JPS6346639A - Pyroelectric material recording medium - Google Patents

Abstract

PURPOSE:To reduce an electrode area and to improve recording and reproducing capacity, etc., by controlling the connection of a divided electrode and common 3rd electrode by a conductivity imparting means. CONSTITUTION:The recording of an information signal to a pyroelectric material layer 2 is executed by impressing a prescribed voltage to the 2nd electrode 3 of a recording medium 1 and the 3rd electrode 5 disposed annularly to the outer periphery of the disk-shaped recording medium 1 and irradiating a photoconductor 4 formed in continuation with the one divided electrode DP(k) corresponding to the region of the pyroelectric material layer 2 to be recorded by using the conductivity imparting means B. The photoconductor 4 is imparted with the conductivity by such irradiation; therefore, the one divided electrode DP(k) is short circuited and is electrically connected to the 3rd electrode 5. The change of the polarization state arises and the recording is executed when the pyroelectric material layer 2 is heated by using a heating means A at this time. The characteristics such as high-speed writing, high-speed reading out and increase of the current of a leading out signal to large current are improved by such division of the electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a pyroelectric recording and reproducing method for recording and reproducing information signals using a pyroelectric layer disposed between opposing electrodes.

B1 Summary of the Invention The present invention provides a pyroelectric recording and reproducing method in which information signals are recorded and reproduced using a heating means on a recording medium in which a pyroelectric layer is arranged between opposing electrodes. By controlling the connection between the electrode and the common third electrode,
The purpose is to improve the recording and reproducing system by reducing the actual electrode area.

C1 Conventional technology As one of the recording and reproducing methods for recording and reproducing information signals,
There is a pyroelectric recording and reproducing method that uses a pyroelectric layer. For example, as shown in FIG.
Using a recording medium 30 having an electric layer 33 such as a polymer material 4 between them, a voltage is applied between the electric conductors 1. In addition to applying this voltage, a predetermined voltage of the pyroelectric layer 33 The region is heated by the laser beam C, and the dielectric polarization of the pyroelectric layer is generated in the region, or the polarized state is canceled by pre-polarization and heating.Then, after the applied voltage and heating are stopped, respectively. Even if there is, this dielectric polarization state remains in the pyroelectric layer, and the presence or absence of this polarization state and its direction are recorded and stored as an information signal.

On the other hand, during reproduction, a predetermined region of the pyroelectric layer 33 is heated, and a pyroelectric current corresponding to the presence or absence of the residual polarization of the pyroelectric layer 33 or the polarization direction thereof is detected using a charge amplifier 34 or the like. By amplifying it, the information signal can be reproduced. Further, as a method for recording and re-tracing information using such a technique, methods described in Japanese Patent Laid-Open No. 59-215096 and Japanese Patent Laid-Open No. 59-215097 are known.

By the way, in such a pyroelectric recording and reproducing method,
The information signal is reproduced by detecting the pyroelectric current, but as shown in the equivalent circuit in FIG. 4, not all of the pyrocurrent 10 generated by heating the recording medium is detected and amplified.
A part of it flows out to the capacitor co formed by the opposing electrodes of the recording medium. If the current flowing into this capacitor CO is current 1c, in order to suppress the flowing current Tc and increase the detected current Ia, it is necessary to suppress the capacitor FI Co itself to a small value, and in the end, the capacitor MI Co must be reduced. Therefore, it becomes necessary to reduce the area of the opposing electrode during recording and reproduction.

Then, as shown in FIG. 5, as a technique for reducing the area of the opposing electrodes during recording and reproducing and increasing the detected current +a (and further improving the speed), as shown in FIG. A divided electrode 51 in which one electrode is divided into a plurality of parts.
Techniques using such a structure, and techniques in which they are arranged in a matrix as described in, for example, Japanese Patent Application Laid-Open No. 61-105792, are known.

D1 Problems to be Solved by the Invention By dividing the electrodes and using them in this manner, the capacitance Co becomes smaller and the recording/reproducing characteristics of the recording/reproducing method using a pyroelectric material are improved.

However, if the electrodes are simply divided and used, it is necessary to provide wiring for electrical connection to each divided electrode, and the more the divided electrodes are formed at the density of the descendants, the more the detection part can be connected. It becomes more necessary to route the wiring.

And in order to route the wiring, is it necessary to have a structure like that? 3
In addition, the manufacturing process becomes more difficult, and it is difficult to reduce the manufacturing cost.

Therefore, in view of the above-mentioned problems, the present invention avoids the complicated routing of wiring to the divided electrodes, and also does not make the structure of the recording medium used structurally complicated in any way.
Furthermore, it is an object of the present invention to provide a pyroelectric recording/reproducing method that is easy to manufacture.

Means for Solving Problem E1 The present invention provides a first electrode group consisting of a pyroelectric layer for recording information signals and a plurality of divided electrodes arranged on one surface of the pyroelectric layer. a second electrode disposed on the other surface of the pyroelectric layer and made of a transparent conductor; and a common electrode connected to the first electrode group via a photoconductor or a thermal conductor. a heating means for heating a pyroelectric layer corresponding to one divided electrode of the first electrode group using a recording medium formed with three electrodes; and a photoconductive layer connected to the one divided electrode. The above-mentioned problems are solved by a pyroelectric recording and reproducing method characterized in that recording and reproducing on the pyroelectric layer is performed by a conductivity imparting means that irradiates or heats a body or a thermal conductor.

F1 action In the recording medium used in the pyroelectric recording and reproducing method of the present invention, at least one of the opposing electrodes is a first electrode group consisting of divided electrodes, and each divided electrode is made of a photoconductor or Since it is connected to a common third electrode via a thermal conductor, one divided electrode is electrically connected to the third electrode by controlling this photoconductor or thermal conductor with the conductivity imparting means. I will do it. Therefore, during recording and reproduction, the pyroelectric layer is heated using a heating means, and the photoconductor or thermal conductor is connected to the divided electrode corresponding to the heated pyroelectric layer by means of imparting conductivity. By irradiating or heating the divided electrode with light, the third electrode common to the divided electrode is short-circuited, and recording and reproduction can be performed.

G. Embodiment A preferred embodiment of the present invention will be explained with reference to the drawings. The pyroelectric recording and reproducing method of this embodiment can be implemented using a recording medium as shown in FIG. Since the electrical connection to is controlled by the conductivity imparting means, it is possible to improve the recording and reproducing characteristics without the need for complicated routing of wiring or the like.

First, as shown in FIG. 1, a recording medium 1 used in the pyroelectric recording and reproducing method of this embodiment includes a pyroelectric layer 2 for recording information signals by dielectric polarization, and a pyroelectric layer 2. n divided electrodes (n is a natural number) arranged on one side of DP (1
) ~DP (n), a second electrode 3 arranged on the other surface of the pyroelectric layer 2 and made of a transparent conductor, and the first electrode group and a common third electric conductor 4T1 connected via the photoconductor (or thermal conductor) 4
5 are formed on the substrate 6.

The pyroelectric layer 2 is a recording layer for recording information signals, and is made of, for example, polyvinylidene fluoride (PVD F
)-polymer pyroelectric materials such as polytrifluoroethylene (PTrFE) copolymers, and PLZT.

Inorganic pyroelectric materials such as PZT and LiNbO3 can be used, and are formed as a thin film between the first electrode group and the second electrode 3.

The first electrode group is one of the opposing electrodes, and is divided into three parts by the groove 7, for example, as shown in FIG.
A plurality of fan-shaped (n) divided electrodes DP (
1) to DP (n). Note that the shape of the divided electrodes is not limited, and may be divided and arranged concentrically. Moreover, the number is not limited either.

Furthermore, the size of each divided electrode is not limited either.

In this embodiment, the first electrode group is formed on one side of the group Fi, 6, for example A1. A metal thin film such as Au or a conductive thin film such as ITO, In2 o3, SnO2, etc. can be used. Note that the divided electrodes can be formed by dividing the conductive thin film etc. by means such as etching, and although recording as a medium cannot be performed in the area removed by etching etc., it can be used for tracking control of the medium. It is possible to use it for several purposes.

The second electrode 3 is an electrode formed on the pyroelectric layer 2 and serves as the other counter electrode, and is made of ITO, In20
It is made of a transparent conductive material such as 3+5n02. Note that this second electrode 3 can be formed at the same time as a third electrode 5 formed on a photoconductor (thermal tetraconductor) 4, which will be described later.

Here, the formation of the second electrode 3 which is preferable for use in such a recording medium will be described in detail.For example, in the case of an In2O3 film, it can be formed by a reactive RF ion blating method. In this reactive RF ion blating method, first, the degree of vacuum in the Herjar on which the substrate on which the transparent electrode is to be formed is placed is raised to approximately 1×10 (Torr) using a predetermined exhaust system of a Rochry pump and a diffusion pump.

Next, oxygen gas is introduced into the herger, and an oxygen plasma is generated by high frequency oscillating electric field discharge. continue,
Metal indium is heated to melt and evaporate. This evaporated metallic indium reacts with the oxygen plasma to become indium oxide, which is deposited on the substrate. At this time, two stages of film deposition are performed at different film formation speeds. That is, first, a thickness of about 500 layers was deposited at a deposition rate of 60 layers/min,
Next, a thickness of about 1,300 layers is deposited at a deposition rate of 120 layers/minute. Further, at this time, by maintaining the substrate at a low temperature of, for example, about 75° C., indium oxide can be deposited favorably.

The photoconductor (thermal conductor) 4 functions as a conductor according to the action of the electrical conductivity imparting means described later, and functions as an insulator where the electrical conductivity imparting means does not act. become. Therefore, by applying light irradiation (heating) to this photoconductor (thermal conductor) 4 by the conductivity imparting means, it becomes selectively conductive, and the above-mentioned division tt
At least one divided electrode DP (k) among MDP (1) to DP (n) and the common third electrode 5 are electrically connected. This photoconductor 4 is made of, for example, Cd
It can be constructed using materials such as S, PVK (polyvinyl carbanol), etc., and when it is used as the thermal conductor 4,
Materials such as VzO3 (fluidized vanadium) can be used. In this embodiment, the photoconductor (thermal conductor) 4 is located at the end of the first electrode group and is annularly disposed on the outer circumferential side of the disc-shaped recording medium l.

The third electrode 5 includes each divided electrode DP (1) to DP
(n) is a common electrode, and is selectively short-circuited to one divided electrode by acting on the photoconductor (thermal conductor) 4 with conductivity imparting means.

The third electrode 5 may be formed of a transparent conductive material and patterned at the same time as the second electrode 3. In this embodiment, a third electrode 5 common to each divided electrode is arranged in an annular manner above the photoconductor (heat 4 main body) 4.

The substrate 6 is for supporting the first electrode group, the pyroelectric layer 2, the second electrode 3, the photoconductor (thermal conductor) 4, and the third electrode 5, and is made of, for example, glass. Various materials such as metals, polymer materials, etc. can be used. In addition, its shape is not limited to the disk shape shown in this example,
It can be of any shape such as board, film, sheet, card, drum, etc.

And, such a recording medium 1, as shown in FIG.
Group #5.6, first electrode 3. Pyroelectric layer 2. Although the second electrode 4 is laminated, a first electrode group consisting of split electrodes and a pyroelectric layer are further laminated, and a corresponding combination of a photoconductor (thermal conductor) and a third electrode is laminated. A multi-layered structure may also be provided in which .

Further, the structure is such that a second electrode 3 is formed on the substrate 6 of the recording medium 1, and a first electrode group consisting of divided electrodes is formed on the surface side with the pyroelectric layer 2 interposed therebetween. Alternatively, the combination of the photoconductor (thermal conductor) and the third electrode for selective conduction may be formed not on the outer circumference but on the inner circumference or in other areas such as in the radial direction.

Further, the selectivity of light irradiation can be increased by mixing a substance such as a dye that differs in the absorption capacity of irradiated light into the photoconductor 4 and the pyroelectric layer 2, respectively.

Next, a pyroelectric recording and reproducing method using the recording medium 1 as described above will be explained.

First, a laser beam (Fig. ) can be used. The laser beam B is e.g. an L/- laser diode, a lens,
A galvanometer mirror or the like may be used to selectively irradiate a predetermined 9j region. Further, the heating means for heating the pyroelectric layer corresponding to the one divided electrode DP (k) used in the Mokuyo electric recording and reproducing method uses a laser beam as shown by laser beam A in FIG. be able to. Here, during recording and reproduction, one divided electrode DP (k) having the pyroelectric layer 2 to be recorded and reproduced is used.
In order to write or read only one segmented electrode, laser beams A and B are operated synchronously and are used to act on the same single segmented electrode. Note that at this time, such synchronized control can be performed by a control device or the like that controls the respective laser beams A and B, if necessary.

Then, recording and reproducing to and from the pyroelectric layer 2 of the recording medium 1 described above is performed using such conductivity imparting means and heating means. First, an information signal is recorded on the pyroelectric layer 2 at 4f'. Let me explain the case.

First, when recording an information signal on the pyroelectric layer 2, the second electrode 3 of the recording medium l and the third electrode 5 arranged annularly around the outer periphery of the disc-shaped recording medium l are used. A predetermined voltage is applied to.

Next, using the above-mentioned conductivity imparting means, one side electrode DP corresponding to the region of the pyroelectric layer 2 to be
Photoconductor (thermal conductor) formed continuously in (k)
4 is irradiated (heated). Due to this irradiation (heating), the photoconductor (thermal conductor) 4 becomes electrically conductive, so that one division T;
This will short-circuit and electrically connect to the electrode 5 of.

Then, due to the electrical connection between one divided electrode DP (k) and the third electrode 5, a voltage is applied between the opposing electrodes in the one divided electrode DP (k). Become. At this time, when the pyroelectric layer 2 is heated using the heating means, the polarization state changes based on the applied voltage at the heated portion, which is the beam spot (indicated by B in the figure), and recording is performed. That is, from the irradiation (heating) operation by the conductivity imparting means and the heating operation by the heating means, the third electrode 5. Photoconductor (thermal conductor) 4. One divided electrode DP (k), pyroelectric layer 2. An electrical path is formed between the second electrodes 3, and an information signal is recorded based on the presence or absence of polarization or the direction of polarization corresponding to the applied voltage.

Note that during recording, a method may be used in which the entire surface of the recording medium is polarized in one direction in advance, and the recording is performed by releasing the polarized state.

Next, when reading out and reproducing the information signal from the pyroelectric layer 2, the 1
1 split type + 1P (k) i! ! ! Subsequently, the formed photoconductor (thermal conductor) 4 is irradiated (heated) to electrically connect the divided electrode DP (k) and the common third electrode 5,
Further, the area for reading is heated by the heating means. Due to this heating, a pyroelectric current is generated in the region involved in reading, depending on the presence or absence of polarization or the direction of polarization, making it possible to extract information signals.

Furthermore, in the case of erasing a recorded information signal, the information signal is erased by applying zero voltage to operate the recording medium or by polarizing the entire surface of the recording medium.

Note that transmission and reception of information signals in the case of reading and the like can be performed mechanically, for example, via a rotary transformer provided at the bottom of a turntable or the like, or an electronic component such as a photocoupler.

In the pyroelectric recording and reproducing method of this embodiment using the method described above, first, a photoconductor (thermal conductor) is
4 is electrically conductive, and current can be taken out from the divided electrodes through a common third T, pole 5. For this reason, when split electrodes were used in the pyroelectric layer 2, there was a problem that the structure would become complicated due to the routing of wiring. detection.

Also, needless to say, since it is a single divided electrode,
By reducing the capacitance of the electrode, high-speed writing and high-speed reading are possible, and furthermore, it is possible to maintain a large constant current value, so that recording and reproducing characteristics can be improved.

Also, for example, two or more heads may be placed facing each other on the recording medium to simultaneously write on a plurality of areas. It is easy to create a so-called multi-head system that performs playback, and a multilayer structure is also possible. In addition, when setting it as a multilayer structure, an upper layer electrode becomes a transparent electrode.

H9 Effects of the Invention The pyroelectric recording and reproducing method of the present invention improves the characteristics of I and A reproducing, such as high-speed S input, high-speed readout, and large current of the readout signal, from the electrode division as described above. becomes possible.

The recording medium used in the pyroelectric recording and reproducing method of the present invention does not require distribution of electrodes or routing of parts 9, etc., even though it uses split electrodes, so its structure is surface-heated, and its manufacturing cost is reduced. It also contributes to reduction.

Furthermore, a multilayer structure is also possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining an example of the pyroelectric recording/reproducing method of the present invention, FIG. 2 is a plan view of a recording medium used in the pyroelectric recording/reproducing method of the present invention, and FIG. 3 is a pyroelectric recording/reproducing method of the present invention. A schematic perspective view to explain the principle of the recording and reproducing method, Part 4 is an equivalent circuit diagram during pyroelectric recording and reproducing to explain the problems, and Fig. 5 is a diagram used in the conventional pyroelectric recording and reproducing method. 1 is a perspective view showing an example of a recording medium that can be used. 1−・−・−−−−−1・・−・・−・−・・−・Recording medium 2−−−−・−・−・−・・−・・−・・Pyroelectric material Layer 31. −・−・−・−・−・・・−・・・・・−・
・---11 Second electrode 4---------...
−・・・〜・・・・・・−・Photoconductor thermal conductor) 5−・
・・・−−−１−・・・・−・・・−・・−・−・Third electrode 6 −−−−・・・−−−−−１〜−・−−−
−・−・−−−−−1・· Group) Anti-DP (1) ~D
P (n) ---Divided electrode A ---m----
−−・−・・−・−Laser beam (heating means) B−−・−・・−・・−−−1111−−−−・・
・-Laser beam (conductivity imparting means) Patent Applicant: Sony Corporation Representative Patent attorney Kobu Miwami Tamura Sakae- 2 Koji body Figure 1 7 Figure 2

Claims (1)

[Claims] A pyroelectric layer for recording information signals, a first electrode group composed of a plurality of divided electrodes arranged on one surface of the pyroelectric layer, and the pyroelectric layer A second electrode arranged on the other surface and made of a transparent conductor, and a common third electrode connected to the first electrode group via a photoconductor or a thermal conductor are formed. a heating means for heating a pyroelectric layer corresponding to one divided electrode of the first electrode group, and a photoconductor or thermal conductor connected to the one divided electrode, using a recording medium consisting of A pyroelectric recording and reproducing method characterized in that recording and reproducing on the pyroelectric layer is carried out using conductivity imparting means that irradiates or heats the pyroelectric layer.