JPH05325571A - Information recording medium - Google Patents

Abstract

PURPOSE:To obtain an information recording medium which does not require scanning for reading and does not require a driving mechanism by providing thin-film recording media of specific film thicknesses, multiplexing elements, analyzers and photodetectors. CONSTITUTION:The recording part 3 on a substrate 2 includes 4 layers of successively provided Faraday rotators 4A to 4D of memory means and the multiplexing elements 5A to 5C, polarizer 6, analyzers 7A to 7D and photodetectors 8A to 8D therebetween. The element 4A is selected at the film thickness d1 and rotates the plane of polarization of transmitted light at a specific angle theta1 by utilizing a Faraday effect. The element 4B has similarly a film thickness D2 and rotates the plane of polarization at an angle theta2. The elements 4C, 4D have similarly specific film thicknesses and rotate the plane of polarization at specific angles. The multiplexing element 5A multiplexes the light to the analyzer 7A and allows the transmission of only the light rotated in the plane of polarization by the angle theta2. The photodetector 8A outputs a signal A upon receiving of the transmitted light. The same holds true of the other photodetectors. The information is recorded by the thicknes D of the element 4 and the reading and reproducing of the information are executed by detecting the rotating angle of the plane of polarization of the light progressing in the elements and, therefore, the particular need for mechanical scanning is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel information recording body capable of recording various information.

[0002]

2. Description of the Related Art Various recording media have been proposed and developed as means for recording various information. For example, a recording medium of a type in which a reflective film is formed on a disk-shaped substrate according to recorded information and recording is read from optical information returned when a laser beam is projected (hereinafter referred to as an information recording body). )It has been known.

[0003]

By the way, in such an information recording medium, for example, the information recording medium is usually rotated and the reading device side such as a light source or a light receiving element is moved to perform reading scanning. However, a complicated driving mechanism is required on the side of the reading device, which causes various problems such as an increase in size of the device and an increase in manufacturing cost. Therefore, in view of the above-mentioned circumstances, it is an object of the present invention to provide an information recording body which does not require scanning at the time of reading and therefore does not need a driving mechanism at all.

[0004]

That is, the present invention is an information recording body for recording various kinds of information, wherein the polarization plane of the transmitted light is formed in a specific film thickness which is rotated by an amount according to the information to be recorded. Thin-film recording medium, and a demultiplexing element that is interposed between the recording media in which a plurality of laminated layers are arranged and demultiplexes a part of incident light, and demultiplexed by each of these demultiplexing elements It is provided with an analyzer that transmits only light whose surface is rotated at a specific angle, and a light receiving element that receives light transmitted through the analyzer and outputs a signal in accordance with the information.

[0005]

The information recording medium of the present invention utilizes the Faraday effect in which the plane of polarization is rotated according to the thickness of the Faraday rotator when light is transmitted through the Faraday rotator, and the information recording medium is adapted to the information to be recorded. The film thickness is formed. Therefore, when reading the recorded information, it suffices to project the laser light on a predetermined portion. In other words, the laser light travels in the Faraday rotator to be laminated, and a part of the polarization plane is a demultiplexing element. By deflecting and demultiplexing in a specific direction, each information is automatically read while being sequentially sorted.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an information recording medium according to the present invention. The information recording medium 1 of this embodiment functions as a ROM (read only memory) used in electronic equipment such as a personal computer. The recording portion 3 is formed on the substrate 2. Recording unit 3
As shown in FIG. 2, four layers (4
Faraday rotator 4A, 4B, 4 connected to
C, 4D and the demultiplexing elements 5A, 5B provided between them,
5C, a polarizer 6, first to fourth analyzers 7A to 7D, and first to fourth light receiving elements 8A to 8D. The Faraday rotator 4A is for recording information by rotating the plane of polarization according to information, and uses the Faraday effect to rotate the plane of polarization of the transmitted laser light by a specific angle θ ₁ Formed in ₁ . And
The Faraday rotator 4A of this embodiment is made of a magnetic material of a rare earth element (YiG or the like) or is made of a transparent material such as acrylic. The Faraday rotator 4B is also a recording medium of information in the same manner.
The polarization plane of the laser light whose polarization plane is rotated by the angle θ ₁ after passing through A is formed to have a specific film thickness D ₂ which is rotated by the specific angle θ ₂ , and is made of the same material as the Faraday rotator 4A.

The Faraday rotator 4C is also an information recording medium, and has a specific film thickness D ₃ that rotates the polarization plane of the laser light whose polarization plane has rotated by the angle θ ₁ + θ ₂ after passing through the Faraday rotators 4A and 4B by the specific angle θ _3. The Faraday rotators 4A and 4B are made of the same material. The Faraday rotator 4D has a polarization plane of an angle of θ ₁ + θ ₂ + after passing through the Faraday rotators 4A, 4B, and 4C.
It is formed with a specific film thickness D ₄ that rotates the polarization plane of the laser beam rotated by θ ₃ by a specific angle θ ₄ , and is made of the same material as the Faraday rotators 4A, 4B, and 4C.

The demultiplexing element 5A is a Faraday rotator 4
As shown in FIG. 2, a part of the laser light after passing through A
It is for demultiplexing toward the analyzer 7A, and a half mirror or the like is used. The demultiplexing elements 5B and 5C are the same as the demultiplexing element 5A. The demultiplexing elements 5B and 5C demultiplex the laser light at specific ratios, and a part thereof is divided into the second and third analyzers 7.
It is designed to demultiplex toward B and 7C. The first analyzer 7A transmits only the laser beam demultiplexed by the demultiplexing element 5A, which is in a specific polarization state (the polarization plane of the first analyzer 7A is rotated by an angle θ ₁ ). The same polarizer as the polarizer 6 is used, and the polarizer 6 is arranged and attached in a state rotated by an angle θ ₁ . The second to fourth analyzers 7B to 7D are also made of the same material and have the same shape as the first analyzer 7A.
Compared with the polarizer 6, the angles (θ ₁ + θ ₂ ) and (θ ₁ +
θ ₂ + θ ₃ ) and (θ ₁ + θ ₂ + θ ₃ + θ ₄ ) are rotated and installed.

The first light receiving element 8A is designed to output a predetermined signal A when receiving the laser light transmitted through the first analyzer 7A, and a semiconductor formed in a thin film is formed to serve as a photocoupler. It is supposed to work. The first light receiving element 8A is mounted on the substrate 2 while being fixed to the first analyzer 7A, and the pattern wiring 9 is provided.
Is connected to a predetermined element (not shown) via. 2nd
The fourth light receiving elements 8B to 8D also have the same configuration as the first light receiving element 8A, and are mounted on the substrate 2 in a state of being fixed to the second to fourth analyzers 7B to 7D, respectively. The signals B, C and D are output to predetermined elements (not shown) via the pattern wiring 9.

Therefore, according to this embodiment, information is stored by the thicknesses D _{1 to} D ₄ of the Faraday rotators 4A to 4D, and the Faraday rotators 4A to 4D are stored.
Information is read (reproduced) by detecting the rotation angle of the plane of polarization of the laser light traveling in D, and mechanical scanning is not particularly required. Further, according to this embodiment, since the angle change of the polarization plane of the laser light is used as the information recording means, the information recording body 1 can be significantly downsized. Although the recorded information is not erased in this embodiment, for example, a coil is attached in the vicinity of each Faraday rotator, the magnetic field is excited from this to change the information recorded in the Faraday rotator, or relatively. Information may be erased by irradiating the Faraday rotator with a laser beam of high power to heat it and demagnetize it. Further, in this embodiment, it is used as an information storage element, but since it is used as a single card such as an IC card, a one-chip recording unit may be mounted on a thin substrate. Good. In this case, for example, when the card is inserted from the insertion slot, a reading light is emitted from a light source such as a built-in laser to the recording unit of the card to read information, and a reader is separately prepared. Good.

[0011]

As described above, according to the information recording medium of the present invention, the polarization plane of the laser beam incident on the recording medium (Faraday rotator) has the thickness of the recording medium (rotator). Since the Faraday effect that rotates in accordance with the Faraday effect is used, information can be read simply by projecting light from the light source onto the recording medium (Faraday rotator), so there is no need to perform a scanning operation, The mechanism is greatly simplified, and the device is downsized and the manufacturing cost is reduced accordingly.

[Brief description of drawings]

FIG. 1 is a perspective view of essential parts showing an information recording medium according to the present invention.

FIG. 2 is an optical path diagram showing the progress of laser light in the information recording body shown in FIG.

[Explanation of symbols]

 2 substrate 3 recording unit 4A to 4D Faraday rotator (recording medium) 5A to 5C demultiplexing element 6 polarizer 7A to 7D analyzer 8A to 8D light receiving element

Claims (1)

[Claims] 1. An information recording body for recording various information, comprising: a thin film-like recording medium having a specific film thickness for rotating a polarization plane of transmitted light by an amount corresponding to the information to be recorded; A demultiplexing element that is interposed between the recording media that are stacked and that demultiplexes a part of the incident light, and only the light that is demultiplexed by each of these demultiplexing elements and whose polarization plane is rotated at a specific angle. An information recording body, comprising: an analyzer that transmits the light; and a light receiving element that receives light transmitted through the analyzer and outputs a signal in accordance with the information.