JPH0158645B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a nonlinear ceramic capacitor made of a dielectric ceramic composition containing barium titanate as a main component, and is characterized in that it generates high voltage pulses by coupling with an inductive element. BACKGROUND ART Conventionally, pulse generators having a structure consisting of an inductive element and a nonlinear capacitor having a perovskite structure have been known. It is known that polycrystalline solid solutions such as barium titanate and lead titanate are effective for this perovskite dielectric element, but it is difficult to obtain high pulse voltages with good reproducibility, and there are many variations in pulse voltage. It had the following drawbacks. The present invention provides a nonlinear ceramic capacitor that can generate high pulse voltages with good reproducibility and has little variation in pulse voltage. That is, it has been discovered that by adding fluoride to a barium titanate solid solution having a perovskite crystal structure, a nonlinear ceramic capacitor that generates a high pulse voltage can be obtained with good reproducibility. Hereinafter, the present invention will be explained in detail based on examples. Example (1) As starting materials, BaCO ₃ , TiO ₂ , SnO ₂ , and CrF ₃ were weighed to have the composition shown in Table 1, wet-mixed with water and agate cobbles in a polyethylene pot for about 16 hours, filtered, It was dried to obtain a prepared raw material. this
Calcined at 1120℃ for 2 hours, and then ground in a polyethylene pot with water and agate cobbles for about 16 hours.
Approximately 3.0% organic binder is added to the filtered and dried raw material to make it into granules, which are then granulated with a diameter of 16.0 mmφ under a pressure of 1 ton/cm ² .
Form into a disk shape with a thickness of 0.65 mm. Next, it was fired at 1350°C for about 2 hours, a 12.0 mmφ silver electrode was applied to the obtained porcelain, and it was baked at 800°C for 30 minutes to obtain an element for a nonlinear capacitor. Electrical properties such as dielectric constant, tan δ, insulation resistance (IR), and pulse voltage were measured, and the results are shown in Table 1.

[Table] In Table 1, Nos. 2 to 6 and Nos. 9 to 17 are products of the present invention, and Nos. 1, 7, and 8 are properties shown for reference and are outside the scope of the present invention. In the electrical properties shown in Table 1, the capacitance (permittivity) and tan δ were measured at 1 KHz and 1 Vrms, and the insulation resistance (IR) was the value after applying 100 VDC for 30 seconds. FIG. 1 shows an embodiment of a circuit of a pulse generator for non-contact starting of a fluorescent lamp using the nonlinear ceramic capacitor of the present invention, where a is an inductive element (ballast);
b is a fluorescent lamp, b ₁ and b ₂ are fluorescent lamp filaments, c
is a nonlinear ceramic capacitor according to the present invention, d
is a switching circuit, e is a commercial frequency power supply,
When the switching circuit d is open, a waveform as shown in FIG. are doing. That is, the nonlinear ceramic capacitor according to the present invention has good square hysteresis as shown in FIG. 3, and has a spontaneous polarization near E ₀ and -E ₀ . Since the amount of charge on D ₀ changes suddenly, by repeating charging and discharging, a pulse corresponding to the back electromotive force is induced by the inductive element as shown in FIG. 2B. However, the pulse shown in FIG. 2B cannot provide enough pulses to light the fluorescent lamp. By adjusting the voltage applied to the nonlinear ceramic capacitor as shown in FIG. 4 using switching circuit d in FIG. 1, it has become possible to induce extremely high pulses. In the AC waveform, the switching circuit d turns OFF at point a near E ₀ in Figure 4A (corresponding to E ₀ in Figure 3), and the switching circuit turns OFF at point b before the voltage reaches -E ₀ . When d is set to be ON, at point a in Fig. 4, the induced voltage (L x di/dt) due to the inductive element a and the nonlinear ceramic capacitor c in Fig. 1 is added to the pulse in Fig. 2 A. overlap, and can generate an extremely high pulse voltage as shown in FIG. 4B. In FIG. 4A, when the switching circuit is turned on at point c, it is necessary to turn it on at point b because high pulses are also generated in the negative direction. When the waveform shown in Fig. 4 is applied to the circuit of the fluorescent lamp shown in Fig. 1, the broken line part becomes the impedance of only the inductive element a, and the filament at both ends of the fluorescent lamp b.
b ₁ and b ₂ are heated, a discharge is induced by the pulse shown in FIG. 4B, and the fluorescent lamp is lit. The pulse voltage of the nonlinear ceramic capacitor having a ceramic composition according to the present invention shown in Example 1 was measured using the circuit shown in FIG. A feature of the porcelain composition according to the present invention is that fluoride is used as an additive. Table 2 shows examples of properties when Cr ₂ O ₃ and CrCO ₃ are added.

[Table] The raw material composition was adjusted in the same manner as shown in Example (1). From the characteristic results in Tables 1 and 2, it is clear that
The pulse voltages obtained with CrCO ₃ and Cr ₂ O ₃ are extremely low values, which is clearly due to the remarkable effect of fluorides in the ceramic composition of the present invention, compared to those obtained with ordinary oxides and carbonates. No high voltage pulses are obtained. Further, fluorides other than CrF ₃ will be explained based on Examples. Example (2) Among the claimed compositions, Bax (Ti _0.94 Sn _0.06 ) O ₃ is the main component, each fluoride is added, and the amounts added are shown in Table 3, and BaCO ₂ , TiO ₂ , SnO ₂ For each fluoride, use a reagent class or higher. For example, use acetone for water-soluble substances such as AgF, CoF ₃ , ZnF ₂ , and KF, and use water for other fluorides that are not soluble in water. The mixture was mixed with cobblestones in a polyethylene pot for about 16 hours, filtered, and dried to obtain a prepared raw material. In the following, exactly the same method as in Example (1) was used, and the characteristic results are shown in Table 3. From the results in Tables 1 and 2, CrF ₃ , CaF ₂ ,
With SnF ₂ , CeF ₃ , and BaF ₂ , a pulse voltage of 900 V or more can be obtained, and with this element, lighting can be done in about 0.4 to 0.5 seconds, instead of several seconds using the glow starter method of conventional fluorescent lamps. This not only contributes to improving the performance of the fluorescent lamp, but also prevents overheating of the filament. In addition, Tables 1, 2, and 3 show examples of adding Cr ₂ O ₃ , CaCO ₃ , SrCO ₃ , and MnO other than fluorides, but each fluoride can provide extremely high pulses, but other Even if approximately the same amount of metal salt is added, characteristics equivalent to those obtained by adding fluoride cannot be obtained. The amount of fluoride added is 0.005% to 1.0% by weight.
For example, in the case of CrF ₃ , it is 0.05
The amount of addition of ~0.1% by weight is appropriate, and pulses of 400V or more were obtained even with addition of 1.0% by weight, and the effect is not manifested with addition of less than 0.005% by weight, so the scope of the claims was limited.

【table】

[Table] The A/B ratio of AxByO ₃ , a barium titanate solid solution, was limited to 1.02 to 0.95 because sintering is difficult when A/B is 1.02 or more, and when A/B is 0.95 or less, In this case, fusion may occur, which is undesirable. Furthermore, although the present invention has been described with reference to a polycrystalline solid solution of Ba(Ti,Sn) _O3 , it is not limited thereto.In order to generate a high pulse voltage near room temperature, other solid solution components other than Sn may be used. , for example (Ba,
Similar properties can be obtained with barium titanate solid solutions containing Sr, Pb, Zr, and Ca, which change the Curie point, such as Sr)TiO ₃ and Ba(Ti,Zr)O ₃ . Applications of the nonlinear ceramic capacitor having a ceramic composition according to the present invention are not limited to lighting a fluorescent lamp, but also require high voltage pulses. For example, city gas, propane gas igniters,
It can be used in a wide range of applications, including starting circuits for discharge lamps such as mercury lamps and sodium lamps, and other pulse generators, and can greatly contribute to the electronics industry.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a pulse generator for non-contact starting of a fluorescent lamp using the non-linear ceramic capacitor of the present invention, and Fig. 2 shows a waveform diagram in Fig. 1. Figure 3 is a diagram of the hysteresis characteristics of the nonlinear ceramic capacitor; Figure 4 is a diagram of the pulse voltage waveform applied by the circuit in Figure 1; The voltage waveform (b) is the voltage waveform induced by the inductive element.

Claims (1)

[Claims] 1. For a polycrystalline solid solution composition mainly composed of barium titanate, Ca, Ag, Cr, Co, Sr, Fe, Zn,
A nonlinear ceramic capacitor characterized by containing fluorides of K, Ce, Pb, Ni, Ba, Bi, Mg, and Mn in an amount of 0.005 to 1.0% by weight. 2. In the nonlinear ceramic capacitor according to claim 1, the chemical formula of the polycrystalline solid solution of barium titanate is (Ba _1-x Srx)TiO ₃ , Ba(Ti _1-x Snx)O ₃ or Ba(Ti ₁ A nonlinear ceramic capacitor characterized in that, when expressed as _-x Srx)O ₃ , the value of X is from 0.01 to 0.12. 3 In the nonlinear ceramic capacitor according to claim 2, when the polycrystalline solid solution of barium titanate is expressed as AxByO ₃ , 0.95≦X/Y≦
1.02. 4. The nonlinear ceramic capacitor according to claim 1, which is used as a starting element for a pulse generator.