JPS6350941A - Rewritable optical recording device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rewritable optical storage device.

(Prior Art) Recently, various optical storage devices have been proposed that irradiate the surface of a storage medium with a beam of light such as a laser beam and read information recorded on the storage medium based on the state of reflection of the laser beam. Some are already at the stage of practical application. This optical disk can be accessed randomly to a certain extent,
It is characterized by extremely large storage capacity.

Laser vision discs, compact discs, etc., which have been put into practical use as optical discs, record information using minute irregularities called pits, and the information tL Q IT , I'1. A pit corresponding to jl is formed on the surface of the storage medium, and stored information is read based on the difference in the state of reflection of laser light between the concave portion and the protrusion of the pit.

(Problems to be Solved by the Invention) However, this type of optical storage device is classified as a playback-only type of storage device, and it is not possible to add new information or record information that has already been recorded. It was impossible to erase and rewrite. In addition, optical storage devices classified as write-once types, which create pits later by increasing laser output to punch holes in the surface of the storage medium or by changing the reflectance, have moved from the development stage to the practical stage. However, this type of optical storage device also writes stored information by punching a hole in the storage medium, so once the hole is punched, it is impossible to erase it, and writing information to new memory cells is difficult. Even if it were possible, it was impossible to erase already recorded information and rewrite new information there.

The present invention has been made with attention to these points, and aims to realize an optical storage device in which stored information can be rewritten.

(Means for Solving the Problems) Therefore, in the present invention, a rewritable optical storage device is provided with a storage medium formed of a substrate and a liquid crystal polymer layer covering the surface of the substrate, and a light beam that is A drive reading means for irradiating desired memory cells formed in the polymer layer and detecting the light beam reflected by the memory cells; The liquid crystal polymer layer becomes liquid crystal when heated above a predetermined temperature, and when an electric field or magnetic field is applied in the liquid crystal state, the liquid crystal portion of the liquid crystal polymer layer becomes liquid crystal. The optical properties are determined, and when the temperature drops in that state, the optical properties at that time are fixed.

(Function) In the rewritable optical storage device of the present invention configured as described above, when erasing or rewriting information, the drive reading means irradiates a desired memory cell of the storage medium with a light beam to erase the part of the memory cell. The temperature is raised above a predetermined value to turn the part into liquid crystal, and the writing means applies an electric or magnetic field corresponding to the information to be written, thereby changing the optical properties of the liquid crystal part to one corresponding to the written information. In this state, the light flux from the drive reading means is stopped to lower the temperature of that part, and the optical properties at that time are fixed, thereby erasing and rewriting information, and when reading information, Memory information is read by irradiating a desired memory cell with a light beam from the drive reading means, detecting the reflected light from the memory cell by the drive reading means, and identifying the optical properties of the memory cell. be.

(Example) Next, an example of implementation of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of a rewritable optical storage device according to the present invention, and FIG. 2 is a vertical sectional view of a main part of a storage medium for explaining the write operation thereof. In the drawings, 1 is a storage medium, 3 is a driving reading means, and 5 is a writing means.

The storage medium 1 consists of a disk-shaped base 11 and a liquid crystal polymer layer 13 covering the surface of the base 11, and memory cells 15 are formed in this liquid crystal polymer layer 13. The substrate 11 has a reflective layer 17 formed on its surface by vapor deposition of aluminum or the like, and the liquid crystal polymer layer 13 covers the reflective layer 17. This liquid crystal polymer layer 1
3. When heated to a predetermined temperature, for example 200°C or higher, it melts and becomes a liquid crystal, and when an electric or magnetic field is applied in the liquid crystal state, its optical properties change and it becomes transparent or opaque. It has a property of solidifying and fixing the optical properties when the temperature is lowered below the predetermined temperature. As such a liquid crystal polymer layer 13, any material can be used as long as it exhibits anisotropy when melted and is used as a liquid crystal as described above. Polymers described in JP-A-54-77691, JP-A-57-472921, etc. are used. In the initial state, the storage medium 1 configured as described above is provided with only a track that guides the irradiated light beam and pits that indicate storage positions at key points on this track, and the memory cells 15 are located on this track. Information is written there, erased, and rewritten.

The driving/reading means 3 includes a semiconductor laser device 31 that generates a desired luminous flux, a coupling lens 33, a polarizing beam splitter 35 that switches the optical path, a tracking mirror 37 that guides the luminous flux to a desired memory cell 15 of the storage medium 1, and a tangen. It is composed of a mirror 39, an objective lens 41, a fixed mirror 43 for detecting read light, a photodiode 45, and the like. Further, the writing means 5 is constituted by a writing circuit 51 that sends out stored information in the form of an electric signal, and a writing head 53 made of a coil that generates a magnetic field according to the electric signal from the writing circuit 51. Here, if the optical properties of the memory cell 15 are controlled by an electric field, an electrode is used in the write head 53 instead of a coil.

Next, its operation will be explained.

In order to erase the memory information of the memory cell shown by 15a in FIG. 2(A) and rewrite new information, first, the coupling lens 33. Polarizing beam splitter 35. Tracking mirror 37. The memory cell 15a of the storage medium 1 is irradiated with a light beam indicated by an arrow P in FIG. 2(B) via the tangential mirror 39 and the objective lens 41. The memory cell 15a is heated by the energy of this luminous flux P, and when the temperature of this portion exceeds 200° C., the liquid crystal polymer layer 13 melts and becomes liquid crystal only in that portion. At this time, a current corresponding to the write information is supplied from the write circuit 51 to the write head 51, and a magnetic field in the direction indicated by the arrow M in FIG. 2(B) is applied to the memory cell 15a. Therefore, in the memory cell 15a, the optical properties of the liquid crystal polymer layer 13 change from opaque to transparent, for example. Here, as shown in Fig. 2(C), the luminous flux P
When the heating of the memory cells 15a is stopped, the memory cells 15a portion of the liquid crystal polymer layer 13 cools and solidifies, fixing the optical properties (transparent state) at that time as shown in FIG. 2(D).

In order to erase the information written in this manner and rewrite the opposite information, the liquid crystal polymer layer 13 in the corresponding memory cell 15a portion is similarly melted and a magnetic field is applied.

The direction of the magnetic field applied at this time is opposite to that in the above case, as shown by arrow m in FIG. 2(E). The memory cell 1 in which the liquid crystal polymer layer 13 has become liquid crystal due to stiffness.
．． 5a, the optical properties change from transparent to opaque, and when cooled in this state, the optical properties (opaque state) at that time are fixed as shown in FIG. 2(F). In this way, in the rewritable optical storage device of this embodiment, the stored information is
0 u , 111 IT is stored in association with optical properties such as transparency and opacity of the liquid crystal polymer layer 13 .

Next, in order to read the storage information written in this way, while rotating the storage medium 1, the light beam from the semiconductor laser device 31 is directed to the coupling lens 33. Polarizing beam splitter 35. Tracking mirror 37. The corresponding memory cells 15 are irradiated through a tangential mirror 39° objective lens 41. Here, the luminous flux at this time does not have to be of high energy like the luminous flux at the time of rewriting. The amount of reflected light of this light beam differs depending on the optical properties of the memory cell 15. That is, the light flux is
If 5 is transparent, the amount of reflected light will be large because it will be transmitted through the liquid crystal polymer layer 13 and reflected by the reflective layer 17, and if it is opaque, it will be reflected from the surface of the liquid crystal polymer layer 13 and the amount of reflected light will be small.

This reflected light is reflected by the objective lens 41. Tangential mirror 39. It is sent to the polarizing beam splitter 35 via the tracking mirror 37, where it is split and sent to the fixed mirror 4.
3 to the photodiode 45. The photodiode 45 converts the magnitude of the amount of received light into an electrical signal, thereby reading stored information stored in association with optical properties such as transparency or opacity of the liquid crystal polymer layer 13.

(Effects of the Invention) The present invention is configured as described above, and a desired memory cell portion of a liquid crystal polymer layer is irradiated with a light beam, the portion is heated to a predetermined temperature or higher to become a liquid crystal, and in this state, an electric or magnetic field is applied. By applying a
Since OIT, II, and II are stored in association with each other, unlike those that write stored information by drilling holes in the storage medium, it is possible to erase the information that has already been recorded and rewrite new information there. This provides an excellent effect in that it is possible to easily realize an optical storage device in which data can be written, and stored information can be rewritten.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of a rewritable optical storage device according to the present invention, and FIG. 2 is a vertical sectional view of a main part of a storage medium for explaining the write operation thereof. 1...Storage medium, 3...Drive reading means. 5...Writing means, 13...Liquid crystal polymer layer, 15.15a...Memory cell. Patent applicant Polyplastics Co., Ltd. 150-51/; (D) m' (C) 1$ (E) (F) ・Bu11\

Claims (1)

[Claims] (1) A liquid crystal polymer that becomes liquid crystal when heated above a predetermined temperature, the optical properties of that part are determined by the applied electric or magnetic field, and the optical properties at that time are fixed by lowering the temperature. a storage medium having a liquid crystal polymer layer; a drive reading means for irradiating a light beam onto desired memory cells formed in a liquid crystal polymer layer of the storage medium and detecting a light beam reflected by the memory cells;
A rewritable optical storage device comprising: a writing means for applying an electric field or a magnetic field corresponding to stored information to memory cells that have become liquid crystal due to temperature rise caused by irradiation with a luminous flux from the drive reading means.