JPS61931A - Optical recording and reproducing device - Google Patents

Optical recording and reproducing device

Info

Publication number
JPS61931A
JPS61931A JP59121141A JP12114184A JPS61931A JP S61931 A JPS61931 A JP S61931A JP 59121141 A JP59121141 A JP 59121141A JP 12114184 A JP12114184 A JP 12114184A JP S61931 A JPS61931 A JP S61931A
Authority
JP
Japan
Prior art keywords
photodetector
sector address
optical
light
optical recording
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.)
Pending
Application number
JP59121141A
Other languages
Japanese (ja)
Inventor
Toshiyuki Kori
俊之 郡
Noboru Wakami
昇 若見
Tomiya Miyazaki
富弥 宮崎
Yoshikazu Goto
芳和 後藤
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 JP59121141A priority Critical patent/JPS61931A/en
Publication of JPS61931A publication Critical patent/JPS61931A/en
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
    • G11B7/005—Reproducing
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
    • G11B27/19—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier
    • G11B27/28—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording
    • G11B27/30—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on the same track as the main recording
    • G11B27/3027—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on the same track as the main recording used signal is digitally coded
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces

Landscapes

  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Recording Or Reproduction (AREA)
  • Moving Of The Head For Recording And Reproducing By Optical Means (AREA)

Abstract

PURPOSE:To obtain an optical system recording and reproducing device that can obtain a sector address gate surely by detecting a sector address signal by a photodetector of large beam diameter. CONSTITUTION:The photodetector 16 having large beam diameter is installed near an optical pickup 6, and made to move simultaneously with the optical pickup 6. It consists of a light emission element and a photodetector and light output of the light emission element is stopped down to spot diameter of about 1mm.. Reflected light is diffused by uneven sector address section, and the quantity of light that returns to the photodetector is reduced. This change of quantity of light becomes change of output of the photodetector 16, and this is detected by a detector 17 and compared at a fixed level by a comparator 18, and a selector address gate is obtained from the compared signal. Thus, by detecting by a photodetector of large beam diameter, the sector address gate can be obtained even when there are fluctuation in amplitude of sector address signals and drop- out etc. in the sector address section.

Description

【発明の詳細な説明】 産業上の利用分野 本発明は、光学式情報処理を有する光学式記録再生装置
に関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical recording/reproducing device having optical information processing.

従来例の構成とその問題点 近年、光ディスクが大容量記録媒体として注目を浴びて
いる。以下に従来の光学式記録再生装置について説明す
る。Conventional Structure and Problems In recent years, optical disks have attracted attention as large-capacity recording media. A conventional optical recording/reproducing device will be explained below.

第１図は、ディスク状の光学的記録媒体（以下ディスク
という）のフォーマットを示すものであり、１はスタン
パ作成時に同心円状、あるいはスパイラルにカッティン
グされているトラックを識別する凹凸信号によるセクタ
ーアドレス信号である。Figure 1 shows the format of a disc-shaped optical recording medium (hereinafter referred to as a disc), where 1 is a sector address signal using a concave-convex signal that identifies tracks that are cut concentrically or spirally during stamper creation. It is.

２はディスクが１回転したことを識別する１回転基準信
号である。３は記録再生される情報トラック案内溝であ
る。2 is a one-rotation reference signal that identifies that the disk has made one rotation. Reference numeral 3 denotes an information track guide groove for recording and reproduction.

第２図は従来の光学式記録再生装置の１例の構成図を示
すものであり、１はレーザー光源で半導体レーザーより
なり一定光量のレーザー光を発光する。２はコリメータ
レンズでレーザー光源１からのレーザー光を平行光にす
る。３は偏光ビームスプリッタ、４はλ／４波長板であ
る。６は対物レンズ、６は対物レンズ６をフォーカス及
びトラッキング方向に動作させる光学ピックアップであ
り、ボイスコイルモータ等の既知の駆動手段にて構成さ
れる。７は第１図の様な構成からなるディスクである。FIG. 2 shows a configuration diagram of an example of a conventional optical recording/reproducing apparatus. Reference numeral 1 denotes a laser light source which is made of a semiconductor laser and emits a constant amount of laser light. A collimator lens 2 converts the laser beam from the laser light source 1 into parallel light. 3 is a polarizing beam splitter, and 4 is a λ/4 wavelength plate. 6 is an objective lens, and 6 is an optical pickup that operates the objective lens 6 in the focusing and tracking directions, and is constituted by known driving means such as a voice coil motor. 7 is a disk having the structure shown in FIG.

８はハーフミラ−でディスク７からの反射光を分割する
。９は集光レンズ、１ｏは分割ミラーである。１１はフ
ォーカス制御用光検出器で２分割の光検出器より構成さ
れ、各々の光検出器の差動出力にてフォーカス誤差信号
を得る。A half mirror 8 divides the reflected light from the disk 7. 9 is a condensing lens, and 1o is a dividing mirror. Reference numeral 11 denotes a focus control photodetector, which is composed of two divided photodetectors, and obtains a focus error signal from the differential output of each photodetector.

１２はトラッキング制御用光検出器でフォーカス制御用
光検出器１１と同様な構成にてトラッキング誤差信号を
得る。１３は光検出器でディスク７からの反射光を受光
する。１４は検波器で光検出器１３の出力を検波し、エ
ンベロープ出力する。Reference numeral 12 denotes a tracking control photodetector which has the same configuration as the focus control photodetector 11 and obtains a tracking error signal. A photodetector 13 receives reflected light from the disk 7. A detector 14 detects the output of the photodetector 13 and outputs an envelope.

１６は比較器で検波器１４から出力されるエンベロープ
波形をあるレベルでコンパレートしトラックを識別する
セクターアドレスゲートを出力する。A comparator 16 compares the envelope waveform output from the detector 14 at a certain level and outputs a sector address gate for identifying a track.

以上のように構成された従来の光学式記録再生装置につ
いて、以下その動作について説明する。The operation of the conventional optical recording/reproducing apparatus configured as described above will be explained below.

レーザー光源１から出たレーザー光はコリメータレンズ
２を通過して平行光となシ偏光ビームスプリッタ３、λ
／４波長板４を介し、対物レンズ５によりディスク７に
形成された情報トラックに集光される。この時、ディス
ク７の情報トランクは面振れ及び芯振れをともなって回
転しているので、所定の情報トラックにレーザー光を集
光させるために、後述するフォーカス誤差信号及びトラ
ッキング誤差信号に基づいた駆動電圧を光学ピックアッ
プ６に印加して対物レンズ６をフォーカス及びトラッキ
ング方向に動作させ、レーザー光を所定のトラックに追
従させている。ディスク７からの反射光は入射光路と逆
光路をたどり、λ／４波長板４を２度通過することによ
り入射光と９０°偏光された光となり偏光ビームスプリ
ッタ３を直進してハーフミラ−８に入いる。反射光はハ
ーフミラ−８によって２方向に分かれ、一方は集光レン
ズ９に他方は光検出器１３に入射する。集光レンズ９を
出た反射光は分割ミラー１ｏによって分割され、一方は
フォーカス制御用光検出器１１に集光され、他方はトラ
ッキング制御用光検出器１２に集光される。フォーカス
制御用光検出器１１及びトラッキング制御用光検出器１
２は２分割の光検出器より構成され、各々の光検出器か
らの出方の差動を得ることによりフォーカス誤差信号及
びトラッキング誤差信号を作り出す。これらの誤差信号
を前述した光学ピンクアップ６の駆動回路（図示せず）
にフィードバックすることによりフォーカス制御及びト
ラッキング制御がなされる。Laser light emitted from laser light source 1 passes through collimator lens 2 and becomes parallel light.Polarizing beam splitter 3, λ
The light is focused by an objective lens 5 through a /4 wavelength plate 4 onto an information track formed on a disk 7 . At this time, the information trunk of the disk 7 is rotating with surface runout and center runout, so in order to focus the laser beam on a predetermined information track, driving is performed based on a focus error signal and a tracking error signal, which will be described later. A voltage is applied to the optical pickup 6 to move the objective lens 6 in the focusing and tracking directions, thereby causing the laser beam to follow a predetermined track. The reflected light from the disk 7 follows the incident optical path and the reverse optical path, passes through the λ/4 wavelength plate 4 twice, and becomes light polarized by 90 degrees with the incident light, and then passes straight through the polarizing beam splitter 3 and enters the half mirror 8. Enter. The reflected light is split into two directions by the half mirror 8, one of which enters the condenser lens 9 and the other enters the photodetector 13. The reflected light exiting the condensing lens 9 is split by a splitting mirror 1o, one of which is focused on a focus control photodetector 11, and the other focused on a tracking control photodetector 12. Focus control photodetector 11 and tracking control photodetector 1
Reference numeral 2 is composed of a two-split photodetector, and a focus error signal and a tracking error signal are generated by obtaining a difference in output from each photodetector. These error signals are transferred to the drive circuit (not shown) of the optical pink-up 6 described above.
Focus control and tracking control are performed by feeding back to the.

一方、光検出器１３は１個の光検出器より構成され、デ
ィスク７の情報トラックからの反射光量に比例した出力
を得て、検波器１４で検波し比較器１６にであるレベル
でコンパレートし、トラックを識別するセクターアドレ
スゲートを得る。前記セクターアドレスゲートと１回転
基準信号を用いてセクター記録とかドロップアウト測定
を行なうことが可能となる。On the other hand, the photodetector 13 is composed of one photodetector, which obtains an output proportional to the amount of reflected light from the information track of the disk 7, detects it with a detector 14, and compares it at a certain level with a comparator 16. and obtain a sector address gate that identifies the track. It becomes possible to perform sector recording or dropout measurement using the sector address gate and the one-rotation reference signal.

しかしながら上記のような構成では、光学系の絞りレン
ズを介して得られた信号によりセクターアドレス信号と
１回転基準信号を検出していたため、振幅がディスクの
内周と外周で異なる。従って前記セクターアドレス信号
と１回転基準信号の検出レベルを適宜調整する必要があ
る。この方法としては、ＡＧＣ回路等で検出レベルを前
記セクターアドレス振幅の変化に応じて変化させる手段
等が考えられるが、回路構成が複雑となる。また、前記
セクターアドレス信号部にドロップアウトが存在し前記
セクターアドレス信号が検出できない場合には、情報ト
ラックが無駄になるという問題点を有していた。However, in the above configuration, since the sector address signal and the one-rotation reference signal are detected by signals obtained through the aperture lens of the optical system, the amplitude differs between the inner and outer circumferences of the disk. Therefore, it is necessary to adjust the detection levels of the sector address signal and the one-rotation reference signal as appropriate. A conceivable method for this would be to use an AGC circuit or the like to change the detection level according to the change in the sector address amplitude, but the circuit configuration would be complicated. Furthermore, if there is a dropout in the sector address signal section and the sector address signal cannot be detected, there is a problem in that the information track is wasted.

発明の目的 本発明は上記従来の問題点を解消するもので、絞りレン
ズを有する光学系とは別に簡単で情報トラック溝上でビ
ーム径の大きい光検出器を設けることによシ容易にセク
ターアドレス信号、１回転基準信号を検出し、トラック
を識別するセクターアドレスゲートを得ることができる
光学式記録再生装置を提供することにある。OBJECTS OF THE INVENTION The present invention solves the above-mentioned problems of the conventional art.It is an object of the present invention to easily detect sector address signals by providing a photodetector with a large beam diameter on the information track groove in addition to an optical system having an aperture lens. An object of the present invention is to provide an optical recording/reproducing device capable of detecting a one-rotation reference signal and obtaining a sector address gate for identifying a track.

発明の構成 本発明は予め光ディスク上に形成されている情報トラッ
ク溝上でビーム径の大きい光検出器にょリセクターアド
レス信号を検出する検出手段と、絞りレンズを有する光
学系で情報トラック溝に微小スポットを照射する光学手
段を備えた光学式記録再生装置であり、前記セクターア
ドレス信号振幅の内外周での差異やドロップアウト等に
より前記セクターアドレス信号が検出できない場合でも
セクターアドレスゲートを効率的に得ることができるも
のである。Structure of the Invention The present invention uses a detection means for detecting a sector address signal on an information track groove formed in advance on an optical disk using a photodetector having a large beam diameter, and an optical system having an aperture lens to detect a minute spot on the information track groove. To efficiently obtain a sector address gate even when the sector address signal cannot be detected due to a difference in the amplitude of the sector address signal between the inner and outer circumferences, dropout, etc. It is something that can be done.

実施例の説明 第３図は本発明のこの実施例における光学式記録再生装
置の構成図を示すものである。第３図で第２図と全く同
じ構成の所は同じ番号を付して説明は省略する。１６は
゛ビーム径の大きい光検出器で光学ピックアップ６の近
くに設置され前記光学ピックアップ６と同時に動くよう
になっている。DESCRIPTION OF THE EMBODIMENT FIG. 3 shows a block diagram of an optical recording/reproducing apparatus according to this embodiment of the present invention. Components in FIG. 3 that are exactly the same as those in FIG. 2 are designated by the same numbers and their explanations will be omitted. Reference numeral 16 denotes a photodetector with a large beam diameter, which is installed near the optical pickup 6 and moves simultaneously with the optical pickup 6.

１７は光検出器１６の出力を検波し、エンベロープ波力
をする。１８は比較器で検波器１７から出力されるエン
ベロープ波形をある一定レベルでコバレートしトラック
を識別するセクターアドレスゲートを出力する。17 detects the output of the photodetector 16 and generates an envelope wave force. A comparator 18 covers the envelope waveform output from the detector 17 at a certain level and outputs a sector address gate for identifying a track.

以上のように構成されたこの実施例の光学式記録再生装
置について、以下その動作について説明する。第２図と
同じ構成部の動作は全く同じ動作であるので動作説明は
省略する。光検出器１６は発光素子と受光素子からなり
発光素子の光出力はる ディスク上でスポット径１ｔＩｒＩｎ程度に絞られる。The operation of the optical recording/reproducing apparatus of this embodiment configured as described above will be explained below. Since the operations of the same components as in FIG. 2 are exactly the same, the explanation of the operations will be omitted. The photodetector 16 consists of a light emitting element and a light receiving element, and the optical output of the light emitting element is focused to a spot diameter of about 1tIrIn on the disk.

反射光は凹凸状であるセクターアドレス部で散乱され受
光素子に戻ってくる光量は減少する０この光量変化は受
光素子の出力変化即ち光検出器１６の出力変化となり検
波器１７で検波され比較器１８である一定レベルでコン
パレートされる。このコンパレートされた信号よりセク
ターアドレスゲートを得る。The reflected light is scattered by the uneven sector address area, and the amount of light returning to the light receiving element decreases. This change in light amount results in a change in the output of the light receiving element, that is, a change in the output of the photodetector 16, which is detected by the detector 17 and detected by the comparator. They are compared at a certain level of 18. A sector address gate is obtained from this compared signal.

以上のように情報トラック上でビーム径の大きい光検出
器でセクターアドレス信号を検出することによシ、前記
セクターアドレス信号の振幅変化及びドロップアウト等
がセクターアドレス部に存在する場合にもセクターアド
レスゲートを得ることができる。さらに光検出器１６は
従来の光学ピックアップ６０近くに設置されてしかも前
記光学ピックアップ６と同時に移動するように構成され
ている。このことは光検出器１６が常に読み出したい情
報トラックに基づいてセクターアドレスゲート信号を得
るだめ、例えば情報トラックのセクターアドレス信号の
トラック中心との位相関係が内外周でずれていても常に
正しいセクターアドレスゲートを得ることができる。従
って光検出器１６を内周又は外周に固定しておく方式と
比べて光検出器１６の調整も簡単になる。As described above, by detecting the sector address signal on the information track using a photodetector with a large beam diameter, it is possible to detect the sector address signal even when amplitude changes or dropouts of the sector address signal exist in the sector address part. You can get the gate. Further, the photodetector 16 is installed near a conventional optical pickup 60 and is configured to move simultaneously with the optical pickup 6. This means that the photodetector 16 always obtains the sector address gate signal based on the information track that it wants to read. You can get the gate. Therefore, the adjustment of the photodetector 16 becomes easier compared to a method in which the photodetector 16 is fixed on the inner or outer circumference.

発明の効果 以上のように本発明の光学式記録再生装置はビーム径の
大きい光検出器でセクターアドレス信号と１回転基準信
号を検出することにより、ディスクの内外周でセクター
アドレス信号振幅の差異があっても検出レベルを変化さ
せることなくセクターアドレス信号を得、ドロップアウ
ト等がセクターアドレス部に存在しても確実にセクター
アドレスゲートを得ることができその効果は大きい。ま
た、従来の光学ピンクアップ６０近くに前記光検出器１
６を設置し、前記光学ピックアップ６と同時に移動する
ことにより、光検出器１６の位置調整も簡単にでき、そ
の実用的効果は大きい。Effects of the Invention As described above, the optical recording/reproducing apparatus of the present invention detects the sector address signal and the one-rotation reference signal using a photodetector with a large beam diameter, thereby reducing the difference in sector address signal amplitude between the inner and outer circumferences of the disk. Even if there is a dropout in the sector address part, the sector address signal can be obtained without changing the detection level, and even if there is a dropout in the sector address part, the sector address gate can be reliably obtained, which is highly effective. In addition, the photodetector 1 is placed near the conventional optical pink-up 60.
By installing the optical pickup 6 and moving it simultaneously with the optical pickup 6, the position of the photodetector 16 can be easily adjusted, which has a great practical effect.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は光ディスクの平面図、第２図は従来例における
光学式記録再生装置の原理図、第３図は本発明の実施例
における光学式記録再生装置の原理図である。 １・・・・・・レーザー光源、２・・・・・・コリメー
タレンズ、３・・・・・・偏光ビームスプリッタ、４・
・・・・・λ／４波長板、６・・・・・・対物レンズ、
６・・・・・・光学ピックアップ、７・・・・・・光デ
ィスク、８・・・・・・ハーフミラ−１９・・・・・・
集光レンズ、１０・・・・・・分割ミラー、１１・・・
・・・フォーカス制御用光検出器、１２・・・・・トラ
ッキング制御用光検出器、１３・・・・・・光検出器、
１４・・・・・・検波器、１５・・・・・・比較器、１
６・・・・・・セクターアドレス信号検出用光検出器、
１７・・・・・・検波器、１８・・・・・比較器。 代理人の氏名　弁理士　中　尾　敏　男　ほか１名第１
図 第２図FIG. 1 is a plan view of an optical disc, FIG. 2 is a principle diagram of an optical recording/reproducing apparatus in a conventional example, and FIG. 3 is a principle diagram of an optical recording/reproducing apparatus in an embodiment of the present invention. 1... Laser light source, 2... Collimator lens, 3... Polarizing beam splitter, 4...
...λ/4 wavelength plate, 6...Objective lens,
6...Optical pickup, 7...Optical disc, 8...Half mirror-19...
Condensing lens, 10... Division mirror, 11...
...Focus control photodetector, 12...Tracking control photodetector, 13...Photodetector,
14...Detector, 15...Comparator, 1
6...Photodetector for sector address signal detection,
17...Detector, 18...Comparator. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (3)

【特許請求の範囲】[Claims] （１）予め光ディスク上に形成されている情報トラック
溝上でビーム径の大きい光検出器によりセクターアドレ
ス信号と１回転基準信号を検出する検出手段と、絞りレ
ンズを有する光学系で前記情報トラック溝に微小スポッ
ト光を照射する光学手段と、前記光学手段を光ディスク
の内周から外周または外周から内周に移動する移動手段
とを備えたことを特徴とする光学式記録再生装置。(1) A detection means for detecting a sector address signal and a one-rotation reference signal using a photodetector with a large beam diameter on an information track groove formed in advance on an optical disk, and an optical system having an aperture lens to detect the information track groove. An optical recording/reproducing apparatus comprising: an optical means for irradiating a minute spot light; and a moving means for moving the optical means from an inner circumference to an outer circumference or from an outer circumference to an inner circumference of an optical disc. （２）移動手段として、光検出器と光学手段とを同時に
動くことを特徴とする特許請求の範囲第１項記載の光学
式記録再生装置。(2) The optical recording and reproducing apparatus according to claim 1, wherein the photodetector and the optical means are moved simultaneously as the moving means. （３）光検出器は光学手段の微小スポット光と隣接して
いることを特徴とする特許請求の範囲第１項記載の光学
式記録再生装置。(3) The optical recording/reproducing apparatus according to claim 1, wherein the photodetector is adjacent to the minute spot light of the optical means.
JP59121141A 1984-06-12 1984-06-12 Optical recording and reproducing device Pending JPS61931A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP59121141A JPS61931A (en) 1984-06-12 1984-06-12 Optical recording and reproducing device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP59121141A JPS61931A (en) 1984-06-12 1984-06-12 Optical recording and reproducing device

Publications (1)

Publication Number Publication Date
JPS61931A true JPS61931A (en) 1986-01-06

Family

ID=14803874

Family Applications (1)

Application Number Title Priority Date Filing Date
JP59121141A Pending JPS61931A (en) 1984-06-12 1984-06-12 Optical recording and reproducing device

Country Status (1)

Country Link
JP (1) JPS61931A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0269759U (en) * 1988-11-16 1990-05-28
US10409066B2 (en) 2017-01-19 2019-09-10 Coretronic Corporation Head-mounted display device with waveguide elements
US10422997B2 (en) 2017-05-16 2019-09-24 Coretronic Corporation Head-mounted display device
US10809609B2 (en) 2017-12-20 2020-10-20 Coretronic Corporation Projection apparatus

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0269759U (en) * 1988-11-16 1990-05-28
US10409066B2 (en) 2017-01-19 2019-09-10 Coretronic Corporation Head-mounted display device with waveguide elements
US10422997B2 (en) 2017-05-16 2019-09-24 Coretronic Corporation Head-mounted display device
US10809609B2 (en) 2017-12-20 2020-10-20 Coretronic Corporation Projection apparatus

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