JPS6313414U

JPS6313414U -

Info

Publication number: JPS6313414U
Application number: JP10733186U
Authority: JP
Priority date: 1986-07-11
Filing date: 1986-07-11
Publication date: 1988-01-28

Description

[Brief explanation of the drawing]

第１図は本考案の一実施例を示すブロツク図、
第２図は情報検出用光スポツトとピツトとの位置
関係を示す図であり、ａは光スポツトがピツト上
にある場合、ｂはピツト間にある場合をそれぞれ
示しており、第３図ａ，ｂは第２図ａ，ｂの状態
における光検出器の受光面上の光強度分布を模式
化して示した図、第４図は本考案の他の実施例を
示すブロツク図、第５図は本考案の更に他の実施
例を示すブロツク図、第６図は光学系を示す構成
図、第７図は従来例を示すブロツク図、第８図は
ピツト回折によつて生じる光検出器の受光面上の
光強度分布を模式化して示した図であり、ａは光
スポツトが合焦状態でかつトラツク上に位置する
とき、ｂは光スポツトがトラツクに対してトラツ
ク直交方向に位置ずれが生じたときをそれぞれ示
している。主要部分の符号の説明、１……光源、２……ビ
ームスプリツタ、４……デイスク、５……シリン
ドリカルレンズ、６……光検出器、１２，１３，
１４ａ〜１４ｄ，１６……ピーク検出回路。 FIG. 1 is a block diagram showing an embodiment of the present invention.
FIG. 2 is a diagram showing the positional relationship between the information detection light spot and the pit, where a shows the case where the light spot is on the pit, and b shows the case where it is between the pits, and FIGS. b is a diagram schematically showing the light intensity distribution on the light receiving surface of the photodetector in the states shown in FIGS. 2a and b, FIG. 4 is a block diagram showing another embodiment of the present invention, and FIG. A block diagram showing still another embodiment of the present invention, FIG. 6 is a configuration diagram showing an optical system, FIG. 7 is a block diagram showing a conventional example, and FIG. 8 shows light reception by a photodetector caused by pit diffraction. These are diagrams schematically showing the light intensity distribution on a surface, where (a) shows when the light spot is in focus and is located on the track, and (b) shows when the light spot is misaligned with respect to the track in the direction perpendicular to the track. Each time is shown. Explanation of symbols of main parts, 1...Light source, 2...Beam splitter, 4...Disk, 5...Cylindrical lens, 6...Photodetector, 12, 13,
14a to 14d, 16...Peak detection circuit.

Claims

[Claims for Utility Model Registration] (1) A photodetector consisting of four independent elements arranged close to each other with two substantially orthogonal dividing lines as boundaries, and a photodetector that illuminates the recording surface of an information recording disk. and an optical system that guides the light beam of the information detection light spot that has passed through the recording surface onto the light receiving surface of the photodetector in an astigmatic form, and focuses based on the output signals of each of the four elements. A focus error signal generation circuit that generates an error signal, the focus error signal generation circuit having a detection means for detecting that the optical spot is located at a position other than a pit portion on the recording surface, and the focus error signal generation circuit includes a detection means for detecting that the optical spot is located at a position other than a pit portion on the recording surface, A focus error signal generation circuit that generates a focus error signal based on each output signal of an element. (2) The utility model registration claim 1 is characterized in that the detection means comprises a peak detection circuit that detects each output signal of the four elements or a peak value of a signal based on these output signals. focus error signal generation circuit.