JPS5950083B2 - pulse generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulse generator comprising an inductive element and a nonlinear capacitor connected together.

The above-mentioned pulse generator has been reported to be used as a discharge lamp starting element in a discharge lamp circuit such as a fluorescent lamp or a high-pressure steam discharge lamp. Single-crystal BaTiO was reported to be a promising material. However, BaTiO
Since No. 3 is an oxide with a high melting point (1613° C.), it is extremely difficult to grow crystals of a size that can be used for practical purposes, and it is not industrially practical. The object of the present invention is to use BaTiO as the above-mentioned nonlinear capacitor.

Using a highly practical high voltage generation material that replaces single crystal,
By connecting this with an inductive element, it is an object of the present invention to provide a highly practical and useful pulse generator. As mentioned above, the pulse generator of the present invention is currently most promising to be applied to a discharge lamp starting element.

Therefore, the present invention will be explained in more detail below using an example of application to a discharge lamp circuit. Of course, the application of the pulse generator of the present invention is not limited to discharge lamp circuits; therefore, it is only necessary to set appropriate inductive elements according to the teachings of electrical theory. Ru. J As is well known, a conventional household fluorescent lamp starting circuit consists of a combination of a glow lamp and a choke coil ballast as shown in FIG. 1.

In FIG. 1, 1 is a fluorescent discharge tube, 2 is a ballast, 3 is a glow lamp, and 4 is a noise prevention capacitor. Although the glow lamp on this circuit is inexpensive, it has the following drawbacks: (1) It takes a long time to light up, averaging 3 seconds, and (2) its lifespan is short, 2 to 3 years under normal use. ing. One method to compensate for these drawbacks is to use a nonlinear capacitor instead of a glow lamp. Figure 2 shows an example of a fluorescent discharge lamp circuit using a nonlinear capacitor.
icalSwitch) and a diode. Here, the nonlinear capacitor 5 has a charge Q with respect to the voltage V.
It exhibits a hysteresis characteristic as shown in Figure a, which is obtained by a ferroelectric material. Figure 3b shows a ferroelectric material with a hysteresis characteristic as shown in a, which is connected to a capacitor with a capacitance of C.
This is shown as a change in When such a nonlinear capacitor is incorporated into a circuit, the ferroelectric material follows the path shown in FIG. 3a (7) ABD as the applied voltage increases. If we look at this as a change in capacitor capacity, we get something like the figure b. In other words, the capacitor's large capacitance state B and small capacitance state D are alternately realized every half cycle on the hysteresis curve.
The same changes occur when the switch is set to the 0n state and the 0ff state, and the switch is set to the 0n state and the 0ff state. It is possible to suddenly cut off the current flowing through the yoke coil and generate a high voltage pulse voltage. Therefore, instantaneous lighting is possible by this operation.
The effects of ferroelectric materials as described above are not only effective in fluorescent lamps, but also in high-pressure vapor dischargers such as high-pressure mercury lamps and high-pressure sodium lamps. It is also meaningful to use it in electric lighting circuits. Figure 4 shows an example of using the nonlinear condenser 5 in a high-pressure sodium vapor discharge lamp.
indicates a ballast. High-pressure steam discharge lamps do not require preheating like fluorescent lamps. Therefore, the circuit has an extremely simple configuration, just by placing a nonlinear capacitor in parallel with the discharge tube. The object of the present invention is to use Ba as the above-mentioned nonlinear capacitor.
We use TiO, a highly practical material for generating high voltage instead of single crystal, and connect it to an inductive element. This provides a useful pulse generator.

The material of the nonlinear capacitor according to the present invention has the general formula AB
It is a ferroelectric ceramic material that satisfies the following conditions: O, (where A is Pb and at least one of Ba and Sr, and B is both Zr and Ti). A terminal of the nonlinear capacitor formed of the ferroelectric ceramic material is connected to one end of the AC power source via the inductive element, and the other terminal of the nonlinear capacitor is connected to the other end of the power source. For example, when a fluorescent lamp requires preheating, a preheating circuit is inserted as appropriate. This ferroelectric ceramic has an ABO (A, B are cations) perovskite structure and is an easily sinterable material. Consequently, BaTiO
，Unlike single crystal, the material is easily produced and the industrial benefits are huge. The inventor also produced BaTiO, sintered body (hot press method), and Pb(Zr, Ti)0. A pulse generator was manufactured using materials such as ceramics. Ba
The sintered body of TiO has a hysteresis curve like c shown in FIG. 3, has poor squareness, and cannot be used as a pulse generator. It has also become clear that Pb(Zr,Ti)03 ceramics cannot be used as a pulse generator.
Next, the most preferred method for manufacturing the ferroelectric material according to the present invention is as follows.

In order to satisfy the general formula ABO, (where A is composed of at least one of Ba and Sr and Pb, and B is both Zr and Ti), it is possible to form oxides of each metal element or easily change to oxides by heating. The temperature is 1200 to 1500°C, preferably 130°C.
0 to 1,450°C) and a pressure of 70 kg/Cm2 or more (practically preferably 70 to 210 kg/Cm2) under hot press conditions (5 to 20 hours is practically preferred and practical).

) to heat and sinter. The amount of Ba and Sr added is approximately 5 to 3
0 at% is preferable. Details will be described in Examples. In addition, when synthesizing these materials, adding PbO in an amount of 1 to 20 ωt% in excess of the stoichiometric composition for the purpose of promoting sintering is effective in speeding up the synthesis. This synthesis method makes it possible to synthesize a ferroelectric material with square characteristics that are practically sufficient for pulse generation. Also, high temperature isostatic pressing method,
Synthesis methods such as a high-pressure synthesis method or a sintering method based on a coprecipitation method may be used, but they are not very practical because they are particularly poor in mass production. Sintering by a powder method is not preferred as a method of manufacturing a ferroelectric material for a pulse generator according to the present invention. Generally, it is inferior to other synthesis methods in terms of composition, grain uniformity, and high density;
It is thought that forming a practical nonlinear capacitor will be difficult. The ferroelectric material according to the present invention has a saturation polarization value of 10, which is a characteristic required for a material intended for a discharge lamp starting element.
It was concluded that μQ/Cm2 or more and coercive electric field of 10 kV/Cm or less can be sufficiently satisfied.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 Part of the Pb ions in Pb(Zr,Ti)03 ceramics were replaced with Ba ions (Pbl-X, Bax)(Z
An example of a pulse generator using a five-element solid solution of rl-Y, Tiy)03 will be described.

Ceramics with this composition have three ferroelectric phases, tetragonal, rhombohedral, and orthorhombic, as shown in Figure 5 (tetragonal, rhombohedral, and orthorhombic in Figures 5 and 6), based on the composition ratio of the component elements. The three ferroelectric phases of crystal, and orthorhombic are shown as F, FR, and FO.A. is an antiferroelectric (orthorhombic), and PO is a paraelectric (cubic) A1 antiferroelectric. ), but as mentioned above, the ferroelectric phase near BbTiO3 is difficult to sinter and has poor square characteristics, so it cannot be used as a material for pulse generators. . As a representative example (P
bO. 8, BaO. 2) (ZrO.8, TiO.2)0
The synthesis of composition No. 3 will be described below. PbO (average particle size 5
．． 2 microns, purity 99.9%), ZrO2 (2.1
micron, purity 99.7%), BaTiO3 solid solution powder (
2.2 microns, purity 99.9%) was weighed to the above composition, thoroughly mixed in a ball mill using distilled water as a solvent, and after evaporation to dryness, the above mixture was calcined at 900°C for 1 hour in an oxygen stream. .

Use this calcined powder! Coarsely grind in a mortar or the like, and mix again in a ball mill using acetone as a solvent. This powder is heated at 700° C. for 1 hour in an oxygen stream to evaporate and remove the acetone adsorbed on the powder. The calcined powder was heated at a pressure of 350 kg/cm2 using a steel die. Form into a size of 15 mm in diameter and 8 mm in height. This green compact was inserted into an alumina die, set in an electric furnace, and then sintered under pressure (hot press). In the sintering method used here, first, an alumina die loaded with a sample was set in an electric furnace for hot pressing, and heated at 200 to 400°C.
After evacuating for about 1 hour to a straight air degree of 10-2T0rr, the inside of the furnace was replaced with oxygen gas, and then heated in an oxygen stream.
This is a method of hot pressing at 400° C. for 5 hours at a pressure of 150 kg/Cnl2. The density of the sintered body obtained by this method was 99.8% or more of the theoretical value. The hot-pressed sample is taken out from the alumina die using a diamond core drill and cut into desired dimensions with a diamond cutter (thickness: 400 μM, approximately 1Cnl·).

The thickness d of the sample is generally determined by the coercive electric field EO and the power supply voltage E used.
. Depending on
In the case of 140 μM and 2OOV, it is about 150 to 250 μm. After polishing the cut sample, the area 1CII1・
Attach the silver electrode. When used as a pulse generator for a discharge lamp, approximately 1 to 2 cn12 is practical. The sample obtained in this way was combined with a 0.4H (Hetree) fluorescent lamp oscillator, and the pulse voltage was determined using the circuit shown in Figure 2, and a pulse voltage of 730 (V) was obtained. I was able to start the fluorescent lights. The composition surrounded by the diagonally shaded region 1 in FIG. 5 is a composition that can generate pulses that can be practically used in discharge lamps. Furthermore, a pulse having a higher peak value can be obtained with the composition surrounded by the region 11. Table 1 summarizes the characteristics of the materials described in the Examples of the present invention.

Each sample corresponds to the material plotted in FIGS. 5 and 6. Note that the shape of the sample is similar to that described above. Example 2 FIG. 6 shows a phase diagram in the case where some of the Pb ions in Pb(Zr,Ti)03 ceramics are replaced with Sr ions.

The sample was prepared by hot press synthesis in the same manner as in Example 1, using SrTiO3 (purity 99.9%) instead of BaFiO3. (By this method, the density of the sintered body was 99.8% or more of the theoretical value.) As an example, (PbO.8SrO.2) (ZrO.7,Ti
O. 3) Composition No. 03 was selected and the pulse voltage obtained in the same manner as in Example 1 was 670 (V). The composition surrounded by the shaded area 1 in FIG. 6 is a composition suitable for generating pulses that can be practically used in discharge lamps. Furthermore, a pulse having a higher peak value can be obtained with the composition surrounded by the region 11. Example 3 An example is shown in which a part of the Pb ions of Pb(Zr,Ti)03 is replaced with Ba ions and Sr ions using a ceramic ceramic.

Using both BaTiO3 and SrTiO3 solid solution powders, (P
bO. 8, BaO. lSrO. l) (ZrO.8Ti
O. 2) It was blended into the composition of 03 and hot press synthesized by the same method as in Example 1 (the density of the sintered body was the same as in Examples 1 and 2).

The pulse voltage obtained for this sample in the same manner as in Example 1 was 780 (V). Also, (PbO.8
, BaO. l, SrO. l) (ZrO.7, TlO.3
)03, the pulse voltage was 700 (V).
In this way, it was possible to synthesize a ferroelectric material for a starting element even in a composition in which Sr, Ba, etc. were simultaneously dissolved in solid solution. FIG. 7 shows the (PbO.8, BaO.l, S
rO. l) The life of pulse voltage was determined using a sample of (ZrO.8, TiO.2)03.

These are the results obtained in a life test of a fluorescent lamp discharge circuit (FIG. 2) in which the discharge lamp was turned on for 3 seconds and then paused for 27 seconds, that is, the cycle was 30 seconds. The pulse voltage shows almost no change up to 105 times, indicating that the present composition is extremely stable.

As clarified by this example, the ferroelectric ceramic according to the present invention, that is, the general formula ABO3 (where A is composed of at least one of Ba and Sr and Pb, and B
Ferroelectric ceramics (both Zr and Ti) are less likely to be destroyed even by repeated polarization reversals. Therefore, the pulse generator using ferroelectric ceramics according to the present invention can have a long life. In addition, as explained in the manufacturing method, when ceramics having the composition of this example are manufactured by the normal firing method, the ferroelectric hysteresis loop becomes as shown in Figure 3C, which is insufficient for use as a nonlinear capacitor and is not suitable for practical pulse generation. It cannot be applied to vessels.

[Brief explanation of drawings]

Figure 1 shows a fluorescent lamp circuit using a glow lamp, Figure 2 shows a fluorescent lamp circuit using a nonlinear capacitor, Figure 3 shows a ferroelectric hysteresis loop and its corresponding change in capacitance, and Figure 4 shows a nonlinear capacitor. The high-pressure steam discharge lamp circuit used, Figure 5 shows the phase diagram of (Pb, Ba) (Zr, Ti)03 ceramics, and Figure 6 shows the (Pb, Sr) (Zr,
The phase diagram of Ti)03 ceramics, FIG. 7, shows the lifetime characteristics of the nonlinear capacitor material according to the invention.

Claims (1)

[Scope of Claims] 1. A pulse generator having at least an inductance element and a nonlinear capacitor connected in series with the inductance element, the nonlinear capacitor having the general formula ABO_3 (where A is at least one of Ba and Sr). 1. A pulse generator comprising a ferroelectric ceramic that satisfies the following conditions: (Pb), and B (B consists of both Zr and Ti). 2. The pulse generator according to claim 1, wherein the nonlinear capacitor is made of ferroelectric ceramics sintered by hot pressing. 3. The pulse generator according to claim 1, wherein the inductance element is an inductive ballast for a discharge lamp.