JPS58100243A - Optical information reading method - Google Patents

Abstract

PURPOSE:To obtain an optical information readout system which provides excellent optical information readout performance by providing plural photodetectors and allowing a selected photodetector to generate a signal. CONSTITUTION:When pit information P is readout optically by plural photodetectors and three detectors S12, S22 and S32 detect the signal, coordinate addresses of those detectors S12, S22 and S32 are stored through a microcomputer, etc., to decide on the center coordinates, thereby selecting a corresponding detector 22. Similarly, when two detectors S22 and S32 detect the output, the detectors S22 or S32 is selected. Thus, an optical information readout system which provides an excellent optical information readout is obtained by purely electronic simple constitution without performing tracking control over the mechanical movement of the photodetectors, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method (1. reading and reproducing information in an optical disk device or: YT magnetic disk device, etc.), in which a plurality of photodetectors for reading are provided, and a plurality of photodetectors for reading are selected. The aim is to obtain a better readout signal than the conventional photodetector.

Recently, digital information is recorded as pits (unevenness) on a disc, and by irradiating light (generally laser light) onto these pits and receiving the reflected or transmitted light, the information can be recorded. An optical tisf device has been proposed for reading .

Furthermore, a device that utilizes the interaction between light and magnetism is also conceivable. That is, the information recording medium is irradiated with light (laser light) (-2
At the same time, when the local temperature rises and disappears, a magnetic field is applied from the outside to densify the local area M and align it in the direction of the externally applied TBM (writing operation).The recorded magnetization M is read with light. To achieve this, the Kerr effect or Faraday effect, which is an interaction between light and magnetism, is used. Immediate order,
Light is an N fundamental wave, and its vibration direction is usually in any direction in a plane perpendicular to the direction in which the light travels. The light is passed through a polarizer to make it a straight beam (that is, it vibrates only once).''C
Recording medium [to shoot. When the linearly polarized light is reflected on the surface of the recording medium, the plane of polarization rotates depending on the rotation of the sensitizer M. If photodetectors are arranged so that the rotating polarization plane is perpendicular to the part vc, the direction of magnetization can be converted to the intensity of the light, so it is possible to reproduce the light record (R output operation) - fl
“Hro.

Since such devices usually have high-density recording parts τ, it is necessary to correctly irradiate the readout light onto the recording tracks (pits) and receive (detect) the τ reflected light or transmitted light at the correct location. be. In the present invention, a plurality of photodetectors are provided, and a plurality of photodetectors are selected from among them so that good readout (readout and reproduction) can be performed even when the optical axis of reflected light or transmitted light and the photodetector are misaligned. The purpose of this invention is to obtain better readout accuracy than the conventional photodetector.

A detailed description will be given below with reference to the drawings. FIG. 1 shows the relationship between the disk pitch (P) and a plurality of photodetectors fs). In the case shown on the left in Figure 1, a photodetector (S
2z) should be selected. To do so, the selection can be made according to the flowchart shown in FIG.

First, if the X address of the photodetector (IE) is 1",
A timer is set based on the output of this X address. For example, after setting 'r'751 as the initial value and counting down to T=0, the photodetector ("II+s, 2.
Determine whether or not there is an output at "li). For example, if you use a microcomputer to determine the (X, Y) address even though a timer is used, after specifying the X address, This is because there is a slight delay until the specified output occurs.
513), the X and X addresses at that time are stored. In the example of a flash, an output is generated from the photodetector (812), and (X=,1,
, Y=2) are stored. If there is no output from the corresponding photodetector, the process moves to the next step.

next! =2 and do the same thing. ζ force is the final X
Repeat until address N=3. Jtll" and find the address (X, Y) of the photodetector (81) that is producing the output. In the example on the left side of FIG. 1, the photodetector ("+21'N?
Output is generated from 5x2), and the stiffness (X.

Y) Addresses (1, 2), (2, 2), (3, 2) are stored. If we find the center of these (X, Y) coordinates, we get X=2. Y=2 is calculated and the photodetector (E'?) is selected.

The two photodetectors ("
ot S32) If the store is producing an output, then it is only necessary to choose one of the two.

Note that when the readout light is irradiating between the bits and the pits, the reflected light or the transmitted light is largely polarized, and no output is produced from any of the photodetectors. Therefore, for example,
Information "0" can be read.

According to the present invention described above, it is possible to obtain a good readout signal using a purely electronic method without performing tracking techniques such as mechanically moving a photodetector.

[Brief explanation of the drawing]

The first M is a diagram showing the relationship between the bit and the photodetector, and the second bacterium is a flowchart diagram for realizing the present invention. (Pl is a pit, (S) is a photodetector. Figure 1

Claims (1)

[Claims] (1) A so-called emitted light is irradiated onto an optical information recording medium, and its reflected light or transmitted light is received by a plurality of photodetectors, and a selected one of these photodetectors is detected. An optical information reading method characterized in that the output is a read signal.