JPH0528492A - Optical card and optical card information reproducing device - Google Patents

Abstract

PURPOSE:To obtain an optical card and an optical card information reproducing device improving an S/N without increasing the light quantity of a light source and without reducing recording density. CONSTITUTION:Since the shape of an information pit and the shape of the cell 9 of a detecting part 7 are similar figures, the image 10 of pit information occupying to the cell 9 of the detecting part 7 is a larger area than a conventional image and the S/N is increased. Thus, the high S/N ratio is secured even by the light source of the same energy with a conventional source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical card on which information is recorded and an optical card information reproducing apparatus for reading the information.

[0002]

2. Description of the Related Art An optical card is a recording medium having a large capacity and good portability. As shown in FIG. 6, the conventional optical card decides a predetermined area of the optical card 20 as an information recording area 21. As shown in a partially enlarged view on the right side, the arrangement state of the circular information pits 22 is determined corresponding to the information, and the information tracks 23 are formed by arranging them linearly and forming a plurality of the information tracks 23. And it records a lot of information.

The information pit 22 has a lower reflectance than its surroundings, and when the optical card 20 is irradiated with light, the reflected light is reflected by the cell 26 of the detector 25 as shown in FIG.
Image on. At this time, the image 24 of the information pit formed by the light reflected by the information pit 22 is dark and the other portions are bright. FIG. 8 shows the signals obtained at this time. The low level portion is the signal obtained from the information pit image 24, and the high level portion is the signal obtained from other portions.

[0004]

However, in one cell of the detection unit, a dark image due to the information pits and bright light from a portion other than the information pits are formed.
Even if a signal whose level is lowered by the information pit is obtained, the signal from the bright part is added to this, so that the part corresponding to the information pit does not drop below a certain value as shown in FIG. , S / N, which is the ratio of the level B to the level A, has a problem that a value higher than a certain value cannot be obtained.

This is not a serious problem when reading one type of information, but when attempting to reproduce a plurality of information at the same time in order to improve the reproduction speed, it is necessary to irradiate a plurality of information tracks with light at one time. Therefore, the amount of light assigned to one piece of information becomes small and the S / N ratio is lowered. A high-energy light source such as a semiconductor laser may be used to compensate for the decrease in S / N, but this method has a problem in order to prevent damage to the optical card.
The current situation is that light sources such as LEDs are used.

S / N without using a high energy light source
In order to improve the ratio, the image of the information pit formed on the detection surface of the detection unit may be enlarged, that is, the pit may be enlarged. However, this method causes a problem that the recording density of the optical card becomes low.

The present invention has been made in view of the above circumstances, and an optical card and an optical card information reproducing apparatus for improving the S / N ratio without increasing the light amount of the light source and reducing the recording density. The purpose is to obtain the device.

[0008]

In order to solve such a problem, the first invention is data read by a detector of a reproducing apparatus from a row of pits whose arrangement state is determined corresponding to information content. In the optical card using, the shape of the pit is similar to the shape of the cell of the detection unit. According to a second aspect of the present invention, in the optical card information reproducing apparatus in which the information of the pit string whose arrangement state is determined corresponding to the information content is detected by the detection unit, the shape of the cell of the detection unit is similar to the shape of the pit. It is characterized by

[0009]

In both the first and second inventions, since the shape of the pit and the shape of the cell in the detection section are similar, the image of the pit information occupying the detection section has a larger area than the conventional one, and S / N is improved.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing an embodiment of an optical card to which the present invention is applied. An optical card 1 is provided with an information recording area 2 in the longitudinal direction, and a part of it is enlarged to the right. As shown, a rectangular information pit 3 is provided. The information pit 3 is written according to the recorded information, and the area of the information pit 3 is configured to have a lower reflectance than the surrounding area, which is the same as in the conventional case, but the rectangular shape will be described later. It is characterized in that it is configured in a shape similar to the shape of the detection unit that operates.

FIG. 2 is a schematic view of an optical card information reproducing apparatus, in which an optical head 8 faces the optical card 1, and the optical head 8 collects the light from the LED light source 4 on the optical card 1 by a condenser lens 5. The imaging lens 6 receives the light that is reflected and reflected there.
By means of this, an image is formed on the detection section 7 which comprises a CCD line sensor, for example.

The optical head 8 is fixed, and the optical card 1
Is configured to move in the arrow direction of FIG. 2 by a scanning mechanism (not shown). As shown in FIG. 3, the detection unit 7 has a plurality of rectangular cells 9 arranged side by side. This is shown in FIG. 2 in which the longitudinal direction (right direction in FIG. 3) is the front-back direction of the paper surface.
That is, the optical card 1 is attached at a right angle to the moving direction. FIG. 4 shows a state in which the light reflected by the optical card 1 is condensed on the detection unit 7, and the hatched area shown by the symbol 10 is the image of the information pit, and the image of the information pit is the light. When the card 1 moves, it moves up and down on the paper surface. Therefore, as the optical card 1 moves, the information pit image 10 passes over the plurality of cells arranged adjacent to each other, and the information of each track can be obtained from each of the plurality of cells 9 at the same time. .

As described above, the shape of the information pit 3 and the shape of the cell 9 are similar to each other. Then, in FIG. 2, the imaging magnification determined by the positional relationship between the imaging lens 6 and the detection unit 7 is set so that the cell 9 and the image 10 of the information pit imaged thereon have the same area as shown in FIG. Has been done.

By doing so, the shape of the cell 9 and the shape of the image 10 of the information pit become equal. Therefore, for example, when the reflectance of the information pit 3 is zero, the reproduction signal level becomes as shown in FIG. Fall to ground level. This results in very high contrast and high S / N.

Since the shape of the cell 9 and the shape of the information pit 3 are similar to each other, the area of the image of the information pit occupying in the cell 9 becomes larger than the conventional relationship between the corners and the circles. S / N is better than that of the one. Therefore,
For applications that do not require maximum S / N, use cell 9
In some cases, it is not necessary to adjust the magnification in order to match the shape of the image with the shape of the information pit image 10. Further, the shapes of the cells and the information pits are described as being rectangular, but the shape is not limited to this, and in essence, similar shapes may be used.

[0016]

As described above, according to the optical card and the optical card information reproducing apparatus of the present invention, the information pits of the optical card and the detecting portion for detecting the information pits have a similar shape. The area of the image is increased, and the S / N can be improved without increasing the light amount of the light source and without decreasing the recording density.

[Brief description of drawings]

FIG. 1 is a diagram showing an external appearance of an embodiment of an optical card configured by applying the present invention.

FIG. 2 is a diagram showing a relationship between an optical card and a detection unit.

FIG. 3 is a diagram showing details of a detection unit.

FIG. 4 is a diagram showing a relationship between a cell and an image of an information pit formed thereon.

5 is a diagram showing an output signal waveform when the information pit shown in FIG. 4 is read.

FIG. 6 is a diagram showing the appearance of an example of a conventional optical card.

FIG. 7 is a diagram showing a relationship between a cell and an image of an information pit in a conventional device.

8 is a diagram showing an output signal waveform read from the detector shown in FIG. 7.

[Explanation of symbols]

1 optical card 2 Information recording area 3 information pits 4 LED light source 5 Condensing lens 6 Imaging lens 7 Detector 8 optical heads 9 cells 10 Information pit image

Claims (2)

[Claims] 1. In an optical card in which data read by a detection unit of a reproducing device is used from a pit row in which an array state is determined corresponding to information content, a pit shape is defined as a cell shape of the detection unit. An optical card featuring a similar shape. 2. In an optical card information reproducing apparatus in which information of a pit string whose arrangement state is determined corresponding to information content is detected by a detecting section, the cell shape of the detecting section is similar to the pit shape. An optical card information reproducing device characterized by the above.