JP2003123304A - Optical head device - Google Patents
Optical head deviceInfo
- Publication number
- JP2003123304A JP2003123304A JP2001315404A JP2001315404A JP2003123304A JP 2003123304 A JP2003123304 A JP 2003123304A JP 2001315404 A JP2001315404 A JP 2001315404A JP 2001315404 A JP2001315404 A JP 2001315404A JP 2003123304 A JP2003123304 A JP 2003123304A
- Authority
- JP
- Japan
- Prior art keywords
- phase correction
- correction element
- resistor
- voltage
- head device
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Links
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- Optical Head (AREA)
- Optical Recording Or Reproduction (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、光ディスクや光磁
気ディスクなどの光記録媒体の情報の記録・再生を行う
光ヘッド装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head device for recording / reproducing information on / from an optical recording medium such as an optical disk or a magneto-optical disk.
【０００２】[0002]
【従来の技術】光ディスクであるＤＶＤは、同じく光デ
ィスクであるＣＤに比べデジタル情報が高密度で記録さ
れており、ＤＶＤを再生するための光ヘッド装置は、光
源の波長をＣＤの７８０ｎｍよりも短い６５０ｎｍまた
は６３５ｎｍとしたり、対物レンズの開口数（ＮＡ）を
ＣＤの０．４５よりも大きい０．６にして光ディスク面
上に集光するスポット径を小さくしている。2. Description of the Related Art A DVD, which is an optical disc, has digital information recorded at a higher density than a CD, which is also an optical disc, and an optical head device for reproducing a DVD has a light source wavelength shorter than 780 nm of a CD. The diameter of the objective lens is set to 650 nm or 635 nm, or the numerical aperture (NA) of the objective lens is set to 0.6, which is larger than 0.45 of CD, to reduce the spot diameter condensed on the optical disk surface.
【０００３】さらに、次世代の光記録においては光源の
波長を４００ｎｍ程度、ＮＡを０．６以上とすること
で、より大きな記録密度を得ることが提案されている。
しかし、光源の短波長化や対物レンズの高ＮＡ化が原因
で、光ディスク面が光軸に対して直角より傾くチルトの
許容量や光ディスクの厚みムラの許容量が小さくなる。Further, in the next-generation optical recording, it has been proposed to obtain a larger recording density by setting the wavelength of the light source to about 400 nm and the NA to 0.6 or more.
However, due to the shorter wavelength of the light source and the higher NA of the objective lens, the permissible tilt for tilting the optical disk surface from a right angle with respect to the optical axis and the permissible uneven thickness of the optical disk become smaller.
【０００４】これら許容量が小さくなる理由は、光ディ
スクのチルトの場合にはコマ収差が発生し、光ディスク
の厚みムラの場合には球面収差が発生するために、光ヘ
ッド装置の集光特性が劣化して信号の読み取りが困難に
なることによる。高密度記録において、光ディスクのチ
ルトや厚みムラに対する光ヘッド装置の許容量を拡げる
ためにいくつかの方式が提案されている。The reason why these allowances are small is that coma aberration occurs when the optical disc is tilted, and spherical aberration occurs when the optical disc has uneven thickness, so that the condensing characteristics of the optical head device deteriorate. It becomes difficult to read the signal. In high-density recording, some methods have been proposed in order to expand the allowable amount of the optical head device with respect to tilt and thickness unevenness of the optical disc.
【０００５】一つの方式として、通常光ディスクの接線
方向と半径方向との２軸方向に移動する対物レンズのア
クチュエータに、検出されたチルト角に応じて対物レン
ズを傾けるように傾斜用の軸を追加する方式がある。し
かし、この追加方式では球面収差は補正できないこと
や、アクチュエータの構造が複雑になることなどの問題
がある。As one method, a tilt axis is added to an actuator of an objective lens which normally moves in two axial directions of a tangential direction and a radial direction of an optical disk so as to tilt the objective lens according to a detected tilt angle. There is a method to do. However, this additional method has problems that spherical aberration cannot be corrected and that the structure of the actuator is complicated.
【０００６】また別の方式として、対物レンズと光源と
の間に備えた位相補正素子により波面収差を補正する方
式がある。この補正方式では、アクチュエータに大幅な
改造を施すことなく光ヘッド装置に素子を組み入れるだ
けで光ディスクのチルトの許容量や厚みムラの許容量を
拡げることができる。As another method, there is a method of correcting the wavefront aberration by a phase correction element provided between the objective lens and the light source. With this correction method, the allowable amount of tilt and uneven thickness of the optical disk can be increased by simply incorporating the element in the optical head device without making a large modification to the actuator.
【０００７】例えば、位相補正素子を用いて光ディスク
のチルトを補正する上記の補正方式に特開平１０−２０
２６３がある。これは、位相補正素子を構成している液
晶などの複屈折性材料を挟持している一対の基板のそれ
ぞれに、電極が分割されて形成された分割電極に電圧を
印加して、複屈折性材料の実質的な屈折率を光ディスク
のチルト角に応じて変化させ、この屈折率の変化により
発生した透過光の位相（波面）変化により、光ディスク
のチルトで発生したコマ収差を補正する方式である。For example, the above-mentioned correction method for correcting the tilt of an optical disk by using a phase correction element is disclosed in Japanese Patent Laid-Open No. 10-20.
There is 263. This is because a voltage is applied to a divided electrode formed by dividing an electrode on each of a pair of substrates sandwiching a birefringent material such as liquid crystal that constitutes a phase correction element, and the birefringence This is a method in which the substantial refractive index of the material is changed according to the tilt angle of the optical disc, and the coma aberration caused by the tilt of the optical disc is corrected by the phase (wavefront) change of the transmitted light caused by the change of the refractive index. .
【０００８】[0008]
【発明が解決しようとする課題】液晶を利用した位相補
正素子で波面収差を補正するには、位相補正素子の場所
により異なる電圧を印加して液晶分子の配向を変化さ
せ、生じた屈折率分布による位相変化と補正する波面収
差を相殺させる。したがって、発生させる位相変化量は
液晶に印加する電圧で制御するが、位相変化の電圧依存
性が急峻である場合、細かく位相変化を制御するために
は、電圧の変化量を微細に制御する必要があるために、
制御性が悪くなる。特に、ある種の液晶において、液晶
の厚さを増加して複屈折性を高めた場合、制御電圧をほ
とんど変化させなくとも、位相変化量が大きくなるため
に、位相変化の制御性が悪くなる。In order to correct the wavefront aberration with a phase correction element using liquid crystal, different voltages are applied depending on the location of the phase correction element to change the orientation of liquid crystal molecules, and the resulting refractive index distribution The wavefront aberration to be corrected is canceled by the phase change due to. Therefore, the amount of phase change generated is controlled by the voltage applied to the liquid crystal, but when the voltage dependence of the phase change is steep, it is necessary to finely control the amount of voltage change in order to finely control the phase change. Because there is
Controllability deteriorates. Particularly, in the case of a certain type of liquid crystal, when the thickness of the liquid crystal is increased to increase the birefringence, the phase change amount becomes large even if the control voltage is hardly changed, and thus the controllability of the phase change becomes poor. .
【０００９】このように制御性が悪い場合の解決方法し
て、電圧依存性の緩やかな特性を有する液晶材料を用い
る、また液晶駆動用のより高精度な電圧発生回路を用い
る方法があった。しかし、前者の場合は、液晶材料選定
に制約があるとともに、他の特性とのトレードオフとな
ることがあり、また、後者の場合は、液晶駆動用の電圧
発生回路のコスト高になる問題があった。したがって、
液晶材料の特性に依存せず、また汎用の液晶駆動用の電
圧発生回路を用いても、高精度に位相補正素子の位相変
化を制御できる技術が望まれていた。As a solution to the problem of poor controllability, there has been a method of using a liquid crystal material having a gradual voltage dependence characteristic and a more accurate voltage generating circuit for driving the liquid crystal. However, in the former case, there are restrictions on the selection of the liquid crystal material, and there is a trade-off with other characteristics. In the latter case, there is a problem that the cost of the voltage generation circuit for driving the liquid crystal becomes high. there were. Therefore,
There has been a demand for a technique capable of controlling the phase change of the phase correction element with high accuracy without depending on the characteristics of the liquid crystal material and using a general-purpose liquid crystal driving voltage generation circuit.
【００１０】[0010]
【課題を解決するための手段】本発明は、上記の課題を
解決するためになされたものであり、光源と、光源から
の出射光を光記録媒体上に集光させるための対物レンズ
と、光源と対物レンズとの間に設けられた出射光の波面
を変化させる位相補正素子と、波面を変化させるための
電圧を位相補正素子へ出力する制御電圧発生手段とを備
えた光ヘッド装置であって、位相補正素子は一対の透明
基板と、透明基板間に挟持された液晶層と、液晶層への
電圧印加時に使用される、透明基板面上の分割された複
数の電極とを備えており、同一透明基板上の複数の電極
のうち２つ以上が第１の抵抗体を挟んで導電接続されて
おり、さらに少なくとも１つの第１の抵抗体の一方の末
端と制御電圧発生手段とが第２の抵抗体を挟んで導電接
続されていることを特徴とする光ヘッド装置を提供す
る。The present invention has been made to solve the above problems, and includes a light source, an objective lens for converging light emitted from the light source on an optical recording medium, An optical head device provided with a phase correction element provided between a light source and an objective lens for changing a wavefront of emitted light, and a control voltage generating means for outputting a voltage for changing the wavefront to the phase correction element. The phase correction element includes a pair of transparent substrates, a liquid crystal layer sandwiched between the transparent substrates, and a plurality of divided electrodes on the surface of the transparent substrate, which are used when a voltage is applied to the liquid crystal layer. , Two or more of the plurality of electrodes on the same transparent substrate are conductively connected to each other with the first resistor interposed therebetween, and further, at least one end of the first resistor and the control voltage generating means are connected to each other. Conductive connection with the resistor 2 in between To provide an optical head apparatus characterized.
【００１１】また、第１、第２の抵抗体は導電性薄膜に
より形成された薄膜抵抗であり、前記位相補正素子の透
明基板上に形成されている上記の光ヘッド装置を提供す
る。The first and second resistors are thin film resistors formed of a conductive thin film, and the above optical head device is provided which is formed on the transparent substrate of the phase correction element.
【００１２】また、第１、第２の抵抗体は透明基板外に
配置された抵抗素子である上記の光ヘッド装置を提供す
る。Further, the above-mentioned optical head device is provided in which the first and second resistors are resistor elements arranged outside the transparent substrate.
【００１３】また、第１の抵抗体は導電性薄膜により形
成された薄膜抵抗であって前記位相補正素子の透明基板
上に形成されており、第２の抵抗体は透明基板外に配置
された抵抗素子である上記の光ヘッド装置を提供する。Further, the first resistor is a thin film resistor formed of a conductive thin film and is formed on the transparent substrate of the phase correction element, and the second resistor is arranged outside the transparent substrate. There is provided the above optical head device which is a resistance element.
【００１４】また、第２の抵抗体の抵抗値は、第１の抵
抗体の抵抗値の総和の０.２倍から１倍までの値を有す
る上記の光ヘッド装置を提供する。Further, the above-mentioned optical head device is provided in which the resistance value of the second resistor has a value of 0.2 to 1 times the sum of the resistance values of the first resistor.
【００１５】[0015]
【発明の実施の形態】図４に本発明の光ヘッド装置の原
理構成の一例を示す。図４に示した光ヘッド装置はＣＤ
またはＤＶＤなどの光ディスク８に記録された情報を再
生するためのものであり、光源である例えば半導体レー
ザ１から出射した光は例えばホログラムタイプの偏光ビ
ームスプリッタ２を透過した後、コリメートレンズ３に
より平行光となり、位相補正素子４を透過後、４分の１
波長板５を透過し、立ち上げミラー１１で９０°方向に
反射され、アクチュエータ７に設置された対物レンズ６
により光ディスク８上に集光される。集光された光は光
ディスク８により反射され対物レンズ６、立ち上げミラ
ー１１、４分の１波長板５、位相補正素子４、コリメー
トレンズ３を順次先程とは逆に透過した後、偏光ビーム
スプリッタ２により回折され光検出器９に入射する。前
述の半導体レーザ１からの出射光が光ディスク８により
反射される際、光ディスクの面上に記録された情報によ
り反射光は振幅変調され、光検出器９により光強度信号
として記録情報を読み取ることができる。FIG. 4 shows an example of the principle configuration of an optical head device of the present invention. The optical head device shown in FIG. 4 is a CD
Alternatively, it is for reproducing information recorded on an optical disk 8 such as a DVD, and light emitted from a light source such as a semiconductor laser 1 is transmitted through a hologram type polarization beam splitter 2 and then collimated by a collimator lens 3. It becomes light, and after passing through the phase correction element 4, a quarter
The objective lens 6 which is transmitted through the wave plate 5 and reflected in the 90 ° direction by the rising mirror 11 and which is installed on the actuator 7
Is focused on the optical disk 8. The condensed light is reflected by the optical disk 8 and sequentially passes through the objective lens 6, the rising mirror 11, the quarter-wave plate 5, the phase correction element 4, and the collimating lens 3 in the opposite order to the above, and then the polarization beam splitter. The light is diffracted by 2 and enters the photodetector 9. When the emitted light from the semiconductor laser 1 is reflected by the optical disk 8, the reflected light is amplitude-modulated by the information recorded on the surface of the optical disk, and the photodetector 9 can read the recorded information as a light intensity signal. it can.
【００１６】偏光ビームスプリッタ２は例えば偏光性の
ホログラムを備えており、異方性方向（屈折率に差があ
る方向）に偏光成分を有する光を強く回折して光検出器
９に導く。光検出器９より得られる光ディスクの例えば
再生信号の強度が最適となるように、位相補正素子４に
向けて制御電圧発生手段である位相補正素子制御回路１
０により電圧が出力される。位相補正素子制御回路１０
より出力される電圧は、光ディスクのチルト量や厚みム
ラに応じた電圧であり、位相補正素子４の電極に印加す
る実質的に変化する電圧となる。The polarization beam splitter 2 is provided with a polarizing hologram, for example, and strongly diffracts light having a polarization component in the anisotropic direction (direction in which there is a difference in refractive index) and guides it to the photodetector 9. The phase correction element control circuit 1 which is a control voltage generating means toward the phase correction element 4 so that the intensity of, for example, a reproduction signal of the optical disk obtained from the photodetector 9 becomes optimum
A voltage of 0 is output. Phase correction element control circuit 10
The output voltage is a voltage corresponding to the tilt amount and thickness unevenness of the optical disc, and is a substantially varying voltage applied to the electrode of the phase correction element 4.
【００１７】次に本発明において使用する位相補正素子
の構成を図２を用いて説明する。透明基板２１ａ、２１
ｂが、例えばエポキシ系樹脂を主成分とするシール材２
２により接着され液晶セルを形成している。透明基板２
１ａ、２１ｂには、ガラス、アクリル系樹脂、エポキシ
系樹脂、塩化ビニル系樹脂、ポリカーボネートなどが使
用できるが、耐久性などの点からガラスの基板が好まし
い。したがって、以下では基板の材料としてガラスを使
用する場合について説明する。Next, the structure of the phase correction element used in the present invention will be described with reference to FIG. Transparent substrates 21a, 21
b is a sealing material 2 whose main component is, for example, an epoxy resin
The two are bonded to form a liquid crystal cell. Transparent substrate 2
Glass, acrylic resin, epoxy resin, vinyl chloride resin, polycarbonate, or the like can be used for 1a and 21b, but a glass substrate is preferable from the viewpoint of durability and the like. Therefore, the case where glass is used as the material of the substrate will be described below.
【００１８】シール材２２には例えばガラス製のスペー
サと、例えば樹脂の表面に金などを被膜した導電性スペ
ーサが含有されている。ガラス基板２１ａの内側表面に
は、内側表面から電極２４ａ、シリカなどを主成分とす
る絶縁膜２５ａ、配向膜２６ａがこの順に、またガラス
基板２１ｂの内側表面には、内側表面から電極２４ｂ、
シリカなどを主成分とする絶縁膜２５ｂ、配向膜２６ｂ
がこの順に被膜されている。液晶セルの外側表面には反
射防止膜が被膜されていてもよい。The sealing material 22 contains, for example, a glass spacer and a conductive spacer having a resin surface coated with gold or the like. On the inner surface of the glass substrate 21a, the electrode 24a, the insulating film 25a containing silica as a main component, and the alignment film 26a are arranged in this order from the inner surface, and on the inner surface of the glass substrate 21b, the electrode 24b is arranged from the inner surface to the electrode 24b.
Insulating film 25b and alignment film 26b containing silica as a main component
Are coated in this order. An antireflection film may be coated on the outer surface of the liquid crystal cell.
【００１９】電極２４ａは電極引出部２７でフレキシブ
ル基板などによって位相補正素子制御回路と接続できる
ようパターン配線されている。また電極２４ｂは上述の
金などを被膜した導電性スペーサによりガラス基板２１
ａ上に形成された電極２４ａと電気的に接続しており、
したがって、電極２４ｂは電極引出部２７で接続線によ
って位相補正素子制御回路と接続できる。図２には、電
極２４ｂと電極２４ａとがシール材２２と接している様
子が示されていないが、紙面と平行なシール材とは接し
ており両電極は電性スペーサを通じて電気的に接続され
ている。液晶セル内部には液晶が充填され液晶層２３と
されており、図２に示した液晶分子２８は、一方向に配
向されたホモジニアス配向の状態にある。使用される液
晶はディスプレイなどで用いられているネマティック液
晶が好ましく、ツイストしていてもよい。The electrode 24a is patterned in the electrode lead-out portion 27 so as to be connected to the phase correction element control circuit by a flexible substrate or the like. Further, the electrode 24b is formed of the above-mentioned conductive spacer coated with gold or the like on the glass substrate 21.
electrically connected to the electrode 24a formed on a,
Therefore, the electrode 24b can be connected to the phase correction element control circuit by the connection line at the electrode lead-out portion 27. FIG. 2 does not show that the electrodes 24b and 24a are in contact with the sealing material 22, but they are in contact with the sealing material parallel to the paper surface and both electrodes are electrically connected through the electrically conductive spacer. ing. The inside of the liquid crystal cell is filled with liquid crystal to form a liquid crystal layer 23, and the liquid crystal molecules 28 shown in FIG. 2 are in a unidirectionally aligned homogeneous alignment state. The liquid crystal used is preferably a nematic liquid crystal used in a display or the like, and may be twisted.
【００２０】配向膜２６ａ、ｂの材料としては、液晶分
子２８のプレチルト角が２〜１０゜となれば好ましく、
ポリイミド膜を図２の紙面に平行で左右方向にラビング
したものや、シリカ膜を斜め蒸着したものなどがよい。
電極２４ａ、２４ｂの材質は透過率が高い方が望まし
く、ＩＴＯ膜などの透明導電膜を使用すればよい。As a material for the alignment films 26a and 26b, it is preferable that the pretilt angle of the liquid crystal molecules 28 is 2 to 10 °,
A polyimide film rubbed in the left-right direction parallel to the paper surface of FIG. 2 or a silica film obliquely deposited is preferable.
It is desirable that the materials of the electrodes 24a and 24b have a high transmittance, and a transparent conductive film such as an ITO film may be used.
【００２１】以上は位相補正素子を用いて波面を変化さ
せる機能に必要な構成を述べたが、波長板や偏光性のホ
ログラムを位相補正素子４に積層することにより、波長
板５や偏光ビームスプリッタ２の機能を位相補正素子４
が併せ持つようにできる。この場合、光ヘッド装置を構
成する光学部品の点数が減ることで組立、調整が簡易と
なり、生産性が向上して好ましい。The configuration necessary for the function of changing the wavefront by using the phase correction element has been described above. However, by stacking a wave plate or a polarizing hologram on the phase correction element 4, the wave plate 5 or the polarization beam splitter is formed. The function of 2 is the phase correction element 4
Can have both. In this case, it is preferable that the number of optical components constituting the optical head device is reduced, the assembly and the adjustment are simplified, and the productivity is improved.
【００２２】また位相補正素子４に、回折格子や光源の
波長により光束径を変化させるためのダイクロイック開
口制限層などを積層し、またガラス基板２１ａ、２１ｂ
の外側表面上に直接形成することもでき、この場合も個
々の部品を新たに追加することに比べて生産性が向上し
て好ましい。波長板を積層する場合には、光ディスク側
のガラス基板に直接貼り合せるか、または貼り合わせた
ガラス基板をさらに積層すればよい。Further, a dichroic aperture limiting layer for changing the luminous flux diameter according to the wavelength of a diffraction grating or a light source is laminated on the phase correction element 4, and the glass substrates 21a and 21b are also laminated.
It can be formed directly on the outer surface of the base material. In this case as well, productivity is improved as compared with the case where a new individual component is added, which is preferable. When the wave plates are laminated, they may be directly bonded to the glass substrate on the optical disk side, or the bonded glass substrates may be further laminated.
【００２３】次に本発明における位相補正素子を用いて
波面収差を補正する方法について述べる。図３はディス
クチルトにより発生するコマ収差分布を示すものであ
り、対物レンズのＮＡが０.６、光ディスクの厚さ０.１
ｍｍ、ディスクチルト角は１°である。Next, a method of correcting wavefront aberration using the phase correction element of the present invention will be described. FIG. 3 shows the coma aberration distribution generated by the disc tilt. The NA of the objective lens is 0.6 and the thickness of the optical disc is 0.1.
mm, the disc tilt angle is 1 °.
【００２４】図１は、本発明における位相補正素子の電
極パターンおよび変圧用抵抗の等価回路の一例を示し、
ラジアル方向（図中の上下方向）のディスクチルトによ
り発生したコマ収差を補正するための例である。分割さ
れた電極３１〜３５は位相補正素子内部の電極２４ａ
（図２）を、フォトリソグラフィー技術を用いてパター
ニングしたものであり、さらに電極３１と電極３４、お
よび電極３２と電極３５は、第１の抵抗体である電極内
部の配線によりおのおの導電接続されていて（太線で図
示）、等電位電極になっている。また、抵抗値Ｒｓを有
する変圧用抵抗３６、および抵抗値Ｒｔを有する変圧用
抵抗３７（これら変圧用抵抗は第２の抵抗体である）
は、本例の場合各２個の抵抗が直列接続されており、そ
の両末端は位相補正素子制御回路と接続されている。図
４に示す光ヘッド装置では、図１に示す電極３１〜３５
のパターン中心点を光軸が通過するように位相補正素子
を設置する。FIG. 1 shows an example of an equivalent circuit of an electrode pattern of a phase correction element and a transformer resistor according to the present invention,
This is an example for correcting coma aberration caused by disc tilt in the radial direction (vertical direction in the drawing). The divided electrodes 31 to 35 are the electrodes 24a inside the phase correction element.
(FIG. 2) is patterned using a photolithography technique. Further, the electrodes 31 and 34, and the electrodes 32 and 35 are conductively connected to each other by wiring inside the electrodes that are the first resistors. (Shown by a thick line), it is an equipotential electrode. In addition, a transformer resistor 36 having a resistance value R s and a transformer resistor 37 having a resistance value R t (these transformer resistors are second resistors).
In the case of this example, two resistors are connected in series, and both ends thereof are connected to the phase correction element control circuit. In the optical head device shown in FIG. 4, the electrodes 31 to 35 shown in FIG.
The phase correction element is installed so that the optical axis passes through the pattern center point.
【００２５】上述のように、位相補正素子制御回路はデ
ィスクチルト量に応じて、異なる電圧を位相補正素子に
供給する。図１に示した例の場合、固定電圧をＶａ、Ｖ
ｂ、ディスクチルトに比例した補正電圧をΔＶとして、
電圧Ｖａ＋ΔＶは電極３２、３５へ、電圧Ｖａは電極３
３へ、電圧Ｖａ−ΔＶは電極３１、３４に対して出力さ
れる。一方、電圧Ｖｂの信号は液晶層を挟んで電極３１
〜３５と対向する電極２４ｂに印加される。As described above, the phase correction element control circuit supplies different voltages to the phase correction element according to the disc tilt amount. In the case of the example shown in FIG. 1, the fixed voltages are V a and V
b , the correction voltage proportional to the disc tilt is ΔV,
The voltage V a + ΔV is applied to the electrodes 32 and 35, and the voltage V a is applied to the electrode 3
3, the voltage V a −ΔV is output to the electrodes 31 and 34. On the other hand, the signal of the voltage V b is applied to the electrode 31 with the liquid crystal layer interposed therebetween.
~ 35 is applied to the electrode 24b facing.
【００２６】図５は本発明における位相補正素子への印
加電圧波形の一例を示す模式図である。Ｖａ、Ｖａ±Δ
Ｖは、同位相であるが振幅が異なっている（図５の
（ａ）、（ｂ）、（ｃ））。また、Ｖｂは、Ｖａとは逆
位相の実効電圧値（時間的二乗平均根）が一定である交
流波（ｄ）か、または電圧値が一定である直流波（ｅ）
のいずれであってもよく、結果的に液晶に印加される実
効電圧（電極２４ａ、２４ｂ間の電圧）が直流成分を持
たないようにすればよい。FIG. 5 is a schematic diagram showing an example of a voltage waveform applied to the phase correction element in the present invention. V a , V a ± Δ
V has the same phase but different amplitude ((a), (b), (c) in FIG. 5). Further, V b is an alternating current wave (d) having a constant effective voltage value (temporal root mean square) having a phase opposite to that of V a , or a direct current wave (e) having a constant voltage value.
Any of the above may be applied, and as a result, the effective voltage applied to the liquid crystal (voltage between the electrodes 24a and 24b) does not have a DC component.
【００２７】変圧用抵抗３６、３７に比べ電極３２、３
５などを導電接続する配線の抵抗が無視できるほど小さ
い場合、光軸が通過する電極３３には電圧Ｖａが印加さ
れる。一方、電極３３に対する電極３１と３４の電圧差
ΔＶ’、および電極３３に対する電極３２と３５の電圧
差ΔＶ’は、位相補正素子制御回路の補正電圧ΔＶが変
圧用抵抗３６、３７により変圧され、数（１）のように
表される。Compared with the transformer resistors 36 and 37, the electrodes 32 and 3
When the resistance of the wiring that electrically connects 5 and the like is negligible, the voltage V a is applied to the electrode 33 through which the optical axis passes. On the other hand, regarding the voltage difference ΔV ′ between the electrodes 31 and 34 with respect to the electrode 33 and the voltage difference ΔV ′ between the electrodes 32 and 35 with respect to the electrode 33, the correction voltage ΔV of the phase correction element control circuit is transformed by the transformation resistors 36 and 37, It is expressed as the number (1).
【００２８】[0028]
【数１】 [Equation 1]
【００２９】したがって、本発明の位相補正素子の場
合、変圧用抵抗３６と３７との抵抗値の比Ｒｓ／Ｒｔに
より、位相補正素子制御回路が発生する電圧幅ΔＶより
小さな電圧を液晶に印加できる。Therefore, in the case of the phase correction element of the present invention, a voltage smaller than the voltage width ΔV generated by the phase correction element control circuit is applied to the liquid crystal by the ratio R s / R t of the resistance values of the transformer resistors 36 and 37. Can be applied.
【００３０】図６は本発明における位相補正素子に対す
る位相差電圧特性の一例を示す図であり、１.８Ｖ
ｒｍｓを基準にし位相差ゼロとして縦軸＋側は位相が遅
れる方向、−側は位相が進む方向である。従来の変圧用
抵抗を用いない位相補正素子の場合、位相補正素子制御
回路は図６の傾きである−１λ／Ｖｒｍｓで制御する必
要があるが、図１に示した例においてＲｓ＝Ｒｔとした
場合、（１）式よりΔＶ’＝０.５×ΔＶであるため、
０.５λ／Ｖｒｍｓで制御できるため、制御性は向上す
る。FIG. 6 is a diagram showing an example of the phase difference voltage characteristic with respect to the phase correction element according to the present invention.
The phase difference is zero with rms as a reference, and the vertical axis is the direction in which the phase is delayed and the negative side is the direction in which the phase is advanced. In the case of the conventional phase correction element that does not use the resistance for voltage transformation, the phase correction element control circuit needs to control with the inclination of −1λ / V rms in FIG. 6, but in the example shown in FIG. 1, R s = R When t is set, ΔV ′ = 0.5 × ΔV from the equation (1),
The controllability is improved because it can be controlled at 0.5λ / V rms .
【００３１】以上は、図１に示した例を用いて本発明に
おける位相補正素子の動作原理を説明したが、同じ原理
を用いることにより電極３１〜３５以外の電極形状を有
する位相補正素子にも適用できる。図７は一般化された
本発明における位相補正素子の等価回路を示す模式図で
ある。電極Ａ１〜Ａｎ、電極Ｂ１〜Ｂｍは、位相補正素
子の電極２４ａ、２４ｂ部分におのおの形成された電極
であり液晶を挟んで対向している。以下、電極Ａ１〜Ａ
ｎに関して述べる。The operation principle of the phase correction element according to the present invention has been described above with reference to the example shown in FIG. 1. However, the same principle is used to apply a phase correction element having an electrode shape other than the electrodes 31 to 35. Applicable. FIG. 7 is a schematic diagram showing an equivalent circuit of a generalized phase correction element according to the present invention. The electrodes A 1 to An and the electrodes B 1 to B m are electrodes formed on the electrodes 24 a and 24 b of the phase correction element, and face each other with the liquid crystal interposed therebetween. Hereinafter, the electrodes A 1 to A
n will be described.
【００３２】ｎ＋１個の変圧用抵抗ＲＡｔ、ＲＡ１〜Ｒ
Ａｎ−１、ＲＡｔ’は直列接続され、各抵抗間には電極
Ａ１〜Ａｎが接続されており、両末端は位相補正素子制
御回路に接続され電圧ＶＡ１、ＶＡ２が印加される。し
たがって、電極Ａ１〜Ａｎには、変圧用抵抗ＲＡｔ、Ｒ
Ａ１〜ＲＡｎ−１、ＲＡｔ’により分圧された電圧が印
加され、ＲＡ１〜ＲＡｎ−１とＲＡｔ、ＲＡｔ’の値を
適切に選ぶことにより、位相補正素子制御回路の電圧制
御範囲を所望の範囲に調整できる。N + 1 transformer resistors R At , R A1 to R
An-1 and R At ' are connected in series, electrodes A 1 to An are connected between the resistors, and both ends are connected to the phase correction element control circuit and voltages V A1 and V A2 are applied. . Thus, the electrode A 1 to A n, transformer resistor R At, R
The voltage divided by A1 to R An-1 and R At ' is applied, and the voltage of the phase correction element control circuit is adjusted by appropriately selecting the values of R A1 to R An-1 and R At and R At'. The control range can be adjusted to a desired range.
【００３３】また、ＲＡ１〜ＲＡｎ−１が全て同じ抵抗
値の場合、電極Ａ１〜電極Ａｎに印加される電圧は等分
割の電圧であるため、各対向電極間で発生する位相変化
量は等分割になる。また、電極Ａ２〜電極Ａｎ−１のう
ちのいくつかは、ＶＡ３、Ｖ Ａ４・・の電圧を個々に印
加することもできる。しかし、ＶＡ３、ＶＡ４・・の電
圧数が多くなると位相補正素子制御回路が複雑になるた
め好ましくなく、例えば光軸が通過する電極など、基準
となる電極にのみＶＡｋを印加することが好ましい。以
上、ｎ個の電極Ａ１〜Ａｎの場合、２つの変圧用抵抗Ｒ
Ａｔ、ＲＡｔ’とｎ−１個の変圧抵抗ＲＡ１〜
Ｒｎ−１、および最低２つの電圧ＶＡ１、ＶＡ２により
位相補正素子は動作できる。Also, RA1~ RAn-1All have the same resistance
In case of value, electrode A1~ Electrode AnThe voltage applied to the
Since the voltage is relatively high, the phase change that occurs between the opposing electrodes
The quantity is divided into equal parts. Also, the electrode ATwo~ Electrode An-1Nou
Some of them are VA3, V A4..Indicating individual voltage
You can also add. But VA3, VA4..Power
The phase correction element control circuit became complicated as the pressure increased.
It is not preferable because it is a reference such as an electrode through which the optical axis passes.
V only for the electrodeAkIs preferably applied. Since
Top, n electrodes A1~ AnIn the case of,
At, RAt 'And n-1 transformer resistance RA1~
Rn-1, And at least two voltages VA1, VA2By
The phase correction element is operable.
【００３４】２つのガラス基板間で、電極Ａ１〜Ａｎと
対向するｍ個の電極Ｂ１〜Ｂｍにおいても、電極Ａ１〜
Ａｎと同様に動作させることができる。しかし、図１に
示した例のように、変圧用抵抗を用いず１つの平面電極
に一つの電圧を印加する構成を採ることもできる。ま
た、変圧用抵抗を用いずｍ個の電極Ｂ１〜Ｂｍ全てに対
して、電圧ＶＢ１〜Ｖｍをそれぞれ印加できるよう位相
補正素子制御回路を構成できる。複数の電極Ｂ１〜Ｂｍ
とすることで、前述したコマ収差だけでなく、球面収
差、非点収差など異なる複数の波面収差成分を同時に補
正できる。[0034] In between the two glass substrates, in the electrode A 1 to A n opposite to m electrodes B 1 .about.B m, electrodes A 1 ~
It can be operated similarly to A n. However, as in the example shown in FIG. 1, it is also possible to adopt a configuration in which one voltage is applied to one plane electrode without using a resistor for transformation. In addition, the phase correction element control circuit can be configured so that the voltages V B1 to V m can be applied to all of the m electrodes B 1 to B m without using a resistance for transformation. A plurality of electrodes B 1 to B m
Thus, not only the coma aberration described above but also a plurality of different wavefront aberration components such as spherical aberration and astigmatism can be corrected at the same time.
【００３５】電極数、電極形状、印加電圧数などは、波
面収差の補正性能、位相補正素子制御回路の製作コスト
などにより最適化すればよく、変圧用抵抗の抵抗値は所
望の駆動電圧範囲が得られるように選択すればよい。変
圧用抵抗の抵抗値は、配線などその他の部分の抵抗値に
比べて大きくした方がよい。変圧用抵抗の抵抗値が小さ
い場合には、配線部分の電気的影響を無視できなくなる
ために、（１）式においても配線の影響を考慮する必要
がある。場合によっては、各電極の配線長の違いなどに
より電圧のバランスが崩れるなどするため好ましくな
い。したがって、変圧用抵抗の抵抗値は１ｋΩ以上にす
ることが好ましい。また、制御電圧幅を大きくするため
には、第１の抵抗体と第２の抵抗体の比を適切にする必
要がある。ここで、第１の抵抗体の抵抗値とは図７のＲ
ＡｔとＲＡｔ’の和Ｒｔであり、第２の抵抗体の抵抗値
はＲＡ１〜ＲＡｎ−１の総和Ｒｓとする。ここで、ΔＶ
＝Ｖ Ａ１−ＶＡ２、電極Ａ１と電極Ａｎの電位差をΔ
Ｖ’とすると、オームの法則より制御電圧幅の拡大率β
は、β＝ΔＶ／ΔＶ’＝１＋Ｒｔ／Ｒｓ、したがって、
抵抗比Ｒｔ／Ｒｓを０.２から１までとすると、制御電
圧幅の拡大率βを１.２倍から２倍にすることができ、
位相補正素子制御回路の特性面において現実的な値とな
り好ましい。変圧用抵抗Ｒｔ、Ｒｓは位相補正素子内部
に形成してもよく（点線の囲みで表わした、図７の形態
１）、位相補正素子外部の位相補正素子制御回路との間
の結線中に配置してもよいし（破線の囲みで表わした、
図７の形態２）、変圧用抵抗Ｒｓのみ位相補正素子内部
に形成し、変圧用抵抗Ｒｔを位相補正素子外部に配置し
てもよい。The number of electrodes, electrode shape, number of applied voltages, etc.
Surface aberration correction performance, manufacturing cost of phase correction element control circuit
The resistance value of the transformer resistor is
It may be selected so as to obtain a desired driving voltage range. Strange
The resistance value of the pressure resistor is the same as the resistance value of other parts such as wiring.
It is better to increase the size. The resistance value of the transformer resistor is small
If not, you cannot ignore the electrical effects of the wiring.
Therefore, it is necessary to consider the influence of wiring also in equation (1).
There is. Depending on the case, due to the difference in the wiring length of each electrode
It is not preferable because the voltage balance is lost.
Yes. Therefore, the resistance value of the transformer resistor should be 1 kΩ or more.
Preferably. Also, to increase the control voltage range
Must have an appropriate ratio between the first resistor and the second resistor.
There is a point. Here, the resistance value of the first resistor is R in FIG.
AtAnd RAt 'Sum RtAnd the resistance value of the second resistor
Is RA1~ RAn-1Sum of RsAnd Where ΔV
= V A1-VA2, Electrode A1And electrode AnThe potential difference of Δ
Assuming V ′, the expansion ratio β of the control voltage width is based on Ohm's law.
Is β = ΔV / ΔV ′ = 1 + Rt/ Rs, Therefore
Resistance ratio Rt/ RsIs from 0.2 to 1, the control voltage is
The expansion ratio β of the pressure range can be increased from 1.2 times to 2 times,
It is not a realistic value in terms of the characteristics of the phase correction element control circuit.
More preferable. Transformer resistance Rt, RsIs inside the phase correction element
May be formed in the form of (the shape of FIG.
1), between the phase correction element control circuit outside the phase correction element
It may be placed in the wiring of (represented by the broken line box,
Form 2) of FIG. 7, resistance R for transformationsOnly inside the phase correction element
Formed into a resistor R for transformationtIs placed outside the phase correction element
May be.
【００３６】位相補正素子の内部に変圧用抵抗を配置す
る場合、透明電極２４ａ、２４ｂと同じ面に、所望の抵
抗値が得られるよう寸法調整された薄膜抵抗を形成する
ことで達成できる。また、位相補正素子の外部に変圧用
抵抗を配置する場合は、例えば、位相補正素子と位相補
正素子制御回路を結線するためのフレキシブル基板上に
抵抗素子などを配置することで達成できる。いずれの場
合も電気的には同等であるが、位相補正素子の内部に配
置した場合の方が、引き出し配線数が減るため好まし
い。When the transformer resistor is arranged inside the phase correction element, it can be achieved by forming a thin film resistor whose dimensions are adjusted so as to obtain a desired resistance value on the same surface as the transparent electrodes 24a and 24b. In addition, when the transformation resistor is arranged outside the phase correction element, it can be achieved, for example, by arranging a resistance element or the like on a flexible substrate for connecting the phase correction element and the phase correction element control circuit. In either case, the electrical equivalence is the same, but it is preferable to arrange the phase compensation element inside the phase correction element because the number of lead wires is reduced.
【００３７】以上のように、本発明の光ヘッド装置を用
いるとき、変圧用抵抗を上記の例のように配置すること
により、実際の液晶の電圧駆動幅が狭い場合でも、位相
補正素子制御回路の制御電圧幅を広げられるため、制御
が容易となり、低コストの位相補正素子制御回路を使用
できる。また、位相補正素子を用いることにより、コマ
収差をはじめ球面収差、非点収差などの波面収差を補正
できる。As described above, when the optical head device of the present invention is used, by arranging the transformer resistance as in the above example, the phase correction element control circuit is realized even when the actual voltage drive width of the liquid crystal is narrow. Since the control voltage width can be widened, the control becomes easy and a low-cost phase correction element control circuit can be used. Moreover, by using the phase correction element, it is possible to correct wavefront aberrations such as spherical aberration and astigmatism as well as coma.
【００３８】[0038]
【実施例】「例１」本例の光ヘッド装置は、光ディスク
のチルトにより発生するコマ収差を補正する位相補正素
子を備えており、同じ液晶材料を用いた従来例に比べ約
２倍の電圧幅で制御できるため、電圧制御精度が低い位
相補正素子制御回路を用いても精度よく補正できること
が特徴である。本例における位相補正素子を組み込んだ
光ヘッド装置は、図４に示したものと同じである。ま
た、位相補正素子の断面構成は図２に示したものと同じ
である。[Example 1] The optical head device of this example is provided with a phase correction element that corrects coma aberration caused by tilting of the optical disc, and the voltage is about twice as high as that of the conventional example using the same liquid crystal material. Since the width can be controlled, the characteristic is that the voltage can be accurately corrected even if a phase correction element control circuit having low voltage control accuracy is used. The optical head device incorporating the phase correction element in this example is the same as that shown in FIG. The cross-sectional structure of the phase correction element is the same as that shown in FIG.
【００３９】図１は本例における位相補正素子の電極パ
ターンおよび変圧用抵抗の等価回路を示し、図２に示す
電極２４ａ部に形成されている。斜線部はＩＴＯ膜によ
り形成され分割された電極３１〜３５であり、ガラス基
板にスパッタ法にてＩＴＯ膜を形成した後、フォトリソ
グラフィー技術によりパターニングして形成した。同時
に変圧用抵抗３６、３７もＩＴＯ膜をパターニングして
形成した。変圧用抵抗３６、３７は、幅５０μｍ、長さ
１ｍｍの線状抵抗であり、抵抗値はＲｓ＝Ｒｔ＝１０ｋ
Ωであった。FIG. 1 shows an equivalent circuit of the electrode pattern and the transformer resistor of the phase correction element in this example, which is formed on the electrode 24a portion shown in FIG. The shaded portions are the electrodes 31 to 35 formed by the ITO film and divided, and they were formed by forming the ITO film on the glass substrate by the sputtering method and then patterning it by the photolithography technique. At the same time, the transformer resistors 36 and 37 were also formed by patterning the ITO film. The transformer resistors 36 and 37 are linear resistors having a width of 50 μm and a length of 1 mm, and the resistance value is R s = R t = 10k.
It was Ω.
【００４０】位相補正素子と位相補正素子制御回路はフ
レキシブル基板により導電接続されており、電圧Ｖａ、
Ｖａ＋ΔＶおよびＶａ−ΔＶが電極２４ａに印加され、
電圧Ｖｂ＝０Ｖが一様な電極２４ｂに印加された。本例
では、電圧Ｖａは１.８Ｖｒ ｍｓであり、ΔＶは発生し
たディスクチルト量に比例して変化する補正電圧とし
た。おのおのの電圧波形は図５に示すような周波数１ｋ
Ｈｚの矩形交流波であり、交流波の上下幅の中心を０Ｖ
に設定した。The phase correction element and the phase correction element control circuit are conductively connected by a flexible substrate, and the voltage V a ,
V a + ΔV and V a −ΔV are applied to the electrode 24a,
A voltage Vb = 0V was applied to the uniform electrode 24b. In this example, the voltage V a is 1.8V r ms, [Delta] V was corrected voltage that varies in proportion to the amount of disc tilt generated. Each voltage waveform has a frequency of 1k as shown in Fig. 5.
It is a rectangular AC wave of Hz, and the center of the vertical width of the AC wave is 0V.
Set to.
【００４１】液晶による位相差の電圧特性は図６に示し
たものであり、-１λ／Ｖｒｍｓの勾配を有している。
一方、式（１）によりＲｔ＝Ｒｓ＝１０ｋΩの場合は、
ΔＶ’＝ΔＶ／２であるから、位相補正素子制御回路が
発生する補正電圧ΔＶに対する位相差の電気特性の勾配
は-０.５λ／Ｖｒｍｓであり、勾配が緩やかになったた
め位相補正素子の電圧制御が容易になった。The voltage characteristic of the phase difference due to the liquid crystal is shown in FIG. 6, and has a slope of -1λ / V rms .
On the other hand, when R t = R s = 10 kΩ according to the equation (1),
Since ΔV ′ = ΔV / 2, the gradient of the electrical characteristic of the phase difference with respect to the correction voltage ΔV generated by the phase correction element control circuit is −0.5λ / V rms , and since the gradient becomes gentle, the phase correction element Voltage control has become easier.
【００４２】「例２」本例の光ヘッド装置は、光ディス
クの厚さムラにより生ずる球面収差を補正する位相補正
素子を備えている。対物レンズは光ディスクの厚さが設
計値からずれると球面収差を発生し信号の読み取り精度
が低下する。この球面収差を補正する位相補正素子を図
４の光ヘッド装置の位相補正素子４として組み込んだ。
ただし、位相補正素子制御回路１０は本例の位相補正素
子用に改良されている。[Example 2] The optical head device of this example includes a phase correction element for correcting spherical aberration caused by uneven thickness of the optical disk. When the thickness of the optical disk of the objective lens deviates from the designed value, spherical aberration occurs and the signal reading accuracy deteriorates. A phase correction element that corrects this spherical aberration is incorporated as the phase correction element 4 of the optical head device of FIG.
However, the phase correction element control circuit 10 is improved for the phase correction element of this example.
【００４３】本例の位相補正素子の素子構造は図２に示
したものと同じで、以下に述べる電極パターンおよび変
圧用抵抗のみが異なっている。したがって位相補正素子
の製造方法、構成材料などは例１と同じものを使用し
た。The element structure of the phase correction element of the present example is the same as that shown in FIG. 2, except for the electrode pattern and the transformer resistor described below. Therefore, the same manufacturing method, constituent materials, and the like as the phase correction element were used.
【００４４】図８は本例における位相補正素子の電極パ
ターンおよび変圧用抵抗の等価回路を示し、図２に示す
電極２４ａ部に形成されている。斜線部はＩＴＯ膜によ
り形成され分割された電極４１〜４４であり、ガラス基
板にスパッタ法にてＩＴＯ膜を形成した後、フォトリソ
グラフィー技術によりパターニングして形成した。電極
４１〜４４は、第１の抵抗体である変圧用抵抗Ｒｓ１〜
Ｒｓ３および、第２の抵抗体である変圧用抵抗Ｒｔ１、
Ｒｔ２の間のＡ、Ｂ、Ｃ、Ｄ各点に接続されている。変
圧用抵抗Ｒｔ１、Ｒｓ１〜Ｒｓ３、Ｒｔ２は直列接続さ
れ、その末端は位相補正素子制御回路に接続されてい
る。位相補正素子制御回路は、固定電圧Ｖ ａ、Ｖｂ、お
よび光ディスクの厚さムラにより発生する球面収差量に
比例した補正電圧ΔＶを発生する。本例では、電圧Ｖｂ
は０Ｖとし、電圧Ｖａ、Ｖａ±ΔＶの波形は図５に示す
ような周波数１ｋＨｚの矩形交流波とし、上下幅の中心
を０Ｖに設定した。FIG. 8 shows the electrode pattern of the phase correction element in this example.
An equivalent circuit of the turn and transformer resistors is shown in Figure 2.
It is formed on the electrode 24a. The shaded area is made of ITO film.
Electrodes 41 to 44 formed and divided into a glass base.
After the ITO film is formed on the plate by the sputtering method, photolithography is performed.
It was formed by patterning by a graphic technique. electrode
Numerals 41 to 44 denote a resistor R for transformation which is a first resistor.s1~
Rs3And a resistor R for transformation which is a second resistor.t1,
Rt2It is connected to each point of A, B, C, and D between. Strange
Pressure resistor Rt1, Rs1~ Rs3, Rt2Are connected in series
And its end is connected to the phase correction element control circuit.
It The phase correction element control circuit has a fixed voltage V a, Vb,
And the amount of spherical aberration caused by uneven thickness of the optical disc
A proportional correction voltage ΔV is generated. In this example, the voltage Vb
Is 0V, and the voltage Va, VaThe waveform of ± ΔV is shown in FIG.
With a rectangular AC wave with a frequency of 1 kHz, the center of the vertical width
Was set to 0V.
【００４５】図９に本例の位相補正素子と位相補正素子
制御回路を導電接続するために用いたフレキシブル基板
５２を模式的に図示した。接続部５３は位相補正素子制
御回路と接続される部分であり、３つのメタルランド部
が露出している（図中黒塗り）。一方、位相補正素子５
１との接続は電極４１〜４４および対向電極２４ｂに対
応する５本の接続線により導電接続されており、フレキ
シブル基板中に設置された第１の変圧用抵抗５４および
第２の変圧用抵抗５５が接続されている。FIG. 9 schematically shows the flexible substrate 52 used for conductively connecting the phase correction element and the phase correction element control circuit of this example. The connection portion 53 is a portion connected to the phase correction element control circuit, and the three metal land portions are exposed (painted in black in the figure). On the other hand, the phase correction element 5
1 is electrically conductively connected by five connecting wires corresponding to the electrodes 41 to 44 and the counter electrode 24b, and is connected to the first transformer resistor 54 and the second transformer resistor 55 installed in the flexible substrate. Are connected.
【００４６】図９の配線は図８の等価回路と同等であ
り、変圧用抵抗５４は図８のＲｓ１〜Ｒｓ３に、変圧用
抵抗５５はＲｔ１、Ｒｔ２にそれぞれ対応している。変
圧用抵抗５４、５５はフレキシブル基板上にハンダ付け
された抵抗素子であり、抵抗値はおのおの１０ｋΩと１
５ｋΩであった。The wiring of FIG. 9 is equivalent to that of the equivalent circuit of FIG. 8, the transformation resistor 54 corresponds to R s1 to R s3 of FIG. 8, and the transformation resistor 55 corresponds to R t1 and R t2 . The transformer resistors 54 and 55 are resistor elements soldered on a flexible substrate, and the resistance values are 10 kΩ and 1 respectively.
It was 5 kΩ.
【００４７】液晶による位相差の電圧特性は、例１と同
様に図６に示したものであり、-１λ／Ｖｒｍｓの勾配
を有している。一方、図８におけるＡ点とＤ点の電圧差
を２×ΔＶ’とすると、２×ΔＶ’＝２×ΔＶ×（Ｒ
ｓ１＋Ｒｓ２＋Ｒｓ３）／（Ｒ ｔ１＋Ｒｓ１＋Ｒｓ２＋
Ｒｓ３＋Ｒｔ２）の関係から、Ｒｓ１＝Ｒｓ２＝Ｒｓ３
＝１０ｋΩ、Ｒｔ１＝Ｒｔ２＝１５ｋΩでは、ΔＶ’＝
ΔＶ／２となる。したがって、位相補正素子制御回路が
発生する補正電圧ΔＶに対する位相差の特性勾配は-０.
５λ／Ｖｒｍｓとなり、特性勾配が緩やかになったため
位相補正素子の電圧制御が容易になった。The voltage characteristics of the phase difference due to the liquid crystal are the same as in Example 1.
As shown in Fig. 6, -1λ / VrmsThe gradient of
have. On the other hand, the voltage difference between points A and D in FIG.
Is 2 × ΔV ′, 2 × ΔV ′ = 2 × ΔV × (R
s1+ Rs2+ Rs3) / (R t1+ Rs1+ Rs2+
Rs3+ Rt2), Rs1= Rs2= Rs3
= 10 kΩ, Rt1= Rt2= 15 kΩ, ΔV ′ =
It becomes ΔV / 2. Therefore, the phase correction element control circuit
The characteristic gradient of the phase difference with respect to the generated correction voltage ΔV is -0.
5λ / VrmsAnd because the characteristic gradient became gentle
The voltage control of the phase correction element has become easier.
【００４８】[0048]
【発明の効果】以上説明したように、本発明の光ヘッド
装置においては、位相補正素子と位相補正素子制御回路
の間に設置された変圧用抵抗により、位相補正素子制御
回路が発生する電圧幅より小さな電圧を位相補正素子に
印加できるので、実際の液晶動作電圧幅より広い電圧幅
で位相補正素子を制御できる。それにより、小さな電圧
差で位相差量が急激に変化する場合においても、より大
きな電圧差により位相差量を制御できるため、制御性が
向上し通常の位相補正素子制御回路においても高精度で
制御できる。As described above, in the optical head device of the present invention, the voltage width generated by the phase correction element control circuit is changed by the resistor for transformation installed between the phase correction element and the phase correction element control circuit. Since a smaller voltage can be applied to the phase correction element, the phase correction element can be controlled with a voltage width wider than the actual liquid crystal operating voltage width. As a result, even if the phase difference amount changes abruptly with a small voltage difference, the phase difference amount can be controlled with a larger voltage difference, so the controllability is improved and highly accurate control is possible even in a normal phase correction element control circuit. it can.
【図１】本発明における位相補正素子の電極パターンと
変圧用抵抗の等価回路の一例を示す模式図。FIG. 1 is a schematic diagram showing an example of an equivalent circuit of an electrode pattern of a phase correction element and a transformer resistance according to the present invention.
【図２】本発明における位相補正素子の一例を示す断面
図。FIG. 2 is a sectional view showing an example of a phase correction element according to the present invention.
【図３】光ディスクのチルト１゜が発生したときの波面
収差を示す図。FIG. 3 is a diagram showing wavefront aberration when a tilt of 1 ° of an optical disc occurs.
【図４】本発明の光ヘッド装置の原理構成の一例を示す
概念的断面図。FIG. 4 is a conceptual cross-sectional view showing an example of a principle configuration of an optical head device of the present invention.
【図５】本発明における位相補正素子制御回路が発生す
る電圧波形の一例を示す模式図、（ａ）Ｖａ＋ΔＶ、
（ｂ）Ｖａ、（ｃ）Ｖａ−ΔＶ、（ｄ）Ｖａで、（ｂ）
と逆位相、（ｅ）直流波。FIG. 5 is a schematic diagram showing an example of a voltage waveform generated by the phase correction element control circuit according to the present invention, (a) V a + ΔV,
(B) V a , (c) V a −ΔV, (d) V a , and (b)
, Opposite phase, (e) DC wave.
【図６】実施例１、２などにおける位相補正素子により
発生した位相変化の電圧特性を示す図。FIG. 6 is a diagram showing a voltage characteristic of a phase change generated by the phase correction element in Examples 1 and 2 and the like.
【図７】一般化された位相補正素子の電極と変圧用抵抗
の等価回路を示す模式図。FIG. 7 is a schematic diagram showing an equivalent circuit of electrodes and transformer resistors of a generalized phase correction element.
【図８】実施例２における位相補正素子の電極パターン
と変圧用抵抗の等価回路を示す模式図。FIG. 8 is a schematic diagram showing an equivalent circuit of an electrode pattern of a phase correction element and a transformer resistor according to a second embodiment.
【図９】実施例２における位相補正素子とフレキシブル
基板を示す模式図。FIG. 9 is a schematic diagram showing a phase correction element and a flexible substrate according to a second embodiment.
１：半導体レーザ ２：偏光ビームスプリッタ ３：コリメートレンズ ４、５１：位相補正素子 ５：４分の１波長板 ６：対物レンズ ７：アクチュエータ ８：光ディスク ９：光検出器 １０：位相補正素子制御回路 １１：立ち上げミラー ２１ａ、２１ｂ：ガラス基板 ２２：シール材 ２３：液晶層 ２４ａ、２４ｂ：電極 ２５：絶縁膜 ２６：配向膜 ２７：電極引出部 ２８：液晶分子 ３１〜３５、４１〜４４：電極 ３６、３７：変圧用抵抗 ５２：フレキシブル基板 ５３：電極取り出し部 ５４、５５変圧用抵抗 1: Semiconductor laser 2: Polarization beam splitter 3: Collimating lens 4, 51: Phase correction element 5: quarter wave plate 6: Objective lens 7: Actuator 8: Optical disc 9: Photodetector 10: Phase correction element control circuit 11: Start-up mirror 21a, 21b: glass substrates 22: Seal material 23: Liquid crystal layer 24a, 24b: electrodes 25: Insulating film 26: Alignment film 27: Electrode extraction part 28: Liquid crystal molecule 31-35, 41-44: Electrodes 36, 37: Resistance for transformation 52: Flexible substrate 53: Electrode take-out part 54,55 Transformer resistance
───────────────────────────────────────────────────── フロントページの続き Ｆターム(参考） 5D118 AA16 BA01 BB01 CD02 CD04 CD13 DC16 5D119 AA11 AA22 BA01 EB02 EB05 EC01 JA09 5D789 AA11 AA22 BA01 EB02 EB05 EC01 JA09 ─────────────────────────────────────────────────── ─── Continued front page F-term (reference) 5D118 AA16 BA01 BB01 CD02 CD04 CD13 DC16 5D119 AA11 AA22 BA01 EB02 EB05 EC01 JA09 5D789 AA11 AA22 BA01 EB02 EB05 EC01 JA09
Claims (5)
に集光させるための対物レンズと、光源と対物レンズと
の間に設けられた出射光の波面を変化させる位相補正素
子と、波面を変化させるための電圧を位相補正素子へ出
力する制御電圧発生手段とを備えた光ヘッド装置であっ
て、 位相補正素子は一対の透明基板と、透明基板間に挟持さ
れた液晶層と、液晶層への電圧印加時に使用される、透
明基板面上の分割された複数の電極とを備えており、同
一透明基板上の複数の電極のうち２つ以上が第１の抵抗
体を挟んで導電接続されており、さらに少なくとも１つ
の第１の抵抗体の一方の末端と制御電圧発生手段とが第
２の抵抗体を挟んで導電接続されていることを特徴とす
る光ヘッド装置。1. A light source, an objective lens for condensing light emitted from the light source onto an optical recording medium, and a phase correction element provided between the light source and the objective lens for changing the wavefront of the emitted light. An optical head device comprising control voltage generating means for outputting a voltage for changing a wavefront to a phase correction element, wherein the phase correction element includes a pair of transparent substrates and a liquid crystal layer sandwiched between the transparent substrates. , A plurality of divided electrodes on the surface of the transparent substrate, which are used when a voltage is applied to the liquid crystal layer, and two or more of the plurality of electrodes on the same transparent substrate sandwich the first resistor. 2. The optical head device is characterized in that it is electrically conductively connected with each other, and further, one end of at least one first resistor and the control voltage generating means are electrically conductively sandwiched with the second resistor interposed therebetween.
成された薄膜抵抗であり、前記位相補正素子の透明基板
上に形成されている請求項１記載の光ヘッド装置。2. The optical head device according to claim 1, wherein the first and second resistors are thin film resistors formed of a conductive thin film and are formed on the transparent substrate of the phase correction element.
れた抵抗素子である請求項１記載の光ヘッド装置。3. The optical head device according to claim 1, wherein the first and second resistors are resistance elements arranged outside the transparent substrate.
た薄膜抵抗であって前記位相補正素子の透明基板上に形
成されており、第２の抵抗体は透明基板外に配置された
抵抗素子である請求項１記載の光ヘッド装置。4. The first resistor is a thin film resistor formed of a conductive thin film and is formed on the transparent substrate of the phase correction element, and the second resistor is arranged outside the transparent substrate. The optical head device according to claim 1, which is a resistance element.
抵抗値の総和の０.２倍から１倍までの値を有する請求
項１〜４いずれか記載の光ヘッド装置。5. The optical head device according to claim 1, wherein the resistance value of the second resistor has a value of 0.2 to 1 times the sum of the resistance values of the first resistor. .
Priority Applications (1)
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|---|---|---|---|
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001315404A JP4547118B2 (en) | 2001-10-12 | 2001-10-12 | Optical head device |
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| Publication Number | Publication Date |
|---|---|
| JP2003123304A true JP2003123304A (en) | 2003-04-25 |
| JP4547118B2 JP4547118B2 (en) | 2010-09-22 |
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|---|---|---|---|
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| US7773489B2 (en) | 2004-08-04 | 2010-08-10 | Asahi Glass Company, Limited | Liquid crystal lens element and optical head device |
| JP4552556B2 (en) * | 2004-08-04 | 2010-09-29 | 旭硝子株式会社 | Liquid crystal lens element and optical head device |
| KR100619400B1 (en) * | 2004-08-31 | 2006-09-12 | 엘지전자 주식회사 | Liquid device |
| JP2006085801A (en) * | 2004-09-15 | 2006-03-30 | Asahi Glass Co Ltd | Liquid crystal lens element and optical head device |
| JP4501611B2 (en) * | 2004-09-15 | 2010-07-14 | 旭硝子株式会社 | Liquid crystal lens element and optical head device |
| JP2007017510A (en) * | 2005-07-05 | 2007-01-25 | Citizen Watch Co Ltd | Liquid crystal optical element and camera using the same, and optical pickup device |
| JP2007248986A (en) * | 2006-03-17 | 2007-09-27 | Citizen Holdings Co Ltd | Liquid crystal aberration correction element and manufacturing method thereof |
| JP2009181142A (en) * | 2009-05-20 | 2009-08-13 | Citizen Holdings Co Ltd | Liquid crystal aberration correction element |
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|---|---|
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