JP2834014B2 - Drive power supply for externally charged liquid crystal display element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive power supply for an externally charged liquid crystal display device. More specifically, displaying or erasing an image using a liquid crystal dispersed polymer layer that selectively transmits and scatters light using an electro-optic effect that changes the light scattering state of liquid crystal depending on the presence or absence of an electrostatic field. The present invention relates to a drive power supply device for charging an electrostatic charge on the surface of an externally charged liquid crystal display element.

[0002]

2. Description of the Related Art Hitherto, many liquid crystal display devices utilizing the electro-optic effect of liquid crystal and liquid crystal display devices using the liquid crystal display device have been proposed. In particular, liquid crystal display devices using a liquid crystal dispersed polymer layer in which liquid crystal is finely dispersed in a polymer matrix have attracted attention in recent years because bright and large screens can be obtained relatively easily because no polarizing plate or alignment film is required. ing.

[0003] In Japanese Patent Publication No. 3-52843, for example,
A liquid crystal light control panel in which a liquid crystal dispersed polymer layer is sandwiched between transparent electrodes has been proposed. In this liquid crystal light control panel, a nematic liquid crystal or the like is finely dispersed in an aqueous solution of a water-soluble polymer such as polyvinyl alcohol, and dried to form a liquid crystal dispersed polymer layer. As for the driving method, after the liquid crystal dispersed polymer layer is sandwiched between two transparent electrodes, an AC voltage is applied between the electrodes by an AC voltage power supply to orient the liquid crystal molecules in the liquid crystal dispersed polymer layer in the direction of the electric field. Let it. This driving method is not limited to this patent but is a method which is almost common to conventional liquid crystal display elements.

The applicant has also disclosed in Japanese Patent Application Laid-Open No. 5-224182, a transparent high electric resistance layer, a liquid crystal dispersed polymer layer in which liquid crystal is finely dispersed in a polymer matrix, and a conductive layer. And an “externally charged liquid crystal display element” in which transparent insulator layers are sequentially laminated. Further, using such a liquid crystal display element, writing means for applying an electrostatic charge on the surface of the transparent insulator layer from the outside, and erasing means for removing the electrostatic charge on the surface,
A power supply for generating a surface potential on the surface, and by applying and removing an electrostatic charge to and from the surface by the writing means and the erasing means, an image can be easily written and erased on the screen repeatedly. A "handwritten liquid crystal board set" was proposed in Japanese Patent Application Laid-Open No. 5-281530.

[0005]

In the externally charged liquid crystal display element, a transparent high electric resistance layer having a high volume resistivity is provided in the structure thereof, and the volume resistivity of the liquid crystal dispersed polymer layer is further increased. As a result, the electric field applied between the conductive layer and the surface of the transparent insulator layer of the present liquid crystal display element is maintained without flowing as a current, thereby maintaining the orientation of the liquid crystal molecules in the liquid crystal dispersed polymer layer in the direction of the electric field. You can do it. However, on the other hand, it is necessary to apply a relatively high DC voltage in order to align the liquid crystal molecules and display them on the liquid crystal display device. Therefore, as a drive power supply for operating the externally charged liquid crystal display element of the present applicant, a conventional drive power supply using an AC low voltage for a liquid crystal display element has a continuous writing line on a display screen. I can't get it.

The present inventors have proposed the aforementioned "handwritten liquid crystal board set" using the externally charged liquid crystal display element. However, the "handwritten liquid crystal board set" has been proposed to be provided to the market as a toy. For this reason, the present inventors have not been satisfied with the conventional general DC voltage power supply due to its size, cost, safety, and the like.
In addition, a dry battery is preferable as the primary power supply of the DC voltage power supply due to its characteristics as a toy, because it is easily available and easy to handle. Power consumption must be as low as possible. The present inventors have a duty to obtain a drive power supply device that outputs a DC voltage with a simple structure, low cost, excellent safety as a toy, and low power consumption. A drive power supply device for a new externally charged liquid crystal display device that satisfies the inventors has been obtained, and the present invention has been achieved.

An object of the present invention is to provide a transparent material having a high volume resistivity.
Akiradaka have an electrical resistance layer, der that as a drive power supply for the memory is good external charging type liquid crystal display device of the image, inexpensive with a simple structure, to obtain a good driving power supply safety
Another object of the present invention is to provide a drive power supply device with low power consumption.

[0008]

Means for Solving the Problems The present invention provides at least:
On the conductive layer, a transparent high-resistance layer and a liquid crystal-dispersed polymer layer in which a liquid crystal is finely dispersed in a polymer matrix are sequentially laminated to charge an electrostatic charge on the surface of an externally charged liquid crystal display element. In a drive power supply device, an output terminal is connected to the conductive layer, one output terminal is electrically connected to the erasing means, and the other output terminal is electrically connected to the writing means. At least a DC low-voltage power supply, a power switch, and a step for raising the low voltage generated by the DC low-voltage power supply to 50 to 2000 V;
A blocking oscillation circuit including an oscillation transistor and a boosting oscillation transformer, a rectifying diode for rectifying the voltage generated by the blocking oscillation circuit, and charging the rectified voltage to smooth an output voltage And a smoothing capacitor for performing
And a resistor that regulates the output current value to 5 mA or less.
Connected to the smoothing capacitor and writing means.
Between the smoothing capacitor and the erasing means.
Between the output terminals to be connected and the smoothing capacitor.
Connected between the output terminals connected to the electrical layer.
This is a driving power supply for an externally charged liquid crystal display element.

Further, there is provided a drive power supply device for an externally charged liquid crystal display element, wherein a current flowing to a primary winding side of the blocking oscillation circuit is 10 mA or less.

The externally charged liquid crystal display device of the present invention is disclosed in Japanese Patent Application Laid-Open No. Hei 5-224182 as described above, and will be briefly described here. The conductive layer may be either transparent or opaque. Alternatively, a material having a surface resistance of 10 ⁷ Ω / □ or less may be used. metal,
It can be obtained by making the surface or the whole of a metal alloy sheet foil, plastic, or glass substrate conductive with a conductive material such as a metal, a metal alloy, a metal oxide, graphite, or a conductive polymer.

The high electric resistance layer means a layer having a volume resistivity of 10 ¹³ Ω · cm or more at a temperature of 20 ° C. and a relative humidity of 90%.
Laminate with adhesive, apply various polymer solutions,
It can be obtained by drying.

As the liquid crystal, a nematic liquid crystal having a positive dielectric anisotropy is used.

In the drive power supply device used for the externally charged liquid crystal display element composed of each of the above-mentioned materials, a dry cell or a solar cell can be used as a low voltage power supply. 1.5 for ease
V dry cells are preferred.

The oscillation transistor, the step-up oscillation transformer, and the rectifier diode are generally provided on the market, and are not special.

In the step-up oscillation transformer, the ratio of the number of turns on the primary side to the number of turns on the secondary side is determined from the relationship between the input voltage and the output voltage to be obtained.

As the smoothing capacitor, a capacitor having a capacity corresponding to the voltage after rectification is used. When this drive power supply device is used for a handwritten liquid crystal board set, one terminal of the drive power supply device is connected to the conductive layer of the externally charged liquid crystal display element, and the other terminal is connected to writing means made of a conductive material. hand,
Writing is performed by charging the surface of the liquid crystal display element with writing means while the switch is turned ON. At this time, when writing is performed at a high speed, when a voltage is supplied by the smoothing capacitor, stable operation is achieved. Handwriting can be obtained.

Generally, when a current flows through a human body, a current value that does not cause an electric shock is said to be 5 mA or less. Therefore, a resistor is connected to regulate the output current from the smoothing capacitor to 5 mA or less, and the resistor is preferably in the range of 200 KΩ to 100 MΩ in view of the relationship with the above-described members.

[0018]

In the drive power supply of the present invention, when the power switch is turned on, a current flows from the DC low voltage power supply to the primary winding connected to the collector of the oscillation transistor, and the current is excited to the winding connected to the base. And the current flowing through the collector increases. At some point, the collector-emitter saturation voltage increases rapidly and the voltage on the primary winding connected to the collector decreases. As a result, the oscillation transistor is switched off. At this time, a current is excited in the secondary winding by the energy stored in the step-up oscillation transformer (core). The current excited in the secondary winding excites the current again in the winding connected to the base, and the oscillation transistor
Switched to N, current flows through the primary winding connected to the collector.

Oscillation occurs by repeating the above operations, and a pulse-like voltage proportional to the number of turns of the primary winding and the secondary winding is generated in the secondary winding. This pulsed voltage is half-wave rectified by a diode and stored in a capacitor.

One output terminal of the capacitor is connected via a resistor to the conductive layer of the externally charged liquid crystal display element and the erasing means, and the other output terminal is connected via a resistor to the writing means to provide an externally charged type liquid crystal display element. Writing / erasing is performed on the screen of the liquid crystal display element using the writing means and the erasing means,
Due to the resistance, even if an output current flows through the human body, the current value is regulated to 5 mA or less.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

The driving power supply device 1 for an externally charged liquid crystal display element of the present embodiment is configured as shown by the dotted line in FIG. 1 which is a schematic diagram showing the circuit diagram and the operating state. In the figure, reference numeral 2 denotes a DC low-voltage power supply composed of a 1.5 V alkaline battery. 3 is a power switch. 4 is a 47 μF smoothing capacitor. 5
Is an oscillation transistor. 6 is 56KΩ and 7
Is a resistance of 560Ω. Reference numeral 8 denotes a 0.22 μF oscillation capacitor. Reference numeral 9 denotes a step-up oscillation transformer having a turn ratio of about 1: 380. 4 to 9 constitute a blocking oscillation circuit. 10 is a rectifier diode, 11 is 330p
F is a smoothing capacitor. 2-11, DC-DC
Constructs a converter circuit. Reference numerals 12, 13, 14 and 15 denote current value regulating resistors of 5.1 MΩ. 1
Reference numerals 6, 17 and 18 are output terminals.

The voltage between the output terminals 16 and 18 was measured by connecting the high-voltage probe 9014 to a digital HiTester 3231-01 manufactured by Hioki Electric Co., Ltd. while the power switch 3 was turned on. Was.

Next, as shown in FIG. 1, a transparent high electric resistance layer, a liquid crystal dispersed polymer layer in which liquid crystal is finely dispersed in a polymer matrix, and a transparent insulator layer are sequentially laminated on the conductive layer. One output terminal 18 of the drive power supply 1 was connected to the conductive layer of the externally charged liquid crystal display element 19.
In addition, a conductive sponge having a volume resistivity of 4 × 10 ³ Ω · cm at a temperature of 23 ° C. and 50% RH was connected as an erasing means 20 to the output terminal 17 having the same electric potential as the one output terminal 18. . Further, a writing means 21 is connected to the other output terminal 16 of the drive power supply 1 at a temperature of 23 ° C. and 50%
In H, a conductive sponge having a volume resistivity of 4 × 10 ⁴ Ω · cm was connected.

While the power switch 3 of the driving power supply 1 is turned on, the writing means 21 controls the externally charged liquid crystal display element 19.
Was written on the surface (ie, on the transparent insulator layer).
When the power switch 3 is turned on, the output terminal 1
8 and the output terminal 16 (between the conductive layer and the writing means 21), a DC voltage of 560 V is generated.
By writing on the surface of the liquid crystal display element with the above, an electric field was applied between the surface of the liquid crystal display element and the conductive layer.
The liquid crystal molecules in the liquid crystal dispersed polymer layer were oriented in the direction of the electric field, and a difference in the contrast of light transmitted or scattered into the liquid crystal board was generated, so that a written image could be displayed.

Further, when the written image was erased by using the erasing means 20, the erased image was clearly erased. Since the conductive layer and the erasing means 20 have the same electric potential, the electric field applied between the surface of the liquid crystal display element and the conductive layer is neutralized and removed, and the orientation of the liquid crystal molecules in the liquid crystal dispersed polymer layer is changed. It disappears and the written image can be erased.

Also, with the power switch 3 kept ON,
The conductive layer and the writing means 21 were brought into contact with the human body at the same time, but there was no electric shock. When the current flowing through the output terminal 16 was measured by the aforementioned digital high tester 3231-01, the current value was 1 μA.

Further, the current flowing through the primary winding of the step-up transformer 9 with the power switch 3 kept ON was measured using the above-mentioned digital hitester 3231-01 and found to be 3 mA. Also, turn on the power switch 3
Even if the battery is left for 300 hours, the externally charged liquid crystal display element
Was able to display the handwritten image.

[0029]

The driving power supply for an externally charged liquid crystal display element of the present invention has the above-described structure, and therefore can be manufactured relatively easily and at low cost.

Further , between the smoothing capacitor and the output terminal
Is connected to a limiting resistor so that the output current value is 5 mA or less.
Since the connection is continued, there is no electric shock even if the human body comes in direct contact between the output terminals.

When the current flowing through the primary winding of the oscillation circuit is 10
Since the current is regulated to mA or less, power consumption during continuous oscillation is small. In particular, when a dry battery is used as a low-voltage power supply, there is no need to replace the dry battery over a long period of time.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a driving power supply device for an externally charged liquid crystal display element of the present invention, and a schematic diagram showing a state of use thereof.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 drive power supply for externally charged liquid crystal display element 2 DC low voltage power supply 3 power switch 5 oscillation transistor 9 boosting oscillation transformer 10 rectifier diode 11 smoothing capacitor 12, 13, 14, 15 resistance

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02F 1/133 G02F 1/13 505 G02F 1/1333 G09G 3/36

Claims (2)

(57) [Claims] An electrostatic charge is applied to the surface of an externally charged liquid crystal display element comprising a transparent high resistance layer and a liquid crystal dispersed polymer layer in which a liquid crystal is finely dispersed in a polymer matrix. For charging, one output terminal is connected to the conductive layer, one output terminal is electrically connected to the erasing means, and the other output terminal is electrically connected to the writing means. A driving power supply device connected to the DC power supply, at least a DC low voltage power supply, a power switch, and a low voltage generated by the DC low voltage power supply.
A blocking oscillation circuit including an oscillation transistor and a boosting oscillation transformer for boosting the voltage to 000 V, a rectifying diode for rectifying the voltage generated by the blocking oscillation circuit, and charging the rectified voltage; And a smoothing capacitor for smoothing the output voltage, and an output current value from the smoothing capacitor being 5 mA or less.
The smoothing capacitor.
Between the output terminal connected to the writing device and the writing means.
Between the capacitor for output and the output terminal connected to the erasing means.
Between the smoothing capacitor and the output terminal connected to the conductive layer
A drive power supply for an externally charged liquid crystal display element , characterized in that the drive power supply is connected to a device. 2. The driving power supply for an externally charged liquid crystal display device according to claim 1, wherein a current flowing through a primary winding of the blocking oscillation circuit is 10 mA or less.