensor of the present invention, FIG. 2 is an exploded perspective view schematically showing one embodiment of the image sensor of the present invention, and FIG. FIG. 4 is a cross-sectional view schematically showing the operation principle of the device, and FIG. 4 is a diagram showing the spectral sensitivity characteristics of an embodiment of the imaging device of the present invention.
【０００８】図１及び図２において、本発明の撮像素子
１は、透明な基板２ａ，２ｂが略均等な間隔で平行に対
向しており、この基板２ａの基板２ｂに対向する側には
複数の帯状の透明な水平走査電極３ａが、基板２ｂの基
板２ａに対向する側には複数の帯状の垂直走査電極３ｂ
が設けられている。そして、この水平走査電極３ａ上に
は、入射光８の光強度で比抵抗が変化する光導電体層４
が積層形成されている。また、光導電体層４上には液晶
分子配向層５ａが、垂直走査電極３ｂ上には液晶分子配
向層５ｂが設けられている。なお、本実施例では、水平
走査電極３ａ上のみに光導電体層４を形成しているが、
垂直走査電極３ｂ上に光導電体層４を形成してもよく、
少なくとも一方に形成すればよい。1 and 2, in an image pickup device 1 of the present invention, transparent substrates 2a and 2b face each other in parallel at substantially equal intervals, and a plurality of substrates 2a are provided on the side facing the substrate 2b. A plurality of band-shaped vertical scanning electrodes 3b are provided on the side of the substrate 2b facing the substrate 2a.
Is provided. Then, on this horizontal scanning electrode 3a, a photoconductor layer 4 whose specific resistance changes with the light intensity of the incident light 8 is provided.
Are laminated. Further, a liquid crystal molecule alignment layer 5a is provided on the photoconductor layer 4, and a liquid crystal molecule alignment layer 5b is provided on the vertical scanning electrode 3b. In this embodiment, the photoconductor layer 4 is formed only on the horizontal scanning electrode 3a.
The photoconductor layer 4 may be formed on the vertical scanning electrode 3b,
It may be formed on at least one side.
【０００９】このように、基板２ａには水平走査電極３
ａ，光導電体層４，液晶分子配向層５ａが積層して設け
られ、基板２ｂには垂直走査電極３ｂ，液晶分子配向層
５ｂが積層して設けられ、これら基板２ａ，２ｂの間に
は、図１に示すように、液晶層６が挟装されている。図
１において、７ａ及び７ｂは基板２ａ，２ｂの間に所定
間隔を保って液晶を封入させるためのスペーサである。
図２においては、液晶層６及びスペーサ７ａ，７ｂは省
略している。なお、本発明の撮像素子１の場合、複数個
の帯状の水平走査電極３ａと垂直走査電極３ｂとが交差
する部分で画素を形成する。As described above, the horizontal scanning electrodes 3 are provided on the substrate 2a.
a, a photoconductor layer 4, and a liquid crystal molecule alignment layer 5a are provided in a laminated manner, and a vertical scanning electrode 3b and a liquid crystal molecule alignment layer 5b are provided in a laminated manner on the substrate 2b, and between these substrates 2a and 2b. As shown in FIG. 1, a liquid crystal layer 6 is interposed therebetween. In FIG. 1, reference numerals 7a and 7b denote spacers for sealing a liquid crystal at a predetermined interval between the substrates 2a and 2b.
In FIG. 2, the liquid crystal layer 6 and the spacers 7a and 7b are omitted. In the case of the imaging device 1 of the present invention, pixels are formed at a portion where a plurality of strip-shaped horizontal scanning electrodes 3a and vertical scanning electrodes 3b intersect.
【００１０】ここで、基板２ａ，２ｂは本実施例では透
明なガラス板を用いているが、透明な樹脂板を用いるこ
ともできる。また、水平走査電極３ａ及び垂直走査電極
３ｂは、酸化インジウム膜または酸化スズ膜等で形成す
る。水平走査電極３ａ上に形成される光導電体層４は、
本実施例ではＳｉＨ4 ＋Ｈ2 （Ｆ2 ）を原料ガスとして
プラズマＣＶＤ法で得られる２〜３０μｍのアモルファ
スシリコン（ａ−Ｓｉ：Ｈ）膜を用いているが、これに
限定されることはなく、例えば蒸着法で形成されるアモ
ルファスセレン（ａ−Ｓｅ），セレン化カドミウム（Ｃ
ｄＳｅ），セレン化鉛（ＰｂＳｅ），硫化カドミウム
（ＣｄＳ），テルル化カドミウム（ＣｄＴｅ），単結晶
シリコン（Ｓｉ）等の各種の光導電体物質を用いること
ができる。さらに、液晶分子配向層５ａ，５ｂは、どの
ような液晶材料の液晶分子をどのように配列させるかに
より、垂直配向層，水平配向層，傾斜配向層等を適宜選
択して用いる。In this embodiment, the substrates 2a and 2b are formed of transparent glass plates, but may be formed of transparent resin plates. The horizontal scanning electrode 3a and the vertical scanning electrode 3b are formed of an indium oxide film, a tin oxide film, or the like. The photoconductor layer 4 formed on the horizontal scanning electrode 3a is
In this embodiment, an amorphous silicon (a-Si: H) film having a thickness of 2 to 30 μm obtained by a plasma CVD method using SiH 4 + H 2 (F 2 ) as a source gas is used. However, the present invention is not limited to this. , Amorphous selenium (a-Se) formed by vapor deposition, cadmium selenide (C
Various photoconductor materials such as dSe), lead selenide (PbSe), cadmium sulfide (CdS), cadmium telluride (CdTe), and single crystal silicon (Si) can be used. Further, as the liquid crystal molecule alignment layers 5a and 5b, a vertical alignment layer, a horizontal alignment layer, an inclined alignment layer, and the like are appropriately selected and used depending on what kind of liquid crystal material is arranged and how.
【００１１】また、液晶層６の液晶材料は、ネマティッ
ク液晶やスメクティック液晶等を用いる。これらは、フ
ッソ系，シッフ系，アゾ系，アゾキシ系，エステル系，
ビフェニル系，ターフェニル系，シクロヘキサン系，ピ
リミジン系，ジオキサン系等の各種の液晶物質を単独
に、または混合して用いることができ、さらに、それら
の液晶分子を安定に配列させるために適当なカイラル物
質を添加したり、必要な場合は適当な色素を添加しても
よい。As the liquid crystal material of the liquid crystal layer 6, a nematic liquid crystal or a smectic liquid crystal is used. These are fluoro, Schiff, azo, azoxy, ester,
Various liquid crystal substances such as biphenyl-based, terphenyl-based, cyclohexane-based, pyrimidine-based, dioxane-based can be used alone or in combination, and further, suitable chiral for aligning these liquid crystal molecules stably. Substances may be added, and if necessary, appropriate dyes may be added.
【００１２】次に、図３を用いて本発明となる撮像素子
１の動作原理について説明する。水平走査電極３ａ及び
垂直走査電極３ｂは、それぞれ図示しない外部電源に接
続され、水平走査電極３ａと垂直走査電極３ｂとの間に
は、液晶分子配向層５ａ，５ｂの液晶材料及び液晶分子
の配列状態、液晶層６の厚さ、光導電体層４の比抵抗等
に応じて電圧が３〜５０Ｖ程度、周波数が５〜１００Ｈ
ｚ程度の間で最適に設定された低周波の交流電圧が常時
印加される。ここで、図３に示すように、書込光である
被写体からの入射光８が撮像素子１に照射されると、入
射光８は透明な基板２ａと透明な水平走査電極３ａとを
透過して光導電体層４に達し、光導電体層４は比抵抗の
低下を生じる。すると、液晶分子配向層５ａ，５ｂを介
して液晶層６に印加される電界強度は増大し、液晶層６
の液晶分子は配向状態を変える。撮像素子１に光学像を
書き込む際、周波数を５〜１００Ｈｚ程度の低周波とす
るのは、周波数が高くなると液晶分子は応答しなくなる
からである。Next, the operation principle of the image pickup device 1 according to the present invention will be described with reference to FIG. The horizontal scanning electrodes 3a and the vertical scanning electrodes 3b are respectively connected to an external power source (not shown), and the liquid crystal material of the liquid crystal molecule alignment layers 5a and 5b and the alignment of the liquid crystal molecules are arranged between the horizontal scanning electrodes 3a and the vertical scanning electrodes 3b. The voltage is about 3 to 50 V and the frequency is 5 to 100 H according to the state, the thickness of the liquid crystal layer 6, the specific resistance of the photoconductor layer 4, and the like.
A low-frequency AC voltage optimally set between about z is always applied. Here, as shown in FIG. 3, when incident light 8 from a subject, which is writing light, is applied to the image sensor 1, the incident light 8 passes through the transparent substrate 2a and the transparent horizontal scanning electrode 3a. To reach the photoconductor layer 4, and the photoconductor layer 4 causes a decrease in specific resistance. Then, the electric field intensity applied to the liquid crystal layer 6 via the liquid crystal molecule alignment layers 5a and 5b increases,
The liquid crystal molecules of change the alignment state. The reason why the frequency is set to a low frequency of about 5 to 100 Hz when an optical image is written to the image sensor 1 is that liquid crystal molecules do not respond when the frequency is increased.
【００１３】即ち、図３では一例として、液晶層６の液
晶分子の分子長軸方向の誘電率が４、分子短軸方向の誘
電率が８の誘電率異方性が負のネマティック液晶が、入
射光８の非照射状態では液晶分子の分子長軸が基板２
ａ，２ｂに対して垂直なホメオトロピック配向状態を形
成し、入射光８が照射されると、光導電体層４の比抵抗
の低下で液晶層６に印加される電界強度の増加に対応し
て液晶分子の分子長軸が基板２ａ，２ｂに対して傾きを
有する配向状態となった場合を示している。もし、入射
光８の光強度が大きく、液晶層６に充分な電界強度が印
加され、液晶分子の分子長軸が基板２ａ，２ｂに対して
水平なホモジニアス配向状態を呈した時、上記例の液晶
では、水平走査電極３ａと垂直走査電極３ｂとの間の電
気容量は２倍に増大する。That is, as an example in FIG. 3, a nematic liquid crystal having a negative dielectric anisotropy in which the dielectric constant of the liquid crystal molecules of the liquid crystal layer 6 in the long axis direction of the molecule is 4 and the dielectric constant in the short axis direction of the molecule is 8, In the non-irradiation state of the incident light 8, the long axis of the liquid crystal molecules is
When a homeotropic alignment state perpendicular to a and 2b is formed and the incident light 8 is irradiated, the specific resistance of the photoconductor layer 4 decreases and the electric field strength applied to the liquid crystal layer 6 increases. This shows a case where the molecular long axis of the liquid crystal molecules is in an alignment state having an inclination with respect to the substrates 2a and 2b. If the light intensity of the incident light 8 is high and a sufficient electric field intensity is applied to the liquid crystal layer 6 and the long axes of the liquid crystal molecules are in a homogeneous alignment state horizontal to the substrates 2a and 2b, In a liquid crystal, the electric capacitance between the horizontal scanning electrode 3a and the vertical scanning electrode 3b is doubled.
【００１４】ここで、前述した低周波の交流電圧に重畳
して、１０〜１００ｋＨｚの高周波の交流電圧を水平走
査電極３ａ，垂直走査電極３ｂ間に順次印加走査するこ
とにより、各画素の電気容量がインピーダンスとして順
次読み出される。撮像素子１に書き込まれた光学像を読
み出す際、周波数を１０〜１００ｋＨｚ程度の高周波と
するのは、書き込まれた光学像の液晶分子配列に影響を
与えないようにするためである。従って、このように時
系列で取り出される各画素のインピーダンスの情報を再
処理すると、入射光学像を可視化することができる。前
述のように、本発明の撮像素子１は、低周波の交流電圧
を印加して光学像を書き込み、その低周波の交流電圧に
重畳して高周波の交流電圧を印加するので、動画を取り
出すことができるのである。そして、この撮像素子１
は、入射光８の光強度による光導電体層４の比抵抗の変
化に対応して液晶層６の液晶分子の配向状態が可逆的に
変化することを利用しているため、入射光８が照射され
なくなれば自動的に初期の配向状態に戻ることから、蓄
積された入射光学像を消去するために電圧の印加等を行
う必要がない。Here, by superposing on the above-mentioned low-frequency AC voltage and sequentially applying a high-frequency AC voltage of 10 to 100 kHz between the horizontal scanning electrodes 3a and the vertical scanning electrodes 3b, the capacitance of each pixel is measured. Are sequentially read as impedance. When reading the optical image written in the image sensor 1, the frequency is set to a high frequency of about 10 to 100 kHz so as not to affect the liquid crystal molecule arrangement of the written optical image. Therefore, when the information on the impedance of each pixel extracted in time series is reprocessed in this way, the incident optical image can be visualized. As described above, the imaging device 1 of the present invention writes an optical image by applying a low-frequency AC voltage, and applies a high-frequency AC voltage superimposed on the low-frequency AC voltage. Can be done. Then, the image pickup device 1
Utilizes the fact that the orientation state of the liquid crystal molecules of the liquid crystal layer 6 changes reversibly in response to the change in the specific resistance of the photoconductor layer 4 due to the light intensity of the incident light 8. When the irradiation stops, the alignment state automatically returns to the initial state. Therefore, it is not necessary to apply a voltage or the like to erase the accumulated incident optical image.
【００１５】図４は、一例として、光導電体層４にボロ
ン（Ｂ）を約１ｐｐｍドープすることにより入射光８に
対する感度を上げた、プラズマＣＶＤ法で得られる約２
０μｍ厚のアモルファスシリコン（ａ−Ｓｉ：Ｈ）膜を
用いた場合の撮像素子１の分光感度特性を示している。
この図４より、約５５０〜７５０ｎｍの範囲の光学像を
取り出すことができることが分かる。FIG. 4 shows, as an example, about 2 ppm obtained by the plasma CVD method in which the photoconductor layer 4 is doped with about 1 ppm of boron (B) to increase the sensitivity to the incident light 8.
4 shows a spectral sensitivity characteristic of the imaging device 1 when an amorphous silicon (a-Si: H) film having a thickness of 0 μm is used.
FIG. 4 shows that an optical image in the range of about 550 to 750 nm can be taken out.
【００１６】本発明の撮像素子１は全く新規の概念に基
づく発明によりなされたものであり、光導電体層４の材
料及び液晶層６の材料、さらに、水平走査電極３ａ，垂
直走査電極３ｂの形状は上述した実施例に限定されるこ
とはなく、入射光強度で比抵抗が変化する光導電体材料
と分子の配向状態で電気容量が変化する液晶材料、及び
その電気容量の変化を取り出せる電極形状であれば本発
明の思想にいささかの変更をもたらすことなく実現する
ことができ、これらの実施態様の適宜変更が可能なこと
は勿論である。The image pickup device 1 of the present invention is made according to an invention based on a completely new concept. The material of the photoconductor layer 4 and the material of the liquid crystal layer 6, the horizontal scanning electrodes 3a and the vertical scanning electrodes 3b are used. The shape is not limited to the above-mentioned embodiment, and a photoconductor material whose specific resistance changes depending on the incident light intensity, a liquid crystal material whose electric capacity changes depending on the orientation state of molecules, and an electrode which can take out the change of the electric capacity The shape can be realized without slightly changing the concept of the present invention, and it is needless to say that these embodiments can be appropriately changed.
【００１７】[0017]
【発明の効果】以上詳細に説明したように、本発明の撮
像素子は、光により液晶分子の配向状態を変化させて得
られるインピーダンスの変化を出力信号として取り出す
撮像素子であるので、大きさ，重量，消費電力等の運用
性が向上すると共に、信頼性が高く、かつ安価で経済性
に優れているという極めて優れた効果がある。As described above in detail, the image pickup device of the present invention is an image pickup device for extracting a change in impedance obtained by changing the alignment state of liquid crystal molecules by light as an output signal. The operability such as weight and power consumption is improved, and there is an extremely excellent effect of high reliability, low cost and excellent economic efficiency.
【図１】本発明の撮像素子の一実施例を模式的に示した
断面図である。FIG. 1 is a cross-sectional view schematically showing one embodiment of an image sensor of the present invention.
【図２】本発明の撮像素子の一実施例を模式的に示した
分解斜視図である。FIG. 2 is an exploded perspective view schematically showing one embodiment of the imaging device of the present invention.
【図３】本発明の撮像素子の動作原理を模式的に示した
断面図である。FIG. 3 is a cross-sectional view schematically showing the operation principle of the image sensor of the present invention.
【図４】本発明の撮像素子の一実施例の分光感度特性を
示す図である。FIG. 4 is a diagram illustrating spectral sensitivity characteristics of an embodiment of the imaging device of the present invention.
１ 撮像素子 ２ａ，２ｂ 基板 ３ａ 水平走査電極 ３ｂ 垂直走査電極 ４ 光導電体層 ５ａ，５ｂ 液晶分子配向層 ６ 液晶層 ７ａ，７ｂ スペーサ ８ 入射光 DESCRIPTION OF SYMBOLS 1 Imaging element 2a, 2b Substrate 3a Horizontal scanning electrode 3b Vertical scanning electrode 4 Photoconductor layer 5a, 5b Liquid crystal molecule alignment layer 6 Liquid crystal layer 7a, 7b Spacer 8 Incident light
Claims (2)
記電極がマトリクス状に交差するよう対向させて画素を
形成し、 前記１対の基板間に液晶層を挟装すると共に、少なくと
も一方の前記基板の前記液晶層側に、入射される光強度
で比抵抗が変化する光導電体層を積層形成してなり、 前記電極に低周波の交流電圧を印加すると共に被写体か
らの入射光を照射させることにより、前記液晶層の液晶
分子を再配列させて光学像を書き込み、 前記低周波の交流電圧に重畳して高周波の交流電圧を印
加することにより、前記液晶分子の誘電率異方性による
インピーダンス変化を電気信号として取り出して前記書
き込んだ光学像を読み出すことを特徴とする撮像素子。1. A pair of substrates on which a plurality of electrodes are formed are opposed to each other so that the electrodes intersect in a matrix form to form a pixel, and a liquid crystal layer is sandwiched between the pair of substrates. A photoconductor layer whose specific resistance changes according to the incident light intensity is formed on at least one of the substrates on the liquid crystal layer side, and a low-frequency AC voltage is applied to the electrodes and incident from a subject. By irradiating light, the liquid crystal molecules of the liquid crystal layer are rearranged to write an optical image, and superposed on the low frequency AC voltage, and a high frequency AC voltage is applied thereto, thereby changing the dielectric constant of the liquid crystal molecules. An image pickup device wherein an impedance change due to anisotropy is taken out as an electric signal and the written optical image is read out.
光導電体層は、アモルファスシリコン（ａ−Ｓｉ：Ｈ）
であることを特徴とする請求項１記載の撮像素子。2. The photoconductor layer of which specific resistance changes with the intensity of incident light is made of amorphous silicon (a-Si: H).
The imaging device according to claim 1, wherein
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4078459A JP2669253B2 (en) | 1992-02-28 | 1992-02-28 | Image sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4078459A JP2669253B2 (en) | 1992-02-28 | 1992-02-28 | Image sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05244509A JPH05244509A (en) | 1993-09-21 |
| JP2669253B2 true JP2669253B2 (en) | 1997-10-27 |
Family
ID=13662616
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4078459A Expired - Lifetime JP2669253B2 (en) | 1992-02-28 | 1992-02-28 | Image sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2669253B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3149257B2 (en) | 1992-02-28 | 2001-03-26 | 株式会社巴川製紙所 | Imaging device having phthalocyanine photoconductive layer and imaging device using the imaging device |
-
1992
- 1992-02-28 JP JP4078459A patent/JP2669253B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3149257B2 (en) | 1992-02-28 | 2001-03-26 | 株式会社巴川製紙所 | Imaging device having phthalocyanine photoconductive layer and imaging device using the imaging device |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05244509A (en) | 1993-09-21 |
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