JP4235484B2 - Optical deflection apparatus and optical deflection method - Google Patents

Description

【０２３１】
【発明の効果】
請求項１記載の発明の光偏向装置によれば、一対の電極に対して偏向周波数の交流電圧を印加してキラルスメクチックＣ相の液晶層に形成される電界方向を切り替えることで、構成を容易化した光偏向素子であってもキラルスメクチックＣ相の液晶の自発分極を利用して光路シフト動作の高速化を図るとともに、電圧の印加を停止する前に、光偏向方向の切り替え周期よりも短い周期で電界方向を切り替えることで、自発分極と外部電界により定まる方向への液晶分子の再配向を促進し、光偏向動作によって配向状態が乱れた液晶分子を基板に対して略垂直に配向させることが可能になり、繰り返し使用による配向欠陥の発生を抑制し、信頼性の高い光偏向装置を提供することができる。
【０２３３】
請求項２記載の発明によれば、請求項１記載の光偏向装置において、電極に対する電圧の印加停止に際して、液晶分子の配向状態に乱れを生じさせる電圧よりも大きな電圧を印加することにより、光偏向素子における光偏向動作によって配向状態が乱れた液晶分子を、基板に対して確実に略垂直配向させることが可能になるので、繰り返し使用による配向欠陥の発生をより確実に抑制し、より信頼性の高い光偏向装置を提供することができる。
【０２３４】
請求項３記載の発明によれば、請求項１または２記載の光偏向装置において、一対の電極に対して偏向周波数の交流電圧を印加してキラルスメクチックＣ相の液晶層に形成される電界方向を切り替えることで、構成を容易化した光偏向素子であってもキラルスメクチックＣ相の液晶の自発分極を利用して光路シフト動作の高速化を図るとともに、偏向周波数の交流電圧の印加に続いて、電圧の印加を停止する前にパルス状の直流電圧を断続的に印加して、液晶分子の配向状態を液晶層全体に亘って一時的に乱した後、偏向周波数よりも高周波数の交流電圧を印加して、光偏向方向の切り替え周期よりも短い周期で方向が切り替わる電界を形成することにより、偏向素子における光偏向動作によって液晶分子の配向状態が部分的に乱れた場合にも、部分的に配向状態が乱れた部分と乱れていない部分との界面部分を無くして、液晶層全体に亘って液晶分子を自発的に再配向させ、液晶分子の自発的な再配向過程と比較して、より短時間で該液晶分子を液晶層全体で略垂直方法に均一に配向させることができる。
【０２３５】
請求項４記載の発明の光偏向装置によれば、一対の電極に対して偏向周波数の交流電圧を印加してキラルスメクチックＣ相の液晶層に形成される電界方向を切り替えることで、構成を容易化した光偏向素子であってもキラルスメクチックＣ相の液晶の自発分極を利用して光路シフト動作の高速化を図るとともに、電圧の印加を停止する前に、偏向周波数の交流電圧の印加に続いて、パルス状の直流電圧を断続的に印加して、液晶分子の配向状態を液晶層全体に亘って一時的に乱すことで、光偏向素子における光偏向動作によって液晶分子の配向状態が部分的に乱れた場合にも、部分的に配向状態が乱れた部分と乱れていない部分との界面部分を無くして、液晶層全体に亘って液晶分子を自発的に再配向させ、繰り返し使用による配向欠陥の発生を抑制し、液晶分子を液晶層全体で均一に配向させることができる。
【０２３６】
請求項５記載の発明によれば、請求項３または４記載の光偏向装置において、液晶分子の配向状態を液晶層全体に亘ってより効果的に乱して、液晶分子の再配向過程を液晶層全体で確実に行なわせることが可能になるので、液晶分子の配向状態を液晶層全体でより確実に均一化することができる。
【０２３８】
請求項６記載の発明の光偏向装置によれば、一対の電極に対して偏向周波数の交流電圧を印加してキラルスメクチックＣ相の液晶層に形成される電界方向を切り替えることで、構成を容易化した光偏向素子であってもキラルスメクチックＣ相の液晶の自発分極を利用して光路シフト動作の高速化を図るとともに、電圧の印加開始に際し、印加する偏向周波数の交流電圧の電圧値を連続的または段階的に減少させ、光偏向方向の切り替えを可能とする電圧値よりも小さい電圧値で印加を停止することで、印加される電圧値が液晶分子の切り替えの飽和電界よりも小さくなるにしたがい、液晶分子が垂直状態に戻った状態に近い状態で停止させることができるので、偏向周波数を変化させることなく光偏向動作停止時に発生する液晶分子の乱れを防止することができ、簡単な構成で信頼性の高い光偏向方法を提供することができる。
【０２３９】
請求項７記載の発明の光偏向装置によれば、一対の電極に対して偏向周波数の交流電圧を印加して液晶層に形成される電界方向を切り替えることで、構成を容易化した光偏向素子であってもキラルスメクチックＣ相の液晶の自発分極を利用して光路シフト動作の高速化を図るとともに、電圧の印加開始に際して、偏向周波数よりも高周波数の交流電圧を印加させた後に、偏向周波数の交流電圧を印加して、液晶層中に、光偏向方向の切り替え周期よりも短い周期で切り替わる電界を形成することで、この高周波電界によって液晶層の中間層付近の液晶分子にも垂直方向に配向する力を作用させ、素子の停止中に配向方向が乱れて白濁を形成し易くなっている部分の液晶分子を垂直配向状態に戻すことができるので、配向状態の乱れが固定化することによる白濁部分の発生を防止することができる。
【０２４０】
請求項８記載の発明によれば、請求項７記載の光偏向装置において、光偏向素子の動作停止中に、外部電界や温度変化等の影響で液晶分子方向が乱れた場合でも、比較的低い周波数の交流電圧で液晶層に振動を与え、液晶層が流動し易く配向状態が変化し易い状態にしてから連続的または段階的に周波数を上げて高周波数の交流電圧を印加することで、周波数切り替え時に配向状態を乱すことなく、液晶分子を垂直配向状態に戻すことができる。
【０２４１】
請求項９記載の発明によれば、請求項７記載の光偏向装置において、光偏向素子の動作停止中に、外部電界等の影響で液晶分子方向が乱れた場合でも、高い周波数の交流電圧で液晶分子方向を垂直状態に戻した後、連続的または段階的に周波数を減少させて偏向周波数を印加することにより、周波数切り替え時に配向状態を乱すことなく、短い時間で、光偏向動作の動作開始前に液晶分子を垂直配向状態に戻すことができ、急激な周波数の切換え時に発生し易い液晶分子の乱れを防止することができる。
【０２４３】
請求項１０記載の発明によれば、請求項７から９のいずれかに記載の光偏向装置において、液晶分子に働く静電力を大きくし、液晶分子を垂直方向に配向させようとする力が大きくすることができるので、光偏向素子における光偏向動作によって配向状態が乱れて白濁を形成し易い部分が発生した場合でも、周波数切り替え時に配向状態を乱すことなく、光偏向動作の動作開始前により確実にかつ速やかに液晶分子を垂直配向状態に戻すことができる。
【０２４４】
請求項１１記載の発明によれば、請求項７から９のいずれかに記載の光偏向素子において、光偏向素子の動作停止時に液晶分子の乱れが発生していた場合にも、最初に液晶分子切り替えの飽和電界よりも小さい電圧値を印加することにより、液晶分子に対して光偏向方向の切り替え位置よりも垂直に近い角度で切り替えを行わせ、続いて印加する電圧値を連続的または段階的に増加することにより液晶分子を連続的または段階的に光偏向方向の角度に近付けることができるので、偏向周波数の急激な切り替えに起因する液晶分子の配向状態の乱れを防止することができる。
【０２４５】
請求項１２記載の発明の光偏向装置によれば、請求項７から９のいずれかに記載の光偏向装置において、パルス状の直流電圧を断続的に印加することで、液晶層全体の配向性を大きく乱し、一時的に全体が白濁状態を形成し易い状態とすることで、白濁部と正常部との界面部分をなくし、その後高周波電界を印加することで、液晶層全体を均一な垂直配向状態に戻すことができるので、白濁部と正常部との界面部分が跡として残ることを防止することができる。
【０２４６】
請求項１３記載の発明の光偏向装置によれば、一対の電極に対して偏向周波数の交流電圧を印加して液晶層に形成される電界方向を切り替えることで、構成を容易化した光偏向素子であってもキラルスメクチックＣ相の液晶の自発分極を利用して光路シフト動作の高速化を図るとともに、第三の電圧印加手段によってパルス状の直流電圧を断続的に印加することで、液晶分子の配向状態を液晶層全体に亘って一時的に乱し、その後偏向周波数の交流電圧を印加することで、液晶分子をより短時間で光偏向動作の動作開始前に液晶分子を垂直配向状態に戻すことができ、パルス状の直流電圧の印加で、光偏向動作開始の前に白濁があった場合にも白濁部と正常部との界面部分が跡として残ることを防止することができる。
【０２４７】
請求項１４記載の発明によれば、請求項１２または１３記載の光偏向装置において、大きな電圧を印加することにより液晶分子の配向状態を液晶層全体に亘ってより効果的に一時的に乱すことが可能になり、上記の白濁部と正常部との界面部分の跡を効果的に乱して消すことができる。
【０２４９】
請求項１５記載の発明の光偏向方法によれば、一対の電極に対して偏向周波数の交流電圧を印加してキラルスメクチックＣ相の液晶層に形成される電界方向を切り替えることで、構成を容易化した光偏向素子であってもキラルスメクチックＣ相の液晶の自発分極を利用して光路シフト動作の高速化を図るとともに、電圧の印加を停止する前に、光偏向方向の切り替え周期よりも短い周期で電界方向を切り替えることで、自発分極と外部電界により定まる方向への液晶分子の再配向を促進し、光偏向動作によって配向状態が乱れた液晶分子を基板に対して略垂直に配向させることが可能になり、繰り返し使用による配向欠陥の発生を抑制し、信頼性の高い光偏向方法を提供することができる。
【０２５０】
請求項１６記載の発明の光偏向方法によれば、一対の電極に対して偏向周波数の交流電圧を印加してキラルスメクチックＣ相の液晶層に形成される電界方向を切り替えることで、構成を容易化した光偏向素子であってもキラルスメクチックＣ相の液晶の自発分極を利用して光路シフト動作の高速化を図るとともに、電圧の印加を停止する前に、偏向周波数の交流電圧の印加に続いて、パルス状の直流電圧を断続的に印加して、液晶分子の配向状態を液晶層全体に亘って一時的に乱すことで、光偏向素子における光偏向動作によって液晶分子の配向状態が部分的に乱れた場合にも、部分的に配向状態が乱れた部分と乱れていない部分との界面部分を無くして、液晶層全体に亘って液晶分子を自発的に再配向させ、繰り返し使用による配向欠陥の発生を抑制し、液晶分子を液晶層全体で均一に配向させることができる。
【０２５１】
請求項１７記載の発明の光偏向方法によれば、一対の電極に対して偏向周波数の交流電圧を印加してキラルスメクチックＣ相の液晶層に形成される電界方向を切り替えることで、構成を容易化した光偏向素子であってもキラルスメクチックＣ相の液晶の自発分極を利用して光路シフト動作の高速化を図るとともに、偏向周波数の交流電圧の印加に続いて、電圧の印加を停止する前にパルス状の直流電圧を断続的に印加して、液晶分子の配向状態を液晶層全体に亘って一時的に乱した後、偏向周波数よりも高周波数の交流電圧を印加して、光偏向方向の切り替え周期よりも短い周期で方向が切り替わる電界を形成することにより、偏向素子における光偏向動作によって液晶分子の配向状態が部分的に乱れた場合にも、部分的に配向状態が乱れた部分と乱れていない部分との界面部分を無くして、液晶層全体に亘って液晶分子を自発的に再配向させ、液晶分子の自発的な再配向過程と比較して、より短時間で該液晶分子を液晶層全体で略垂直方向に均一に配向させることができる。
【０２５２】
請求項１８記載の発明の光偏向方法によれば、一対の電極に対して偏向周波数の交流電圧を印加してキラルスメクチックＣ相の液晶層に形成される電界方向を切り替えることで、構成を容易化した光偏向素子であってもキラルスメクチックＣ相の液晶の自発分極を利用して光路シフト動作の高速化を図るとともに、電圧の印加開始に際し、印加する偏向周波数の交流電圧の電圧値を連続的または段階的に減少させ、光偏向方向の切り替えを可能とする電圧値よりも小さい電圧値で印加を停止することで、印加される電圧値が液晶分子の切り替えの飽和電界よりも小さくなるにしたがい、液晶分子が垂直状態に戻った状態に近い状態で停止させることができるので、偏向周波数を変化させることなく光偏向動作停止時に発生する液晶分子の乱れを防止することができ、簡単な構成で信頼性の高い光偏向方法を提供することができる。
【０２５３】
請求項１９記載の発明の光偏向方法によれば、一対の電極に対して偏向周波数の交流電圧を印加してキラルスメクチックＣ相の液晶層に形成される電界方向を切り替えることで、構成を容易化した光偏向素子であってもキラルスメクチックＣ相の液晶の自発分極を利用して光路シフト動作の高速化を図るとともに、電圧の印加開始に際して、偏向周波数の交流電圧の印加前に偏向周波数よりも高周波数の交流電圧を印加して液晶層中に光偏向方向の切り替え周期よりも短い周期で切り替わる電界を形成することで、液晶層の中間層付近の液晶分子に対して垂直方向に配向する力を作用させ、配向方向が乱れて白濁を形成し易い部分を垂直配向状態に戻すことができるので、光偏向動作の停止（待機）中に白濁が発生していても動作開始前に液晶分子を垂直配向状態に戻すことができ、信頼性の高い光偏向方法を提供することができる。
【０２５４】
請求項２０の発明の光偏向方法によれば、一対の電極に対して偏向周波数の交流電圧を印加してキラルスメクチックＣ相の液晶層に形成される電界方向を切り替えることで、構成を容易化した光偏向素子であってもキラルスメクチックＣ相の液晶の自発分極を利用して光路シフト動作の高速化を図るとともに、電圧の印加開始に際して、パルス状の直流電圧を断続的に印加して液晶分子の配向状態を液晶層全体に亘って一時的に乱した後、偏向周波数の交流電圧を印加することで、液晶分子を光偏向方向に揃えることができるので、光偏向動作の停止（待機）中に白濁が発生した場合にも、電圧の印加開始に際しては、液晶層の配向が乱れた部分と正常な部分との界面部分を無くすことができ、より信頼性の高い光偏向方法を提供することができる。
【０２５５】
請求項２１の発明の光偏向方法は、一対の電極に対して偏向周波数の交流電圧を印加してキラルスメクチックＣ相の液晶層に形成される電界方向を切り替えることで、構成を容易化した光偏向素子であってもキラルスメクチックＣ相の液晶の自発分極を利用して光路シフト動作の高速化を図るとともに、電圧の印加開始に際して、偏向周波数の交流電圧を印加する前に、パルス状の直流電圧を断続的に印加して液晶分子の配向状態を液晶層全体に亘って一時的に乱した後、偏向周波数よりも高周波数の交流電圧を印加することで、液晶層全体をより短時間で均一な配向状態にし、光偏向動作の停止（待機）中に白濁が発生した場合にも、液晶層の配向が乱れた部分と正常な部分との界面部分が跡として残ることを防止し、信頼性の高い光偏向方法を提供できる。
【図面の簡単な説明】
【図１】本発明の第一の実施の形態の光偏向装置の原理的な構成例を示しており、（ａ）は平面図、（ｂ）は正面図、（ｃ）は側面図である。
【図２】液晶層における液晶分子の配向状態を示す側面図である。
【図３】一対の電極間に印加する交流電圧の波形を示すタイミングチャートである。
【図４】液晶層における液晶分子の配向状態乱れを説明する側面図である。
【図５】本発明の第二の実施の形態の光偏向装置の原理的な構成例を示しており、（ａ）は平面図、（ｂ）は正面図、（ｃ）は側面図である。
【図６】本発明の第三の実施の形態の光偏向装置の原理的な構成例を示しており、（ａ）は平面図、（ｂ）は正面図、（ｃ）は側面図である。
【図７】一対の電極間に印加する交流電圧の波形を示すタイミングチャートである。
【図８】本発明の第四の実施の形態の光偏向装置の原理的な構成例を示しており、（ａ）は平面図、（ｂ）は正面図、（ｃ）は側面図である。
【符号の説明】
１ 光偏向装置
２，３ 基板
４ 配向膜
５ 光偏向素子
６ 液晶層
７ａ，７ｂ 電極
８ 第一の電圧印加手段、第二の電圧印加手段
１０ 光偏向装置
１１ 第二の電圧印加手段
２０ 光偏向装置
２１ 第三の電圧印加手段
３０ 光偏向装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical deflection apparatus and an optical deflection method.
[0002]
[Prior art]
As an optical deflecting device that deflects and emits incident light using an optical deflecting element, KH has hitherto been used. ₂ PO ₄ (KDP), NH ₄ H ₂ PO ₄ (ADP), LiNbO ₃ , LiTaO ₃ , GaAs, CdTe, and other materials having a large primary electro-optic effect (Pockels effect), KTN, SrTiO ₃ , CS ₂ Electro-optical devices using materials with large secondary electro-optic effect such as nitrobenzene, glass, silica, TeO ₂ Acousto-optic devices using materials such as these are known (for example, see Non-Patent Document 1). Various optical deflecting devices using an optical deflecting element including a liquid crystal material have been proposed.
[0003]
For example, an optical deflecting device (light beam shifter) that reduces optical loss (for example, see Patent Document 1 and Patent Document 2) and an optical deflecting operation using an optical deflecting element can be reduced in power and size. There are optical deflection devices and the like (see, for example, Patent Document 3, Patent Document 4, and Patent Document 5).
[0004]
Further, for example, an optical deflecting device (see, for example, Patent Document 6, Patent Document 7, and Patent Document 8) that expands the deflection angle by the optical deflection element, or light that enables adjustment of the deflection angle by the optical deflection element. There are deflection devices (see, for example, Patent Document 9, Patent Document 10, and Patent Document 11). Some of these optical deflection apparatuses can adjust the deflection angle of the optical path by the optical deflection element without using a mechanical movable part that complicates the configuration (see, for example, Patent Document 12 and Patent Document 13).
[0005]
However, in the above-described technique, a material having a large primary electro-optic effect (Pockels effect), an electro-optic device using a material having a large secondary electro-optic effect, an acousto-optic device, or the like is used as the light deflection element. In this case, in order to obtain a sufficiently large amount of light deflection, it is generally necessary to increase the optical path length. For this reason, it is difficult to reduce the size, and the use is limited because the material is expensive.
[0006]
By the way, the above-described optical deflecting device is a projection optical system in an image display device that displays an image displayed on an image display element on a screen or the like using a projection optical system, and light that uses an optical path shift of outgoing light with respect to incident light. Used for switches and the like.
[0007]
In an image display device using an optical deflection device, an image displayed on the image display element is shifted at high speed according to time by the optical deflection element, and an afterimage phenomenon is caused in human vision, so that the apparent resolution is improved. Some have improved images displayed on the screen. The timing (shift timing) of the light deflection operation by the light deflection device used in such an image display device is high enough to cause an afterimage phenomenon in human vision, and so that no blurring occurs in each image. I have to let it.
[0008]
However, for example, in the technique disclosed in Patent Document 1, since nematic liquid crystal is used as the liquid crystal material, it is difficult to increase the response speed to sub-milliseconds. Further, in the technique disclosed in Patent Document 10, a smectic A phase ferroelectric liquid crystal is used as the liquid crystal material. However, since the smectic A phase liquid crystal material does not have spontaneous polarization, the response speed is sufficiently increased. It is difficult to plan. As described above, the optical deflecting device having a simplified configuration and a small size has a problem that it is difficult to increase the speed of the optical path shifting operation due to the characteristics of the liquid crystal material used.
[0009]
For example, as disclosed in Patent Document 2, when performing optical path shift operation by moving each member arranged on the optical path, each member arranged on the optical path is translated at high speed and accurately. However, for this purpose, accuracy and durability of the movable part are required. With the above-described technique, light loss can be reduced, but generation of vibration and noise and increase in the size of the apparatus are problems. .
[0010]
Further, there is disclosed an image display device in which a display image on an image display element is divided and displayed in a plurality of fields, an image is displayed for each field, and an optical path is shifted for each corresponding field (for example, Patent Documents). 14).
[0011]
However, in the technique disclosed in Patent Document 14, the configuration for driving the optical deflection element becomes complicated and the cost increases.
[0012]
In addition, for example, a light-transmitting piezoelectric element is sandwiched between transparent electrodes, and by applying a voltage, the thickness is changed to shift the optical path so that the overall size can be reduced, and high accuracy and high resolution can be realized. Have been disclosed (for example, see Patent Document 15).
[0013]
However, the technique disclosed in Patent Document 15 requires a relatively large transparent piezoelectric element, which increases the device cost.
[0014]
[Patent Document 1]
Japanese Patent Laid-Open No. 6-18940
[Patent Document 2]
JP-A-5-313116
[Patent Document 3]
JP 2000-193925 A
[Patent Document 4]
JP-A-9-133931
[Patent Document 5]
JP-A-5-204001
[Patent Document 6]
JP-A-6-194695
[Patent Document 7]
JP-A-6-258646
[Patent Document 8]
JP-A-6-222368
[Patent Document 9]
JP-A-9-133904
[Patent Document 10]
Special Table 2000-507005
[Patent Document 11]
JP-A-11-109304
[Patent Document 12]
JP 7-64123 A
[Patent Document 13]
JP-A-8-262391
[Patent Document 14]
JP-A-6-324320
[Patent Document 15]
JP-A-10-133135
[Non-Patent Document 1]
Edited by Shoji Aoki; “Optoelectronic Device”, Shosodo
[0015]
[Problems to be solved by the invention]
As described above, in the conventional technology, the optical deflection device with a simplified configuration and a reduced size cannot sufficiently speed up the optical path shift operation, and the optical deflection device with a high speed optical path shift operation. However, there are problems such as the complexity of the device configuration, the high cost associated with the complexity of the device configuration, and the enlargement of the device.
[0016]
The present inventor performs pixel shift by changing the direction of the liquid crystal molecules to a desired direction by aligning the liquid crystal molecules between the pair of substrates substantially vertically and generating an electric field in a direction substantially parallel to the liquid crystal layer. It has been found that the light deflection element having the configuration enables high-speed pixel shift with a relatively simple configuration.
[0017]
In this optical deflection element, an AC voltage (for example, a rectangular wave voltage) of about several hundred Hz is applied between a pair of electrodes, so that the optical path of incident light is switched in two directions and emitted at a switching timing of several hundred Hz. be able to. As described above, since the optical path shift uses the afterimage phenomenon of the human eye, the switching timing of the optical path of the incident light may be 30 Hz or more, but in order to surely prevent flicker, one hundred to several It is preferable to set to 100 Hz.
[0018]
By the way, in such an optical deflecting element, white turbidity may occur in the liquid crystal part when the optical deflecting element is created or with continuous optical path shift driving. When the liquid crystal molecules are uniformly vertically aligned in the liquid crystal layer, a dark cross-shaped conoscopic image called isojaar can be clearly observed in the liquid crystal layer. The scope image was very unclear, and no isojaal was observed at the part where the cloudiness was strong. This is evidence that the vertical alignment state of the liquid crystal molecules is disturbed, and the directors of the liquid crystal molecules in the white turbid portion are uneven, and the light deflection element in which white turbidity cannot be obtained cannot provide a good optical path shift function. Such white turbidity may occur due to the influence of an external electric field even when the light deflection element is stopped for a long time or for a short time. In addition, even when white turbidity does not occur, there is a concern that the reliability of the light deflection element is lowered in the light deflection element in which the liquid crystal molecules are largely disturbed.
[0019]
By the way, the disorder of alignment of liquid crystal molecules and white turbidity may occur due to the influence of an external electric field or temperature change while the light deflection element is stopped. The light deflection operation with the white turbidity left causes light scattering, and orientation defects grow and cause a decrease in reliability. In fact, it has been confirmed that even if there is no defect such as cloudiness, a good optical path shift can be obtained by returning the liquid crystal molecules to the vertical alignment state before starting the light deflection operation.
[0020]
An object of the present invention is to increase the speed of an optical path shift operation by an optical deflecting element having a simplified configuration, to suppress the occurrence of alignment defects due to repeated use, and to improve reliability.
[0021]
An object of the present invention is to increase the speed of an optical path shift operation by an optical deflecting element having a simplified configuration, to suppress the occurrence of alignment defects due to repeated use, and to uniformly align liquid crystal molecules throughout the liquid crystal layer. .
[0022]
It is important for the purpose of the present invention to form a vertical alignment state without defects before the light deflection operation. That is, in order to maintain a long-term stable operation of the optical deflection apparatus, the optical deflection operation start processing means is effective.
[0023]
[Means for Solving the Problems]
An optical deflecting device according to a first aspect of the present invention includes a pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer. A light deflection element having an alignment film oriented in a direction substantially perpendicular to the liquid crystal layer, and an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer, and switching a light deflection direction by the light deflection element A first voltage applying means for applying an alternating voltage having a deflection frequency to the electrode; a second voltage applying means for applying an alternating voltage having a frequency different from the deflection frequency to the electrode; and When the voltage application is stopped, an AC voltage having a higher frequency than the deflection frequency is applied by the second voltage applying unit after an AC voltage having the deflection frequency is applied by the first voltage applying unit. To anda stop processing means for applying.
[0024]
Therefore, the direction of the electric field formed in the liquid crystal layer is switched by applying the alternating voltage of the deflection frequency to the pair of electrodes by the first voltage applying means, and the light deflection by the light deflecting element is performed by switching the electric field direction. The direction is switched. When stopping the voltage application, the stop processing means applies an alternating voltage having a deflection frequency by the first voltage applying means, and then applies an alternating voltage having a frequency higher than the deflection frequency by the second voltage applying means. As a result, an electric field that is switched at a cycle shorter than the switching cycle of the light deflection direction is formed in the liquid crystal layer. By this high frequency electric field, the liquid crystal molecules in the vicinity of the intermediate layer of the liquid crystal layer also exert a force for aligning in the vertical direction, and the liquid crystal molecules in the portion where the alignment direction is disturbed and white turbidity is easily formed can be returned to the vertical alignment state. As a result, it is possible to prevent the occurrence of white turbidity due to the fixed disorder of the alignment state.
[0027]
Claim 2 The described invention is claimed. 1 In the mounted optical deflection apparatus, the second voltage applying means applies an AC voltage having a voltage value higher than the voltage value applied by the first voltage applying means.
[0028]
Accordingly, the force for aligning the liquid crystal molecules in the vertical direction is increased. Thereby, even when the alignment state is disturbed by the light deflection operation in the light deflection element and a portion where white turbidity is likely to occur is generated, the liquid crystal molecules can be quickly returned to the original vertical alignment state.
[0029]
However, when a cloudy part with a disordered orientation direction occurs locally in the liquid crystal layer, even if the liquid crystal molecules in the cloudy part are returned to the vertical alignment state by applying a high frequency voltage, the interface part between the cloudy part and the normal part May remain as a trace. Therefore, the claim 3 The invention described in claim 1 Or 2 The optical deflection apparatus according to claim 1, further comprising a third voltage applying unit that applies a pulsed DC voltage to the electrode, wherein the stop processing unit is configured to stop the application of the voltage to the electrode. After the application of the alternating voltage of the deflection frequency by the applying means, the pulsed DC voltage is intermittently applied by the third voltage applying means, and then the second voltage applying means has a frequency higher than the deflection frequency. Apply AC voltage.
[0030]
Therefore, the direction of the electric field formed in the liquid crystal layer is switched by applying the alternating voltage of the deflection frequency to the pair of electrodes by the first voltage applying means, and the light deflection by the light deflecting element is performed by switching the electric field direction. The direction is switched. When stopping the voltage application, the stop processing means applies the pulsed DC voltage intermittently by the third voltage applying means after the application of the alternating voltage of the deflection frequency by the first voltage applying means. Thus, after the alignment state of the liquid crystal molecules is temporarily disturbed throughout the liquid crystal layer, an alternating voltage higher than the deflection frequency is applied by the second applying means, so that in the liquid crystal layer, Before stopping the application of the voltage, an electric field that is switched at a cycle shorter than the switching cycle of the light deflection direction is formed. That is, when a pulsed DC electric field is applied intermittently, the orientation of the entire liquid crystal layer is greatly disturbed, and the entire liquid crystal layer is likely to form a cloudy state. Therefore, the interface portion between the cloudy part and the normal part is no longer present. End up. Thereafter, by applying a high-frequency electric field, the entire liquid crystal layer returns to a uniform vertical alignment state, so that it is possible to prevent the interface portion between the cloudy portion and the normal portion from being left as a trace.
[0031]
Claim 4 The optical deflecting device according to the invention includes a pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer as the liquid crystal layer. An optical deflection element having an alignment film oriented in a direction substantially perpendicular to the liquid crystal, an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer, and a deflection frequency for switching a light deflection direction by the light deflection element. A first voltage applying means for applying an AC voltage to the electrode; a third voltage applying means for applying a pulsed DC voltage to the electrode; Stop processing means for applying a pulsed DC voltage intermittently by the third voltage applying means after applying an AC voltage of the deflection frequency by one voltage applying means.
[0032]
Therefore, the direction of the electric field formed in the liquid crystal layer is switched by applying the alternating voltage of the deflection frequency to the pair of electrodes by the first voltage applying means, and the light deflection by the light deflecting element is performed by switching the electric field direction. The direction is switched. Further, when the voltage application is stopped, the stop processing means applies the pulsed DC voltage intermittently by the third voltage applying means following the application of the alternating voltage of the deflection frequency by the first voltage applying means. As a result, the alignment state of the liquid crystal molecules is temporarily disturbed over the entire liquid crystal layer, and then the liquid crystal molecules are spontaneously re-aligned by the alignment regulating force of the vertical alignment film. It can be in an oriented state.
[0033]
Claim 5 The described invention is claimed. 3 Or 4 In the described optical deflection apparatus, the third voltage applying unit applies a DC voltage having a voltage value higher than a voltage value applied by the first voltage applying unit.
[0034]
Therefore, it becomes possible to more effectively disturb the alignment state of the liquid crystal molecules over the entire liquid crystal layer, and can effectively disturb and erase the trace of the interface portion between the above-described cloudy part and the normal part, When the liquid crystal molecules are spontaneously realigned by the alignment regulating force of the vertical alignment film, a uniform vertical alignment state can be obtained in the entire liquid crystal layer.
[0037]
Claim Item 6 The optical deflecting device according to the invention includes a pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer as the liquid crystal layer. An optical deflection element having an alignment film oriented in a direction substantially perpendicular to the liquid crystal, an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer, and a deflection frequency for switching a light deflection direction by the light deflection element. A fourth voltage applying means for changing the voltage value of the alternating voltage to be applied to the electrode, and a voltage value of the alternating voltage of the deflection frequency applied by the fourth voltage applying means are continuously or stepwise. Stop processing means for stopping the application at a voltage value smaller than a voltage value that can be decreased and switch the light deflection direction.
[0038]
Therefore, the direction of the electric field formed in the liquid crystal layer is switched by applying the alternating voltage of the deflection frequency to the pair of electrodes by the fourth voltage applying means, and the light deflection by the light deflecting element is performed by switching the electric field direction. The direction is switched. Further, when stopping the application of voltage, the voltage value of the alternating voltage of the deflection frequency applied by the fourth voltage applying means is continuously or stepwise reduced by the stop processing means, and the light deflection direction can be switched. When the application is stopped at a voltage value smaller than the voltage value to be applied, the applied voltage value becomes smaller than the saturation electric field for switching the liquid crystal molecules, and the liquid crystal molecules are in a state close to the vertical state. Since it can be stopped, it is possible to prevent the liquid crystal molecules from being disturbed when the light deflection operation is stopped. Here, the voltage value smaller than the saturation electric field for switching the liquid crystal molecules includes a state where the voltage value is zero.
[0039]
Claim 7 The optical deflecting device according to the invention includes a pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer as the liquid crystal layer. An optical deflection element having an alignment film oriented in a direction substantially perpendicular to the liquid crystal, an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer, and a deflection frequency for switching a light deflection direction by the light deflection element. A first voltage applying means for applying an alternating voltage to the electrode; a second voltage applying means for applying an alternating voltage having a frequency different from the deflection frequency to the electrode; and applying a voltage to the electrode. At the start, an AC voltage having a frequency higher than the deflection frequency is applied by the second voltage applying unit, and then an AC voltage having the deflection frequency is applied by the first voltage applying unit. And start processing means for, including a.
[0040]
Here, “at the start of voltage application to the electrode” indicates a period before the application of the alternating voltage of the deflection frequency is started by the first voltage application means in order to perform the original optical deflection operation. In particular, it is particularly preferable to immediately before the start of application of an alternating voltage having a deflection frequency by the first voltage applying means.
[0041]
Therefore, the direction of the electric field formed in the liquid crystal layer is switched by applying the alternating voltage of the deflection frequency to the pair of electrodes by the first voltage applying means, and the light deflection by the light deflecting element is performed by switching the electric field direction. The direction is switched. When starting the voltage application, the start processing means applies an AC voltage having a frequency higher than the deflection frequency by the second voltage applying means, and then applies the AC voltage having the deflection frequency by the first voltage applying means. As a result, an electric field that is switched at a cycle shorter than the switching cycle of the light deflection direction is formed in the liquid crystal layer. This high-frequency electric field also exerts a vertical alignment force on the liquid crystal molecules in the vicinity of the intermediate layer of the liquid crystal layer, causing the alignment direction to be disturbed while the device is stopped and causing the liquid crystal molecules in the vertical alignment state to be easily formed. Can be returned to. As a result, it is possible to prevent the occurrence of white turbidity due to the fixed disorder of the alignment state.
[0042]
Claim 8 The described invention is claimed. 7 In the optical deflecting device described above, the second voltage applying means increases the frequency of the AC voltage continuously or stepwise after applying an AC voltage having a frequency lower than the deflection frequency to the electrode. And applying an alternating voltage having a frequency higher than the deflection frequency by the second voltage applying means when the application of the voltage to the electrode is started. Subsequently, an AC voltage having the deflection frequency is applied by the first voltage applying means.
[0043]
Therefore, even when the liquid crystal molecule direction is disturbed due to the influence of an external electric field, temperature change, etc. while the operation of the optical deflection element is stopped, the liquid crystal layer is vibrated with an alternating voltage having a relatively low frequency, and the liquid crystal layer easily flows. A vertical alignment state can be reliably obtained by increasing the frequency continuously or stepwise and applying a high-frequency AC voltage after making the alignment state easy to change.
[0044]
Claim 9 The described invention is claimed. 7 In the above-described optical deflection apparatus, the second voltage applying unit may reduce the frequency of the AC voltage continuously or stepwise after applying an AC voltage having a frequency higher than the deflection frequency to the electrode. The start processing means applies the first voltage following the application of the alternating voltage of the deflection frequency by the second voltage application means when the application of the voltage to the electrode is started. An AC voltage having the deflection frequency is applied by the applying means.
[0045]
Therefore, even if the liquid crystal molecule direction is disturbed due to the influence of an external electric field or the like while the operation of the optical deflection element is stopped, the liquid crystal molecule direction is returned to the vertical state with a high frequency AC voltage, and then the frequency is continuously or stepwise. Since the deflection frequency is applied while decreasing the above, it is possible to prevent the liquid crystal molecules from being disturbed easily when the frequency is rapidly switched to the deflection frequency.
[0048]
Claim 10 The described invention is claimed. 7 to 9 In the described optical deflection apparatus, the second voltage applying unit applies an AC voltage having a voltage value higher than a voltage value applied by the first voltage applying unit.
[0049]
Accordingly, the electrostatic force acting on the liquid crystal molecules increases, and the force for aligning in the vertical direction increases. Thereby, even when the alignment state is disturbed by the light deflection operation in the light deflection element and a portion where white turbidity is likely to occur is generated, the liquid crystal molecules can be quickly returned to the original vertical alignment state.
[0050]
Claim 11 The described invention is claimed. 7 to 9 In the optical deflection element described above, the second voltage applying unit applies an AC voltage having a voltage value smaller than a voltage value applied by the first voltage applying unit at the start of voltage application to the electrode. The deflection operation voltage value is applied by increasing the voltage value of the AC voltage continuously or stepwise.
[0051]
Therefore, when the liquid crystal molecules are disturbed when the operation of the optical deflection element stops, the voltage deflection direction is switched to the liquid crystal molecules by first applying a voltage value smaller than the saturation electric field for switching the liquid crystal molecules. By switching at an angle closer to the vertical than the position and increasing the voltage value to be applied continuously or stepwise, the liquid crystal molecules can approach the angle of the light deflection direction continuously or stepwise. Thereby, it is possible to prevent the liquid crystal molecules from being disturbed due to abrupt switching of the deflection frequency.
[0052]
However, when a cloudy part with a disordered orientation direction occurs locally in the liquid crystal layer, even if the liquid crystal molecules in the cloudy part are returned to the vertical alignment state by applying a high-frequency voltage, the interface part between the cloudy part and the normal part May remain as a trace. Therefore, the claim 12 An optical deflecting device according to the invention described in claim 7 to 9 In the optical deflection apparatus described above, there is provided a third voltage applying unit that applies a pulsed DC voltage to the electrode, and the application starting unit is configured to apply the third voltage when starting the application of the voltage to the electrode. After intermittently applying a pulsed DC voltage by the applying means, an AC voltage having a frequency higher than the deflection frequency is applied by the second voltage applying means, and then the deflection frequency is applied by the first voltage applying means. Apply an alternating voltage.
[0053]
Therefore, by intermittently applying a pulsed direct-current voltage by the third voltage application means, the orientation of the entire liquid crystal layer is greatly disturbed, and it becomes easy to form a white turbid state temporarily. The interface part between the cloudy part and the normal part disappears. Thereafter, by applying a high-frequency electric field, the entire liquid crystal layer can be returned to a uniform vertical alignment state, so that the interface portion between the cloudy portion and the normal portion can be prevented from remaining as a trace.
[0054]
Claim 13 The optical deflecting device according to the invention includes a pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer as the liquid crystal layer. An optical deflection element having an alignment film oriented in a direction substantially perpendicular to the liquid crystal, an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer, and a deflection frequency for switching a light deflection direction by the light deflection element. A first voltage applying means for applying an AC voltage to the electrode; a third voltage applying means for applying a pulsed DC voltage to the electrode; And a start processing means for applying an AC voltage of the deflection frequency by the first voltage applying means after intermittently applying a pulsed DC voltage by the three voltage applying means.
[0055]
Therefore, by intermittently applying a pulsed DC voltage by the third voltage applying means, the alignment state of the liquid crystal molecules is temporarily disturbed over the entire liquid crystal layer, and then an AC voltage with a deflection frequency is applied. Thus, the liquid crystal molecules can be aligned in the light deflection direction. Thus, application of a pulsed DC voltage can prevent an interface portion between the white turbid portion and the normal portion from remaining as a trace even when white turbidity occurs before the start of the light deflection operation. Also, the operation time of the start processing means can be shortened.
[0056]
Claim 14 The described invention is claimed. 12 Or 13 In the described optical deflection apparatus, the third voltage applying unit applies a DC voltage having a voltage value higher than a voltage value applied by the first voltage applying unit.
[0057]
Therefore, the alignment state of the liquid crystal molecules can be temporarily disturbed more effectively over the entire liquid crystal layer, and the above-mentioned trace of the interface portion between the cloudy part and the normal part can be effectively disturbed and erased. Can do.
[0060]
Claim 15 The light deflection method according to the present invention includes a pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer as the liquid crystal layer. Deflection that switches an optical deflection direction by the optical deflection element using an optical deflection element having an alignment film oriented in a direction substantially perpendicular to the liquid crystal and an electrode that generates an electric field in a direction substantially parallel to the liquid crystal layer An optical deflection step of applying an alternating voltage of a frequency to the electrode, and when the application of the voltage to the electrode is stopped, the application of the alternating voltage of the deflection frequency to the electrode is continued to be less than the deflection frequency to the electrode. An application stopping step of applying a high-frequency AC voltage.
[0061]
Therefore, in the optical deflection step, the direction of the electric field formed in the liquid crystal layer is switched by applying an alternating voltage of the deflection frequency to the pair of electrodes, and the optical deflection direction by the optical deflection element is changed by switching the electric field direction. Can be switched. Further, in the application stop step, when the voltage application is stopped, an AC voltage having a frequency higher than the deflection frequency is applied subsequent to the application of the AC voltage having the deflection frequency, so that the light deflection direction switching period in the liquid crystal layer. An electric field that switches at a shorter period is formed. By this high frequency electric field, the liquid crystal molecules in the vicinity of the intermediate layer of the liquid crystal layer also exert a force for aligning in the vertical direction, and the portion where the alignment direction is disturbed and easily forms white turbidity can be returned to the vertical alignment state. As a result, it is possible to prevent the occurrence of white turbidity due to the fixed disturbance in the alignment direction.
[0062]
Claim 16 The light deflection method according to the present invention includes a pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer as the liquid crystal layer. Deflection that switches an optical deflection direction by the optical deflection element using an optical deflection element having an alignment film oriented in a direction substantially perpendicular to the liquid crystal and an electrode that generates an electric field in a direction substantially parallel to the liquid crystal layer A light deflection step of applying an alternating voltage of a frequency to the electrode, and a pulsed direct current voltage applied to the electrode following the application of the alternating voltage of the deflection frequency to the electrode when the application of the voltage to the electrode is stopped. An application stopping step of intermittently applying.
[0063]
Therefore, in the optical deflection step, the direction of the electric field formed in the liquid crystal layer is switched by applying an alternating voltage of the deflection frequency to the pair of electrodes, and the optical deflection direction by the optical deflection element is changed by switching the electric field direction. Can be switched. In the application stop step, when the voltage application is stopped, the pulsed DC voltage is intermittently applied following the application of the alternating voltage of the deflection frequency, so that the alignment state of the liquid crystal molecules extends over the entire liquid crystal layer. Is temporarily disturbed. Thereafter, when the film is spontaneously realigned by the alignment regulating force of the vertical alignment film, the whole can be in a uniform vertical alignment state.
[0064]
Claim 17 The light deflection method according to the present invention includes a pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer as the liquid crystal layer. Deflection that switches an optical deflection direction by the optical deflection element using an optical deflection element having an alignment film oriented in a direction substantially perpendicular to the liquid crystal and an electrode that generates an electric field in a direction substantially parallel to the liquid crystal layer A light deflection step of applying an alternating voltage of a frequency to the electrode, and a pulsed direct current voltage applied to the electrode following the application of the alternating voltage of the deflection frequency to the electrode when the application of the voltage to the electrode is stopped. A step of releasing the orientation intermittently, and applying an AC voltage having a frequency higher than the deflection frequency to the electrode following application of the pulsed DC voltage to the electrode. Comprising the application stop step of pressurizing, the.
[0065]
Therefore, in the optical deflection step, the direction of the electric field formed in the liquid crystal layer is switched by applying an alternating voltage of the deflection frequency to the pair of electrodes, and the optical deflection direction by the optical deflection element is changed by switching the electric field direction. Can be switched. Further, when the application of voltage to the electrode is stopped, the alignment state of the liquid crystal molecules is changed in the alignment release step by intermittently applying a pulsed DC voltage following the application of the alternating voltage of the deflection frequency in the alignment release step. An electric field that is temporarily disturbed throughout and then switched in a period shorter than the switching period of the light deflection direction in the liquid crystal layer by applying an alternating voltage higher than the deflection frequency in the application stop step. Is formed. That is, when a pulsed DC electric field is applied intermittently, the orientation of the entire liquid crystal layer is greatly disturbed, and the entire liquid crystal layer is likely to form a cloudy state. Therefore, the interface portion between the cloudy portion and the normal portion is no longer present. End up. Thereafter, by applying a high-frequency electric field, the entire liquid crystal layer returns to a uniform alignment state, so that it is possible to prevent the interface portion between the cloudy portion and the normal portion from remaining as a trace.
[0066]
Claim 18 The light deflection method according to the present invention includes a pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer as the liquid crystal layer. Deflection that switches an optical deflection direction by the optical deflection element using an optical deflection element having an alignment film oriented in a direction substantially perpendicular to the liquid crystal and an electrode that generates an electric field in a direction substantially parallel to the liquid crystal layer An optical deflection step of applying an alternating voltage of a frequency to the electrode, and a voltage value of the alternating voltage of the deflection frequency applied subsequent to the application of the alternating voltage of the deflection frequency to the electrode is decreased continuously or stepwise. An application stop step of stopping application at a voltage value smaller than a voltage value that enables switching of the light deflection direction.
[0067]
Therefore, in the optical deflection step, the direction of the electric field formed in the liquid crystal layer is switched by applying an alternating voltage of the deflection frequency to the pair of electrodes, and the optical deflection direction by the optical deflection element is changed by switching the electric field direction. Can be switched. Further, in the application stop step, the application is stopped at a voltage value smaller than the voltage value that allows the switching of the optical deflection direction by continuously or stepwise decreasing the voltage value of the AC voltage of the applied deflection frequency. Therefore, as the applied voltage value becomes smaller than the saturation electric field for switching the liquid crystal molecules, the liquid crystal molecules can be stopped in a state close to the vertical state, and therefore, generated when the light deflection operation is stopped. Disturbance of liquid crystal molecules can be prevented. Here, the voltage value smaller than the saturation electric field for switching the liquid crystal molecules includes a state where the voltage value is zero.
[0068]
Claim 19 The light deflection method according to the present invention includes a pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer as the liquid crystal layer. Deflection that switches an optical deflection direction by the optical deflection element using an optical deflection element having an alignment film oriented in a direction substantially perpendicular to the liquid crystal and an electrode that generates an electric field in a direction substantially parallel to the liquid crystal layer An optical deflection step of applying an alternating voltage of a frequency to the electrode, and an application start step of applying an alternating voltage of a higher frequency than the deflection frequency before the application of the alternating voltage of the deflection frequency to the electrode. To do.
[0069]
Therefore, in the optical deflection step, the direction of the electric field formed in the liquid crystal layer is switched by applying an alternating voltage of the deflection frequency to the pair of electrodes, and the optical deflection direction by the optical deflection element is changed by switching the electric field direction. Can be switched. In addition, in the application start step, an AC voltage having a frequency higher than the deflection frequency is applied before the application of the AC voltage having the deflection frequency at the start of voltage application, so that the light deflection direction is switched in the liquid crystal layer. An electric field that is switched at a short period is formed. By this high frequency electric field, the liquid crystal molecules in the vicinity of the intermediate layer of the liquid crystal layer also exert a force for aligning in the vertical direction, and the portion where the alignment direction is disturbed and easily forms white turbidity can be returned to the vertical alignment state.
[0070]
Claim 20 The light deflection method of the invention includes a pair of transparent substrates arranged opposite to each other, a pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, Using an optical deflection element having an alignment film for aligning liquid crystal molecules in the liquid crystal layer in a direction substantially perpendicular to the liquid crystal layer, and an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer, A light deflection step of applying an alternating voltage of a deflection frequency for switching the light deflection direction by the optical deflection element to the electrode, and a pulsed direct current to the electrode before the application of the alternating voltage of the deflection frequency to the electrode An application start step for intermittently applying a voltage.
[0071]
Therefore, in the optical deflection step, the direction of the electric field formed in the liquid crystal layer is switched by applying an alternating voltage of the deflection frequency to the pair of electrodes, and the optical deflection direction by the optical deflection element is changed by switching the electric field direction. Can be switched. In addition, in the application start step, when the voltage application is started, the pulsed DC voltage is intermittently applied before the AC voltage is applied at the deflection frequency, so that the alignment state of the liquid crystal molecules is applied to the entire liquid crystal layer. It is disturbed temporarily. Then, by applying an alternating voltage with a deflection frequency, the liquid crystal molecules can be aligned in the light deflection direction.
[0072]
Claim 21 The light deflection method of the invention includes a pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer into the liquid crystal layer. A deflection frequency for switching a light deflection direction by the light deflection element using an optical deflection element having an alignment film oriented in a substantially vertical direction and an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer. An optical deflection step of applying an alternating voltage of the electrode to the electrode, and an alignment releasing step of intermittently applying a pulsed direct-current voltage to the electrode before the application of the alternating voltage of the deflection frequency to the electrode; And an application start step of applying an alternating voltage having a frequency higher than the deflection frequency to the electrode following the application of a pulsed DC voltage to the electrode.
[0073]
Therefore, in the optical deflection step, the direction of the electric field formed in the liquid crystal layer is switched by applying an alternating voltage of the deflection frequency to the pair of electrodes, and the optical deflection direction by the optical deflection element is changed by switching the electric field direction. Can be switched. In addition, when the voltage application to the electrode is started, the pulsed DC voltage is intermittently applied before the AC voltage having the deflection frequency is applied, so that the alignment state of the liquid crystal molecules is temporarily applied over the entire liquid crystal layer. After being disturbed, an AC voltage having a frequency higher than the deflection frequency is applied, whereby an electric field that is switched in a cycle shorter than the switching cycle of the optical deflection direction is formed in the liquid crystal layer. That is, when a pulsed DC electric field is applied intermittently, the orientation of the entire liquid crystal layer is greatly disturbed, and the entire liquid crystal layer is likely to form a cloudy state. Therefore, the interface portion between the cloudy portion and the normal portion is no longer present. End up. Thereafter, by applying a high-frequency electric field, the entire liquid crystal layer returns to a uniform alignment state, so that it is possible to prevent the interface portion between the cloudy portion and the normal portion from remaining as a trace.
[0074]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS. This embodiment shows an application example to an optical deflection apparatus.
[0075]
FIG. 1 shows an example of the basic configuration of the optical deflecting device of the present embodiment, where (a) is a plan view, (b) is a front view, and (c) is a side view. As shown in FIG. 1 (c), the optical deflecting device 1 includes a pair of transparent substrates 2, 3 arranged opposite to each other, an alignment film 4 provided on the substrate 2, an alignment film 4, and the other substrate 3. And a liquid crystal layer 6 of a ferroelectric liquid crystal forming a chiral smectic C phase filled in between. In the present embodiment, the alignment film 4 is provided only on the substrate 2. However, the present invention is not limited to this, and it is sufficient that at least one of the pair of substrates 2 and 3 has the alignment film 4. The alignment film 4 may be provided on the substrate 3 or the alignment film 4 may be provided on the substrates 2 and 3 (see FIG. 2). In the present embodiment, light is incident from the substrate 2 side and emitted from the substrate 3 side.
[0076]
Here, the liquid crystal will be described. A “smectic liquid crystal” is a liquid crystal layer in which liquid crystal molecules in a liquid crystal layer are arranged in parallel in the major axis direction of the liquid crystal molecules. With regard to such a liquid crystal, a liquid crystal in which the normal direction of the liquid crystal layer (layer normal direction) and the major axis direction of the liquid crystal molecules coincide with each other is referred to as “smectic A phase”. Liquid crystals that do not match are called “smectic C phase”. In general, a ferroelectric liquid crystal composed of a smectic C phase has a so-called spiral structure in which the direction of liquid crystal molecules is spirally rotated for each layer in the state where an external electric field does not work, and is called “chiral smectic C phase”. be called. “Chiral smectic C phase” is an antiferroelectric liquid crystal composed of a smectic C phase, in which the direction of liquid crystal molecules in each layer faces in the opposite direction. Liquid crystals composed of these chiral smectic C phases have asymmetric carbon in the molecular structure, and are thus spontaneously polarized. For this reason, the liquid crystal composed of the chiral smectic C phase can control the optical characteristics by rearranging the liquid crystal molecules in a direction determined by the spontaneous polarization Ps and the external electric field E. In this embodiment, a ferroelectric liquid crystal is described as an example of the liquid crystal layer 6. However, the liquid crystal layer 6 is not limited to the ferroelectric liquid crystal, and an anti-ferroelectric liquid crystal can be similarly used as the liquid crystal layer 6.
[0077]
The structure of a ferroelectric liquid crystal composed of a chiral smectic C phase is composed of a main chain, a spacer, a skeleton, a bonding part, a chiral part and the like. As the main chain structure, polyacrylate, polymethacrylate, polysiloxane, polyoxyethylene or the like can be used. The spacer is used for linking a skeleton responsible for molecular rotation, a bonding portion, and a chiral portion to the main chain, and a methylene chain having an appropriate length is selected. In addition, a —COO— bond or the like is selected as a bond portion that bonds the chiral portion and a rigid skeleton such as a biphenyl structure.
[0078]
As shown in FIG. 2, the liquid crystal molecules 6a in the liquid crystal layer 6 of the ferroelectric liquid crystal composed of a chiral smectic C phase are arranged so that the rotation axis of the spiral rotation of the liquid crystal molecules 6a is relative to the surfaces of the substrates 2 and 3 as shown in FIG. It is oriented so as to face in a substantially vertical direction. In the present embodiment, as shown in FIG. 2, the liquid crystal molecules 6a are aligned so that the rotation axis of the spiral rotation of the liquid crystal molecules 6a is oriented substantially perpendicular to the surfaces of the substrates 2 and 3. On average, it is assumed that the alignment is in the vertical direction, and hereinafter, this state is simply referred to as “substantially vertical state” or “substantially vertical alignment state”. FIG. 2 shows a state in which the alignment film 4 is provided on each of the pair of substrates 2 and 3.
[0079]
As shown in FIG. 1A, the light deflection element 5 includes a pair of electrodes 7a and 7b disposed at positions that do not overlap the incident optical path to the light deflection element 5. The pair of electrodes 7a and 7b are connected to a first power supply 8 that functions as a first voltage applying unit and a second voltage applying unit. The first power supply 8 applies an alternating voltage having a drive frequency of about several hundred Hz between the pair of electrodes 7a and 7b. Although illustration and description are omitted because it is a known technique, the first power supply 8 has an alternating voltage of a deflection frequency for switching the light deflection direction by the light deflection element 5 with respect to the pair of electrodes 7a and 7b, and this deflection. It has the structure which can apply two types of alternating voltage with the alternating voltage of a frequency different from a frequency. In the present embodiment, the deflection frequency is set to about several hundred Hz. Examples of the AC voltage applied between the pair of electrodes 7a and 7b include a rectangular wave AC voltage as shown in FIG.
[0080]
When a voltage is applied between the pair of electrodes 7 a and 7 b by the first power supply 8, the direction is approximately parallel to the layer direction of the liquid crystal layer 6 and the rotation axis of the helical rotation of the liquid crystal molecules 6 a in the liquid crystal layer 6. An electric field is formed in a direction substantially perpendicular to the direction. Since the first power supply 8 of the present embodiment applies an alternating voltage between the pair of electrodes 7a and 7b, the first power supply 8 is connected between the pair of electrodes 7a and 7b according to the polarity of the applied voltage. An electric field having electric field vectors in two directions of electric field direction A and second electric field direction B is formed (see FIGS. 1A and 1B).
[0081]
As shown in FIGS. 1A and 1B, the electric field vector in the first electric field direction A is generated when a voltage (+) is applied to the electrode 7a, and the electric field vector in the second electric field direction B is This occurs when a voltage (−) is applied to the electrode 7a.
[0082]
The alignment direction of the liquid crystal molecules 6 a in the liquid crystal layer 6 changes along the electric field formed in the liquid crystal layer 6. Due to the change in the alignment state of the liquid crystal molecules 6 a, the light incident on the pair of substrates 2 is deflected and emitted from the substrate 3. When an electric field having an electric field vector in the first electric field direction A is formed, the incident light is optically deflected so as to become the first outgoing light a. When an electric field having an electric field vector in the second electric field direction B is formed, the incident light is deflected in the optical path so as to become the second outgoing light b. That is, the light incident on the light deflection element 5 is subjected to light deflection in different directions according to the direction of the electric field vector of the electric field generated between the pair of electrodes 7a and 7b. In the present embodiment, the pair of electrodes 7a and 7b are arranged so that the incident light corresponds to the target light deflection direction.
[0083]
In addition, the pair of electrodes 7 a and 7 b also function as spacers that regulate the thickness of the liquid crystal layer 6 while keeping the distance between the pair of substrates 2 and 3 constant.
[0084]
In such a configuration, when the optical deflecting operation of the optical deflecting device 1 is performed, an alternating voltage having a deflection frequency of about several hundred Hz is applied between the pair of electrodes 7a and 7b by the first power source 8. Thereby, the light deflection direction is switched at the switching timing of several hundred Hz so that the optical path of the incident light to the light deflection element 5 takes either the first outgoing light a or the second outgoing light b (light Deflection step).
[0085]
Further, when stopping the light deflection operation in the light deflection apparatus 1, the voltage application between the pair of electrodes 7a and 7b is stopped. When stopping the application of the voltage between the pair of electrodes 7a and 7b, the frequency of the alternating voltage applied by the first power supply 8 between the pair of electrodes 7a and 7b is set higher than the deflection frequency, A high-frequency AC voltage is applied between the pair of electrodes 7a and 7b (application stop step). Here, the function as the stop processing means is realized.
[0086]
According to the present embodiment, the light deflection operation is performed by switching the electric field direction formed in the liquid crystal layer 6 of the chiral smectic C phase by applying an alternating voltage of the deflection frequency to the pair of electrodes 7a and 7b. Even with the light deflection element 5 having a simplified configuration, the speed of the light deflection operation can be increased by utilizing the spontaneous polarization of the liquid crystal molecules 6a in the chiral smectic C phase.
[0087]
Moreover, according to this Embodiment, it was confirmed that generation | occurrence | production of the cloudiness by repeated use can be suppressed.
[0088]
Below, the mechanism of suppression of the occurrence of cloudiness due to repeated use will be considered. First, in the optical deflection apparatus 1, the electric field vector direction of the electric field generated in the liquid crystal layer 6 is reversed in two directions of the first electric field direction A and the second electric field direction B, so that the tilt angle direction of the smectic C-phase ferroelectric liquid crystal. At the moment when is inverted, the alignment state of the liquid crystal molecules 6a in the liquid crystal layer 6 is greatly disturbed. Hereinafter, the disorder of the vertical alignment state of the liquid crystal molecules 6a and the part where the vertical alignment state of the liquid crystal molecules 6a is disturbed are simply referred to as “alignment defects”. The alignment defect in the liquid crystal layer 6 is likely to occur when the optical path deflection operation is repeated for a long time. Occurrence of alignment defects causes white turbidity in the liquid crystal layer 6 due to light scattering.
[0089]
The white turbidity is influenced by factors such as the fluidity and electric field response of the liquid crystal material and the electric field distribution from the outside, and the liquid crystal molecules 6a in the vicinity of the central portion in the thickness direction of the liquid crystal layer 6 where the alignment film 4 is weakly regulated are repeated. By continuing the operation, it is considered that the alignment state of the liquid crystal molecules 6a in the liquid crystal layer 6 is disturbed to form minute domains 6b having different alignment directions as shown in FIG. The alignment defect of the liquid crystal molecules 6a is a thin line shape from a place where the alignment state of the liquid crystal molecules 6a is likely to be disturbed, such as the vicinity of the electrodes 7a and 7b and the central portion in the thickness direction of the liquid crystal layer 6, and electric field unevenness is likely to occur. Occurs. This fine alignment defect is fixed when the light deflection operation is stopped in a state where the alignment defect starts to grow.
[0090]
However, although the alignment defect of the liquid crystal molecules 6a in the liquid crystal layer 6 causes light scattering as described above, it is considered that there is no practical problem when the region is small or thin.
[0091]
However, when the alignment defect of the liquid crystal molecules 6a in the liquid crystal layer 6 grows, it becomes a clear cloudy state. This white turbidity occurs when the fine line grows in a vortex by repeating the light deflection operation for a long time in the state where the fine line alignment defect is generated. In the cloudy part, the vertical alignment state of the liquid crystal molecules 6a is disturbed, so a conoscopic image that is clearly blurred is observed compared to a conoscopic image that is observed in a general vertical alignment state. Sometimes it is not possible.
[0092]
The fine alignment defect is fixed by stopping the light deflection operation in a state where it starts to grow, and the cloudiness grows with the fixed alignment defect as a nucleus when the optical path deflection operation is started again. Therefore, in order to prevent the occurrence of white turbidity defects, it is presumed that it is effective to prevent the fixation of fine alignment defects at the initial stage of occurrence.
[0093]
According to the optical deflecting device 1 of the present embodiment, when the optical deflecting operation in the optical deflecting device 1 is stopped, before the optical deflecting operation is stopped by the first power supply 8, the deflection frequency is set between the pair of electrodes 7a and 7b. By applying an alternating voltage having a higher frequency than the above, it is possible to eliminate fine alignment defects that have slightly occurred in the vicinity of the electrodes 7a and 7b.
[0094]
Although the mechanism of erasing the fine alignment defect is not clear, the mechanism of erasing the fine alignment defect can be considered as follows.
[0095]
Before stopping the light deflection operation, the first power source 8 applies an alternating voltage having a frequency higher than the drive frequency of the light deflection operation to the pair of electrodes 7a and 7b, thereby causing the liquid crystal layer 6 to In other words, an electric field that is switched at a cycle shorter than the switching cycle of the electric field that acts during the optical deflection operation by applying an alternating voltage with a deflection frequency is formed. As a result, the liquid crystal molecules 6a in the liquid crystal layer 6 are maintained in a state in which the liquid crystal molecules 6a are relatively easy to move than during the light deflection operation. On the other hand, actually, the response time of the liquid crystal molecules 6a corresponding to the direction of the electric field formed in the liquid crystal layer 6 does not sufficiently catch up with the switching time of the electric field direction, and the actual switching motion of the liquid crystal molecules 6a becomes small. . As a result, the liquid crystal molecules 6a vibrate slightly in a state close to the vertical alignment state. As a result, the alignment regulating force in the vertical direction with respect to the liquid crystal molecules 6a acts on the entire liquid crystal layer 6, and this alignment regulation is performed. It is presumed that it can be easily re-oriented to the vertical alignment state by force.
[0096]
That is, since a fine alignment defect that becomes a nucleus is hard to occur, even when the optical path deflection operation is resumed, it becomes difficult to grow into white turbidity with the fine alignment defect as a nucleus. It is considered that it is possible to prevent the orientation defect 6a from being fixed as a cloudy state for a long period of time.
[0097]
According to the above consideration, the frequency of the AC voltage applied before stopping the light deflection operation is preferably a relatively high frequency AC voltage that does not sufficiently catch up the electric field response of the liquid crystal molecules 6a.
[0098]
In addition, according to the above consideration, it is considered that the high-frequency AC voltage waveform applied before stopping the deflection operation should be able to give minute vibrations to the liquid crystal molecules 6a. Either sine wave or the like may be used.
[0099]
By the way, although it is a known technique, a description thereof will be omitted, but a plurality of pixels capable of light ON / OFF control are arranged two-dimensionally, and light ON / OFF in each pixel is controlled according to image information. Thus, there is an image display element that displays an image according to image information.
[0100]
In addition to the image display element described above, the light deflection apparatus 1 of the present embodiment observes a light source that illuminates an image displayed on the image display element, and an image that is displayed on the image display element and illuminated by the light source. And an optical member for changing the optical path between the image display element and the optical member for each of a plurality of subfields obtained by temporally dividing the image display field in the image display element. An image display apparatus that doubles and displays the apparent number of pixels of the image display element by observing an image pattern with the display position shifted in accordance with the deflection of the optical path for each subfield by means of an optical member (both shown in FIG. (Not shown). In the present embodiment, the light deflection means in the image display device is a “pixel shift element”, and the deflection operation of the incident optical path by this pixel shift element is a pixel shift.
[0101]
In the image display device described above, since the pixel shift is performed by the pixel shift element using the afterimage phenomenon of the human eye, the pixel shift timing for each subfield by the pixel shift element, that is, in the light deflection apparatus 1 The frequency (driving frequency) of the rectangular wave voltage that determines the electric field switching timing may be 30 Hz or more. In order to surely prevent flicker, it is preferable to set the driving frequency of the rectangular wave voltage to 100 to several hundred Hz.
[0102]
In such an image display device, it is generated slightly in the vicinity of the electrode by applying an AC voltage having a frequency higher than the drive frequency of the pixel shift operation for a certain time before the pixel shift operation is stopped or before starting. It is possible to eliminate the fine alignment defects that have been formed, and to suppress the occurrence of cloudy portions due to the vertical alignment defects.
[0103]
Next, a second embodiment of the present invention will be described with reference to FIG. This embodiment shows an application example to an optical deflection apparatus. In addition, the same part as 1st embodiment is shown with the same code | symbol, and description is also abbreviate | omitted. The same shall apply hereinafter.
[0104]
5A and 5B show an example of the basic configuration of the optical deflecting device of the present embodiment, where FIG. 5A is a plan view, FIG. 5B is a front view, and FIG. 5C is a side view. The optical deflecting device 10 of the present embodiment is separate from the first power supply 8 as the first voltage applying means for driving the optical deflecting element 5 by applying an alternating voltage with a deflection frequency to the pair of electrodes 7a and 7b. A second power source 11 is provided which functions as a second voltage applying means for applying an AC voltage having a frequency different from the deflection frequency of the AC voltage applied by the first power source 8 between the pair of electrodes 7a and 7b. Yes. The first and second power supplies 8 and 11 are switched by the switch 12 so that one of them becomes effective.
[0105]
The first power supply 8 applies an AC voltage whose deflection frequency is set to about several hundred Hz between the pair of electrodes 7a and 7b. The AC voltage applied by the first power supply 8 is the driving frequency of the light deflection operation (pixel shift). The waveform of the alternating voltage applied by the first power supply 8 is, for example, a rectangular wave as shown in FIG.
[0106]
The second power source 11 has a deflection frequency of the AC voltage applied by the first power source 8 between the pair of electrodes 7a and 7b, that is, a deflection frequency that causes the light deflection element 5 to perform a light deflection operation (pixel shift). An AC voltage having a frequency higher than a few hundred Hz is applied. More specifically, the second power source 11 applies an AC voltage whose half cycle time is shorter than the response time of the liquid crystal molecules 6a to the electrodes 7a and 7b. By applying such a high frequency voltage, the light deflection phenomenon of the light incident on the light deflection element 5 does not occur. The frequency of the alternating voltage applied between the pair of electrodes 7a and 7b is preferably set to a frequency such that the response time of the liquid crystal molecules 6a cannot catch up with the switching time of the electric field direction, and more preferably 1 kHz or more. preferable. Since the response time of the liquid crystal molecules 6a in the liquid crystal layer 6 varies depending on the type of liquid crystal material such as the electrical characteristics and viscosity of the liquid crystal material, the frequency at which the light deflection phenomenon does not occur varies depending on the liquid crystal material constituting the liquid crystal layer 6. For this reason, the optimal frequency of the 2nd power supply 11 can be suitably set according to the electrical property, viscosity, etc. of liquid crystal material based on experiment etc., for example.
[0107]
The second power supply 11 applies an AC voltage having a voltage value higher (larger) than the voltage value of the AC voltage having the deflection frequency applied by the first power supply 8. The second power supply 11 applies an alternating voltage having a voltage value at which the liquid crystal molecules 6 a sufficiently move in the liquid crystal layer 6. The voltage value at which the liquid crystal molecules 6a sufficiently move in the liquid crystal layer 6 varies depending on the element configuration, but is 1 × 10. ⁵ The electric field strength is preferably about V / m.
[0108]
In addition, the waveform of the AC voltage applied by the second power source 11 may be a rectangular wave as shown in FIG. 3, and is not limited to a rectangular wave but a triangular wave, a sine wave, or the like. Also good.
[0109]
In such a configuration, when the optical deflecting operation of the optical deflecting device 10 is performed, an alternating voltage having a deflection frequency of about several hundred Hz is applied between the pair of electrodes 7 a and 7 b by the first power supply 8, The light deflection direction is switched at a switching timing of several hundred Hz so that the optical path of the incident light takes one of the first outgoing light a and the second outgoing light b (light deflection step).
[0110]
Further, when stopping the light deflection operation in the light deflection apparatus 10, the application of voltage to the pair of electrodes 7a and 7b is stopped. When stopping the application of voltage to the pair of electrodes 7a and 7b, the second power source 11 applies an AC voltage having a frequency higher than the deflection frequency between the pair of electrodes 7a and 7b (application stop step). Here, the function as the stop processing means is realized. As a result, an alternating voltage having a higher frequency than the voltage applied by the first power supply 8 is applied to the liquid crystal layer 6.
[0111]
According to the above consideration, the response time of the liquid crystal molecules 6a is switched in the direction of the electric field by applying an AC voltage having a frequency higher than the frequency of the AC voltage applied by the first power supply 8 from the second power supply 11. Without catching up with time, an alignment force in a substantially vertical direction can be applied to the liquid crystal layer 6 to facilitate alignment of the liquid crystal molecules 6a in a substantially vertical direction.
[0112]
Accordingly, the alignment regulating force can be effectively applied to the entire liquid crystal layer 6 and can be easily re-aligned in the vertical alignment state, so that the disturbed liquid crystal molecules 6a in the liquid crystal layer 6 can be transferred to the substrate 2, in a shorter time. 3 can be aligned in a substantially vertical alignment state.
[0113]
In addition, the voltage value applied by the second power supply 11 is set higher (larger) than the voltage value applied by the first power supply 8, so that the liquid crystal layer 6 is larger than the light deflection operation. An electric field is formed. Thereby, the force which vibrates the liquid crystal molecule 6a very finely increases, and the alignment regulating force in the vertical direction can be more reliably applied to the liquid crystal molecule 6a. As a result, the liquid crystal molecules 6a can be more reliably aligned with the substrates 2 and 3 in a substantially vertical alignment state.
[0114]
Next, a third embodiment of the present invention will be described with reference to FIGS. This embodiment shows an application example to an optical deflection apparatus.
[0115]
6A and 6B show examples of the basic configuration of the optical deflecting device of the present embodiment, where FIG. 6A is a plan view, FIG. 6B is a front view, and FIG. 6C is a side view. The optical deflecting device 20 according to the present embodiment is separate from the first power supply 8 as the first voltage applying means for driving the optical deflecting element 5 by applying an alternating voltage with a deflection frequency to the pair of electrodes 7a and 7b. A third power source 21 is provided which functions as third voltage applying means for applying a pulsed DC voltage to the pair of electrodes 7a and 7b. The first and third power supplies 8 and 21 are switched by the switch 12 so that one of them becomes effective.
[0116]
As described above, the AC voltage applied by the first power supply 8 is, for example, a rectangular wave as shown in FIG. 3, and the deflection frequency is set to about several hundred Hz.
[0117]
The third power supply 21 intermittently applies a pulsed direct-current voltage to the liquid crystal layer 6 when stopping an optical deflection operation described later. The waveform of the DC voltage applied by the third power supply 21 is a DC voltage having a pulse waveform as shown in FIG. The intermittent application frequency varies depending on the configuration of the optical deflection element 5, but a period of about 0.1 to 1 Hz is preferable.
[0118]
In addition, the third power source 21 applies an AC voltage whose voltage value is set higher (larger) than the voltage value of the AC voltage applied by the first power source 8. The optimum voltage value applied by the third power source 21 varies depending on the configuration of the optical deflection element 5, but is 1 × 10. ⁵ It is preferably set to V / m or more.
[0119]
In such a configuration, when the optical deflecting operation of the optical deflecting device 20 is performed, an alternating voltage having a deflection frequency of about several hundred Hz is applied between the pair of electrodes 7 a and 7 b by the first power supply 8, The light deflection direction is switched at a switching timing of several hundred Hz so that the optical path of the incident light takes one of the first outgoing light a and the second outgoing light b (light deflection step).
[0120]
Further, when stopping the light deflection operation in the light deflecting device 20, the application of voltage to the pair of electrodes 7a and 7b is stopped. When stopping the application of the voltage to the pair of electrodes 7a and 7b, the application of the alternating voltage with the deflection frequency by the first power source 8 is followed by the pulsed DC voltage between the pair of electrodes 7a and 7b by the third power source 21. Is intermittently applied (application stop step). Here, the function as the stop processing means is realized.
[0121]
By the way, a white turbid portion in which the alignment state is locally disturbed in the liquid crystal layer 6 is generated. For example, the liquid crystal molecules in the white turbid portion are returned to the vertical alignment state by applying a high frequency voltage as in the above-described embodiment. In some cases, the interface portion between the cloudy portion and the normal orientation portion may remain as a trace.
[0122]
According to the present embodiment, the pulsed DC voltage is intermittently applied between the pair of electrodes 7 a and 7 b by the third power source 21 before the voltage application is stopped, and intermittently applied to the liquid crystal layer 6. By applying an electric field in the first electric field direction A to the liquid crystal molecules 6a, the occurrence of white turbidity due to alignment defects is suppressed, and the interface between the white turbidity and normal alignment is not left as a trace. Was confirmed.
[0123]
Here, a mechanism for suppressing the occurrence of alignment defects in the liquid crystal molecules 6a will be considered. The mechanism for preventing the occurrence of white turbidity by intermittently applying a pulsed DC voltage between the pair of electrodes 7a and 7b before stopping the application of the voltage is not clear, but can be estimated as follows. Is possible. That is, an electric field in the first electric field direction A is intermittently formed in the liquid crystal layer 6 by intermittently applying a pulsed DC voltage between the pair of electrodes 7 a and 7 b. At this time, at the moment when the pulsed DC voltage is turned ON / OFF, the liquid crystal molecules 6a in the liquid crystal layer 6 are disordered in the form of waves from the vicinity of the electrodes 7a and 7b, and this disturbance propagates to the adjacent liquid crystal molecules 6a. As a result, the liquid crystal molecules 6 s vibrate intermittently across the entire liquid crystal layer 6, and this vibration temporarily disturbs the alignment state of the liquid crystal molecules 6 a in the entire liquid crystal layer 6, and the liquid crystal molecules 6 partially in the liquid crystal layer 6. Even when the orientation state of 6a is disturbed, it is estimated that there is no trace in the interface portion between the portion where the orientation state is disturbed and the portion where the orientation state is not disturbed. Since the liquid crystal molecules 6a have a property of spontaneously realigning when the alignment state is disturbed, by temporarily disturbing the alignment state of the liquid crystal molecules 6a in the entire liquid crystal layer 6, the liquid crystal layer 6 It is estimated that the spontaneous realignment of the liquid crystal molecules 6 a can be effectively performed over the whole, and the liquid crystal molecules 6 a can be aligned substantially vertically over the entire liquid crystal layer 6.
[0124]
Note that this effect is small when a DC voltage is applied continuously for a long time or when an AC voltage having a frequency about the deflection frequency is applied. This also confirms the importance of the wave-like movement in which the disorder of the alignment state generated when the electric field direction is switched propagates throughout the liquid crystal layer 6 and then re-aligns.
[0125]
According to the present embodiment, even when an alignment defect is partially generated by the light deflection operation in the optical deflecting element 5, the alignment defect is prevented from being fixed, thereby causing the occurrence of the alignment defect. It is possible to provide a highly reliable optical deflection device 20 that suppresses the occurrence of white turbidity.
[0126]
Further, the third power source 21 applies an AC voltage whose voltage value is set to be larger than the voltage value of the AC voltage applied by the first power source 8, and therefore, in the moment when the electric field direction is switched, Since the liquid crystal molecules 6a can move more easily, the interface portion between the alignment defect portion and the normal alignment portion is more effectively removed as a trace, and the realignment of the liquid crystal molecules 6a can be performed uniformly in a shorter time. Can be oriented.
[0127]
Next, a fourth embodiment of the present invention will be described with reference to FIG.
[0128]
8A and 8B show examples of the basic configuration of the optical deflecting device of the present embodiment, where FIG. 8A is a plan view, FIG. 8B is a front view, and FIG. 8C is a side view. The optical deflection apparatus 30 according to the present embodiment includes a first power supply 8 that functions as a first voltage application unit that drives an optical deflection element 5 by applying an alternating voltage with a driving frequency to the pair of electrodes 7a and 7b. A second power source 11 that functions as a second voltage applying means for applying an alternating voltage having a higher frequency than the alternating voltage of the driving frequency applied by the first power source 8 between the pair of electrodes 7a and 7b; And a third power source 31 functioning as third voltage applying means for continuously applying a pulsed DC voltage between 7a and 7b. The first power supply 8 has a function of making the voltage value variable. The second power supply 11 has a function of making both the frequency and the AC voltage value variable. The first, second, and third power supplies 8, 11, and 21 are switched by the switch 12 so that one of them becomes effective.
[0129]
In such a configuration, when the optical deflecting operation of the optical deflecting device 30 is performed, an AC voltage having a driving frequency of about several hundred Hz is applied between the pair of electrodes 7 a and 7 b by the first power supply 8, The light deflection direction is switched at a switching timing of several hundred Hz so that the optical path of the incident light takes one of the first outgoing light a and the second outgoing light b (light deflection step).
[0130]
When stopping the optical deflection operation in the optical deflection apparatus 1, the application of voltage to the pair of electrodes 7a and 7b is stopped. When stopping the application of the voltage to the pair of electrodes 7a and 7b, the pulsed DC voltage was intermittently applied between the pair of electrodes 7a and 7b by the third power source 21 following the application of the alternating voltage of the deflection frequency. After (orientation release step), an AC voltage having a frequency higher than the frequency of the deflection direction switching operation is applied between the pair of electrodes 7a and 7b by the second power source 11 (application stop step). Here, the function as the stop processing means is realized.
[0131]
At this time, by applying an AC voltage having a frequency lower than the deflection frequency by the second power source 11, an AC voltage having a frequency higher than the deflection frequency is applied by increasing the frequency of the AC voltage continuously or stepwise. You may make it do.
[0132]
At this time, an AC voltage having a voltage value higher than the voltage value applied by the first power supply 8 may be applied by the second power supply 11.
[0133]
According to the present embodiment, when the voltage application to the pair of electrodes 7a and 7b is stopped, the third power source 21 applies a pulsed direct current between the pair of electrodes 7a and 7b following the application of the alternating voltage of the deflection frequency. A voltage is intermittently applied, and after the AC voltage having a frequency larger than the frequency of the deflection direction switching operation is applied between the pair of electrodes 7a and 7b by the second power source 11, the application of the voltage to the electrodes is stopped. As a result, it was confirmed that the occurrence of white turbidity was suppressed and the interface part between the white turbid part and the normal part was not left as a trace.
[0134]
The mechanism for preventing white turbidity is discussed below. Although the mechanism of the occurrence of white turbidity is not clear, as described above, after applying an alternating voltage with a deflection frequency by the first power supply 8, a pulsed direct current is applied between the pair of electrodes 7 a and 7 b by the third power supply 21. By intermittently applying the voltage, the alignment of the liquid crystal molecules 6a in the entire liquid crystal layer 6 is disturbed, and the trace of the interface portion between the normal alignment portion and the alignment defect portion disappears. In this state, the second power source 11 applies an AC voltage having a frequency higher than the drive frequency between the pair of electrodes 7a and 7b to apply an AC voltage having a shorter cycle than the electric field direction switching cycle that is applied during the optical deflection operation. As a result, the liquid crystal molecules 6a in the liquid crystal layer 6 are maintained in a relatively easy to move state, but the response time due to the switching of the electric field direction cannot sufficiently catch up, so that the liquid crystal molecules 6a vibrate slightly in a state close to the vertical alignment state.
[0135]
By the way, it takes a relatively long time for the liquid crystal molecules 6a whose alignment state is disturbed over the entire liquid crystal layer 6 to realign completely and spontaneously.
[0136]
In the present embodiment, after disturbing the alignment of the liquid crystal molecules 6a in the entire liquid crystal layer 6, the liquid crystal molecules 6a are vibrated minutely in a state close to the vertical alignment state while maintaining a relatively easy movement state. The realignment operation of 6a is promoted, and the realignment can be surely performed in a short time as compared with the case where the liquid crystal molecules are completely realigned spontaneously.
[0137]
In this embodiment, after applying a pulsed DC voltage, a high-frequency AC voltage is applied, thereby speeding up the subsequent realignment process of the entire liquid crystal layer 6 and applying no pulsed DC voltage. Compared with the case where a high-frequency AC voltage is applied to the liquid crystal layer, realignment over the entire liquid crystal layer 6 can be reliably performed in a short time.
[0138]
Next, a fifth embodiment of the present invention will be described. The present invention can be applied to, for example, the various optical deflection devices 1, 10, 20, or 30 described above. The first power supply 8 of the present embodiment has a function of making the voltage value variable, and functions as a fourth voltage application unit.
[0139]
When stopping the optical deflection operation in the optical deflecting device 1 (10, 20 or 30), the first power source 8 continuously reduces the voltage value of the AC voltage applied between the pair of electrodes 7a and 7b and stops the operation. (Application stop step). Here, the function as the stop processing means is realized.
[0140]
The first power supply 8 is not limited to continuously decreasing the voltage value of the AC voltage applied between the pair of electrodes 7a and 7b, but may be decreased intermittently.
[0141]
Thereby, when the application of the voltage is stopped, the voltage value of the alternating voltage of the deflection frequency applied between the pair of electrodes 7a and 7b is continuously or stepwise reduced so that the light deflection direction can be switched. By stopping the application at a smaller voltage value, the applied voltage value becomes smaller than the saturation electric field for switching the liquid crystal molecules 6a, and the liquid crystal molecules 6a are stopped in a state close to the state in which they return to the vertical state. Therefore, it is possible to prevent the liquid crystal molecules 6a from being disturbed when the light deflection operation is stopped.
[0142]
In the present embodiment, the voltage value smaller than the saturation electric field for switching the liquid crystal molecules 6a includes a state where the voltage value is zero.
[0143]
Further, when the application stop step in the above-described embodiment is performed, when the second power source 11 applies an AC voltage having a voltage value higher than the voltage value applied by the first power source 8, liquid crystal molecules The electrostatic force acting on the surface increases, and the force to orient in the vertical direction increases. Thereby, even when the alignment state is disturbed by the light deflection operation in the light deflection element and a portion where white turbidity is likely to occur is generated, the liquid crystal molecules can be quickly returned to the original vertical alignment state.
[0144]
Next, a sixth embodiment of the present invention will be described below. In the present embodiment, the above-described various points are that the dielectric anisotropy of the liquid crystal layer 6 forming the chiral smectic C phase is negative in the frequency band of the alternating voltage whose half cycle time is shorter than the response time of the liquid crystal molecules 6a. Different from the embodiment.
[0145]
Here, the ferroelectric liquid crystal will be described. There are two types of ferroelectric liquid crystal: ferroelectric liquid crystal having positive dielectric anisotropy and ferroelectric liquid crystal having negative dielectric anisotropy. In general, when a high-frequency electric field is applied to the liquid crystal layer, the liquid crystal molecules 6a in the liquid crystal layer 6 tend to be aligned in a direction in which electrostatic energy is minimized.
[0146]
Therefore, for example, when an AC voltage is applied to the liquid crystal layer 6 of the optical deflection element 5 shown in FIG. 1 in a substantially parallel direction, the liquid crystal molecules 6a of the liquid crystal material having a positive dielectric anisotropy are applied to the applied electric field. Try to align in a direction parallel to the direction. Conversely, a liquid crystal material having a negative dielectric anisotropy tends to be aligned in a direction perpendicular to a given electric field direction.
[0147]
In such a configuration, when the optical deflecting operation of the optical deflecting device 1 is performed, an alternating voltage having a driving frequency of about several hundred Hz is applied between the pair of electrodes 7 a and 7 b by the first power source 8, The light deflection direction is switched at a switching timing of several hundred Hz so that the optical path of the incident light takes one of the first outgoing light a and the second outgoing light b (light deflection step).
[0148]
Further, when stopping the light deflection operation in the light deflection apparatus 1, the application of voltage to the pair of electrodes 7a and 7b is stopped. When stopping the application of voltage to the pair of electrodes 7a and 7b, an alternating voltage having a deflection frequency is applied by the first power source 8, and then an alternating voltage having a frequency higher than the deflection frequency is applied between the pair of electrodes 7a and 7b. (Application stop step). Here, the function as the stop processing means is realized.
[0149]
The liquid crystal layer 6 of the present embodiment is a negative liquid crystal material having a dielectric anisotropy in the frequency band of an alternating voltage whose half cycle time is shorter than the response time of the liquid crystal molecules 6a. When an attempt is made to align the liquid crystal molecules 6a so that electrostatic energy is minimized by applying a high-frequency electric field in a parallel direction, as a result, the liquid crystal molecules 6a take a vertical alignment state with respect to the layer direction of the liquid crystal layer 6. I will try. Thereby, in addition to the alignment regulation force by the alignment film 4, an electrostatic force can be applied, and the liquid crystal molecules 6a can be reliably aligned in the vertical alignment state.
[0150]
Further, every time a voltage is applied between the pair of electrodes 7a and 7b, an electrostatic force can be applied in addition to the alignment regulating force by the alignment film 4, so that an alignment defect is generated by the deflection direction switching operation. It is possible to improve the reliability by suppressing the occurrence of an alignment defect due to repeated use, while increasing the speed of the optical path deflecting operation by the optical deflecting element 5 which is suppressed by itself.
[0151]
Next, a seventh embodiment of the present invention will be described. The present invention can be applied to, for example, the optical deflection apparatus 1 shown in FIG. 1, and in this embodiment, an application example to the optical deflection apparatus 1 shown in FIG. 1 is shown.
[0152]
Also in the present embodiment, the first power supply 8 applies an alternating voltage with a drive frequency of about several hundred Hz between the pair of electrodes 7a and 7b, and the optical deflection element is applied to the pair of electrodes 7a and 7b. 5 has a configuration capable of applying two types of AC voltages, that is, an AC voltage having a deflection frequency for switching the light deflection direction by 5 and an AC voltage having a frequency different from the deflection frequency. In the present embodiment, a first voltage application unit is realized by the first power supply 8.
[0153]
In such a configuration, when the optical deflecting operation of the optical deflecting device 1 is performed, an alternating voltage having a deflection frequency of about several hundred Hz is applied between the pair of electrodes 7a and 7b by the first power source 8. Thereby, the light deflection direction is switched at the switching timing of several hundred Hz so that the optical path of the incident light to the light deflection element 5 takes either the first outgoing light a or the second outgoing light b (light Deflection step).
[0154]
According to the present embodiment, the light deflection operation is performed by switching the electric field direction formed in the liquid crystal layer 6 of the chiral smectic C phase by applying an alternating voltage of the deflection frequency to the pair of electrodes 7a and 7b. Even with the light deflection element 5 having a simplified configuration, the speed of the light deflection operation can be increased by utilizing the spontaneous polarization of the liquid crystal molecules 6a in the chiral smectic C phase.
[0155]
In the present embodiment, at the start of this optical deflection operation, the frequency of the AC voltage applied between the pair of electrodes 7a and 7b is set higher than the deflection frequency, and an AC voltage having a frequency higher than the deflection frequency is set. Is applied between the electrodes 7a and 7b (application start step). Here, the function as the start processing means is realized. As a result, an alternating voltage having a higher frequency than the voltage applied by the first power supply 8 is applied to the liquid crystal layer 6.
[0156]
By the way, it is conceivable that even if the optical deflection element is stopped in a state where there is no alignment defect, the alignment defect may occur due to long-term operation stoppage or other factors.
[0157]
As one factor, for example, when a liquid crystal material that operates at a very low voltage is used, the influence of static electricity can be considered. Actually, the flow of liquid crystal molecules due to static electricity can be confirmed. That is, it is expected that the liquid crystal molecules change from the vertical state even when the operation is stopped.
[0158]
As another factor, it is also conceivable that the pressure distribution in the liquid crystal layer changes due to minute deformation of the substrate due to temperature change, and alignment defects occur.
[0159]
As described above, the alignment defect of the liquid crystal molecules 6a in the liquid crystal layer 6 causes light scattering, but it is considered that there is no practical problem when the region is small or thin. When the light deflection operation is started in a certain state, the alignment defect of the liquid crystal molecules 6a grows to become a clear cloudy state. Therefore, in order to prevent the occurrence of the cloudy defect, the alignment defect is eliminated before the light deflection operation is started. It is speculated that it is effective to keep it.
[0160]
According to the optical deflecting device 1 of the present embodiment, when the optical deflecting operation in the optical deflecting device 1 is started, before the optical deflecting operation is started by the first power supply 8, the deflection frequency is set between the pair of electrodes 7a and 7b. By applying an alternating voltage having a higher frequency than the above, it is possible to eliminate fine alignment defects that have slightly occurred in the vicinity of the electrodes 7a and 7b.
[0161]
Before starting the optical deflection operation, the first power supply 8 applies an alternating voltage having a frequency higher than the drive frequency of the optical deflection operation to the pair of electrodes 7a and 7b, thereby causing the liquid crystal layer 6 to In other words, an electric field that is switched at a cycle shorter than the switching cycle of the electric field that acts during the optical deflection operation by applying an alternating voltage with a deflection frequency is formed. As a result, the liquid crystal molecules 6a in the liquid crystal layer 6 are maintained in a state in which the liquid crystal molecules 6a are relatively easy to move than during the light deflection operation. On the other hand, actually, the response time of the liquid crystal molecules 6a corresponding to the direction of the electric field formed in the liquid crystal layer 6 does not sufficiently catch up with the switching time of the electric field direction, and the actual switching motion of the liquid crystal molecules 6a becomes small. . As a result, the liquid crystal molecules 6a vibrate slightly in a state close to the vertical alignment state. As a result, the alignment regulating force in the vertical direction with respect to the liquid crystal molecules 6a acts on the entire liquid crystal layer 6, and this alignment regulation is performed. It is presumed that it can be easily re-oriented to the vertical alignment state by force.
[0162]
That is, since a fine alignment defect that becomes a nucleus is difficult to occur, even when the optical path deflection operation is started (or resumed), it becomes difficult to grow into white turbidity that has a fine alignment defect as a nucleus, and is repeated. It is considered that it is possible to prevent the alignment defect of the liquid crystal molecules 6a from being fixed as a cloudy state by use over a long period of time.
[0163]
According to the above consideration, it is preferable that the frequency of the alternating voltage applied before starting the optical deflection operation is a relatively high frequency that does not sufficiently catch up the electric field response of the liquid crystal molecules 6a.
[0164]
In addition, according to the above consideration, it is considered that the high-frequency AC voltage waveform applied before starting the deflection operation should be able to give minute vibrations to the liquid crystal molecules 6a. Either sine wave or the like may be used.
[0165]
By the way, the light deflection apparatus 1 of the present embodiment also includes an image display element, a light source that illuminates an image displayed on the image display element, and an optical for observing an image displayed on the image display element and illuminated by the light source. And a light deflection means for changing the optical path between the image display element and the optical member for each of a plurality of subfields obtained by dividing the image display field in the image display element in time. An image display device for doubling the apparent number of pixels of the image display element by observing an image pattern with the display position shifted in accordance with the deflection of the optical path for each field with an optical member (none of which is shown) It can be applied as a light deflection means.
[0166]
The application start step at the start of the light deflection operation may be executed by the light deflection apparatus 1, 10, 20 or 30 of the various embodiments described above that executes the application stop step at the stop of the light deflection operation. Good.
[0167]
Next, an eighth embodiment of the present invention will be described. The present invention can be applied to, for example, the optical deflection apparatus 10 shown in FIG. 5, and in this embodiment, an application example to the optical deflection apparatus 10 shown in FIG. 5 is shown.
[0168]
The first power source 8 in the present embodiment functions as a first voltage applying unit by applying an alternating voltage of about several hundred Hz of driving frequency between the pair of electrodes 7a and 7b.
[0169]
The second power source 11 has a deflection frequency of the AC voltage applied by the first power source 8 between the pair of electrodes 7a and 7b, that is, a deflection frequency that causes the light deflection element 5 to perform a light deflection operation (pixel shift). An AC voltage having a frequency higher than a few hundred Hz is applied, and functions as a second voltage applying unit. The voltage applied by the second power supply 11 is set higher (larger) than the voltage value applied by the first power supply 8. The second power supply 11 applies an AC voltage having a half cycle shorter than the response time of the liquid crystal molecules 6a to the electrodes 7a and 7b.
[0170]
The second power supply 11 applies an AC voltage having a voltage value larger than the voltage value of the AC voltage having the deflection frequency applied by the first power supply 8. The second power supply 11 applies an alternating voltage having a voltage value at which the liquid crystal molecules 6 a sufficiently move in the liquid crystal layer 6. The voltage value at which the liquid crystal molecules 6a sufficiently move in the liquid crystal layer 6 varies depending on the element configuration, but is 1 × 10. ⁵ The electric field strength is preferably about V / m.
[0171]
In addition, the waveform of the AC voltage applied by the second power source 11 may be a rectangular wave as shown in FIG. 3, and is not limited to a rectangular wave but a triangular wave, a sine wave, or the like. Also good.
[0172]
In such a configuration, when the optical deflecting operation of the optical deflecting device 10 is performed, an alternating voltage having a deflection frequency of about several hundred Hz is applied between the pair of electrodes 7 a and 7 b by the first power supply 8, The light deflection direction is switched at a switching timing of several hundred Hz so that the optical path of the incident light takes one of the first outgoing light a and the second outgoing light b (light deflection step).
[0173]
In the present embodiment, at the start of this optical deflection operation, the frequency of the AC voltage applied between the pair of electrodes 7a and 7b is set higher than the deflection frequency, and an AC voltage having a frequency higher than the deflection frequency is set. Is applied between the electrodes 7a and 7b (application start step). Here, the function as the start processing means is realized. As a result, an alternating voltage having a higher frequency than the voltage applied by the first power supply 8 is applied to the liquid crystal layer 6.
[0174]
According to the above consideration, the response time of the liquid crystal molecules 6a is switched in the direction of the electric field by applying an AC voltage having a frequency higher than the frequency of the AC voltage applied by the first power supply 8 from the second power supply 11. Without catching up with time, an alignment force in a substantially vertical direction can be applied to the liquid crystal layer 6 to facilitate alignment of the liquid crystal molecules 6a in a substantially vertical direction.
[0175]
Accordingly, the alignment regulating force can be effectively applied to the entire liquid crystal layer 6 and can be easily re-aligned in the vertical alignment state, so that the disturbed liquid crystal molecules 6a in the liquid crystal layer 6 can be transferred to the substrate 2, in a shorter time. 3 can be aligned in a substantially vertical alignment state.
[0176]
Further, since the voltage value applied by the second power supply 11 is set to be larger than the voltage value applied by the first power supply 8, a larger electric field is formed on the liquid crystal layer 6 than during the light deflection operation. Is done. Thereby, the force which vibrates the liquid crystal molecule 6a very finely increases, and the alignment regulating force in the vertical direction can be more reliably applied to the liquid crystal molecule 6a. As a result, the liquid crystal molecules 6a can be more reliably aligned with the substrates 2 and 3 in a substantially vertical alignment state.
[0177]
Next, a ninth embodiment of the present invention will be described. The present invention can be applied to, for example, the optical deflection apparatus 20 shown in FIG. 6, and in this embodiment, an application example to the optical deflection apparatus 20 shown in FIG. 6 is shown.
[0178]
As described above, the AC voltage applied by the first power supply 8 is, for example, a rectangular wave as shown in FIG. 3, and the deflection frequency is set to about several hundred Hz. In the present embodiment, the first power supply 8 functions as a first voltage applying unit.
[0179]
The third power supply 21 intermittently applies a pulsed DC voltage to the liquid crystal layer 6 at the start of an optical deflection operation described later. The waveform of the DC voltage applied by the third power supply 21 is a DC voltage having a pulse waveform as shown in FIG. The intermittent application frequency varies depending on the configuration of the optical deflection element 5, but a period of about 0.1 to 1 Hz is preferable. In the present embodiment, the third power supply 21 functions as a third voltage applying unit.
[0180]
The third power supply 21 applies an AC voltage whose voltage value is set larger than the voltage value of the AC voltage applied by the first power supply 8. The optimum voltage value applied by the third power source 21 varies depending on the configuration of the optical deflection element 5, but is 1 × 10. ⁵ It is preferably set to V / m or more.
[0181]
In such a configuration, when the optical deflecting operation of the optical deflecting device 20 is performed, an alternating voltage having a deflection frequency of about several hundred Hz is applied between the pair of electrodes 7 a and 7 b by the first power supply 8, The light deflection direction is switched at a switching timing of several hundred Hz so that the optical path of the incident light takes one of the first outgoing light a and the second outgoing light b (light deflection step).
[0182]
In the present embodiment, at the start of this optical deflection operation, a pulsed DC voltage is intermittently applied between the pair of electrodes 7a and 7b by the third power source 21, and then the deflection by the first power source 8 is performed. An AC voltage having a frequency is applied (application start step). Here, the function as the start processing means is realized.
[0183]
According to the present embodiment, the pulsed DC voltage is intermittently applied between the pair of electrodes 7 a and 7 b by the third power source 21 before the voltage application is started, and intermittently applied to the liquid crystal layer 6. By applying an electric field in the first electric field direction A to the liquid crystal molecules 6a, the occurrence of white turbidity due to alignment defects is suppressed, and the interface between the white turbidity and normal alignment is not left as a trace. Was confirmed.
[0184]
Here, a mechanism for suppressing the occurrence of alignment defects in the liquid crystal molecules 6a will be considered. Before starting to apply the voltage, the mechanism of preventing the occurrence of white turbidity by intermittently applying a pulsed DC voltage between the pair of electrodes 7a and 7b is not clear, but can be estimated as follows. Is possible. That is, an electric field in the first electric field direction A is intermittently formed in the liquid crystal layer 6 by intermittently applying a pulsed DC voltage between the pair of electrodes 7 a and 7 b. At this time, at the moment when the pulsed DC voltage is turned ON / OFF, the liquid crystal molecules 6a in the liquid crystal layer 6 are disordered in the form of waves from the vicinity of the electrodes 7a and 7b, and this disturbance propagates to the adjacent liquid crystal molecules 6a. As a result, the liquid crystal molecules 6 s vibrate intermittently across the entire liquid crystal layer 6, and this vibration temporarily disturbs the alignment state of the liquid crystal molecules 6 a in the entire liquid crystal layer 6, and the liquid crystal molecules 6 partially in the liquid crystal layer 6. Even when the orientation state of 6a is disturbed, it is estimated that there is no trace in the interface portion between the portion where the orientation state is disturbed and the portion where the orientation state is not disturbed. Since the liquid crystal molecules 6a have a property of spontaneously realigning when the alignment state is disturbed, by temporarily disturbing the alignment state of the liquid crystal molecules 6a in the entire liquid crystal layer 6, the liquid crystal layer 6 It is estimated that the spontaneous realignment of the liquid crystal molecules 6 a can be effectively performed over the whole, and the liquid crystal molecules 6 a can be aligned substantially vertically over the entire liquid crystal layer 6.
[0185]
Note that this effect is small when a DC voltage is applied continuously for a long time or when an AC voltage having a frequency about the deflection frequency is applied. This also confirms the importance of the wave-like movement in which the disorder of the alignment state generated when the electric field direction is switched propagates throughout the liquid crystal layer 6 and then re-aligns.
[0186]
According to the present embodiment, even when an alignment defect is partially generated by the light deflection operation in the optical deflecting element 5, the alignment defect is prevented from being fixed, thereby causing the occurrence of the alignment defect. It is possible to provide a highly reliable optical deflection device 20 that suppresses the occurrence of white turbidity.
[0187]
Further, the third power source 21 applies an AC voltage whose voltage value is set to be larger than the voltage value of the AC voltage applied by the first power source 8, and therefore, in the moment when the electric field direction is switched, Since the liquid crystal molecules 6a can move more easily, the interface portion between the alignment defect portion and the normal alignment portion is more effectively removed as a trace, and the realignment of the liquid crystal molecules 6a can be performed uniformly in a shorter time. Can be oriented.
[0188]
Next, a tenth embodiment of the present invention will be described. The present invention can be applied to, for example, the optical deflection apparatus 30 shown in FIG. 8, and in this embodiment, an application example to the optical deflection apparatus 30 shown in FIG. 8 is shown.
[0189]
The optical deflecting device 30 according to the present embodiment has a first power supply 8 that functions as a first voltage applying unit and an AC voltage with a driving frequency applied by the first power supply 8 between the pair of electrodes 7a and 7b. As a second power supply 11 that functions as a second voltage applying means for applying a high-frequency AC voltage, and a third voltage applying means for continuously applying a pulsed DC voltage between the pair of electrodes 7a and 7b. And a functioning third power source 21. The first power supply 8 has a function of making the voltage value variable. The third power source 21 applies a voltage having a voltage value higher (larger) than the voltage value applied by the first power source 8. The second power supply 11 has a function of making both the frequency and the AC voltage value variable. The first, second, and third power supplies 8, 11, and 21 are switched by the switch 12 so that one of them becomes effective.
[0190]
In such a configuration, when the optical deflecting operation of the optical deflecting device 30 is performed, an AC voltage having a driving frequency of about several hundred Hz is applied between the pair of electrodes 7 a and 7 b by the first power supply 8, The light deflection direction is switched at a switching timing of several hundred Hz so that the optical path of the incident light takes one of the first outgoing light a and the second outgoing light b (light deflection step).
[0191]
At this time, by applying an AC voltage having a frequency lower than the deflection frequency by the second power source 11, an AC voltage having a frequency higher than the deflection frequency is applied by increasing the frequency of the AC voltage continuously or stepwise. You may make it do.
[0192]
At this time, an AC voltage having a voltage value higher than the voltage value applied by the first power supply 8 may be applied by the second power supply 11.
[0193]
In the present embodiment, at the start of the light deflection operation, a pulsed DC voltage is intermittently applied between the pair of electrodes 7a and 7b by the third power source 21 prior to application of the voltage to the pair of electrodes 7a and 7b. (Orientation release step), an alternating voltage having a frequency higher than the frequency of the deflection direction switching operation is applied between the pair of electrodes 7a and 7b by the second power source 11 (application start step), and then the alternating current of the deflection frequency is applied. Apply voltage. Here, the function as the start processing means is realized.
[0194]
According to the present embodiment, when the voltage application to the pair of electrodes 7a and 7b is started, the third power source 21 applies a pulsed direct current between the pair of electrodes 7a and 7b before the application of the alternating voltage having the deflection frequency. After applying a voltage intermittently and applying an AC voltage having a frequency higher than the frequency of the deflection direction switching operation between the pair of electrodes 7a and 7b by the second power source 11, the application of the voltage to the electrodes is started. Thus, it was confirmed that the occurrence of white turbidity was suppressed and the interface part between the white turbid part and the normal part was not left as a trace.
[0195]
The mechanism for preventing white turbidity is discussed below. Although the mechanism of the occurrence of white turbidity is not clear, as described above, after applying an alternating voltage with a deflection frequency by the first power supply 8, a pulsed direct current is applied between the pair of electrodes 7 a and 7 b by the third power supply 21. By intermittently applying the voltage, the alignment of the liquid crystal molecules 6a in the entire liquid crystal layer 6 is disturbed, and the trace of the interface portion between the normal alignment portion and the alignment defect portion disappears. In this state, the second power source 11 applies an AC voltage having a frequency higher than the drive frequency between the pair of electrodes 7a and 7b to apply an AC voltage having a shorter cycle than the electric field direction switching cycle that is applied during the optical deflection operation. As a result, the liquid crystal molecules 6a in the liquid crystal layer 6 are maintained in a relatively easy to move state, but the response time due to the switching of the electric field direction cannot sufficiently catch up, so that the liquid crystal molecules 6a vibrate slightly in a state close to the vertical alignment state.
[0196]
By the way, it takes a relatively long time for the liquid crystal molecules 6a whose alignment state is disturbed over the entire liquid crystal layer 6 to realign completely and spontaneously.
[0197]
In the present embodiment, after disturbing the alignment of the liquid crystal molecules 6a in the entire liquid crystal layer 6, the liquid crystal molecules 6a are vibrated minutely in a state close to the vertical alignment state while maintaining a relatively easy movement state. The realignment operation of 6a is promoted, and the realignment can be surely performed in a short time as compared with the case where the liquid crystal molecules are completely realigned spontaneously.
[0198]
In this embodiment, after applying a pulsed DC voltage, a high-frequency AC voltage is applied, thereby speeding up the subsequent realignment process of the entire liquid crystal layer 6 and applying no pulsed DC voltage. Compared with the case where a high-frequency AC voltage is applied to the liquid crystal layer, realignment over the entire liquid crystal layer 6 can be reliably performed in a short time.
[0199]
By the way, in the above-described various embodiments, the second power source 11 applies an alternating voltage having a frequency lower than the deflection frequency, and then increases the frequency of the alternating voltage continuously or stepwise so that it exceeds the deflection frequency. A high frequency AC voltage may be applied. In this case, even when the liquid crystal molecule direction is disturbed due to the influence of an external electric field or temperature change while the operation of the optical deflection element is stopped, the liquid crystal layer is vibrated by an alternating voltage with a relatively low frequency, and the liquid crystal layer flows. By making the orientation state easy to change and then applying a high frequency AC voltage continuously or stepwise, the vertical orientation state can be obtained reliably.
[0200]
The second power supply 11 may apply an alternating voltage having a deflection frequency by applying an alternating voltage having a frequency higher than the deflection frequency and then decreasing the frequency of the alternating voltage continuously or stepwise. Good. In this case, even when the liquid crystal molecule direction is disturbed due to the influence of an external electric field or the like while the operation of the optical deflecting element is stopped, the liquid crystal molecule direction is returned to the vertical state with a high frequency AC voltage, and then continuously or stepwise Since the deflection frequency is applied by decreasing the frequency, it is possible to prevent the liquid crystal molecules from being disturbed easily when the frequency is rapidly switched to the deflection frequency.
[0201]
Further, when an AC voltage having a voltage value higher than the voltage value applied by the first power source 8 is applied by the second power source 11, the electrostatic force acting on the liquid crystal molecules increases, and the second power source 11 is aligned in the vertical direction. The power to try increases. Thereby, even when the alignment state is disturbed by the light deflection operation in the light deflection element and a portion where white turbidity is likely to occur is generated, the liquid crystal molecules can be quickly returned to the original vertical alignment state.
[0202]
In addition, after applying an alternating voltage having a voltage value smaller than the voltage value applied by the first power supply 8 by the second power supply 11, the voltage value of the alternating voltage is increased continuously or stepwise to perform a deflection operation. When a voltage value is applied, even if the liquid crystal molecules are disturbed when the operation of the optical deflection element stops, the voltage value is first applied to the liquid crystal molecules by applying a voltage value smaller than the saturation electric field for switching the liquid crystal molecules. On the other hand, switching is performed at an angle closer to the vertical than the switching position of the light deflection direction, and the voltage value to be applied is increased continuously or stepwise to change the liquid crystal molecules continuously or stepwise to the angle of the light deflection direction. You can get closer. Thereby, it is possible to prevent the liquid crystal molecules from being disturbed due to abrupt switching of the deflection frequency.
[0203]
Next, an eleventh embodiment of the present invention will be described below. In the present embodiment, the dielectric anisotropy of the liquid crystal layer 6 forming the chiral smectic C phase is negative in the frequency band of the alternating voltage whose half cycle time is shorter than the response time of the liquid crystal molecules 6a, and the application start described above The point which can perform step is different from the above-mentioned various embodiments.
[0204]
According to the present embodiment, for example, when an AC voltage is applied in a substantially parallel direction to the liquid crystal layer 6 of the light deflection element 5 of the sixth embodiment, the liquid crystal material having a positive dielectric anisotropy The liquid crystal molecules 6a try to align in a direction parallel to the applied electric field direction. Conversely, a liquid crystal material having a negative dielectric anisotropy tends to be aligned in a direction perpendicular to a given electric field direction.
[0205]
In such a configuration, when the optical deflecting operation of the optical deflecting device is performed, an alternating voltage having a driving frequency of about several hundred Hz is applied between the pair of electrodes 7 a and 7 b by the first power supply 8, and the incident light enters the liquid crystal layer 6. The optical deflection direction is switched at a switching timing of several hundred Hz so that the optical path of the light takes one of the first outgoing light a and the second outgoing light b (light deflection step).
[0206]
Since the liquid crystal layer 6 of the present embodiment is a liquid crystal material having a negative dielectric anisotropy, the liquid crystal molecules 6a are statically applied by applying a high frequency electric field in a direction substantially parallel to the liquid crystal layer 6 during the optical deflection operation. If the alignment is performed so that the electric energy is minimized, the liquid crystal molecules 6 a end up in a vertical alignment state with respect to the layer direction of the liquid crystal layer 6. Thereby, in addition to the alignment regulating force by the alignment film 4, an electrostatic force can be applied, and the liquid crystal molecules 6a can be reliably aligned in the vertical alignment state at the start of the light deflection operation.
[0207]
Further, every time a voltage is applied between the pair of electrodes 7a and 7b, an electrostatic force can be applied in addition to the alignment regulating force by the alignment film 4, so that an alignment defect is generated by the deflection direction switching operation. It is possible to improve the reliability by suppressing the occurrence of an alignment defect due to repeated use, while increasing the speed of the optical path deflecting operation by the optical deflecting element 5 which is suppressed by itself.
[0208]
【Example】
Next, examples of the present invention will be described. In the present embodiment, three types of optical deflection elements A, B, and C are prepared, and the method of applying a voltage to the optical deflection elements A and B is changed as shown in Examples 1 to 4 and Comparative Examples 1 and 2. Thus, performance change due to repeated use was evaluated.
[0209]
First, the surface of a glass substrate (substrates 2 and 3) having a size of 3 cm × 4 cm and a thickness of 1 mm is treated with a vertical alignment film JALS2021-R2 (manufactured by Nippon Synthetic Rubber) and vertically aligned on one side of the glass substrate. A film (alignment film 4) is formed. Two glass substrates are used, and two aluminum electrode sheets (electrodes 7a and 7b) having a thickness of 50 μm, a width of 1 mm, and a length of 3 cm are interposed as spacers, and the vertical alignment film is bonded to the inner surface. . Here, the two aluminum electrode sheets are parallel, and the interval is set to 2 mm. Subsequently, a ferroelectric liquid crystal (CS1029 manufactured by Chisso) was injected between the two glass substrates bonded together by a capillary method, and after cooling, sealed with an adhesive to produce an optical deflection element A having a liquid crystal layer 6. .
[0210]
Similarly to the optical deflection element A, the surface of a glass substrate having a size of 3 cm × 4 cm and a thickness of 1 mm is treated with a vertical alignment film JALS2021-R2 (manufactured by Nippon Synthetic Rubber) and perpendicular to one surface side of the glass substrate. An alignment film is formed. Two glass substrates are used and bonded together with the vertical alignment film as the inner surface with two aluminum electrode sheets having a thickness of 30 μm, a width of 1 mm, and a length of 3 cm interposed as spacers. The two aluminum electrode sheets are parallel and the interval is set to 2 mm. Subsequently, a ferroelectric liquid crystal having negative dielectric anisotropy (FELIX-016 / 100 manufactured by Clariant Japan) is injected between the two glass substrates by a capillary method, and after cooling, sealed with an adhesive, and a liquid crystal layer An optical deflection element B having 6 was produced.
[0211]
Further, in place of the ferroelectric liquid crystal having negative dielectric anisotropy in the light deflection element B, a ferroelectric liquid crystal having positive dielectric anisotropy (FELIX-018 / 000 manufactured by Clariant Japan) is injected by a capillary method, After cooling, it was sealed with an adhesive to produce a light deflection element C.
[0212]
In any of the light deflection elements A, B, and C, the liquid crystal layer between the aluminum electrode sheets is not cloudy at the time of manufacture, and the alignment state is confirmed by a conoscope device, and the vertical alignment state can be confirmed in all parts. It was.
[0213]
(Comparative Example 1)
In Comparative Example 1, ± 200 V, 100 Hz AC voltage similar to pixel shift driving was applied for 40 minutes using the light deflection element A, and the alignment state of the liquid crystal layer thereafter was observed.
[0214]
As a result, according to Comparative Example 1, a slightly cloudy portion was generated in the vicinity of the electrode.
[0215]
Further, according to Comparative Example 1, when the light deflection operation of applying an AC voltage of ± 200 V and 100 Hz for 40 minutes similar to the similar pixel shift driving was repeated, a cloudy portion around the electrode grew.
[0216]
Example 1
In Example 1, ± 200 V, 100 Hz AC voltage similar to pixel shift driving is applied for 40 minutes using the light deflection element A, and then ± 100 V, 1 kHz AC before stopping the light deflection operation. After applying a voltage for 1 minute, it stopped, and the orientation state of the liquid crystal layer after that was observed.
[0217]
As a result, according to Example 1, white turbidity did not occur in the vicinity of the electrode. Thereafter, white turbidity did not occur even when the same light deflection operation was repeated.
[0218]
(Example 2)
In Example 2, after applying an AC voltage of ± 200 V and 100 Hz, which is similar to pixel shift driving, for 40 minutes using the light deflecting element A, a pulsed DC voltage of +200 V is applied 10 times per minute. After that, the film was stopped and the alignment state of the liquid crystal layer was observed.
[0219]
As a result, according to Example 2, white turbidity did not occur in the vicinity of the electrode. Thereafter, white turbidity did not occur even when the same light deflection operation was repeated.
[0220]
(Example 3)
In Example 3, after applying an AC voltage of ± 200 V and 100 Hz, which is similar to pixel shift driving, for 40 minutes using the light deflecting element A, a pulsed DC voltage of +200 V is applied 5 times in 30 seconds. After that, an alternating voltage of ± 100 V and 1 kHz was further applied for 30 seconds and then stopped, and the alignment state of the liquid crystal layer thereafter was observed.
[0221]
As a result, according to Example 3, white turbidity did not occur in the vicinity of the electrode. Thereafter, white turbidity did not occur even when the same light deflection operation was repeated.
[0222]
(Example 4)
In the fourth embodiment, ± 200 V, 100 Hz AC voltage similar to pixel shift driving is applied for 40 minutes using the light deflection element B, and then ± 100 V, 1 kHz AC voltage is applied 5 before stopping the light deflection operation. After applying for 2 seconds, it was stopped, and the alignment state of the liquid crystal layer thereafter was observed.
[0223]
As a result, according to Example 4, white turbidity did not occur in the vicinity of the electrode. Thereafter, white turbidity did not occur even when the same light deflection operation was repeated.
[0224]
(Comparative Example 2)
In Comparative Example 2, after applying an AC voltage of ± 200 V and 100 Hz similar to pixel shift driving for 40 minutes to the light deflection element C, an AC voltage of ± 100 V and 1 kHz was applied for 5 seconds before stopping the optical deflection operation. It stopped later and the orientation state of the liquid crystal layer after that was observed.
[0225]
As a result, according to Comparative Example 2, slight turbidity was generated in the vicinity of the electrode.
[0226]
(Example 5)
Using the optical deflection element A, an AC voltage of ± 200 V and 100 Hz similar to pixel shift driving was applied for 40 minutes as described above, and then the alignment state of the liquid crystal layer was observed, and the vicinity of the electrode was slightly clouded. . Next, after applying an AC voltage of ± 100 V and 1 kHz for 5 seconds, an AC voltage of ± 200 V and 100 Hz similar to pixel shift driving was applied for 1 minute, and the alignment state of the liquid crystal layer was observed. I couldn't.
[0227]
(Comparative Example 3)
When the alignment state of the liquid crystal layer after observing the light deflection element B for one month was observed, a slight turbidity occurred in the vicinity of the electrode. After that, when an AC voltage of ± 200 V and 100 Hz similar to pixel shift driving was applied for 40 minutes, the cloudy portion was slightly enlarged.
[0228]
(Example 6)
After applying + 200V pulsed DC voltage 10 times per minute to the element of Comparative Example 3, then applying ± 200V, 100Hz AC voltage similar to pixel shift driving for 1 minute to align the liquid crystal layer When the state was observed, there was no cloudiness.
[0229]
(Example 7)
Using the optical deflection element B, the alignment state when the voltage was stopped by changing only the voltage value from an alternating voltage of ± 200 V and 100 Hz similar to pixel shift driving was observed with a conoscope device. Table 1 compares the state of returning to the vertical alignment state after stopping. The state of returning when stopping at a low voltage was good. Table 1 shows the results.
[0230]
[Table 1]

[0231]
【The invention's effect】
According to the optical deflecting device of the first aspect of the present invention, the configuration is easy by switching the direction of the electric field formed in the liquid crystal layer of the chiral smectic C phase by applying an alternating voltage of the deflection frequency to the pair of electrodes. Even in the case of a light deflector, the optical path shift operation is speeded up by utilizing the spontaneous polarization of the liquid crystal of the chiral smectic C phase, and before the voltage application is stopped, it is shorter than the switching period of the light deflection direction. By switching the direction of the electric field periodically, realignment of the liquid crystal molecules in the direction determined by the spontaneous polarization and the external electric field is promoted, and the liquid crystal molecules whose alignment state is disturbed by the light deflection operation are aligned substantially perpendicular to the substrate. Therefore, the occurrence of alignment defects due to repeated use can be suppressed, and a highly reliable optical deflection apparatus can be provided.
[0233]
Claim 2 According to the described invention, the claims 1 In the mounted optical deflection device, when the voltage application to the electrode is stopped, the liquid crystal whose orientation state is disturbed by the light deflection operation of the light deflection element is applied by applying a voltage larger than the voltage that causes the disorder of the orientation state of the liquid crystal molecules. Since the molecules can be surely aligned substantially perpendicularly to the substrate, the occurrence of alignment defects due to repeated use can be more reliably suppressed, and a more reliable optical deflection apparatus can be provided.
[0234]
Claim 3 According to the described invention, claim 1 Or 2 The optical deflecting device according to the present invention is an optical deflecting element that has a simplified configuration by switching an electric field direction formed in a liquid crystal layer of a chiral smectic C phase by applying an alternating voltage of a deflection frequency to a pair of electrodes. However, using the spontaneous polarization of the liquid crystal of the chiral smectic C phase, the optical path shift operation is speeded up, and after applying the alternating voltage of the deflection frequency, the pulsed direct current voltage is applied before the voltage application is stopped. After intermittently applying and temporarily disturbing the alignment state of the liquid crystal molecules over the entire liquid crystal layer, a cycle shorter than the switching cycle of the light deflection direction by applying an AC voltage higher than the deflection frequency. By forming an electric field whose direction is switched at, even if the alignment state of the liquid crystal molecules is partially disturbed by the light deflection operation in the deflecting element, it is not disturbed with the part where the alignment state is partially disturbed. The liquid crystal molecules are spontaneously realigned over the entire liquid crystal layer by eliminating the interface with the liquid crystal layer, and the liquid crystal molecules are moved to the entire liquid crystal layer in a shorter time than the spontaneous realignment process of the liquid crystal molecules. Can be uniformly oriented in a substantially vertical manner.
[0235]
Claim 4 According to the optical deflecting device of the described invention, the light whose structure is simplified by applying an alternating voltage with a deflection frequency to a pair of electrodes and switching the direction of the electric field formed in the liquid crystal layer of the chiral smectic C phase. Even if it is a deflecting element, it uses the spontaneous polarization of the liquid crystal of the chiral smectic C phase to speed up the optical path shift operation, and before stopping the voltage application, the application of the alternating voltage of the deflection frequency is followed by a pulse. The orientation state of the liquid crystal molecules was partially disturbed by the light deflection operation of the light deflection element by intermittently applying a direct current DC voltage and temporarily disturbing the orientation state of the liquid crystal molecules throughout the liquid crystal layer. In some cases, the interface part between the part where the alignment state is partially disturbed and the part where the disorder is not disturbed is eliminated, and the liquid crystal molecules are spontaneously realigned over the entire liquid crystal layer, thereby causing alignment defects due to repeated use. Suppression The liquid crystal molecules can be uniformly aligned across the liquid crystal layer.
[0236]
Claim 5 According to the described invention, the claims 3 Or 4 In the described light deflecting device, the alignment state of the liquid crystal molecules can be more effectively disturbed over the entire liquid crystal layer, and the realignment process of the liquid crystal molecules can be reliably performed in the entire liquid crystal layer. The alignment state of the molecules can be made more uniform throughout the liquid crystal layer.
[0238]
Claim Item 6 According to the optical deflecting device of the described invention, the light whose structure is simplified by applying an alternating voltage with a deflection frequency to a pair of electrodes and switching the direction of the electric field formed in the liquid crystal layer of the chiral smectic C phase. Even if it is a deflecting element, it uses the spontaneous polarization of the liquid crystal of chiral smectic C phase to speed up the optical path shift operation, and at the start of voltage application, the voltage value of the alternating voltage of the applied deflection frequency is continuously or stepwise. By stopping the application at a voltage value smaller than the voltage value that enables switching of the light deflection direction, the applied voltage value becomes smaller than the saturation electric field for switching the liquid crystal molecules. Since the molecules can be stopped in a state close to the vertical state, liquid crystal molecules are prevented from being disturbed when the optical deflection operation is stopped without changing the deflection frequency. Bets can be, it is possible to provide a highly reliable light deflection methods with a simple configuration.
[0239]
Claim 7 According to the optical deflecting device of the invention described above, an optical deflecting element that has a simplified configuration by switching an electric field direction formed in a liquid crystal layer by applying an alternating voltage of a deflection frequency to a pair of electrodes. In addition, the spontaneous polarization of the chiral smectic C phase liquid crystal is used to speed up the optical path shift operation, and at the start of voltage application, an AC voltage having a frequency higher than the deflection frequency is applied, and then the AC voltage at the deflection frequency is applied. Is applied to the liquid crystal layer to form an electric field that switches at a cycle shorter than the switching cycle of the light deflection direction, and this high-frequency electric field causes the liquid crystal molecules near the intermediate layer of the liquid crystal layer to be aligned in the vertical direction. The liquid crystal molecules in the portion where the orientation direction is disturbed and the white turbidity is easily formed while the device is stopped can be returned to the vertical orientation state, so that the orientation state disorder is fixed. It is possible to prevent the occurrence of white turbidity portion that.
[0240]
Claim 8 According to the described invention, the claims 7 In the described optical deflecting device, even when the liquid crystal molecular direction is disturbed by the influence of an external electric field or temperature change while the operation of the optical deflecting element is stopped, the liquid crystal layer is vibrated with an alternating voltage having a relatively low frequency, Applying a high-frequency AC voltage by increasing the frequency continuously or stepwise after making the layer easy to flow and changing the alignment state allows the liquid crystal molecules to be vertically aligned without disturbing the alignment state during frequency switching. The alignment state can be restored.
[0241]
Claim 9 According to the described invention, the claims 7 In the described optical deflecting device, even when the liquid crystal molecule direction is disturbed due to the influence of an external electric field or the like while the operation of the optical deflecting element is stopped, the liquid crystal molecule direction is continuously returned after the liquid crystal molecule direction is returned to the vertical state with a high frequency AC voltage. Alternatively, by applying the deflection frequency by gradually decreasing the frequency, the liquid crystal molecules can be returned to the vertical alignment state in a short time before the start of the optical deflection operation without disturbing the alignment state when switching the frequency. Therefore, it is possible to prevent the liquid crystal molecules from being easily disturbed when the frequency is rapidly switched.
[0243]
Claim 10 According to the described invention, the claims 7 to 9 In the described optical deflecting device, the electrostatic force acting on the liquid crystal molecules can be increased, and the force to align the liquid crystal molecules in the vertical direction can be increased, so that the alignment state is disturbed by the optical deflection operation in the optical deflecting element. Even when a portion that tends to form white turbidity occurs, the liquid crystal molecules can be returned to the vertical alignment state more reliably and promptly before the start of the light deflection operation without disturbing the alignment state when switching the frequency.
[0244]
Claim 11 According to the described invention, the claims 7 to 9 In the optical deflection element described above, even when liquid crystal molecules are disturbed when the operation of the optical deflection element is stopped, first, a voltage value smaller than the saturation electric field for switching the liquid crystal molecules is applied to the liquid crystal molecules. The angle of the light deflection direction is changed continuously or stepwise by changing the applied voltage value continuously or stepwise by switching at an angle closer to the vertical than the light deflection direction changing position. Therefore, the disorder of the alignment state of the liquid crystal molecules due to the rapid switching of the deflection frequency can be prevented.
[0245]
Claim 12 According to the optical deflecting device of the described invention, 7 to 9 In the described light deflection apparatus, by intermittently applying a pulsed DC voltage, the orientation of the entire liquid crystal layer is greatly disturbed, and the entire liquid crystal layer is temporarily made easy to form a cloudy state. The entire liquid crystal layer can be returned to a uniform vertical alignment by eliminating the interface between the normal part and the normal part and then applying a high-frequency electric field, so that the interface part between the cloudy part and the normal part remains as a trace. Can be prevented.
[0246]
Claim 13 According to the optical deflecting device of the invention described above, an optical deflecting element that has a simplified configuration by switching an electric field direction formed in a liquid crystal layer by applying an alternating voltage of a deflection frequency to a pair of electrodes. In addition, the spontaneous polarization of chiral smectic C-phase liquid crystal is used to speed up the optical path shift operation, and the pulsed DC voltage is intermittently applied by the third voltage applying means, thereby aligning the liquid crystal molecules. By temporarily disturbing the entire liquid crystal layer and then applying an alternating voltage with a deflection frequency, the liquid crystal molecules can be returned to the vertical alignment state in a shorter time before the light deflection operation starts. In addition, application of a pulsed DC voltage can prevent the interface portion between the white turbid portion and the normal portion from remaining as a trace even when white turbidity occurs before the start of the light deflection operation.
[0247]
Claim 14 According to the described invention, the claims 12 Or 13 In the light deflection apparatus described above, it is possible to more effectively temporarily disturb the alignment state of the liquid crystal molecules over the entire liquid crystal layer by applying a large voltage, and the interface between the above-described cloudy portion and the normal portion The marks of the part can be effectively disturbed and erased.
[0249]
Claim 15 According to the light deflection method of the described invention, light having a simplified structure can be obtained by switching an electric field direction formed in a liquid crystal layer of a chiral smectic C phase by applying an alternating voltage of a deflection frequency to a pair of electrodes. Even in the case of a deflecting element, the optical path shift operation is speeded up by utilizing the spontaneous polarization of the liquid crystal of chiral smectic C phase, and before the voltage application is stopped, the electric field has a shorter cycle than the switching cycle of the light deflection direction. By switching the direction, realignment of liquid crystal molecules in a direction determined by spontaneous polarization and an external electric field is promoted, and liquid crystal molecules whose alignment state is disturbed by light deflection operation can be aligned substantially perpendicular to the substrate. Thus, the occurrence of alignment defects due to repeated use can be suppressed, and a highly reliable optical deflection method can be provided.
[0250]
Claim 16 According to the light deflection method of the described invention, light having a simplified structure can be obtained by switching an electric field direction formed in a liquid crystal layer of a chiral smectic C phase by applying an alternating voltage of a deflection frequency to a pair of electrodes. Even if it is a deflecting element, it uses the spontaneous polarization of the liquid crystal of the chiral smectic C phase to speed up the optical path shift operation, and before stopping the voltage application, the application of the alternating voltage of the deflection frequency is followed by a pulse. The orientation state of the liquid crystal molecules was partially disturbed by the light deflection operation of the light deflection element by intermittently applying a direct current DC voltage and temporarily disturbing the orientation state of the liquid crystal molecules throughout the liquid crystal layer. In some cases, the interface part between the part where the alignment state is partially disturbed and the part where the disorder is not disturbed is eliminated, and the liquid crystal molecules are spontaneously realigned over the entire liquid crystal layer, thereby causing alignment defects due to repeated use. Suppression The liquid crystal molecules can be uniformly aligned across the liquid crystal layer.
[0251]
Claim 17 According to the light deflection method of the described invention, light having a simplified structure can be obtained by switching an electric field direction formed in a liquid crystal layer of a chiral smectic C phase by applying an alternating voltage of a deflection frequency to a pair of electrodes. Even if it is a deflecting element, it uses the spontaneous polarization of the liquid crystal of chiral smectic C phase to speed up the optical path shift operation, and after applying the alternating voltage of the deflection frequency, it is pulsed before stopping the voltage application. After intermittently applying a direct current voltage to disrupt the alignment state of the liquid crystal molecules throughout the liquid crystal layer, an alternating voltage higher than the deflection frequency is applied to change the optical deflection direction. By forming an electric field that changes direction with a shorter period than that, even if the alignment state of liquid crystal molecules is partially disturbed by the light deflection operation of the deflecting element, the alignment state is partially disturbed with the part where the alignment state is partially disturbed. The liquid crystal molecules are spontaneously realigned over the entire liquid crystal layer by eliminating the interface portion with the non-existing portion, and the liquid crystal molecules can be transferred to the liquid crystal layer in a shorter time than the spontaneous realignment process of the liquid crystal molecules. The entire film can be uniformly oriented in a substantially vertical direction.
[0252]
Claim 18 According to the light deflection method of the described invention, light having a simplified structure can be obtained by switching an electric field direction formed in a liquid crystal layer of a chiral smectic C phase by applying an alternating voltage of a deflection frequency to a pair of electrodes. Even if it is a deflecting element, it uses the spontaneous polarization of the liquid crystal of chiral smectic C phase to speed up the optical path shift operation, and at the start of voltage application, the voltage value of the alternating voltage of the applied deflection frequency is continuously or stepwise. By stopping the application at a voltage value smaller than the voltage value that enables switching of the light deflection direction, the applied voltage value becomes smaller than the saturation electric field for switching the liquid crystal molecules. Since the molecules can be stopped in a state close to the vertical state, liquid crystal molecules are prevented from being disturbed when the optical deflection operation is stopped without changing the deflection frequency. Bets can be, it is possible to provide a highly reliable light deflection methods with a simple configuration.
[0253]
Claim 19 According to the light deflection method of the described invention, light having a simplified structure can be obtained by applying an alternating voltage with a deflection frequency to a pair of electrodes to switch the direction of the electric field formed in the liquid crystal layer of the chiral smectic C phase. Even if it is a deflection element, the optical polarization shift operation is speeded up by utilizing the spontaneous polarization of the liquid crystal of chiral smectic C phase, and at the start of voltage application, the frequency is higher than the deflection frequency before applying the alternating voltage of the deflection frequency. By applying an alternating current voltage of, an electric field that switches at a cycle shorter than the switching cycle of the light deflection direction is formed in the liquid crystal layer, thereby applying a force to orient the liquid crystal molecules in the vertical direction near the intermediate layer of the liquid crystal layer. Therefore, even if white turbidity occurs while the light deflection operation is stopped (standby), the liquid crystal molecules are suspended before the operation starts. Can be returned to alignment state, it is possible to provide a highly reliable light deflection methods.
[0254]
Claim 20 According to the optical deflection method of the present invention, an optical deflection whose configuration is simplified by applying an alternating voltage of a deflection frequency to a pair of electrodes and switching the direction of the electric field formed in the liquid crystal layer of the chiral smectic C phase. Even in the case of an element, the spontaneous polarization of chiral smectic C-phase liquid crystal is used to speed up the optical path shift operation, and at the start of voltage application, a pulsed DC voltage is intermittently applied to align the orientation of liquid crystal molecules. The liquid crystal molecules can be aligned in the direction of light deflection by applying an alternating voltage with a deflection frequency after the state is temporarily disturbed over the entire liquid crystal layer, so that it becomes cloudy while the light deflection operation is stopped (standby). Even in the case of the occurrence of voltage, at the start of voltage application, the interface part between the disordered part and the normal part of the liquid crystal layer can be eliminated, and a more reliable light deflection method can be provided. .
[0255]
Claim 21 The optical deflection method of the present invention is an optical deflection element that has a simplified configuration by applying an alternating voltage with a deflection frequency to a pair of electrodes to switch the direction of the electric field formed in the liquid crystal layer of the chiral smectic C phase. Even so, the spontaneous polarization of the chiral smectic C-phase liquid crystal is used to speed up the optical path shift operation, and at the start of voltage application, the pulsed DC voltage is interrupted before applying the AC voltage at the deflection frequency. The liquid crystal molecules are temporarily disturbed over the entire liquid crystal layer and then applied with an AC voltage having a frequency higher than the deflection frequency, so that the entire liquid crystal layer is uniformly aligned in a shorter time. Even when white turbidity occurs while the light deflection operation is stopped (standby), the interface between the disordered portion of the liquid crystal layer and the normal portion is prevented from remaining as a trace, and is highly reliable. Provides light deflection method Kill.
[Brief description of the drawings]
FIGS. 1A and 1B show an example of the basic configuration of an optical deflector according to a first embodiment of the present invention, where FIG. 1A is a plan view, FIG. 1B is a front view, and FIG. .
FIG. 2 is a side view showing an alignment state of liquid crystal molecules in a liquid crystal layer.
FIG. 3 is a timing chart showing a waveform of an AC voltage applied between a pair of electrodes.
FIG. 4 is a side view for explaining disorder of alignment state of liquid crystal molecules in a liquid crystal layer.
FIGS. 5A and 5B show examples of the basic configuration of an optical deflecting device according to a second embodiment of the present invention, where FIG. 5A is a plan view, FIG. 5B is a front view, and FIG. 5C is a side view; .
FIGS. 6A and 6B show examples of the basic configuration of an optical deflecting device according to a third embodiment of the present invention. FIG. 6A is a plan view, FIG. 6B is a front view, and FIG. .
FIG. 7 is a timing chart showing a waveform of an AC voltage applied between a pair of electrodes.
FIGS. 8A and 8B show examples of the basic configuration of an optical deflecting device according to a fourth embodiment of the present invention, where FIG. 8A is a plan view, FIG. 8B is a front view, and FIG. 8C is a side view; .
[Explanation of symbols]
1 Light deflection device
2, 3 substrate
4 Alignment film
5 Light deflection elements
6 Liquid crystal layer
7a, 7b electrode
8 First voltage applying means, second voltage applying means
10 Optical deflection device
11 Second voltage applying means
20 Optical deflection device
21 Third voltage applying means
30 Optical deflection device

Claims (21)

A pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer are aligned in a direction substantially perpendicular to the liquid crystal layer. An optical deflection element having an alignment film and an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer;
First voltage applying means for applying an alternating voltage of a deflection frequency for switching a light deflection direction by the light deflection element to the electrode;
Second voltage applying means for applying an alternating voltage of a frequency different from the deflection frequency to the electrode;
When stopping the application of voltage to the electrode, the application of the alternating voltage having the deflection frequency after the application of the alternating voltage of the deflection frequency by the first voltage applying means is stopped. Processing means;
An optical deflection apparatus comprising: It said second voltage applying means, said first voltage applying means according to claim 1 Symbol placement of the optical deflecting device for applying an AC voltage of a voltage value higher than the voltage applied. A third voltage applying means for applying a pulsed DC voltage to the electrode;
The stop processing means intermittently applies a pulsed DC voltage by the third voltage applying means following the application of the alternating voltage of the deflection frequency by the first voltage applying means when the application of the voltage to the electrode is stopped. 3. An optical deflecting device according to claim 1, wherein an AC voltage having a frequency higher than the deflection frequency is applied by the second voltage applying means after being applied to the light. A pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer are aligned in a direction substantially perpendicular to the liquid crystal layer. An optical deflection element having an alignment film and an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer;
First voltage applying means for applying an alternating voltage of a deflection frequency for switching a light deflection direction by the light deflection element to the electrode;
A third voltage applying means for applying a pulsed DC voltage to the electrode;
Stop processing means for intermittently applying a pulsed DC voltage by the third voltage applying means after applying the alternating voltage of the deflection frequency by the first voltage applying means when stopping the application of the voltage to the electrode When,
An optical deflection apparatus comprising: It said third voltage applying means, the optical deflecting device according to claim 3 or 4, wherein applying a DC voltage of a voltage value higher than the voltage value of the first voltage applying unit applies. A pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer are aligned in a direction substantially perpendicular to the liquid crystal layer. An optical deflection element having an alignment film and an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer;
A fourth voltage applying means for changing the voltage value of the alternating voltage of the deflection frequency for switching the light deflection direction by the light deflection element and applying it to the electrode;
When stopping the application of the voltage to the electrode, the voltage value of the alternating voltage of the deflection frequency applied by the fourth voltage applying means is continuously or stepwise decreased so that the light deflection direction can be switched. Stop processing means for stopping application at a small voltage value;
An optical deflection apparatus comprising: A pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer are aligned in a direction substantially perpendicular to the liquid crystal layer. An optical deflection element having an alignment film and an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer;
First voltage applying means for applying an alternating voltage of a deflection frequency for switching a light deflection direction by the light deflection element to the electrode;
Second voltage applying means for applying an alternating voltage of a frequency different from the deflection frequency to the electrode;
At the start of voltage application to the electrode, an AC voltage having a frequency higher than the deflection frequency is applied by the second voltage application unit, and then an AC voltage having the deflection frequency is applied by the first voltage application unit. Start processing means;
An optical deflection apparatus comprising: The second voltage application means applies an AC voltage having a frequency lower than the deflection frequency to the electrode, and then increases the frequency of the AC voltage continuously or stepwise to increase the voltage higher than the deflection frequency. Apply an alternating voltage of frequency,
The start processing means starts the application of the voltage to the electrode, and subsequently applies the AC voltage having a frequency higher than the deflection frequency by the second voltage application means, and then sets the deflection frequency by the first voltage application means. 8. The optical deflection apparatus according to claim 7, wherein an alternating voltage is applied. The second voltage applying means applies an AC voltage having a frequency higher than the deflection frequency to the electrode and then decreases the frequency of the AC voltage continuously or stepwise to thereby change the AC voltage of the deflection frequency. Apply
The start processing means applies an alternating voltage of the deflection frequency by the first voltage applying means following the application of the alternating voltage of the deflection frequency by the second voltage applying means when the application of the voltage to the electrode is started. The light deflection apparatus according to claim 7 . 10. The optical deflection apparatus according to claim 7, wherein the second voltage applying unit applies an AC voltage having a voltage value higher than a voltage value applied by the first voltage applying unit. 11. The second voltage applying means continuously applies the AC voltage value after applying an AC voltage having a voltage value smaller than the voltage value applied by the first voltage applying means at the start of applying the voltage to the electrode. The optical deflection apparatus according to claim 7 , wherein the deflection operation voltage value is applied in a stepwise or stepwise manner. A third voltage applying means for applying a pulsed DC voltage to the electrode;
The application start means, when starting to apply a voltage to the electrode, is intermittently applied with a pulsed DC voltage by the third voltage application means, and then is higher than the deflection frequency by the second voltage application means. The optical deflection apparatus according to claim 7 , wherein an alternating voltage having the deflection frequency is applied by the first voltage applying unit after an alternating voltage having a frequency is applied. A pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer are aligned in a direction substantially perpendicular to the liquid crystal layer. An optical deflection element having an alignment film and an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer;
First voltage applying means for applying an alternating voltage of a deflection frequency for switching a light deflection direction by the light deflection element to the electrode;
A third voltage applying means for applying a pulsed DC voltage to the electrode;
At the start of application of voltage to the electrode, start processing means for applying an alternating voltage of the deflection frequency by the first voltage application means after intermittently applying a pulsed DC voltage by the third voltage application means When,
An optical deflection apparatus comprising: The optical deflection apparatus according to claim 12 or 13, wherein the third voltage applying unit applies a DC voltage having a voltage value higher than a voltage value applied by the first voltage applying unit. A pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer are aligned in a direction substantially perpendicular to the liquid crystal layer. Using an optical deflection element having an alignment film and an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer, an alternating voltage having a deflection frequency for switching the optical deflection direction by the optical deflection element is applied to the electrode. Applying an optical deflection step,
An application stop step of applying an alternating voltage having a frequency higher than the deflection frequency to the electrode following application of the alternating voltage of the deflection frequency to the electrode, when stopping the application of the voltage to the electrode;
An optical deflection method comprising: A pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer are aligned in a direction substantially perpendicular to the liquid crystal layer. Using an optical deflection element having an alignment film and an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer, an alternating voltage having a deflection frequency for switching the optical deflection direction by the optical deflection element is applied to the electrode. Applying an optical deflection step,
An application stopping step of intermittently applying a pulsed DC voltage to the electrode following application of the AC voltage of the deflection frequency to the electrode when stopping the application of the voltage to the electrode;
An optical deflection method comprising: A pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer are aligned in a direction substantially perpendicular to the liquid crystal layer. Using an optical deflection element having an alignment film and an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer, an alternating voltage having a deflection frequency for switching the optical deflection direction by the optical deflection element is applied to the electrode. Applying an optical deflection step,
An orientation cancellation step of intermittently applying a pulsed DC voltage to the electrode following application of the AC voltage of the deflection frequency to the electrode upon stopping application of the voltage to the electrode;
An application stopping step of applying an AC voltage having a frequency higher than the deflection frequency to the electrode following application of a pulsed DC voltage to the electrode;
An optical deflection method comprising: A pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer are aligned in a direction substantially perpendicular to the liquid crystal layer. Using an optical deflection element having an alignment film and an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer, an alternating voltage having a deflection frequency for switching the optical deflection direction by the optical deflection element is applied to the electrode. Applying an optical deflection step,
The voltage value of the alternating voltage of the deflection frequency to be applied subsequent to the application of the alternating voltage of the deflection frequency to the electrode is decreased continuously or stepwise to enable switching of the light deflection direction. An application stop step for stopping the application;
An optical deflection method comprising: A pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer are aligned in a direction substantially perpendicular to the liquid crystal layer. Using an optical deflection element having an alignment film and an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer, an alternating voltage having a deflection frequency for switching the optical deflection direction by the optical deflection element is applied to the electrode. Applying an optical deflection step,
An application start step of applying an alternating voltage of a higher frequency than the deflection frequency before the application of the alternating voltage of the deflection frequency to the electrode;
An optical deflection method comprising: A pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer are aligned in a direction substantially perpendicular to the liquid crystal layer. Using an optical deflection element having an alignment film and an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer, an alternating voltage having a deflection frequency for switching the optical deflection direction by the optical deflection element is applied to the electrode. Applying an optical deflection step,
An application start step of intermittently applying a pulsed DC voltage to the electrode before applying an AC voltage of deflection frequency to the electrode;
An optical deflection method comprising: A pair of transparent substrates arranged opposite to each other, a liquid crystal layer filled between the pair of substrates to form a chiral smectic C phase, and liquid crystal molecules in the liquid crystal layer are aligned in a direction substantially perpendicular to the liquid crystal layer. Using an optical deflection element having an alignment film and an electrode for generating an electric field in a direction substantially parallel to the liquid crystal layer, an alternating voltage having a deflection frequency for switching the optical deflection direction by the optical deflection element is applied to the electrode. Applying an optical deflection step,
An orientation release step of intermittently applying a pulsed DC voltage to the electrode before applying an AC voltage of a deflection frequency to the electrode;
An application start step of applying an alternating voltage having a frequency higher than the deflection frequency to the electrode following the application of a pulsed direct current voltage to the electrode;
An optical deflection method comprising:

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