JPH0430538B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a piezoelectric shiatsu meter used to measure the internal cylinder pressure of an engine, that is, a shiatsu chart, and is particularly designed to prevent zero point drift due to leakage charge. This relates to a piezoelectric acupressure meter.

[Prior art]

Generally, piezoelectric acupressure meters are equipped with an acceleration correction mechanism to correct the electric charge generated by inertial force due to acceleration, and its basic structure is as follows:
A piezoelectric element laminate for converting pressure into an electrical signal, an acceleration correction weight serving as an intermediate electrode, and an acceleration correction piezoelectric element are sequentially stacked and housed in a case. Then, the electrode on the bottom surface of the piezoelectric element laminate is used as one output electrode and taken out from the case through the pressure receiving part that is in contact with the electrode, and the electrode on the top surface of the piezoelectric element for acceleration correction is used as the other output electrode. By taking out the charge through a lead wire connected to the electrode, the charge generated in the piezoelectric element stack due to acceleration and the charge generated in the acceleration correction piezoelectric element are canceled out to perform acceleration correction.

However, in the piezoelectric acupressure meter having such a structure, when the output is taken out between the top electrode of the piezoelectric element for acceleration correction and the case, there is a problem in that charge leaks between them and the zero point of the output drifts.

[Summary of the invention]

The present invention has been made in view of the above points, and
When output is taken out between the electrode on the top surface of the piezoelectric element for acceleration correction and the case, an insulating member made of a perforated crystal piece with a Z-axis cut is interposed between the electrodes and the case, thereby preventing the zero point from drifting due to leakage charge. The present invention provides a piezoelectric acupressure meter that can improve the stability of the piezoelectric pressure gauge. Embodiments of the present invention will be described below with reference to the drawings.

〔Example〕

The drawing is a sectional view showing a schematic structure of a piezoelectric shiatsumeter according to an embodiment of the present invention. In the same figure, 1
is a cylindrical sleeve as a case made of metal such as stainless steel, and a plate-shaped pressure receiving part 2 made of the same material is attached to the inner peripheral surface of the bottom part 1a. Further, a cylindrical insulating member 3 made of Teflon or the like is inserted into the inner peripheral surface of the sleeve 1, and a plate-shaped piezoelectric element made of X-axis cut crystal is mounted on the upper surface of the pressure receiving part 2 within the insulating member 3. Four pieces 4a to 4d are stacked and arranged. In this case, each piezoelectric element 4a
The electrodes 5a ₁ to 5d ₂ of the piezoelectric elements 4a to 4d are connected to each other so as to add charges according to the polarity of the charges generated when pressurized in the X-axis direction, and the electrodes of each piezoelectric element 4a to 4d 5a ₁ , 5b ₂ , 5c ₁ and 5d ₂
are commonly connected, and each of the electrodes 5a ₂ ,
5b ₁ , 5c ₂ and 5d ₁ are commonly connected. Note that a predetermined gap A is provided between the insulating member 3 and the piezoelectric elements 4a to 4d in order to improve measurement accuracy.

Moreover, the piezoelectric elements 4a to 4 stacked in this way
An acceleration correction weight (also called mass) 6 made of tungsten or the like, which also serves as an intermediate electrode, is placed on the surface of the electrode 5d ₂ of d, and an acceleration correction weight made of X-axis cut crystal is placed on the top surface of the weight 6. A piezoelectric element 7 is placed thereon. A pair of electrodes 8 ₁ and 8 ₂ are provided on both sides of the piezoelectric element 7, and the electrode 8 on the upper surface
₁ is connected to one electrode 5d1 of the fourth layer piezoelectric element 4d through a connecting electrode ₉ provided on the side surface of the acceleration correction weight 6, and a lead wire 10 is connected to the center of the electrode ₈₁ . There is. The electrode ₈₂ on the lower surface is connected to the other electrode _5d2 of the piezoelectric element 4d through the acceleration correction weight 6, so that the piezoelectric elements 4a to 4d of the laminated structure generated by the inertial force due to acceleration The electric charge and the electric charge of the piezoelectric element 7 for acceleration correction cancel each other out. Further, a conductive bushing member 12 made of stainless steel is placed on the electrode 8 ₁ of the piezoelectric element 7 with an insulating member 11 made of a Z-axis cut perforated crystal piece interposed therebetween. The upper opening 1b of the case 1 is closed.
The lead wire 10 is passed through the through hole 11a of the insulating member 11 into the lead-out hole 12 of the bushing member 12.
a and is pulled out from the terminal 13 at its upper position, and the lead-out hole 12a
By embedding an insulating material 14 such as a fusible resin or ceramic inside, the insulating material 14 reinforces the lead wire 10 and maintains insulation from the bushing member 12.

As described above, according to the above embodiment, the lead wire 10 is connected to the electrode 8 ₁ on the top surface of the acceleration correction piezoelectric element 7 with the electrode 8 ₁ as one of the output electrodes;
Piezoelectric elements 4a to 4d stacked on the upper surface of the pressure receiving part 2
The electrode 5a ₁ on the bottom surface of the electrode 5a 1 is used as the other output electrode to extract an output in which the charge generated due to acceleration has been corrected between the pressure receiving part 2 in contact with the electrode 4a ₁ and the conductive case 1 which is electrically connected. I can do it.
At this time, since the insulating member 11 is interposed between the upper surface electrode ₈₁ of the acceleration correction piezoelectric element 7 and the bushing member 12 attached to the upper surface opening 1b of the case 1, electric charge will not leak between them. Therefore, the drift of the zero point can be prevented and the stability of the output can be improved. Moreover, since the insulating member 11 is composed of a Z-axis cut perforated crystal piece with high mechanical strength and stable physical properties, hysteresis is less likely to occur than when using Teflon or the like with high elasticity. , and has the advantage of improved heat resistance and insulation resistance.

It should be noted that the present invention is not limited to the embodiments described above, and the piezoelectric elements 7 for acceleration correction may be laminated in plurality, or the number of piezoelectric elements 4a to 4d laminated on the upper surface of the pressure receiving part 2 may be arbitrarily selected. Of course, you can also select

〔Effect of the invention〕

As explained above, according to the present invention, in a piezoelectric shiatsumeter having a structure in which the output is taken out between the top electrode of the piezoelectric element for acceleration correction and the case, an insulating member made of a Z-axis cut perforated crystal piece is provided between the piezoelectric shiatsumeter and the case. By intervening, it is possible to prevent drift of the zero point due to leakage charge, and therefore it is possible to improve the stability of the output. Furthermore, since the insulating member is made of a crystal piece, the heat resistance and insulation resistance are improved, and the performance of the shiatsu meter is improved. Also, since the crystal piece is Z-axis cut, it can be easily etched, resulting in good productivity. There are effects such as

[Brief explanation of drawings]

The drawing is a sectional view showing a schematic structure of a piezoelectric shiatsumeter according to an embodiment of the present invention. 1...Sleeve (case), 2...Pressure receiving part, 3
...Insulating member, 4a to 4d...Piezoelectric element, 5a ₁ to
5d ₂ ... Electrodes of piezoelectric elements 4a to 4d, 6 ... Weight for acceleration correction, 7 ... Piezoelectric element for acceleration correction, 8
₁ , 8 ₂ ... electrode, 9 ... connection electrode, 10 ... lead wire, 11 ... insulating member, 12 ... bushing member, 13 ... terminal, 14 ... insulating material.

Claims (1)

[Claims] 1 A piezoelectric element laminate for converting pressure into an electric signal, an acceleration correction weight serving as an intermediate electrode, and an acceleration correction piezoelectric element are sequentially stacked on the top surface of the pressure receiving part attached to the case, and these are placed inside the case. The electrode on the bottom surface of the piezoelectric element laminate is used as one output electrode and taken out from the case through the pressure receiving part that is in contact with the electrode, and the electrode on the top surface of the piezoelectric element for acceleration correction is taken out as the other output electrode. A Z-axis cut is configured to be taken out through a lead wire connected to the output electrode as an output electrode, and a Z-axis cut is provided between a conductive bushing member that closes the top opening of the case and the top electrode of the acceleration correction piezoelectric element. A piezoelectric acupressure gauge characterized by interposing an insulating member made of a perforated crystal piece.