JPH0194266A - Dc voltage detection element - Google Patents

Abstract

PURPOSE:To obtain a detection element wherein the effect on a circuit to be detected is eliminated and a part to be detected and a detection part are made independent, by providing at least a pair of the first electrodes for applying voltage to be detected and at least a pair of the second electrodes for detecting electrostatic capacity arranged so as to contain the space formed between the first electrodes. CONSTITUTION:Four electrodes 1-4 are arranged at a predetermined interval and dielectric porcelains are arranged to the spaces 5 between said electrodes. Lead-out leads 6 are connected to the outer ends of the electrodes 1-4 to respectively form terminal parts C, A, B, D. DC voltage to be detected is applied to a pair of the terminal parts among them, for example, to the terminal parts A, B. Since there is no polarity at this time, either one of them may be selected on a high potential side. Further, on a detection side, the change in the electrostatic capacity, for example, at the ends of a pair of the remaining terminal parts C, D is read to detect voltage change. Since the change in DC voltage can be taken out as the change in electrostatic capacity by this method, the loss of power on a side to be detected is not almost generated. Since input impedance is high, the effect on a circuit to be detected is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a DC voltage detection element that can be used in various electrical and electronic circuits and devices.

[Conventional technology]

In general, direct current voltage detection involves reading the voltage at a resistor end placed on a circuit, or the value at a voltage dividing resistor end by inserting a voltage dividing resistor in parallel into a predetermined circuit. This detected voltage is used to limit the operation of various electronic devices and to perform desired control operations.

Such conventional voltage detection may reduce the efficiency or affect the operation of the device due to power loss consumed by a resistor inserted in the circuit. Furthermore, since the detection section and the control section are connected in a circuit, it cannot be used in circuits or devices that require insulation and separation between the detection section and the control section.

In addition, there are some devices such as variable capacitance diodes that utilize the relationship between voltage and capacitance to extract changes in voltage as changes in capacitance, but there are limits to the voltage that can be used, and circuit isolation It is not suitable for that purpose.

[Problem that the invention seeks to solve]

The object of the present invention is to provide a simple detection element that has no influence on the circuit to be detected and in which the part to be detected and the detection part are independent.

This invention focuses on the phenomenon in which the capacitance of a dielectric ceramic composition changes in response to the application of a DC voltage, and attempts to detect a change in voltage as a change in capacitance. The relationship between voltage and capacitance in dielectric ceramics is such that attempts have been made to minimize this change as much as possible since the characteristics of conventional ceramic capacitors fluctuate.
This invention exclusively utilizes these properties of dielectric ceramics.

[Means for solving problems]

The DC voltage detection element of the present invention includes at least a pair of opposing first electrodes for applying a voltage to be detected, which are formed by containing dielectric ceramic inside, and a space formed between the first electrodes. It is characterized by having at least one pair of opposing second electrodes for detecting capacitance, which are arranged to include part or all of the capacitance.

That is, in the DC voltage detection element of the present invention, a pair of first electrodes are formed with dielectric ceramic inside. Then, a DC output from the circuit to be detected is applied to this first electrode pair. In addition, this detection element includes a second pair of electrodes including a part or all of the space formed by the first pair of electrodes containing dielectric ceramic inside, and the second pair of electrodes is formed by forming a second pair of electrodes. The change in the DC voltage applied to the first electrode is detected by detecting the capacitance between the two electrodes.

FIG. 1 is an explanatory diagram showing the principle of the DC voltage detection element of the present invention. - As shown in the figure, four electrodes 1, 2, 3, and 4 are arranged at predetermined intervals, and a dielectric ceramic (not shown) is arranged in the space 5 between these electrodes. Leading portions 6 are connected to the outer ends of these electrodes 1, 2, 3, 4, forming terminal portions C, A, B, D, respectively.

The DC voltage to be detected is detected by one pair of these terminals.
For example, it is applied to A and B. Since there is no polarity at this time,
Either one may be selected on the higher potential side. Then, the detection side reads the change in capacitance of the remaining pair, that is, the end of the terminal portion C9D, and detects the change in voltage.

Further, the selection of the terminal portions is not limited to the above-mentioned ones, and it is also possible to apply the DC voltage on the side to be detected to the terminal portions C and D and perform detection on the terminal portions A and B. Furthermore, even if the detected side terminal part is on the A, D side and the capacitance detection side is on the terminal part B, C side, or the other way around, that is, the detected side and the detection side electrode are in mesh with each other. good. In any case, the object of the present invention can be achieved as long as the detection electrode is arranged so that part or all of the dielectric ceramic part in which the electric field due to the DC voltage on the detection side exists is included.

The dielectric ceramic that can be used in this invention is not particularly limited as long as it can change the capacitance with respect to DC voltage, and those used as dielectrics for various ceramic capacitors can be used. . In particular, a material with a high dielectric constant is advantageous when it is desired to obtain a high detection capacitance value, but it is not limited thereto.

There are also no particular limitations on the electrodes; silver, palladium,
Molton metal method, in which electrode paste material of mixed metal powder such as copper, titanium, and tin is printed and baked on the surface of porcelain;
Various methods can be used, such as forming nickel by electroless plating or vapor deposition.

[For production]

In the DC voltage detection element of the present invention, a DC voltage to be detected is applied to a pair of electrodes, and when the voltage changes, the dielectric constant of the dielectric ceramic placed between the electrodes changes. By measuring the capacitance between a pair of electrodes placed separately from the pair of electrodes described above, the change in permittivity of the dielectric ceramic is detected as a change in capacitance, and this is calculated as a capacitance. By connecting it to a circuit such as a bridge, it can be read as a capacitance value.

In addition to simply reading the capacitance value, it is also possible to control the operation of electronic circuits and equipment based on changes in the capacitance value.

〔Example〕

Hereinafter, this invention will be explained in more detail according to examples.

Figures 2 and 3 show an embodiment of one of the preferred forms of the DC voltage detection element of the present invention, with Figure 2 being an exploded perspective view showing its structure, and Figure 3 showing its completed state. FIG.

As shown in FIG. 2, the DC voltage detection element 10 of the present invention is made by first kneading a dielectric ceramic composition powder with a binder or the like, and forming the mixture into a green sheet of a predetermined thickness by a doctor blade method or the like.

This green sheet is cut into a predetermined size to form green sheet pieces 11a, llb, llc, and lid.

These green sheet pieces 11a, llb, llc,
The electrode 12 is printed on one surface of the llc+ by a method such as screen printing. This electrode 12 is a green sheet piece 11a.

11b, 11b, 11b, 11b, 11b, 11b, 11b, 11b, 11b, 11b, 11b, 11b, lie, lld are formed inward from the end of one side in a band shape with a width narrower than the - side, and do not reach the other end surface.

As shown in FIG. 2, the four green sheet pieces 11a, llb, llc, and lid on which the electrodes 12 are printed in this manner are shown in FIG. The lids are arranged and overlapped so that the sides of the lids are in different directions. Then, a green sheet piece 13 on which the electrode 12 is not printed is placed on top to protect the electrode 12, and the whole is pressed to integrate and sintered.

As shown in FIG. 3, the sintered laminate has external electrodes 14a, 14b, 14c, and 14d formed on each end face.

These external electrodes 14a, 14b, 14c, 14d are formed by green sheet pieces 11a, llb, l, respectively.
They are electrically connected to internal electrodes 12 formed on the lc and lid, respectively. Note that this external electrode 14 may be formed by applying electrode paste and sintering in the same manner as the internal electrode 12, or may be formed by attaching a metal terminal with a cross-sectional shape to the end using a conductive adhesive. .

Next, we created a DC voltage detection element with the structure just described and investigated its characteristics.

For dielectric ceramics, P b OM g N b s Ob
A green sheet with a thickness of 100 μm was created using a ceramic of the same type, and this green sheet was cut into a size of 30 cranes x 30 cranes, and silver-palladium electrode paste was applied to the surface with a width of 20 m1 and a distance of about 25 m from the edge of the sheet. Screen printed to length. The green sheets were stacked according to the arrangement shown in FIG. 2, a green sheet with no electrodes printed was placed on the top surface, and the pressed green sheet was sintered in a sintering furnace.

After sintering, a silver-palladium electrode paste was applied to each end face of the four sides and baked to form an external electrode.

Next, when a direct current voltage was applied to the completed device of the present invention and the relationship between voltage and capacitance was investigated, the results shown in the graph of FIG. 4 were obtained. The graph shows the relationship between DC voltage and capacitance, and the curve (■) in the graph indicates the DC voltage to be detected when the external electrodes 14c, 14 of the detection element in FIG.
The voltage is applied to the d side, that is, the outside of the four-layer electrode, and the external electrode 14
This is the case where the electrode on the a and 14b side, that is, on the inside, is used as the detection electrode. Curve (2) is a case where the external electrode and the detection electrode for detection are reversed to curve (2). Note that these measurements were performed using the AC bridge method (frequency: 10 KHz).

In either curve, the capacitance changes almost linearly with changes in DC voltage, suggesting that it can be used as a DC voltage detection element. The reason why the capacitance values are different between the two curves is because the distance between the detection side electrodes is different.

The connection position of the electrode may be appropriately selected depending on the capacitance value required for the detection operation.

In addition to this embodiment, multiple pairs of detection electrodes or detection electrodes may be installed instead of one pair each, or one of the detection electrodes and detection electrodes may be made common, and three electrodes may be used. . However, in this case, it is not possible to insulate and separate the detected side and the detected side.

〔Effect of the invention〕

Since the DC voltage detection element of the present invention can detect changes in DC voltage as changes in capacitance, there is almost no power loss on the detected side. Furthermore, since the input impedance is high, there is little influence on the circuit to be detected.

Further, since the detected side and the detection side are insulated, it is suitable as a voltage detection element of a power supply device that requires isolation between the primary side and the secondary side.

Furthermore, the DC voltage detection element of the present invention can be made into a thinner and smaller chip, and can meet the requirements for mounting on a high-density substrate and surface connection.

[Brief explanation of the drawing]

Figure 1 is a perspective view illustrating the principle of the DC voltage detection element of this invention, Figure 2 is an exploded perspective view showing the structure of an embodiment of the DC voltage detection element of this invention, and Figure 3 is its completed state. FIG. 4 is a graph showing the relationship between DC voltage and capacitance. 1.2, 3, 4.12...electrode, 5...space, 6...
Output leads, A, B, C, D...terminal part, 10...DC voltage detection element, 11a, llb, llc, Lld, 13 = green sheet piece, 14a, 14b, 14c, 14d ・
・External electrode.

Claims (1)

[Claims] (1) at least a pair of opposing first electrodes for applying a voltage to be detected, which are formed to include dielectric ceramic therein;
A DC voltage detection element characterized by having at least one pair of second opposed electrodes for capacitance detection arranged to include part or all of the space formed between the first electrodes. .