JP2003317294A - Optical head - Google Patents

Optical head

Info

Publication number
JP2003317294A
JP2003317294A JP2002117246A JP2002117246A JP2003317294A JP 2003317294 A JP2003317294 A JP 2003317294A JP 2002117246 A JP2002117246 A JP 2002117246A JP 2002117246 A JP2002117246 A JP 2002117246A JP 2003317294 A JP2003317294 A JP 2003317294A
Authority
JP
Japan
Prior art keywords
light
light receiving
receiving element
light source
amount
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.)
Granted
Application number
JP2002117246A
Other languages
Japanese (ja)
Other versions
JP2003317294A5 (en
JP3988513B2 (en
Inventor
Takayuki Nagata
貴之 永田
Toru Nakamura
徹 中村
Hirotoshi Tomita
浩稔 冨田
Takuo Hayashi
卓生 林
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Priority to JP2002117246A priority Critical patent/JP3988513B2/en
Publication of JP2003317294A publication Critical patent/JP2003317294A/en
Publication of JP2003317294A5 publication Critical patent/JP2003317294A5/ja
Application granted granted Critical
Publication of JP3988513B2 publication Critical patent/JP3988513B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Landscapes

  • Optical Recording Or Reproduction (AREA)
  • Optical Head (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a light quantity collected onto an optical disk is varied due to the variation of the light quantity transmitted through an objective lens when an actuator is driven accompanying servo operation and the objective lens is moved. <P>SOLUTION: The optical head is provided with: a light source; a first light receiving means for detecting a part of light beams from the light source; a light collecting means which is constituted to collect the light beams from the light source on an information track on an information recording medium and which has a light transmission effective diameter smaller than the optical flux diameter of the light beams from the light source; a moving means for moving the light collecting means in a direction orthogonal to a light axis; and a second light receiving means which is constituted so as to move according to moving of the light collecting means and which detects the light beams of a part which is not incident on the light collecting means in the light beams emitted from the light source toward the light collecting means. The light emitting quantity of the light source is controlled by a signal obtained by calculating signals detected by the first light receiving means and the second light receiving means. <P>COPYRIGHT: (C)2004,JPO

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【発明の属する技術分野】本発明は情報の記録、再生を
行うための光ディスク装置において、光ディスク上の集
光スポットに所定の光量が照射されるように制御が可能
な光学ヘッドに関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head for an optical disk device for recording and reproducing information, which can be controlled so that a predetermined amount of light is irradiated onto a focused spot on the optical disk.

【0002】[0002]

【従来の技術】記録可能な光ディスクとして、相変化光
ディスク、光磁気ディスク、1度だけ記録可能な色素系
光ディスクなどが従来から知られている。これらの光デ
ィスクは、レーザー光を光ディスク上の記録面に集光、
照射して局所的に温度を上昇させることにより相変化や
色素の分解を起こさせて情報の記録を行う、或いはレー
ザー光で記録面の温度を上昇させつつ外部磁界を印加し
て磁化方向を操作することにより情報の記録を行い、記
録時よりも弱いレーザー光量で記録面を照射して、その
反射光の光量、或いは偏光の検出を行うことにより情報
の再生を行う。
2. Description of the Related Art As a recordable optical disk, a phase change optical disk, a magneto-optical disk, a dye-based optical disk capable of recording only once, and the like have been conventionally known. These optical disks focus laser light on the recording surface of the optical disk,
Information is recorded by irradiating and raising the temperature locally to cause phase change and decomposition of the dye, or the temperature of the recording surface is raised by laser light and an external magnetic field is applied to control the magnetization direction. By doing so, information is recorded, and the recording surface is irradiated with a laser light amount weaker than that at the time of recording, and the light amount of the reflected light or polarization is detected to reproduce the information.

【0003】このような情報の記録および再生を行う光
ディスク装置では、記録時のレーザー光量が小さ過ぎる
と情報を確実に記録することができず、また、再生時の
レーザー光量が大き過ぎると記録されていた情報に破壊
等の重大な影響を及ぼす恐れがあるので、記録再生動作
において十分にそのレーザー光量が制御されることが必
要となる。特に相変化光ディスクの場合は、記録時のレ
ーザー光量が2段階あるため(アモルファス化パワー、
および、結晶化パワー)、再生時とあわせて3段階のレ
ーザー光量制御が必要となる。
In the optical disc device for recording and reproducing information as described above, if the laser light amount at the time of recording is too small, the information cannot be surely recorded, and if the laser light amount at the time of reproducing is too large, the information is recorded. Since there is a risk of serious damage such as destruction of the existing information, it is necessary to sufficiently control the laser light amount in the recording / reproducing operation. Especially in the case of a phase change optical disk, there are two levels of laser light at the time of recording (amorphization power,
In addition, it is necessary to control the laser light amount in three steps, including the crystallization power) and the reproduction.

【0004】しかし、光ディスク装置の光源に用いられ
る半導体レーザーは一般に温度特性を有し、周囲温度に
よりそのしきい値電流が変動するため、記録時および再
生時の駆動電流を所定の値に制御しても、発光量は温度
により変動する。そのため従来から、情報の記録再生を
行う光ディスク装置では、半導体レーザーの発光量の変
動を抑えるために、発光量をモニタしてレーザ駆動回路
の帰還制御を行っている。この様な一定強度の出力光を
得るための自動光出力制御はAPC(Automati
c Power Control)と呼ばれる。
However, a semiconductor laser used as a light source of an optical disk device generally has a temperature characteristic, and its threshold current fluctuates depending on the ambient temperature. Therefore, the drive current during recording and reproduction is controlled to a predetermined value. However, the amount of light emission varies depending on the temperature. Therefore, conventionally, in an optical disk device for recording / reproducing information, in order to suppress the fluctuation of the emission amount of the semiconductor laser, the emission amount is monitored and the feedback control of the laser drive circuit is performed. Automatic light output control for obtaining such a constant intensity of output light is performed by an APC (Automati).
c Power Control).

【0005】図8はこのような光ディスク装置に用いら
れる従来の光学ヘッドの構成図である。61は半導体レ
ーザ、62は透過および反射で光を分岐するビームスプ
リッタ、63は対物レンズ、64は記録面に情報トラッ
クを有する光ディスク、65は受光素子、66は検出レ
ンズ、プリズム、或いは回折素子等の光学素子と受光素
子を有しビームスプリッタ62によって反射された光デ
ィスク64からの戻り光を受光し、受光した光量に応じ
た信号に変換し、検出する信号検出手段、67は詳細は
図示しないが、光ディスク64に対して水平方向、およ
び垂直方向に対物レンズ63を駆動するアクチュエータ
である。
FIG. 8 is a block diagram of a conventional optical head used in such an optical disk device. Reference numeral 61 is a semiconductor laser, 62 is a beam splitter that splits light by transmission and reflection, 63 is an objective lens, 64 is an optical disk having an information track on the recording surface, 65 is a light receiving element, 66 is a detection lens, prism, diffractive element, or the like. Although not shown in detail, the signal detecting means 67 for receiving the return light from the optical disc 64, which has an optical element and a light receiving element and is reflected by the beam splitter 62, converts it into a signal according to the received light amount, and detects it. , An actuator that drives the objective lens 63 in a horizontal direction and a vertical direction with respect to the optical disc 64.

【0006】このように構成された光学ヘッドにおい
て、半導体レーザ61から出射した光はビームスプリッ
タ62において一部は透過、一部は反射する。ビームス
プリッタ62において反射した光は受光素子65にて受
光され、この検出光量が所定の値となるようにAPC回
路により、半導体レーザ61の発光量が制御される。
In the optical head having such a structure, the light emitted from the semiconductor laser 61 is partially transmitted and partially reflected by the beam splitter 62. The light reflected by the beam splitter 62 is received by the light receiving element 65, and the light emission amount of the semiconductor laser 61 is controlled by the APC circuit so that the detected light amount becomes a predetermined value.

【0007】ビームスプリッタ62を透過した光は対物
レンズ63により光ディスク64上に集光され、光ディ
スク64にて反射した光は再び対物レンズ63を透過
し、ビームスプリッタ62で反射され、信号検出手段6
6により、サーボ信号および情報記録信号が検出され
る。
The light transmitted through the beam splitter 62 is condensed on the optical disc 64 by the objective lens 63, and the light reflected by the optical disc 64 passes through the objective lens 63 again and is reflected by the beam splitter 62, and the signal detecting means 6
6, the servo signal and the information recording signal are detected.

【0008】なお、信号検出手段66で検出されるサー
ボ信号は、面振れおよび偏心により変動する光ディスク
64上の情報トラックと集光スポットの誤差信号であ
り、この信号に応じてアクチュエータ67を駆動し、対
物レンズ63の位置を制御することにより、情報トラッ
クに集光スポットを追従させて記録および再生が行われ
る。
The servo signal detected by the signal detecting means 66 is an error signal between the information track and the focused spot on the optical disc 64 which fluctuates due to surface wobbling and eccentricity, and the actuator 67 is driven according to this signal. By controlling the position of the objective lens 63, recording and reproduction are performed by causing the focused spot to follow the information track.

【0009】以上のような光学ヘッドにおいて、受光素
子65にて検出される光量はビームスプリッタ62を透
過する光量に略比例し、光ディスク64に集光される光
量はビームスプリッタ62を透過する光量に略比例する
ため、光ディスク64上に集光されるレーザー光量は受
光素子65で検出される光量に略比例する。従って、受
光素子65で受光される信号を所定の値となるように制
御を行えば、周囲温度が変化した場合でも光ディスク6
4上に集光されるレーザー光量を定められた値に制御す
ることができる。
In the above optical head, the amount of light detected by the light receiving element 65 is substantially proportional to the amount of light transmitted through the beam splitter 62, and the amount of light condensed on the optical disc 64 is the amount of light transmitted through the beam splitter 62. Since they are substantially proportional, the amount of laser light focused on the optical disc 64 is substantially proportional to the amount of light detected by the light receiving element 65. Therefore, if the signal received by the light receiving element 65 is controlled so as to have a predetermined value, the optical disk 6 is controlled even when the ambient temperature changes.
It is possible to control the amount of laser light focused on the laser beam 4 on a predetermined value.

【0010】[0010]

【発明が解決しようとする課題】しかしながら、このよ
うな光ディスク装置では、半導体レーザの発光量を一定
に制御しているだけであり、サーボ動作に伴いアクチュ
エータを駆動して対物レンズが移動すると、対物レンズ
を透過する光量が変化し、光ディスク上に集光される光
量が変動してしまうという課題があった。このような光
量変動は、記録時に記録マークの形成のばらつきとな
り、不完全な記録マークや記録を行っている周囲の記録
マークの破壊を生じさせて記録エラーを起こしたり、再
生時に再生信号のS/N比を劣化させて再生エラーを起
こすため、性能悪化の要因となっていた。
However, in such an optical disk device, the light emission amount of the semiconductor laser is only controlled to be constant, and when the objective lens is moved by driving the actuator in accordance with the servo operation, the objective lens is moved. There is a problem that the amount of light that passes through the lens changes, and the amount of light that is condensed on the optical disk also changes. Such fluctuations in the amount of light cause variations in the formation of recording marks during recording, causing incomplete recording marks or destruction of recording marks in the vicinity of recording to cause a recording error, or S of a reproduction signal during reproduction. Since the / N ratio is deteriorated to cause a reproduction error, the performance is deteriorated.

【0011】[0011]

【課題を解決するための手段】本発明の光学ヘッドは、
光源と、前記光源からの光の一部を検出する第1の受光
手段と、前記光源からの光を情報記録媒体上の情報トラ
ックに集光するように構成され、かつ、前記光源からの
光の光束径よりも光透過有効径が小さい集光手段と、前
記集光手段を光軸と直交する方向に移動させる移動手段
と、前記集光手段の移動に応じて移動するように構成さ
れ、かつ、前記光源から前記集光手段に向かう光の内、
前記集光手段に入射しない部分の光を検出する第2の受
光手段を備え、前記第1の受光手段と前記第2の受光手
段で検出された信号を演算して得られる信号により、前
記光源の光量を制御するように構成したことを特徴とす
る。
The optical head of the present invention comprises:
A light source, a first light receiving means for detecting a part of the light from the light source, and a light from the light source, which is configured to focus the light from the light source on an information track on an information recording medium. A light collecting means having a light transmission effective diameter smaller than the light flux diameter, a moving means for moving the light collecting means in a direction orthogonal to the optical axis, and a moving means for moving the light collecting means. And, of the light traveling from the light source to the condensing means,
The light source is provided with a second light receiving unit that detects light in a portion that does not enter the light collecting unit, and the signal obtained by calculating the signals detected by the first light receiving unit and the second light receiving unit. It is characterized in that it is configured to control the amount of light.

【0012】また、情報記録媒体からの反射光を受光す
る第3の受光素子を備え、前記光源と前記第3の受光素
子が同一の筐体内に配置される構成としてもよい。
Further, a third light receiving element for receiving reflected light from the information recording medium may be provided, and the light source and the third light receiving element may be arranged in the same housing.

【0013】また、前記第1の受光手段は前記光源と前
記集光手段の間に設けられた光分岐素子と前記光分岐素
子で分岐した光を受光する受光素子を有する構成として
もよい。
The first light receiving means may include a light branching element provided between the light source and the light collecting means and a light receiving element for receiving the light branched by the light branching element.

【0014】また、前記光源は半導体レーザから成り、
前記第1の受光手段は、前記半導体レーザにおいて前記
集光手段へ向かう光が出射する面の背面から出射する光
を受光する受光素子である構成としてもよい。
The light source comprises a semiconductor laser,
The first light receiving means may be a light receiving element that receives light emitted from a back surface of a surface of the semiconductor laser from which light directed to the light focusing means is emitted.

【0015】また、前記第2の受光手段は、前記移動手
段上に配置された受光素子である構成としてもよい。
Further, the second light receiving means may be a light receiving element arranged on the moving means.

【0016】また、前記第2の受光手段は、前記移動手
段上に配置された反射手段と、前記反射手段で反射した
光を受光する受光素子を有する構成としてもよい。
The second light receiving means may have a reflecting means arranged on the moving means and a light receiving element for receiving the light reflected by the reflecting means.

【0017】また、前記受光素子は、前記情報トラック
に対して平行な直線に対して対称に配置された複数の受
光領域を有し、前記複数の受光領域で検出される信号を
演算することにより前記集光手段の移動量を検出する構
成としてもよい。
Further, the light receiving element has a plurality of light receiving regions symmetrically arranged with respect to a straight line parallel to the information track, and by calculating signals detected in the plurality of light receiving regions. It may be configured to detect the amount of movement of the condensing unit.

【0018】また、前記反射手段は、前記情報トラック
に対して平行な直線に対して対称に配置された複数の反
射領域を有し、前記複数の受光素子で検出される信号を
演算することにより前記集光手段の移動量を検出する構
成としてもよい。
Further, the reflection means has a plurality of reflection areas symmetrically arranged with respect to a straight line parallel to the information track, and calculates the signals detected by the plurality of light receiving elements. It may be configured to detect the amount of movement of the condensing unit.

【0019】[0019]

【発明の実施の形態】以下、本発明の実施の形態につい
て、図面を参照しながら説明する。
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

【0020】(実施の形態1)図1は本発明の実施の形
態1における光学ヘッドの構成図である。1は光源に対
応する半導体レーザ、2は半導体レーザから出射する不
要な光を遮る開口、3は透過および反射で光を分岐する
ビームスプリッタ、4は第1の受光手段に対応する受光
素子、5は集光手段に対応する対物レンズ、6は対物レ
ンズホルダ、7は対物レンズホルダ6に一体に設けられ
た第2の受光手段に対応する受光素子、8は情報記録媒
体に対応する光ディスク、9は検出レンズ、プリズム、
或いは回折素子等の光学素子と受光素子を有し、ビーム
スプリッタ62によって反射された光ディスク64から
の戻り光を受光し、受光した光量に応じた信号に変換
し、検出する信号検出手段、10はビームスプリッタ3
を透過する光束、11はビームスプリッタ3で反射する
光束、12は詳細は図示しないが、光ディスク8に対し
て水平方向および垂直方向に対物レンズ5を駆動する移
動手段に対応するアクチュエータである。
(Embodiment 1) FIG. 1 is a configuration diagram of an optical head according to Embodiment 1 of the present invention. Reference numeral 1 is a semiconductor laser corresponding to a light source, 2 is an opening for blocking unnecessary light emitted from the semiconductor laser, 3 is a beam splitter for splitting light by transmission and reflection, 4 is a light receiving element corresponding to a first light receiving means, 5 Is an objective lens corresponding to the condensing means, 6 is an objective lens holder, 7 is a light receiving element corresponding to the second light receiving means provided integrally with the objective lens holder 6, 8 is an optical disk corresponding to an information recording medium, 9 Is a detection lens, prism,
Alternatively, the signal detecting means 10 which has an optical element such as a diffraction element and a light receiving element, receives the return light from the optical disc 64 reflected by the beam splitter 62, converts it into a signal according to the received light amount, and detects the signal. Beam splitter 3
, 11 is a light beam reflected by the beam splitter 3, and 12 is an actuator corresponding to a moving means for driving the objective lens 5 in a horizontal direction and a vertical direction with respect to the optical disk 8, although not shown in detail.

【0021】図2は実施の形態1における対物レンズ5
および受光素子7の配置を光源側から見た図であり、1
5は光源からの光が対物レンズを透過する領域、17は
受光素子7の受光領域であり、受光領域17は例えばド
ーナツ型をしており、対物レンズ5を透過する光束の周
囲の光を受光するように構成される。
FIG. 2 shows the objective lens 5 in the first embodiment.
FIG. 2 is a view of the arrangement of the light receiving element 7 and the light receiving element 7 as seen from the light source side.
Reference numeral 5 denotes an area through which the light from the light source passes through the objective lens, 17 denotes a light receiving area of the light receiving element 7, and the light receiving area 17 has, for example, a donut shape, and receives light around the light flux passing through the objective lens 5. To be configured.

【0022】このように構成された光学ヘッドにおい
て、半導体レーザ1を出射した光は、開口2を通過し、
ビームスプリッタ3へ入射し、一部が透過、一部が反射
される。ビームスプリッタ3で反射された光束11は受
光素子4で受光され、ビームスプリッタ3を透過した光
束10の一部(中央付近の光束)は対物レンズ5により
光ディスク8上に集光され、光束10の残り(周辺付近
の光束)は受光素子7で受光される。
In the optical head having such a structure, the light emitted from the semiconductor laser 1 passes through the opening 2 and
The light enters the beam splitter 3 and is partially transmitted and partially reflected. The light beam 11 reflected by the beam splitter 3 is received by the light receiving element 4, and a part of the light beam 10 that has passed through the beam splitter 3 (a light beam near the center) is condensed on the optical disk 8 by the objective lens 5 and The rest (light flux near the periphery) is received by the light receiving element 7.

【0023】ここで、受光素子4で検出された光量と受
光素子7で検出された光量を演算して得られる信号が所
定の値となるようにAPC回路により、半導体レーザ1
の発光量が制御される。
Here, the semiconductor laser 1 is controlled by the APC circuit so that the signal obtained by calculating the light amount detected by the light receiving element 4 and the light amount detected by the light receiving element 7 becomes a predetermined value.
Is controlled.

【0024】光ディスク8で反射した光は再び対物レン
ズ5を透過し、ビームスプリッタ3で反射され、信号検
出手段9により、サーボ信号および情報記録信号が検出
される。なお、信号検出手段9で検出されるサーボ信号
は、面振れおよび偏心により変動する光ディスク8上の
情報トラックと集光スポットの誤差信号であり、この信
号に応じてアクチュエータ12を駆動し、対物レンズ5
の位置を制御することにより、情報トラックに集光スポ
ットを追従させて記録および再生が行われる。
The light reflected by the optical disk 8 again passes through the objective lens 5, is reflected by the beam splitter 3, and the signal detecting means 9 detects the servo signal and the information recording signal. The servo signal detected by the signal detecting means 9 is an error signal between the information track and the focused spot on the optical disc 8 which varies due to surface wobbling and eccentricity, and the actuator 12 is driven according to this signal to drive the objective lens. 5
By controlling the position of, the focused spot is made to follow the information track for recording and reproduction.

【0025】以上のような光学ヘッドにおいて、開口2
を通過する光量をP0、受光素子4での受光量をP1、
受光素子7での受光量をP2、光ディスク8上に集光さ
れる光量をP3、ビームスプリッタ3の透過率をKt、
反射率をKrとすると、ビームスプリッタ3を透過する
光量においてKt×P0=P2+P3、反射する光量に
おいてKr×P0=P1となるため、次式が成り立つ。
In the above optical head, the aperture 2
The amount of light passing through P0, the amount of light received by the light receiving element 4 is P1,
The amount of light received by the light receiving element 7 is P2, the amount of light condensed on the optical disk 8 is P3, the transmittance of the beam splitter 3 is Kt,
When the reflectance is Kr, Kt × P0 = P2 + P3 in the amount of light transmitted through the beam splitter 3 and Kr × P0 = P1 in the amount of reflected light, so that the following equation holds.

【0026】 P3=(Kt/Kr)×P1−P2 (数1) (数1)により光ディスク8上に集光される光量P3は
受光素子4および受光素子7で受光される光量と、既存
値から求めることが可能である。
P3 = (Kt / Kr) × P1-P2 (Equation 1) The amount of light P3 condensed on the optical disk 8 by (Equation 1) is the amount of light received by the light receiving elements 4 and 7, and the existing value. Can be obtained from

【0027】図1の例では、受光素子4から得られるP
1に対応する出力信号を増幅率GがP1に対応する出力
信号をKt/Kr倍するに相当する増幅器で増幅したも
のと、受光素子12から得られるP2に対応する出力信
号との差を差動増幅器により出力することで、光ディス
ク8に集光される光量P3を間接的に得ることができ
る。この得た信号をAPC回路へ送りAPC回路は、得
られた信号が一定となるように半導体レーザの発光量を
制御する。
In the example of FIG. 1, P obtained from the light receiving element 4 is used.
The difference between the output signal corresponding to 1 and the output signal corresponding to P2 obtained from the light receiving element 12 is different from the one obtained by amplifying the output signal corresponding to the amplification factor G of P1 by the amplifier corresponding to Kt / Kr times. By outputting by the dynamic amplifier, the light amount P3 condensed on the optical disk 8 can be indirectly obtained. The obtained signal is sent to the APC circuit, and the APC circuit controls the light emission amount of the semiconductor laser so that the obtained signal becomes constant.

【0028】従って、本発明の光学ヘッドでは、実際に
対物レンズ5を透過して光ディスク8上に集光される光
量を(数1)の演算によって間接的にモニタすることが
可能であり、この演算によって得られる信号が一定とな
るように半導体レーザ1の発光量を制御することによ
り、光ディスク8上に集光される光量を所定の値に制御
することができる。
Therefore, in the optical head of the present invention, the amount of light that actually passes through the objective lens 5 and is condensed on the optical disk 8 can be indirectly monitored by the calculation of (Equation 1). By controlling the light emission amount of the semiconductor laser 1 so that the signal obtained by the calculation becomes constant, the light amount condensed on the optical disk 8 can be controlled to a predetermined value.

【0029】以上のように、本発明の光学ヘッドでは、
従来、光源である半導体レーザの発光量をモニタしてA
PCを行っていたのに対し、実際に光ディスク上に集光
される光量を間接的にモニタしてAPCを行うため、サ
ーボ駆動により対物レンズが移動した場合にも光ディス
ク上の光量を所定の値に制御することができる。
As described above, in the optical head of the present invention,
Conventionally, the amount of light emitted from a semiconductor laser, which is a light source, is monitored
In contrast to PC, the amount of light actually condensed on the optical disk is indirectly monitored to perform APC. Therefore, even when the objective lens moves due to servo drive, the amount of light on the optical disk is set to a predetermined value. Can be controlled.

【0030】なお、(数1)の演算式は、受光素子4は
光束11の全光束を受光し、受光素子7は光束10のう
ち対物レンズ5を透過しない全ての光束を受光すると仮
定しているが、実質的にこれらの受光量P1およびP2
に略比例する光量が検出できるのであれば、受光する光
束は領域の一部であっても良い。但しその場合は、受光
された信号にそれぞれ比例係数倍のゲインを与えて演算
することになる。
The arithmetic expression of (Equation 1) is based on the assumption that the light receiving element 4 receives all the light fluxes of the light flux 11, and the light receiving element 7 receives all the light fluxes of the light fluxes 10 which do not pass through the objective lens 5. However, these received light amounts P1 and P2 are substantially
The light flux to be received may be a part of the region as long as the light amount substantially proportional to can be detected. However, in that case, the received signal is calculated by applying a gain that is a proportional coefficient multiple.

【0031】(実施の形態2)図3は本発明の実施の形
態2における光学ヘッドの構成図である。21は光源に
対応する半導体レーザ、22は半導体レーザから出射す
る不要な光を遮る開口、23はビームスプリッタ、24
は第1の受光手段に対応する受光素子、25は集光手段
に対応する対物レンズ、26は対物レンズホルダ、27
は対物レンズホルダ26に一体に設けられた反射手段に
対応するミラー、28は情報記録媒体に対応する光ディ
スク、29は複数の受光領域を持ち、第2の受光手段に
対応する受光素子、30は検出レンズ、プリズム、或い
は回折素子等の光学素子と受光素子29とを具備する信
号検出手段、31はビームスプリッタ23で透過する光
束、32はビームスプリッタ23を反射する光束、33
の破線はミラー27で反射した光束、34は詳細は図示
しないが、光ディスク28に対して水平方向および垂直
方向に対物レンズ25を駆動する移動手段であるアクチ
ュエータである。
(Second Embodiment) FIG. 3 is a block diagram of an optical head according to a second embodiment of the present invention. Reference numeral 21 is a semiconductor laser corresponding to a light source, 22 is an opening for blocking unnecessary light emitted from the semiconductor laser, 23 is a beam splitter, and 24 is a beam splitter.
Is a light receiving element corresponding to the first light receiving means, 25 is an objective lens corresponding to the light collecting means, 26 is an objective lens holder, and 27
Is a mirror corresponding to the reflecting means provided integrally with the objective lens holder 26, 28 is an optical disk corresponding to the information recording medium, 29 is a light receiving element having a plurality of light receiving regions and corresponding to the second light receiving means, and 30 is Signal detecting means including an optical element such as a detection lens, a prism, or a diffraction element and a light receiving element 29, 31 is a light beam transmitted by the beam splitter 23, 32 is a light beam reflected by the beam splitter 23, 33
The broken line indicates a light beam reflected by the mirror 27, and 34, which is not shown in detail, is an actuator that is a moving unit that drives the objective lens 25 in the horizontal and vertical directions with respect to the optical disc 28.

【0032】本実施の形態におけるミラー27は、図2
に示した実施の形態1における受光素子7の受光領域1
7と同様の位置に配置され、対物レンズ25を透過する
光束の周囲の光を反射し、受光素子29に導くように構
成される。
The mirror 27 in this embodiment is shown in FIG.
Of the light receiving element 7 in the first embodiment shown in FIG.
It is arranged at the same position as 7, and is configured to reflect the light around the light flux passing through the objective lens 25 and guide it to the light receiving element 29.

【0033】このように構成された光学ヘッドにおい
て、半導体レーザ21を出射した光は、開口22を通過
し、ビームスプリッタ23へ入射し、一部が透過、一部
が反射される。ビームスプリッタ23で反射された光束
31は受光素子24で受光され、ビームスプリッタ23
を透過した光束30の一部は対物レンズ25により光デ
ィスク28上に集光され、光束30の残りはミラー27
で反射された後、破線で図示している光束33のように
ビームスプリッタ23で反射し、受光素子29で受光さ
れる。
In the optical head constructed as described above, the light emitted from the semiconductor laser 21 passes through the opening 22, enters the beam splitter 23, and is partially transmitted and partially reflected. The light beam 31 reflected by the beam splitter 23 is received by the light receiving element 24, and the beam splitter 23
A part of the light beam 30 that has passed through is condensed on the optical disk 28 by the objective lens 25, and the rest of the light beam 30 is reflected by the mirror 27.
After being reflected by the beam splitter 23, the beam is reflected by the beam splitter 23 as a light flux 33 shown by a broken line and is received by the light receiving element 29.

【0034】ここで、受光素子24で検出された光量と
受光素子29で検出された光量を演算して得られる信号
が所定の値となるようにAPC回路により、半導体レー
ザ1の発光量が制御される。
Here, the light emission amount of the semiconductor laser 1 is controlled by the APC circuit so that the signal obtained by calculating the light amount detected by the light receiving element 24 and the light amount detected by the light receiving element 29 becomes a predetermined value. To be done.

【0035】光ディスク28で反射した光は再び対物レ
ンズ25を透過し、ビームスプリッタ23で反射され、
信号検出手段30により、サーボ信号および情報記録信
号が検出される。サーボ信号および情報記録信号の検出
は、ミラー27の反射光を受光する受光素子29の基板
上に設けられた別の受光領域を用いる。
The light reflected by the optical disk 28 again passes through the objective lens 25 and is reflected by the beam splitter 23.
The signal detecting means 30 detects the servo signal and the information recording signal. For the detection of the servo signal and the information recording signal, another light receiving area provided on the substrate of the light receiving element 29 that receives the reflected light of the mirror 27 is used.

【0036】以上のような光学ヘッドにおいて、開口2
2を通過する光量をP0、受光素子24での受光量をP
1、受光素子29での受光量をP4、光ディスク28上
に集光される光量をP3、ビームスプリッタ23の透過
率をKt、反射率をKrとすると、ビームスプリッタ2
3を透過する光量においてKt×P0=P3+P4、反
射する光量においてKr×P0=P1となるため、次式
が成り立つ。
In the above optical head, the opening 2
2 is P0, the amount of light received by the light receiving element 24 is P
1, the amount of light received by the light receiving element 29 is P4, the amount of light condensed on the optical disk 28 is P3, the transmittance of the beam splitter 23 is Kt, and the reflectance is Kr.
Since Kt × P0 = P3 + P4 in the amount of light transmitted through 3 and Kr × P0 = P1 in the amount of reflected light, the following equation holds.

【0037】 P3=(Kt/Kr)×P1−P4 (数2) (数2)により光ディスク28上に集光される光量P3
は受光素子24および受光素子29で受光される光量
と、既存値から求めることが可能である。
P3 = (Kt / Kr) × P1-P4 (Equation 2) (Equation 2) Amount of light P3 condensed on the optical disc 28
Can be obtained from the amount of light received by the light receiving element 24 and the light receiving element 29 and the existing value.

【0038】図3の例では、受光素子24から得られる
P1に対応する出力信号を増幅率GがP1に対応する出
力信号をKt/Kr倍するに相当する増幅器で増幅した
ものと、受光素子29から得られるP2に対応する出力
信号との差を差動増幅器により出力することで、光ディ
スク28に集光される光量P4を間接的に得ることがで
きる。この得た信号をAPC回路へ送りAPC回路は、
得られた信号が一定となるように半導体レーザの発光量
を制御する。
In the example of FIG. 3, the output signal corresponding to P1 obtained from the light receiving element 24 is amplified by an amplifier corresponding to multiplying the output signal corresponding to the amplification factor G of P1 by Kt / Kr, and the light receiving element. By outputting the difference from the output signal corresponding to P2 obtained from 29 with the differential amplifier, the light amount P4 condensed on the optical disk 28 can be indirectly obtained. The obtained signal is sent to the APC circuit, and the APC circuit
The emission amount of the semiconductor laser is controlled so that the obtained signal becomes constant.

【0039】従って、本実施の形態においても、実際に
対物レンズ25を透過して光ディスク28上に集光され
る光量を(数2)の演算によって間接的にモニタするこ
とが可能であり、この演算によって得られる信号が一定
となるように半導体レーザ21の発光量を制御すること
により、光ディスク28上に集光される光量を所定の値
に制御することができる。
Therefore, also in this embodiment, it is possible to indirectly monitor the amount of light that actually passes through the objective lens 25 and is condensed on the optical disc 28 by the calculation of (Equation 2). By controlling the light emission amount of the semiconductor laser 21 so that the signal obtained by the calculation becomes constant, the light amount condensed on the optical disk 28 can be controlled to a predetermined value.

【0040】さらに、本実施の形態では、実施の形態1
の効果に加え、サーボ信号および情報記録信号を検出す
る受光素子と、対物レンズ25の周囲の光を検出する受
光素子を一体化することにより、受光素子の数が減らせ
るため、低コスト化が図れる。また、アクチュエータ内
に受光素子を設けなくてもよいため、配線等の構成が簡
単になる。
Furthermore, in the present embodiment, the first embodiment is used.
In addition to the above effect, by integrating the light receiving element for detecting the servo signal and the information recording signal and the light receiving element for detecting the light around the objective lens 25, the number of light receiving elements can be reduced, so that the cost can be reduced. Can be achieved. Further, since it is not necessary to provide the light receiving element in the actuator, the structure of the wiring and the like becomes simple.

【0041】なお、本実施の形態ではミラー27は対物
レンズホルダ26に一体に設けるとしたが、対物レンズ
25の縁の部分に蒸着等の手段で設けてもよい。
In this embodiment, the mirror 27 is provided integrally with the objective lens holder 26, but it may be provided at the edge of the objective lens 25 by means of vapor deposition or the like.

【0042】(実施の形態3)図4は本発明の実施の形
態3における光学ヘッドの構成図である。41は光源に
対応する半導体レーザ、42は半導体レーザ41の背面
から出射した光を受光する第1の受光手段に対応する受
光素子、43はビームスプリッタ、44は集光手段に対
応する対物レンズ、45は対物レンズホルダ、46は対
物レンズホルダ45に一体に設けられた第2の受光手段
に対応する受光素子、47は情報記録媒体に対応する光
ディスク、48は検出レンズ、プリズム、或いは回折素
子等の光学素子と受光素子から成る信号検出手段、49
は半導体レーザ41から対物レンズ44に向かって出射
する光束、50は半導体レーザ41において光束47が
出射する面の背面から出射する光束、51は内部に半導
体レーザ41および受光素子42を有する筐体、54は
詳細は図示しないが、光ディスク47に対して水平方向
および垂直方向に対物レンズ44を駆動する移動手段に
対応するアクチュエータである。
(Third Embodiment) FIG. 4 is a configuration diagram of an optical head according to a third embodiment of the present invention. 41 is a semiconductor laser corresponding to the light source, 42 is a light receiving element corresponding to the first light receiving means for receiving the light emitted from the back surface of the semiconductor laser 41, 43 is a beam splitter, 44 is an objective lens corresponding to the light converging means, Reference numeral 45 is an objective lens holder, 46 is a light receiving element corresponding to the second light receiving means provided integrally with the objective lens holder 45, 47 is an optical disk corresponding to an information recording medium, 48 is a detection lens, a prism, a diffraction element, or the like. Signal detecting means comprising an optical element and a light receiving element of
Is a light beam emitted from the semiconductor laser 41 toward the objective lens 44, 50 is a light beam emitted from the rear surface of the surface of the semiconductor laser 41 from which the light beam 47 is emitted, 51 is a housing having the semiconductor laser 41 and the light receiving element 42 therein, Although not shown in detail, 54 is an actuator corresponding to a moving unit that drives the objective lens 44 in the horizontal and vertical directions with respect to the optical disk 47.

【0043】本実施の形態における受光素子46は、実
施の形態1における受光素子7と同様の構成であり、図
2に示した受光領域17と同じ受光領域を持つ。このよ
うに構成された光学ヘッドにおいて、半導体レーザ41
を出射した光束49はビームスプリッタ43を透過し、
一部は対物レンズ44により光ディスク47上に集光さ
れ、光束49の残りは受光素子46で受光される。光デ
ィスク47で反射した光は再び対物レンズ44を透過
し、ビームスプリッタ43で反射され、信号検出手段4
8により、サーボ信号および情報記録信号が検出され
る。
Light receiving element 46 in the present embodiment has the same structure as light receiving element 7 in the first embodiment, and has the same light receiving area as light receiving area 17 shown in FIG. In the optical head configured as described above, the semiconductor laser 41
The light flux 49 emitted from the
Part of the light is focused on the optical disk 47 by the objective lens 44, and the rest of the light flux 49 is received by the light receiving element 46. The light reflected by the optical disk 47 passes through the objective lens 44 again, is reflected by the beam splitter 43, and is detected by the signal detecting means 4.
8, the servo signal and the information recording signal are detected.

【0044】一方、半導体レーザ41の背面から出射し
た光束50は受光素子42で受光され、受光素子42で
検出された光量と受光素子46で検出された光量を演算
して得られる信号が所定の値となるようにAPC回路に
より、半導体レーザ41の発光量が制御される。
On the other hand, the light flux 50 emitted from the back surface of the semiconductor laser 41 is received by the light receiving element 42, and a signal obtained by calculating the amount of light detected by the light receiving element 42 and the amount of light detected by the light receiving element 46 is predetermined. The emission amount of the semiconductor laser 41 is controlled by the APC circuit so that the value becomes a value.

【0045】以上のように構成された本実施の形態にお
いても、半導体レーザ41の背面から出射する光束50
の光量を受光素子42で検出した後、増幅器を用いて適
切なゲインをかけて光束49の光量を推定し、受光素子
46で得られる受光量との差動演算をすることにより、
光ディスク47上に集光される光量を間接的にモニタす
ることが可能であり、この演算によって得られる信号が
一定となるように半導体レーザ41の発光量をAPC回
路により制御することにより、光ディスク47上に集光
される光量を所定の値に制御することができる。
Also in the present embodiment configured as described above, the luminous flux 50 emitted from the back surface of the semiconductor laser 41 is also included.
After the amount of light is detected by the light receiving element 42, an appropriate gain is applied using an amplifier to estimate the amount of light of the light flux 49, and a differential calculation with the amount of light received by the light receiving element 46 is performed,
The amount of light collected on the optical disc 47 can be indirectly monitored, and the amount of light emitted from the semiconductor laser 41 is controlled by the APC circuit so that the signal obtained by this calculation becomes constant. It is possible to control the amount of light condensed above to a predetermined value.

【0046】さらに、本実施の形態では、実施の形態1
の効果に加え、半導体レーザの背面から出る光を受光す
る、いわゆるバックモニタを利用することにより、半導
体レーザ41と受光素子42を一つの筐体51内に収め
ることができるため、構成を簡略化できる。
Further, in the present embodiment, the first embodiment will be described.
In addition to the above effect, by using a so-called back monitor that receives light emitted from the back surface of the semiconductor laser, the semiconductor laser 41 and the light receiving element 42 can be housed in one housing 51, so that the configuration is simplified. it can.

【0047】(実施の形態4)図5は本発明の実施の形
態4における光学ヘッドの構成図である。71は光源に
対応する半導体レーザ、72は半導体レーザ71の背面
から出射した光を受光する第1の受光手段に対応する受
光素子、73は反射面73aおよびビームスプリッタ面
73bを有する台形プリズム、74は集光手段に対応す
る対物レンズ、75は対物レンズホルダ、76は対物レ
ンズホルダ75に一体に設けられた第2の受光手段に対
応する受光素子、77は情報記録担体に相当する光ディ
スク、78は検出レンズ、プリズム、或いは回折素子等
の光学素子から成る信号分岐手段、79は信号分岐手段
で分岐した光束を受光する受光素子、80は内部に半導
体レーザ71、受光素子72および受光素子79を有す
る筐体、81は台形プリズム73から対物レンズ74に
向かって出射する光束、82は半導体レーザ71におい
て光束81が出射する面の背面から出射する光束、83
は詳細は図示しないが、光ディスク77に対して水平方
向および垂直方向に対物レンズ74を駆動する移動手段
に対応するアクチュエータである。
(Fourth Embodiment) FIG. 5 is a block diagram of an optical head according to a fourth embodiment of the present invention. Reference numeral 71 is a semiconductor laser corresponding to a light source, 72 is a light receiving element corresponding to a first light receiving means for receiving light emitted from the back surface of the semiconductor laser 71, 73 is a trapezoidal prism having a reflecting surface 73a and a beam splitter surface 73b, 74 Is an objective lens corresponding to the condensing means, 75 is an objective lens holder, 76 is a light receiving element corresponding to the second light receiving means provided integrally with the objective lens holder 75, 77 is an optical disk corresponding to an information recording carrier, 78 Is a signal branching means composed of a detection lens, a prism, or an optical element such as a diffractive element, 79 is a light receiving element for receiving the light beam branched by the signal branching means, and 80 is a semiconductor laser 71, a light receiving element 72 and a light receiving element 79. The housing has, 81 is a light beam emitted from the trapezoidal prism 73 toward the objective lens 74, and 82 is light in the semiconductor laser 71. Light beam 81 is emitted from the back surface to be emitted, 83
Although not shown in detail, is an actuator corresponding to a moving unit that drives the objective lens 74 in a horizontal direction and a vertical direction with respect to the optical disc 77.

【0048】このように構成された光学ヘッドにおい
て、半導体レーザ71を出射した光束81は台形プリズ
ム73に入射し、反射面73aおよびビームスプリッタ
面73bを反射した後、一部は対物レンズ74により光
ディスク77上に集光され、光束81の残りは受光素子
76で受光される。光ディスク77で反射した光は再び
対物レンズ74を透過し、台形プリズム73のビームス
プリッタ面73bを透過し、信号分岐手段78により、
受光素子79に導かれ、サーボ信号および情報記録信号
が検出される。
In the optical head having such a structure, the light beam 81 emitted from the semiconductor laser 71 is incident on the trapezoidal prism 73, is reflected by the reflecting surface 73a and the beam splitter surface 73b, and is partially reflected by the objective lens 74 on the optical disk. The light beam 81 is condensed on the light beam 77 and the rest of the light beam 81 is received by the light receiving element 76. The light reflected by the optical disk 77 again passes through the objective lens 74, the beam splitter surface 73b of the trapezoidal prism 73, and the signal branching unit 78
The servo signal and the information recording signal are guided to the light receiving element 79 and detected.

【0049】一方、半導体レーザ71の背面から出射し
た光束82は受光素子72で受光され、受光素子72で
検出された後、増幅器を用いて適切なゲインをかけて光
束81の光量を推定したものと、受光素子76で検出さ
れた光量とを差動演算して得られる信号が所定の値とな
るようにAPC回路を用いて制御することにより、半導
体レーザ71の発光量が制御される。
On the other hand, the light beam 82 emitted from the back surface of the semiconductor laser 71 is received by the light receiving element 72, detected by the light receiving element 72, and then the gain of the light beam 81 is estimated by applying an appropriate gain using an amplifier. Then, the light emission amount of the semiconductor laser 71 is controlled by controlling the signal obtained by differentially calculating the light amount detected by the light receiving element 76 using the APC circuit so that the signal has a predetermined value.

【0050】以上のような構成においても図4に示した
実施の形態3と同様に、半導体レーザ71の背面から出
射する光束82の光量に適切なゲインをかけて光束81
の光量を推定し、受光素子76で得られる受光量との差
動演算をすることにより、光ディスク77上に集光され
る光量を間接的にモニタすることが可能であり、この演
算によって得られる信号が一定となるように半導体レー
ザ71の発光量を制御することにより、光ディスク77
上に集光される光量を所定の値に制御することができ
る。
Also in the above-described structure, as in the third embodiment shown in FIG. 4, the light amount of the light beam 82 emitted from the back surface of the semiconductor laser 71 is multiplied by an appropriate gain to obtain the light beam 81.
It is possible to indirectly monitor the amount of light condensed on the optical disk 77 by estimating the amount of light of the light and performing a differential calculation with the amount of light received by the light receiving element 76, which is obtained by this calculation. The optical disc 77 is controlled by controlling the light emission amount of the semiconductor laser 71 so that the signal becomes constant.
It is possible to control the amount of light condensed above to a predetermined value.

【0051】さらに、この実施の形態では、半導体レー
ザ71、受光素子72および受光素子79を同一の筐体
80内に収めることができるため、さらに構成を簡略化
できる。
Further, in this embodiment, the semiconductor laser 71, the light receiving element 72 and the light receiving element 79 can be housed in the same housing 80, so that the structure can be further simplified.

【0052】なお、図5に示した本実施の形態では、対
物レンズホルダ75に受光素子76が一体に設けられる
構成としたが、実施の形態2のように、対物レンズホル
ダ75にミラーを設け、その反射光を筐体80内部の受
光素子で受光する構成としてもよい。
In this embodiment shown in FIG. 5, the light receiving element 76 is integrally provided on the objective lens holder 75, but as in the second embodiment, the objective lens holder 75 is provided with a mirror. Alternatively, the reflected light may be received by a light receiving element inside the housing 80.

【0053】また信号分岐手段78として例えばホログ
ラム等の回折素子84を用いると、図6に示すように台
形プリズム73を省略することもできる。図8において
84は回折素子であり、その他の構成要素は図5と同じ
符号をつけて示し、説明は省略する。
If a diffractive element 84 such as a hologram is used as the signal branching means 78, the trapezoidal prism 73 can be omitted as shown in FIG. In FIG. 8, reference numeral 84 is a diffractive element, and the other constituent elements are denoted by the same reference numerals as those in FIG. 5, and description thereof is omitted.

【0054】(実施の形態5)実施の形態5において、
図1に示した実施の形態1と異なるのは受光素子7のみ
であり、その他の構成要素は図1と同様であるので説明
を省略する。
(Fifth Embodiment) In the fifth embodiment,
Only the light receiving element 7 is different from the first embodiment shown in FIG. 1, and the other components are the same as those in FIG.

【0055】図7は実施の形態4における対物レンズ5
および受光素子7の配置を光源側から見た図であり、1
5は光源からの光が対物レンズを透過する領域、17
a、17bは受光素子7の受光領域であり、受光領域1
7a、17bは情報トラックに対して平行な直線に対し
て対称に配置されると共に、対物レンズ5を透過する光
束の周囲の光を受光するように構成される。このように
構成された光学ヘッドの動作を図1を用いて説明する。
FIG. 7 shows the objective lens 5 according to the fourth embodiment.
FIG. 2 is a view of the arrangement of the light receiving element 7 and the light receiving element 7 as seen from the light source side.
Reference numeral 5 denotes a region where the light from the light source passes through the objective lens, and 17
Reference numerals a and 17b are light receiving regions of the light receiving element 7, and the light receiving region 1
7a and 17b are arranged symmetrically with respect to a straight line parallel to the information track, and are configured to receive light around the light flux passing through the objective lens 5. The operation of the optical head thus configured will be described with reference to FIG.

【0056】半導体レーザ1を出射した光は、開口2を
通過し、ビームスプリッタ3へ入射し、一部が透過、一
部が反射される。ビームスプリッタ3で反射された光束
11は受光素子4で受光され、ビームスプリッタ3を透
過した光束10の一部は対物レンズ5により光ディスク
8上に集光され、光束10の残りは受光素子7の受光領
域17aおよび17bで受光される。
The light emitted from the semiconductor laser 1 passes through the opening 2, enters the beam splitter 3, and is partially transmitted and partially reflected. The light beam 11 reflected by the beam splitter 3 is received by the light receiving element 4, a part of the light beam 10 transmitted through the beam splitter 3 is condensed on the optical disk 8 by the objective lens 5, and the rest of the light beam 10 is received by the light receiving element 7. The light is received by the light receiving regions 17a and 17b.

【0057】ここで、受光素子4で検出された光量と、
受光素子7の受光領域17aおよび17bで検出された
光量の和信号を演算して得られる信号が所定の値となる
ようにAPC回路により、半導体レーザ1の発光量が制
御される。また、受光素子7の受光領域17aおよび1
7bで検出された信号の差信号により対物レンズ6の位
置を検出し、トラッキング信号の補正を行う。光ディス
ク8で反射した光は再び対物レンズ5を透過し、ビーム
スプリッタ3で反射され、信号検出手段9により、サー
ボ信号および情報記録信号が検出される。
Here, the amount of light detected by the light receiving element 4,
The light emission amount of the semiconductor laser 1 is controlled by the APC circuit so that the signal obtained by calculating the sum signal of the light amounts detected by the light receiving regions 17a and 17b of the light receiving element 7 has a predetermined value. In addition, the light receiving regions 17a and 17a of the light receiving element 7
The position of the objective lens 6 is detected by the difference signal of the signals detected by 7b, and the tracking signal is corrected. The light reflected by the optical disk 8 again passes through the objective lens 5, is reflected by the beam splitter 3, and the signal detecting means 9 detects the servo signal and the information recording signal.

【0058】以上のように構成された本実施の形態にお
いても、受光領域17aおよび17bでの受光量の和信
号を用いて(数1)の演算を行うことにより、実施の形
態1と同様の効果が得られる。
Also in the present embodiment configured as described above, the calculation of (Equation 1) is performed using the sum signal of the light receiving amounts in the light receiving regions 17a and 17b, and the same as in the first embodiment. The effect is obtained.

【0059】さらに、本実施の形態では、受光領域17
aおよび17bでの受光量の差を演算することにより、
対物レンズの光ディスク半径方向の移動距離を検出する
ことができる。なぜなら、半導体レーザ1から出射する
光束の光量分布は光束の中心部の光強度が高く、中心か
ら離れるほど光強度が低くなるため、対物レンズが光デ
ィスク半径方向に移動すると、光束の中心部は対物レン
ズの中心からずれ、受光領域17aおよび17bで検出
される光量に差が生じ、明らかに、この光量差は対物レ
ンズの移動量に応じて変化するためである。
Further, in the present embodiment, the light receiving area 17
By calculating the difference in the amount of light received at a and 17b,
It is possible to detect the moving distance of the objective lens in the radial direction of the optical disc. This is because the light intensity distribution of the light flux emitted from the semiconductor laser 1 has a high light intensity at the center of the light flux and a lower light intensity as it moves away from the center. This is because there is a difference in the amount of light detected in the light receiving regions 17a and 17b due to the deviation from the center of the lens, and this difference in light amount obviously changes according to the amount of movement of the objective lens.

【0060】1ビームのトラッキング方式として知られ
るプッシュプル法は、光学ヘッドの構成が簡単であり、
小型化、低コスト化に適した方式であるが、対物レンズ
の光ディスク半径方向の移動によりトラッキングエラー
信号がオフセットする課題がある。本実施の形態では、
上述のように対物レンズの位置の検出が可能なため、プ
ッシュプル法のオフセットを補正することも可能であ
る。
The push-pull method known as the one-beam tracking method has a simple optical head configuration,
Although this method is suitable for downsizing and cost reduction, there is a problem that the tracking error signal is offset by the movement of the objective lens in the radial direction of the optical disc. In this embodiment,
Since the position of the objective lens can be detected as described above, it is also possible to correct the offset of the push-pull method.

【0061】従って、本実施の形態では、実施の形態1
の効果に加え、プッシュプル法或いはプッシュプル法を
応用した1ビームトラッキング方式を用いながらも、そ
の課題であるオフセットを補正し、良好なサーボ特性を
得ることができる。
Therefore, in the present embodiment, the first embodiment
In addition to the effect of 1., the push-pull method or the one-beam tracking method to which the push-pull method is applied can be used to correct the offset, which is the problem, and obtain good servo characteristics.

【0062】なお、本実施の形態では、対物レンズホル
ダに2分割受光素子を一体に設ける構成としたが、実施
の形態2のように、受光素子の代わりにミラーを対物レ
ンズホルダに設けると共に、その反射光を受光する複数
の受光素子を設ける構成としても同様の効果が得られ
る。
In the present embodiment, the objective lens holder is integrally provided with the two-divided light receiving element. However, as in the second embodiment, a mirror is provided in the objective lens holder instead of the light receiving element. Similar effects can be obtained even if a plurality of light receiving elements that receive the reflected light are provided.

【0063】また、半導体レーザ1の発光量を検出する
方法は、実施の形態3のようにバックモニタでもよい。
The method for detecting the light emission amount of the semiconductor laser 1 may be a back monitor as in the third embodiment.

【0064】[0064]

【発明の効果】本発明の光学ヘッドは光源と、前記光源
からの光の一部を検出する第1の受光手段と、前記光源
からの光を情報記録媒体上の情報トラックに集光するよ
うに構成され、かつ、前記光源からの光の光束径よりも
光透過有効径が小さい集光手段と、前記集光手段を光軸
と直交する方向に移動させる移動手段と、前記集光手段
の移動に応じて移動するように構成され、かつ、前記光
源から前記集光手段に向かう光の内、前記集光手段に入
射しない部分の光を検出する第2の受光手段を備え、前
記第1の受光手段と前記第2の受光手段で検出された信
号を演算して得られる信号により、前記光源の発光量を
制御するので、サーボ動作時の対物レンズの移動による
光ディスク上の光量の変動を抑えることができる。これ
により、記録時の情報の書き込みムラ、および、再生時
のS/N比の劣化を抑え、良好な記録、再生特性を有す
る光学ヘッドが提供できる。
According to the optical head of the present invention, the light source, the first light receiving means for detecting a part of the light from the light source, and the light from the light source are focused on the information track on the information recording medium. And a moving means for moving the light collecting means in a direction orthogonal to the optical axis, the light collecting means having a smaller effective light transmission diameter than the light beam diameter of the light from the light source, and the light collecting means. A second light receiving unit configured to move in accordance with the movement, and detecting a portion of the light traveling from the light source to the light collecting unit that does not enter the light collecting unit, The light emission amount of the light source is controlled by the signal obtained by calculating the signals detected by the second light receiving unit and the second light receiving unit, so that the fluctuation of the light amount on the optical disk due to the movement of the objective lens during the servo operation is controlled. Can be suppressed. As a result, it is possible to provide an optical head having good recording and reproducing characteristics by suppressing uneven writing of information during recording and deterioration of the S / N ratio during reproduction.

【0065】また、情報記録媒体からの反射光を受光す
る第3の受光素子を備え、前記光源と前記第3の受光素
子が同一の筐体内に配置されるようにすれば、構成が簡
略化され、小型化が図れる。
Further, if the third light receiving element for receiving the reflected light from the information recording medium is provided, and the light source and the third light receiving element are arranged in the same housing, the structure is simplified. Therefore, the size can be reduced.

【0066】また、前記第1の受光手段は前記光源と前
記集光手段の間に設けられた光分岐素子と前記光分岐素
子で分岐した光を受光する受光素子を有するようにすれ
ば、前記光源から出射する光を精度良く検出することが
可能となり、光ディスク上の光量の変動をより小さく抑
えることができる。
Further, if the first light receiving means has a light branching element provided between the light source and the light collecting means and a light receiving element for receiving the light branched by the light branching element, It is possible to detect the light emitted from the light source with high precision, and it is possible to further suppress the fluctuation of the light amount on the optical disc.

【0067】また、前記光源は半導体レーザから成り、
前記第1の受光手段は、前記半導体レーザにおいて前記
集光手段へ向かう光が出射する面の背面から出射する光
を受光する受光素子とすれば、前記半導体レーザと前記
受光素子を一つの筐体内に収めることができるため、構
成が簡略化され、小型化が図れる。
The light source comprises a semiconductor laser,
Assuming that the first light receiving means is a light receiving element that receives light emitted from the back surface of the surface of the semiconductor laser that emits light toward the light converging means, the semiconductor laser and the light receiving element are provided in one housing. Therefore, the structure can be simplified and the size can be reduced.

【0068】また、前記第2の受光手段は、前記移動手
段上に配置された受光素子とすれば、前記集光手段の移
動に応じて移動し、かつ、前記集光手段に入射しない部
分の光を検出する受光手段を部品点数を増やすことなく
実現できる。
Further, if the second light receiving means is a light receiving element arranged on the moving means, the second light receiving means moves in accordance with the movement of the light collecting means and does not enter the light collecting means. The light receiving means for detecting light can be realized without increasing the number of parts.

【0069】また、前記第2の受光手段は、前記移動手
段上に配置された反射手段と、前記反射手段で反射した
光を受光する受光素子とすれば、サーボ信号および情報
記録信号を検出する受光素子と、対物レンズの周囲の光
を検出する受光素子を一体化することができ、受光素子
の数が減らせるため、低コスト化が図れる。また、前記
移動手段上に受光素子を設けなくてもよいため、配線等
の構成が簡単になる。
Further, if the second light receiving means is a reflecting means arranged on the moving means and a light receiving element for receiving the light reflected by the reflecting means, the second light receiving means detects a servo signal and an information recording signal. Since the light receiving element and the light receiving element that detects the light around the objective lens can be integrated, and the number of light receiving elements can be reduced, the cost can be reduced. Further, since it is not necessary to provide a light receiving element on the moving means, the configuration of wiring and the like becomes simple.

【0070】また、前記受光素子は、前記情報トラック
に対して平行な直線に対して対称に配置された複数の受
光領域を有し、前記複数の受光領域で検出される信号を
演算することにより前記集光手段の移動量を検出すれ
ば、構成が簡単な1ビームトラッキング方式のプッシュ
プル法の課題である、対物レンズの移動によるオフセッ
トを補正し良好なサーボ特性が得られる。
Further, the light receiving element has a plurality of light receiving regions symmetrically arranged with respect to a straight line parallel to the information track, and the signals detected by the plurality of light receiving regions are calculated. By detecting the amount of movement of the light condensing means, it is possible to correct the offset due to the movement of the objective lens, which is a problem of the push-pull method of the one-beam tracking method having a simple structure, and obtain good servo characteristics.

【0071】また、前記反射手段は、前記情報トラック
に対して平行な直線に対して対称に配置された複数の反
射領域を有し、前記複数の受光素子で検出される信号を
演算することにより前記集光手段の移動量を検出すれ
ば、サーボ信号および情報記録信号を検出する受光素子
と、対物レンズの周囲の光を検出する受光素子を一体化
することができ、受光素子の数が減らせるため、低コス
ト化が図れると共に、構成が簡単な1ビームトラッキン
グ方式のプッシュプル法の課題である、対物レンズの移
動によるオフセットを補正し良好なサーボ特性が得られ
る。
Further, the reflecting means has a plurality of reflecting areas symmetrically arranged with respect to a straight line parallel to the information track, and calculates signals detected by the plurality of light receiving elements. If the amount of movement of the condensing means is detected, the light receiving element for detecting the servo signal and the information recording signal and the light receiving element for detecting the light around the objective lens can be integrated, and the number of light receiving elements can be reduced. Therefore, the cost can be reduced, and the offset due to the movement of the objective lens, which is a problem of the push-pull method of the one-beam tracking system having a simple structure, can be corrected and good servo characteristics can be obtained.

【図面の簡単な説明】[Brief description of drawings]

【図1】本発明の実施の形態1における光学ヘッドの構
成図
FIG. 1 is a configuration diagram of an optical head according to a first embodiment of the present invention.

【図2】本発明の実施の形態1の光学ヘッドにおいて対
物レンズおよび受光素子の配置を光源側から見た図
FIG. 2 is a diagram of an arrangement of an objective lens and a light receiving element viewed from the light source side in the optical head according to the first embodiment of the present invention.

【図3】本発明の実施の形態2における光学ヘッドの構
成図
FIG. 3 is a configuration diagram of an optical head according to a second embodiment of the present invention.

【図4】本発明の実施の形態3における光学ヘッドの構
成図
FIG. 4 is a configuration diagram of an optical head according to a third embodiment of the present invention.

【図5】本発明の実施の形態4における光学ヘッドの構
成図
FIG. 5 is a configuration diagram of an optical head according to a fourth embodiment of the present invention.

【図6】本発明の実施の形態4の光学ヘッドにおいて信
号分岐手段として回折素子を用いたときの構成図
FIG. 6 is a configuration diagram when a diffraction element is used as a signal branching unit in the optical head according to the fourth embodiment of the present invention.

【図7】本発明の実施の形態5の光学ヘッドにおいて対
物レンズおよび受光素子の配置を光源側から見た図
FIG. 7 is a diagram of an arrangement of an objective lens and a light receiving element viewed from a light source side in an optical head according to a fifth embodiment of the present invention.

【図8】従来の実施の形態の構成図FIG. 8 is a configuration diagram of a conventional embodiment.

【符号の説明】 1 半導体レーザ 2 開口 3 ビームスプリッタ 4 受光素子 5 対物レンズ 6 対物レンズホルダ 7 受光素子 8 光ディスク 9 信号検出手段 10,11 光束 12 アクチュエータ 15 光が対物レンズを透過する領域 17 受光領域 17a,17b 受光領域 21 半導体レーザ 22 開口 23 ビームスプリッタ 24 受光素子 25 対物レンズ 26 対物レンズホルダ 27 ミラー 28 光ディスク 29 受光素子 30 信号検出手段 31,32,33 光束 34 アクチュエータ 41 半導体レーザ 42 受光素子 43 ビームスプリッタ 44 対物レンズ 45 対物レンズホルダ 46 受光素子 47 光ディスク 48 信号検出手段 49,50 光束 51 筐体 54 アクチュエータ 61 半導体レーザ 62 ビームスプリッタ 63 対物レンズ 64 光ディスク 65 受光素子 66 信号検出手段 67 アクチュエータ 71 半導体レーザ 72 受光素子 73 台形プリズム 73a 反射面 73b ビームスプリッタ面 74 対物レンズ 75 対物レンズホルダ 76 受光素子 77 光ディスク 78 信号分岐手段 79 受光素子 80 筐体 81,82 光束 83 アクチュエータ 84 回折素子[Explanation of symbols] 1 Semiconductor laser 2 openings 3 beam splitter 4 Light receiving element 5 Objective lens 6 Objective lens holder 7 Light receiving element 8 optical disks 9 Signal detection means 10,11 luminous flux 12 actuators 15 Area where light passes through the objective lens 17 Light receiving area 17a, 17b Light receiving area 21 Semiconductor laser 22 opening 23 Beam splitter 24 Light receiving element 25 Objective lens 26 Objective Lens Holder 27 mirror 28 optical disks 29 Light receiving element 30 signal detection means 31, 32, 33 luminous flux 34 Actuator 41 Semiconductor laser 42 Light receiving element 43 beam splitter 44 Objective lens 45 Objective lens holder 46 Light receiving element 47 optical disk 48 signal detection means 49,50 luminous flux 51 housing 54 Actuator 61 Semiconductor laser 62 beam splitter 63 Objective lens 64 optical disks 65 Light receiving element 66 signal detection means 67 Actuator 71 Semiconductor laser 72 Light receiving element 73 Trapezoidal prism 73a reflective surface 73b Beam splitter surface 74 Objective lens 75 Objective lens holder 76 Light receiving element 77 optical disc 78 signal branching means 79 Light receiving element 80 housing 81,82 luminous flux 83 Actuator 84 diffractive element

───────────────────────────────────────────────────── フロントページの続き (72)発明者 冨田 浩稔 大阪府門真市大字門真1006番地 松下電器 産業株式会社内 (72)発明者 林 卓生 大阪府門真市大字門真1006番地 松下電器 産業株式会社内 Fターム(参考) 5D118 AA01 AA04 AA21 BA01 BB03 BB06 BB07 BF02 BF03 CA13 CA22 CD03 CD11 CF03 CG02 DB05 DC03 5D119 AA01 AA05 AA23 AA26 AA29 AA31 BA01 BB02 BB04 BB05 DA01 DA05 EA02 EC16 FA05 HA13 HA14 HA46 HA53 HA55 JA57 KA17 KA22 LB08 5D789 AA01 AA05 AA23 AA26 AA29 AA31 BA01 BB02 BB04 BB05 DA01 DA05 EA02 EC16 FA05 HA13 HA14 HA46 HA53 HA55 JA57 KA17 KA22 LB08    ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hirotoshi Tomita             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Takao Hayashi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5D118 AA01 AA04 AA21 BA01 BB03                       BB06 BB07 BF02 BF03 CA13                       CA22 CD03 CD11 CF03 CG02                       DB05 DC03                 5D119 AA01 AA05 AA23 AA26 AA29                       AA31 BA01 BB02 BB04 BB05                       DA01 DA05 EA02 EC16 FA05                       HA13 HA14 HA46 HA53 HA55                       JA57 KA17 KA22 LB08                 5D789 AA01 AA05 AA23 AA26 AA29                       AA31 BA01 BB02 BB04 BB05                       DA01 DA05 EA02 EC16 FA05                       HA13 HA14 HA46 HA53 HA55                       JA57 KA17 KA22 LB08

Claims (8)

【特許請求の範囲】[Claims] 【請求項1】 光源と、 前記光源からの光の一部を検出する第1の受光手段と、 前記光源からの光を情報記録媒体上の情報トラックに集
光するように構成され、かつ、前記光源からの光の光束
径よりも光透過有効径が小さい集光手段と、 前記集光手段を光軸と直交する方向に移動させる移動手
段と、 前記集光手段の移動に応じて移動するように構成され、
かつ、前記光源から前記集光手段に向かう光の内、前記
集光手段に入射しない部分の光を検出する第2の受光手
段を備え、 前記第1の受光手段と前記第2の受光手段で検出された
信号を演算して得られる信号により、前記光源の発光量
を制御することを特徴とする光学ヘッド。
1. A light source, a first light receiving means for detecting a part of the light from the light source, a light source configured to focus the light from the light source on an information track on an information recording medium, and Condensing means having an effective light transmission diameter smaller than the luminous flux diameter of the light from the light source, moving means for moving the condensing means in a direction orthogonal to the optical axis, and moving according to the movement of the condensing means. Is configured as
Further, a second light receiving unit that detects a portion of the light that goes from the light source to the light collecting unit and does not enter the light collecting unit is provided, and the first light receiving unit and the second light receiving unit are provided. An optical head characterized in that the light emission amount of the light source is controlled by a signal obtained by calculating a detected signal.
【請求項2】 情報記録媒体からの反射光を受光する第
3の受光素子を備え、 前記光源と前記第3の受光素子が同一の筐体内に配置さ
れたことを特徴とする請求項1記載の光学ヘッド。
2. A third light receiving element for receiving the reflected light from the information recording medium, wherein the light source and the third light receiving element are arranged in the same housing. Optical head.
【請求項3】 前記第1の受光手段は前記光源と前記集
光手段の間に設けられた光分岐素子と前記光分岐素子で
分岐した光を受光する受光素子を有することを特徴とす
る請求項1または請求項2に記載の光学ヘッド。
3. The first light receiving means includes a light branching element provided between the light source and the light collecting means, and a light receiving element for receiving light branched by the light branching element. The optical head according to claim 1 or 2.
【請求項4】 前記光源は半導体レーザから成り、前記
第1の受光手段は、前記半導体レーザにおいて前記集光
手段へ向かう光が出射する面の背面から出射する光を受
光する受光素子であることを特徴とする請求項1または
請求項2に記載の光学ヘッド。
4. The light source comprises a semiconductor laser, and the first light receiving means is a light receiving element for receiving light emitted from a back surface of a surface of the semiconductor laser from which light directed to the light converging means is emitted. The optical head according to claim 1 or 2, characterized in that.
【請求項5】 前記第2の受光手段は、前記移動手段上
に配置された受光素子であることを特徴とする請求項1
から請求項4の何れかに記載の光学ヘッド。
5. The second light receiving means is a light receiving element arranged on the moving means.
5. The optical head according to claim 4.
【請求項6】 前記第2の受光手段は、前記移動手段上
に配置された反射手段と、 前記反射手段で反射した光を受光する受光素子を有する
ことを特徴とする請求項1から請求項4の何れかに記載
の光学ヘッド。
6. The second light receiving means comprises a reflecting means arranged on the moving means and a light receiving element for receiving the light reflected by the reflecting means. 4. The optical head according to any one of 4 above.
【請求項7】 前記受光素子は、前記情報トラックに対
して平行な直線に対して対称に配置された複数の受光領
域を有し、前記複数の受光領域で検出される信号を演算
することにより前記集光手段の移動量を検出することを
特徴とする請求項5記載の光学ヘッド。
7. The light receiving element has a plurality of light receiving regions symmetrically arranged with respect to a straight line parallel to the information track, and calculates signals detected in the plurality of light receiving regions. The optical head according to claim 5, wherein the movement amount of the light converging unit is detected.
【請求項8】 前記反射手段は、前記情報トラックに対
して平行な直線に対して対称に配置された複数の反射領
域を有し、前記複数の受光素子で検出される信号を演算
することにより前記集光手段の移動量を検出することを
特徴とする請求項6記載の光学ヘッド。
8. The reflection means has a plurality of reflection areas symmetrically arranged with respect to a straight line parallel to the information track, and calculates the signals detected by the plurality of light receiving elements. 7. The optical head according to claim 6, wherein the amount of movement of the condensing unit is detected.
JP2002117246A 2002-04-19 2002-04-19 Optical head Expired - Fee Related JP3988513B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2002117246A JP3988513B2 (en) 2002-04-19 2002-04-19 Optical head

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2002117246A JP3988513B2 (en) 2002-04-19 2002-04-19 Optical head

Publications (3)

Publication Number Publication Date
JP2003317294A true JP2003317294A (en) 2003-11-07
JP2003317294A5 JP2003317294A5 (en) 2005-08-25
JP3988513B2 JP3988513B2 (en) 2007-10-10

Family

ID=29534521

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2002117246A Expired - Fee Related JP3988513B2 (en) 2002-04-19 2002-04-19 Optical head

Country Status (1)

Country Link
JP (1) JP3988513B2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8144549B2 (en) 2006-12-08 2012-03-27 Hitachi, Ltd. Head stack assembly and information recording apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8144549B2 (en) 2006-12-08 2012-03-27 Hitachi, Ltd. Head stack assembly and information recording apparatus

Also Published As

Publication number Publication date
JP3988513B2 (en) 2007-10-10

Similar Documents

Publication Publication Date Title
EP1589529A2 (en) Method for adjusting focus or tracking detection unit, and optical disc device
JP2007179676A (en) Optical head device and optical disk device
JP2006004596A (en) Optical pickup device, optical recording/reproducing apparatus and gap detection method
US8064320B2 (en) Optical pickup and optical disc apparatus using the same
JP3619371B2 (en) Optical pickup device and tilt detection method thereof
JPH01138627A (en) Optical disk device
JP2009500783A (en) Scanning multilayer optical record carriers
JP3988513B2 (en) Optical head
US20090003182A1 (en) Optical disc apparatus with optical head unit
US6697398B2 (en) Laser light intensity controller
JP2003296958A (en) Optical pickup device and electronic apparatus
US7623435B2 (en) Optical pickup device, and information recording and reproduction device
JP4093209B2 (en) Optical pickup device and optical disk device
JPH10283644A (en) Focus controller, its method and optical disk device
JPH1083540A (en) Focus-error signal detecting method and signal reading device
JP2003059083A (en) Optical head and optical disk playing-back device
JP4359189B2 (en) Optical pickup device
JP2628972B2 (en) Optical recording device
JP3667111B2 (en) Optical pickup device and crosstalk removing method
JP3722670B2 (en) Optical pickup device
KR20040035111A (en) Optical pick-up cutting off optical noise and optical recording and/of reproducing apparatus
JPH1083539A (en) Wobble signal reading method and signal reading device
JP4412149B2 (en) Optical disk device
JP3564883B2 (en) Optical pickup device
JPH04263124A (en) Optical system information reproduction device

Legal Events

Date Code Title Description
A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20050218

A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20050218

RD01 Notification of change of attorney

Free format text: JAPANESE INTERMEDIATE CODE: A7421

Effective date: 20050706

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20070209

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20070220

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20070405

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20070626

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20070709

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20100727

Year of fee payment: 3

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20110727

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20110727

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120727

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120727

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130727

Year of fee payment: 6

LAPS Cancellation because of no payment of annual fees