JPS61144733A - Optical information reproducing device - Google Patents

Abstract

PURPOSE:To obtain an image of high quality by slanting the detection surface of a detector to a surface perpendicular to the optical axis of incident luminous flux. CONSTITUTION:The detection surface of the detection part 0 is slanted to the surface perpendicular to the optical axis of the incident luminous flux 13. Therefore, the surface reflected luminous flux on the detection surface is reflected by the internal surface of cover glass 11 to travels again toward the detection surface, but its position is different from that of the original incident luminous flux, so those pieces of luminous flux do not interfere with each other and there is no increase of noises.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an optical information reproducing device ELC, which reproduces information by irradiating an information recording medium with a semiconductor laser beam and receiving the reflected beam by a detector. be.

[Background of the invention]

The gt diagram is a schematic diagram showing the configuration of an optical system in a conventional optical W141 reproducing apparatus.

Figure 1 Kj? 1 is a semiconductor laser light source, 2 is a collimating lens, 3 is a polarizing prism, 4 is an optical wavelength plate, 5 is an objective lens, 6 is an information recording medium, 7 is a recording surface, 8 is a detection lens, 9 is a detector, It is.

As shown in Figure 1, the linearly polarized light beam emitted from the semiconductor laser beam [1] is spread out, becomes a parallel light beam through the collimating lens 2, passes through the polarizing prisms 3, 3, and the wavelength plate 4, and becomes circularly polarized light. However, the objective lens 5 focuses the light onto the recording surface 7 of the information recording medium 6, and the light is reflected there and follows the original optical path.
After passing through the wave plate 4 again, the polarization direction is perpendicular to the original linearly polarized light, and 7'hi! [It becomes armpit polarized light. This light flux enters the polarizing prism 3 and is reflected, is focused by the detection lens 8 onto the detector 9, and is converted into an electric signal by the detector 9.

FIGS. 2(a) and 2(b) are cross-sectional views showing commonly used detectors, respectively.

In FIGS. 2(a) and (b), 1o is a detection unit, 1
1 is a cover glass, 12 is a glass mold.

As shown in FIGS. 2(a) and 2(b), the detection section 10 of the detector 9 is generally sealed with a cover glass 11 or a plastic mode 12.

In conventional optical information reproducing devices, the detector? Since the detection surface of the VC is perpendicular to the optical axis of the light flux incident on the detector 9, the surface-reflected light flux on the detection surface is reflected on the inner surface of the cover glass 11 or the inner surface of the plastic mold, and is reflected again. It has the disadvantage that it enters the detection surface and interferes with the initial incident light beam, generating noise. This noise is 55 dB to 1 dB higher than the laser noise emitted by a semiconductor laser.
Increases by 0dB.

[Object of the Invention] An object of the present invention is to provide an optical information reproducing device which eliminates the above-mentioned drawbacks of the prior art and does not cause an increase in noise due to detector busyness.

[Summary of the Invention] In order to achieve the above object, the present invention tilts the detection surface of the detector with respect to a plane perpendicular to the optical axis of the light flux incident on the detector, thereby reducing the surface reflection light flux on the detection surface. This is to prevent interference with the original incident light beam.

[Embodiments of the invention j An embodiment of the present invention will be described below with reference to FIG.

FIG. 3 is a sectional view of a detector showing an embodiment of the present invention.

In FIG. 3, 13 is an incident light beam.

Figure 3 (as shown), the detection surface of the detection unit 10 is the incident light beam 13
It is tilted with respect to a plane perpendicular to the zero optical axis.

Therefore, the surface-reflected light flux on the detection surface is reflected on the inner surface of the cover glass 11 and advances again in the direction of the detection surface, but since the position is different from the original incident light flux, these two light fluxes do not interfere and noise increases. does not occur.

FIG. 4 is a graph for explaining the effects of the present invention.

As shown in FIG. 4, in this measurement example, by tilting the detector 2.5' or more with respect to the optical axis, the noise increase is within 2 dB.

[Effects of the Invention J] According to the button of the present invention, there is no increase in noise caused by the detector, so there is an effect that high image quality can be obtained in, for example, an optical video player.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing a conventional optical information reproducing device;
Figures (a) and (b) are cross-sectional views showing a general detector, Figure 3 is a cross-sectional view showing an embodiment of the present invention, and Figure 4 is a diagram illustrating the effects of the present invention. This is the graph of Description of symbols 1... Semiconductor laser light source, 9... Detector, 10... Detection section, 11... Cover glass, 12...... ...Glasstic Mold Representative Patent Attorney Akira Takahashi - - O / Figure 2 Figure 3 Blockf 4 Figure

Claims (1)

[Claims] 1) In an optical information reproducing device that reproduces information by irradiating a light beam emitted from a semiconductor laser light source onto the recording surface of an information recording medium and receiving the reflected light beam by a detector, the detection surface of the detector perpendicular to the optical axis of the incident light beam so that the surface-reflected light beam of the detector is reflected by the inner surface of the medium covering the detection surface of the detector and the light beam that re-enters the detection surface and the initial incident light beam do not interfere with each other. 1. An optical information reproducing device characterized in that a detection surface of the detector is tilted with respect to a horizontal plane.