JP2872495B2 - Ternary digital memory device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital memory device, and more particularly, to a novel writable memory device capable of generating a digital signal according to a ternary system.

[0002]

2. Description of the Related Art At present, many digital memory devices are used in computers, various OA devices, home electric appliances and the like. However, each of these uses the binary system (binary system),
The recording capacity is 2 ⁸ = 256 with 8 bits. In order to improve the recording capacity, it is necessary to reduce the size of the element itself, and efforts are being made for this purpose. On the other hand, in the case of a memory element according to the ternary system, 8 bits is 3 ⁸ = 6561, and theoretically, an improvement in recording capacity of about 25 times as compared with the binary system can be expected.

The material constituting such a ternary memory element is expressed as -1, 0, +1 and gives a physical quantity which can be converted into three kinds of discontinuous signals which can be distinguished from each other. There must be. However, few systems have been realized that can sufficiently satisfy such requirements. For example, JP-A-61-1
No. 33819 discloses a method of recording N-magnetized, S-magnetized and non-magnetized states by a magnetic method. However, since this method is a magnetic method, the S / N ratio is not sufficient. It is anticipated that there will be a problem that data may easily disappear due to accidental magnetic force.

[0004] It is considered that the above-mentioned problems associated with the use of a magnetic memory element can be avoided by employing an optical recording method. However, in practice, a ternary digital memory element is used. Is not found. For example, JP-A Nos. 59-10930, 59-35989, 62
JP-A-112295 and JP-A-62-107448 disclose optical recording systems in which a polymer liquid crystal is used as a memory element and recording is performed using light energy. Both of them are binary recording systems.

[0005]

Means for Solving the Problems and Effects of the Invention The present inventor, while searching for a digital memory device, is an optically active substance, that is, a substance having chirality, and exhibits an optical rotation characteristic according to the chirality. Physical quantity is
It has been found that an excellent ternary digital memory device can be obtained by using a material which can reversibly take positive, negative and zero values.

That is, the present invention relates to a ternary digital memory device comprising a substance whose optical rotation characteristic can be reversibly changed to positive, negative and zero in response to an external stimulus.

Optically active substance, ie, chirality
When plane-polarized light passes through a substance having the following formula, it exhibits optical rotation in which the plane of polarization rotates. This occurs because the refractive indices of left and right circularly polarized light passing through the optically active substance are different, and the frequency dependence of the optical rotation is called optical rotation dispersion (ORD spectrum). The difference between left and right circularly polarized light absorption coefficients is called circular dichroism, and its frequency characteristic is called circular dichroism spectrum (CD spectrum). The term “physical quantity indicating optical rotation characteristics” or “value of optical rotation characteristics” used in the present invention refers to a value of an ORD spectrum or a CD spectrum.

In the material constituting the ternary digital memory device of the present invention, the value of the optical rotation characteristic reversibly changes to positive, negative, and zero, and as a result, +1, −
It can be converted to a discontinuous signal as represented by ones and zeros. Examples of the substance having such characteristics include a molecular aggregate in which a part or the whole of a molecule is considered to have a helical structure, such as a certain kind of liquid crystal or gel.

For example, some cholesterol derivative-based liquid crystals and gels exhibit such properties. Preferred examples thereof include a cholesterol derivative represented by the following general formula [Chemical Formula 1].

[0010]

R ₁ -φ-N = N-φ-R ₂ -Cho wherein φ represents a benzene ring and Cho represents a cholesterol group. In the formula, R ₁ is CH ₃ (CH ₂ ) _n O—,
_{[CH 3 (CH 2) n} ] 2 -N-, hydrogen, or represent like crown ether ring, n is an integer from 0 to 8, as the crown ether ring, benzo-18-crown -
6, benzo-15-crown-5, benzo-12-crown-4 and benzo-13-crown-4 are preferred. Further, R ₂ is -O (CH ₂ ) _m COO- or-
(CH ₂ ) _m COO—, where m is generally an integer of 0 to 3. This cholesterol derivative has a property of forming a gel in various organic solvents. Preferred organic solvents include alcohol solvents such as methanol, ethanol and octanol, hydrocarbon solvents such as hexane, heptane, cyclohexane, methylcyclohexane, benzene and toluene, ketone solvents such as acetone and methyl ethyl ketone, diethyl ether and dipropyl. There are ether solvents such as ethers, silicone solvents, and mixed solvents thereof, and an optimum solvent is selected according to the type of the cholesterol derivative.

The cholesterol derivative / organic solvent gel reversibly appears or disappears due to external stimuli such as heat and light. That is, when the gel is irradiated with ultraviolet light or heated to a high temperature range by laser or infrared heating, the system is in a solution state, the gel disappears, and no CD spectrum appears. The reason for this is that cholesterol derivatives are trans (gel state) -cis (solution state) in response to their external stimuli.
It is considered that a change occurs. Further, the gel has a property that the sign of the CD spectrum is inverted by laser irradiation or infrared heating. This is presumably because the cholesterol derivative takes two structures corresponding to positive and negative chirality while changing in a temperature hysteresis manner according to the gel preparation method. Thus, in this gel system, the value of the optical rotation characteristic such as the CD spectrum can be reversibly positive, zero, and negative values in the room temperature range. It can be used as a ternary digital memory device that generates a digital signal and that can be written.

The above-mentioned [Chemical Formula 1] has an azobenzene moiety as a chromophore, and this moiety has another chromophore, such as -CH = N-, -N = CH- (azomethine) or-. Compounds in which CH = CH- are also possible. Further, even in the case where the chromophore does not have a chromophore, it is possible to increase the spectrum intensity by doping a chromophore such as an azobenzene derivative into a matrix having a helical structure.

Further, examples of the molecular assembly which can be used in the present invention include polypeptides in addition to the cholesterol derivative as described above, and the values such as CD spectrum and optical rotation in response to an external stimulus. Reversibly change 3
Anything that can be converted into a discrete signal of any kind
It can be used for the ternary digital memory device of the present invention.

Further, as a substance which can be used in the device of the present invention, the above-mentioned molecular assembly such as C
Not only those that give a change in optical rotation characteristics such as D spectra, but also those that show a change in chirality as molecular associations are included. For example, some boronic acid compounds form an aggregate with a saccharide, and exhibit a change in chirality due to a difference in the structure of the saccharide. If such a system is such that the value of the optical rotation characteristic is reversibly changed and can be converted into three kinds of digital signals, it can be used as a constituent material of the ternary digital memory element of the present invention. it can. In this case, it is generally used not as a gel system as described above but as a solution system.

The memory element of the present invention is unitized according to a technique known in the art, and is used by being incorporated in various circuits or devices. Since those techniques are not the gist of the present invention, description thereof will be omitted. For example, as described above, the material for a memory element of the present invention obtained as a gel system, a solution system, or a liquid crystal system,
It is used as an element embedded in a hollow fiber or a three-dimensional network structure.

The resulting elements are arranged according to an appropriate number and shape according to the desired amount of information. In the memory device of the present invention, signals necessary for processing information are obtained as values of optical rotation characteristics for specific wavelengths corresponding to the substances constituting the device, and these values are processed through an appropriate conversion circuit. Thus, a ternary digital signal is obtained. Then, writing and erasing of information can be freely performed by optical means.

As will be understood from the above description, the present invention embodies a ternary digital memory device, and this device enables an increase in the amount of processing information in various devices. Further, the memory element of the present invention is based on an optical system, and has a reduced possibility of accidental disappearance of information as compared with a conventional magnetic system, and has a low S / N ratio. We can expect a rise.

Hereinafter, the present invention will be described with reference to Examples to further clarify the features of the present invention.

[0019]

EXAMPLE 1 In order to examine whether or not the compound can be used as a material constituting a ternary digital memory device of the present invention, a system comprising a compound of the following formula [Chemical Formula 2] and an organic solvent was used. A color spectrum (CD spectrum) was measured. CD
The value of the spectrum is shown as [θ] (molar ellipticity).

[0020]

Embedded image

The compound of formula (2) (5 mg) and methylcyclohexane (500 mg) were placed in a tube, dissolved by heating, placed in a quartz plate having a thickness of 0.1 mm and an area of 1 cm ² , and then cooled to form a gel. It was formed and sealed around. CD
When the spectrum was measured, a positive splitting spectrum was observed around 375 nm (see the solid line in FIG. 1). The maximum value is 1.5 × 10 ⁵ deg · c at 382 nm.
m ² / dmol. The minimum value was −1.2 × 10 ⁵ deg · cm ² / dmol at 370 nm.

When heated by infrared for about 2 minutes, 375 nm
A negative splitting spectrum centered at was observed (Fig. 1
Dashed line). The value at 382 nm is −5 × 10 ⁵ deg ·
cm ² / dmol, 8 × 10 ⁴ deg · c at 370 nm
m ² / dmol.

Upon irradiation with ultraviolet light (350-460 nm), the gel collapsed and became a solution. At this time, C
No D spectrum was observed and its value was 0 deg · c
m ² / dmol. After that, when a visible light of 460 nm or more was irradiated, the gel was formed again, and the same spectrum as that at the beginning was obtained.

As described above, in the system of the compound of the formula [Formula 2] and methylcyclohexane, for example, the values of CD spectrum at 382 nm are positive, negative,
And a state change to zero, and these state changes were found to occur reversibly by infrared heating, ultraviolet irradiation and visible light irradiation. Thus, it was confirmed that this system could be a constituent material of a writable ternary digital memory device.

Example 2 In the same manner as in Example 1, the applicability of a compound represented by the following formula [Chemical Formula 3] and an organic solvent as constituent materials of a ternary digital memory element was examined.

[0026]

Embedded image

The compound of the formula (3) (10 mg) and methylcyclohexane / benzene (9: 1) (200 mg) were placed in a tube and dissolved by heating.
It was placed in a m ² quartz plate and sealed.

When the CD spectrum was measured in the same manner as in Example 1, similar results were obtained. The center of the split spectrum is at 360 nm and the maximum is 3 at 390 nm.
× 10 ⁴ deg · cm ² / dmol. When infrared heating was performed for about 4 minutes, the value of the CD spectrum at 390 nm was −5 × 10 ⁴ deg · cm ² / dmol. 33
When irradiated with ultraviolet light of 0 to 380 nm, 0 deg · cm
² / dmol, and upon irradiation with visible light of 460 nm or more, the same spectrum as that at the beginning was obtained again. After irradiation with ultraviolet light, irradiation with visible light while performing infrared heating gave a negative splitting spectrum.

Example 3 In the same manner as in Example 1, the compound of the formula [Chemical Formula 4] / organic solvent system was examined.

[0030]

Embedded image

A compound (5 mg) of the formula [Formula 4] and ethanol (500 mg) were placed in a tube, and the same examination as in Example 1 was conducted.

The center of the split spectrum is at 350 nm, and the maximum of the positive spectrum is 4 × 10 at 390 nm.
⁵ deg · cm ² / dmol, 390n of negative spectrum
The value of m was 1 × 10 ⁵ deg · cm ² / dmol.
The irradiated ultraviolet light and visible light were 330 to 38, respectively.
0 nm and 460 nm or more.

The results shown in Examples 2 and 3 also indicate that the respective systems can take values such that the CD spectrum gives three kinds of signals at a specific wavelength, and the state showing those values is reversible. Therefore, it shows that it is suitable as a constituent material of a ternary digital memory device.

Example 4 In order to show the function as a digital element, a unit in which five elements (cells) obtained in Example 1 were arranged in parallel was manufactured. The cells are referred to as a, b, c, d, and e in sequence. C
The encoder was connected so that the value of the D spectrum was encoded.

The entire device is exposed to ultraviolet light (350 to 460 nm)
The value of the CD spectrum at 382 nm after light irradiation in each cell was about 0 deg · cm ² / dmol, and (a, b, c, d, e) = (0, 0, 0, 0, 0)
Signal was obtained. When the cells a, c, and e are irradiated with visible light of 460 nm or more, the CD spectrum values are a, c,
e is about 5 × 10 ⁵ deg · cm ² / dmol, b and d
Is about 0 deg · cm ² / dmol, and (a, b,
c, d, e) = (1, 0, 1, 0, 1). Furthermore, after irradiating visible light of 460 nm or more to the cell b, the cells b and e were heated. As a result, the CD spectrum (382 nm) showed that a and c were about 5 × 10 ⁵ deg · cm ^2.
/ Dmol, b and e are about -4 × 10 ⁵ deg · cm ² / d
mol and d are about 0 deg · cm ² / dmol,
(A, b, c, d, e) = (1, -1, 1, 0, -1)
Met.

Thus, the device of the present invention has +1, 0,-
A digital signal corresponding to 1 is generated, and data can be written and erased.

[Brief description of the drawings]

FIG. 1 shows a CD spectrum of a cholesterol derivative applicable to the digital memory device of the present invention.

Claims (1)

(57) [Claims] 1. The method according to claim 1, wherein the value of the optical rotation characteristic is positive,
A ternary method comprising a cholesterol derivative represented by the following general formula [Chemical Formula 1], which can be reversibly changed to negative and zero, and an organic solvent capable of forming a gel with the cholesterol derivative. Digital memory element. R ₁ -φ-N = N-φ-R ₂ -Cho [Formula 1] (where φ is a benzene ring, Cho is a cholesterol group,
R ₁ is CH ₃ (CH ₂ ) _n O—, [CH ₃ (CH ₂ )
_{n] 2} -N-, hydrogen or crown ether ring, n represents 0-8 _{integer,, R} 2 is, _{-O (CH} 2) m COO- or _{- (CH} 2) represents a m COO-, m is 0 -3. )