Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Means for analyzing liquid or solid sample
Reexamination Certificate
1998-07-16
2001-05-15
Soderquist, Arlin (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Means for analyzing liquid or solid sample
C073S054240, C310S328000, C422S051000, C422S082010
Reexamination Certificate
active
06231811
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a sensor element carrying a piezoelectric element and a ceramic substrate with an envelopment space formed in it preferably used for the sensor element.
A sensor element carrying a piezoelectric element or the like is used for measurement of the viscosity of a fluid, detection of solid particles in a fluid, and detection of vibrations.
For example, a sensor element is disclosed (official gazette of Japanese Patent Laid-Open No. 8-201265) which measures the viscosity of a fluid by using the characteristic of a piezoelectric film or vibrational portion (hereafter referred to as piezoelectric film or the like) that the amplitude of the piezoelectric film or the like decreases when the piezoelectric film or the like contacts a fluid to be measured (hereafter referred to as fluid) and the fluid has a large viscosity and increases when it has a small viscosity and thereby, applying a voltage to the piezoelectric film to detect a current corresponding to amplitude or the like, and measuring the changes of loss factors, electric resistances, and reactances of the piezoelectric film.
In the case of the sensor element, when the viscosity of a fluid such as a sulfuric-acid solution has a correlation with the specific gravity or component concentration of the fluid, it is possible to measure the specific gravity or component concentration of the fluid. Therefore, for example, it is possible to measure the change of specific gravities of sulfuric acid used as the electrolyte of a lead acid battery in accordance with the change of viscosities of the sulfuric acid and obtain the charge or discharge state of the battery.
FIG. 2
shows an example of the state in which the sensor element
1
is set in a lead acid battery. A porous separator
14
is inserted between a pair of electrodes
13
a
and
13
b
of the lead acid battery and the sensor element
1
is held so as to be embedded in the separator
14
.
By storing the sensor element
1
in a battery case and injecting an electrolyte into a liquid case under the state, it is possible to measure the viscosity of the electrolyte because the electrolyte permeates the separator
14
and the gap between the electrodes
13
a
and
13
b
is filled with the electrolyte, and the electrolyte leaking out of the gap enters an envelopment space
6
through communication holes
15
a and
15
b formed on a flat substrate
2
and contacts led a vibrational portion
8
.
In the case of the sensor element, however, if a fluid to be measured is a fluid having a large viscosity such as an aqueous solution or sulfuric acid or a fluid having a low wettability with the ceramics forming the flat substrate, or the envelopment space of the flat substrate is communicated with the outside of the substrate through a small communication hole, a difficult problem occurs that the air in the envelopment space of the flat substrate is not easily replaced with the fluid.
Moreover, there is a problem that even after a fluid to be measured is sufficiently supplied into the envelopment space, a sufficient amount of fluid is not present nearby the envelopment space or even if the fluid is sufficiently present, the fluid once supplied is replaced with bubbles again when many bubbles are present.
SUMMARY OF THE INVENTION
The present invention is made to solve the above conventional problems and its object is to prevent a fluid in an envelopment space from being replaced with bubbles again even when the fluid is not sufficiently present nearby the envelopment space and many bubbles are present.
That is, the present invention provides a ceramic substrate comprising a flat substrate with an envelopment space formed in it and a flexible porous body disposed so as to cover the envelopment space, and contact-bonding means for contact-bonding the porous body to the flat substrate in a laminate direction.
In the case of a ceramic substrate of the present invention, it is preferable that the relation of 0.1t
0
≦t<t
0
is satisfied when assuming the thickness of the porous body contact-bonded by the contact-bonding means with the flat substrate in the laminate direction as t and the thickness of the porous body before contact-bonded as t
0
. Preferably, the porous body is formed from a woven fabric or non-woven fabric made of any one of natural fiber, synthetic fiber, and inorganic formed from envelopment space communicates with an external space preferably through at least two communication holes formed in the flat substrate, and the porous body is disposed so as to cover all of the two or more communication holes.
Moreover, in the case of the ceramic substrate of the present invention, it is preferable that the contact-bonding means has a window for making the porous body face-contact with a fluid, the porous body is sealed by the contact-bonding means, and moreover the window is formed on a portion of the contact-bonding means other than the portion of it for directly contact-bonding the porous body over the communication hole.
Moreover, it is preferable that the porous body has an overhanging portion to the outside of the flat substrate. In this case, it is more preferable that one end of the overhanging portion in the longitudinal direction contacts a fluid and the other end of it contacts a fluid absorbent.
Furthermore, it is preferable that the flat substrate at a portion contacting at least the porous body has a surface roughness of 50 &mgr;m or less.
Furthermore, the present invention provides a sensor element comprising a substrate having a vibrational portion and a piezoelectric element having a piezoelectric film and a pair of electrodes secured to one surface of the vibrational portion and contacting the piezoelectric film, in which the other surface of the vibrational portion serves as a sensor element facing an envelopment space and the substrate uses the ceramic substrate of the present invention.
In the case of the sensor element of the present invention, it is preferable that the envelopment space and the hole of the porous body disposed so as to cover the envelopment space are filled with at least one selected from the group consisting of a solid soluble in a fluid, a high-viscosity liquid soluble in a fluid, a solid reactive on a fluid, and a high-viscosity liquid reactive on a fluid, and it is more preferable that the at least one selected from the group consisting of a solid soluble in a fluid, a highviscosity viscosity liquid soluble in a fluid, a solid reactive on a fluid, and a high-viscosity liquid reactive on a fluid is replaced with a fluid.
REFERENCES:
patent: 4892794 (1990-01-01), Scholz
patent: 5489465 (1996-02-01), Natarajan et al.
patent: 5622871 (1997-04-01), May et al.
patent: 5698931 (1997-12-01), Shibata et al.
patent: 5889351 (1999-03-01), Okumura et al.
patent: 5892143 (2000-04-01), Namerikawa et al.
patent: 5933170 (1999-08-01), Takeuchi et al.
patent: 0409250936A (1997-09-01), None
Namerikawa Masahiko
Shibata Kazuyoshi
Burr & Brown
NGK Insulators Ltd.
Soderquist Arlin
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