JPS627619U

JPS627619U -

Info

Publication number: JPS627619U
Application number: JP9697885U
Authority: JP
Priority date: 1985-06-26
Filing date: 1985-06-26
Publication date: 1987-01-17

Description

[Brief explanation of the drawing]

第１図は、この考案の一実施例を示すブロツク
図である。第２図は、３分割受光素子法によるフ
オーカスエラー検出の機構を示す斜視図である。
第３図は、従来のフオーカスエラー検出回路を示
すブロツク図である。第４図は、第３図のフオー
カスエラー検出回路により検出されるフオーカス
エラー検出信号の特性図である。第５図は、第１
図のフオーカスエラー検出回路において係数αを
様々に変化させた場合のフオーカスエラー検出信
号の特性の変化を示す図である。第６図は、第１
図のフオーカスエラー検出回路において係数を最
適値にした場合のフオーカスエラー検出信号の特
性を示す図である。１８…３分割受光素子、２２…引算器、２４…
差演算比変化回路。 FIG. 1 is a block diagram showing one embodiment of this invention. FIG. 2 is a perspective view showing a focus error detection mechanism using the three-part light receiving element method.
FIG. 3 is a block diagram showing a conventional focus error detection circuit. FIG. 4 is a characteristic diagram of a focus error detection signal detected by the focus error detection circuit of FIG. 3. Figure 5 shows the first
FIG. 6 is a diagram showing changes in the characteristics of the focus error detection signal when the coefficient α is variously changed in the focus error detection circuit shown in the figure. Figure 6 shows the first
FIG. 7 is a diagram showing characteristics of a focus error detection signal when coefficients are set to optimal values in the focus error detection circuit shown in the figure. 18...Three-split light receiving element, 22...Subtractor, 24...
Difference calculation ratio changing circuit.

Claims

[Claims for Utility Model Registration] The beam for focus error detection is sent to a light receiving element divided into three in the direction in which the beam for focus error detection moves by tracking control, with its light distribution shape remaining circular. In the focus error detection circuit, the focus error detection circuit detects a focus error by calculating the difference between the output of the central light receiving section and the sum of the outputs of the two light receiving sections on both sides. A focus error detection circuit comprising a difference calculation ratio setting means for calculating a difference between the sum of the outputs of the two light receiving sections at an appropriate ratio.