JPS5892908A - Detector using piezo vibrator - Google Patents

Abstract

PURPOSE:To provide direct digital processing by a compact simple construction wherein two vibrating regions are formed on a piezo vibrator and, as a back electrode, a material whose electric resistance changes in response to an object to be detected is used to detect the object based on the difference in oscillating frequency between the vibrating regions. CONSTITUTION:There is shown a crystal vibrator P as a piezo vibrator and one of the surfaces is provided with two pairs of single side driving electrodes E11, E12 and E21, E22, the electrodes forming vibrating regions A1, A2, respectively. The other surface of the crystal vibrator P is used as a free surface, whereas back electrodes B1, B2 are formed on the back surfaces of the electrodes E11, E12 and E21, E22. Then an oscillation circuit OS1 is formed by connecting a C-MMOS invertor V1, a resistor R1 and capacitors C11, C12 to the electrodes E11, E12, whereas an oscillation circuit OS2 is formed by connecting a C-MOS invertor V2, a resistor V2 and capacitors C21, C22 to the electrodes E21, E22. There is also shown a mixer M in the Figure.

Description

[Detailed Description of the Invention] This invention relates to detection devices using piezoelectric actuators. For example, sensors that detect light, magnetism, temperature, humidity, and gas temperature have been rapidly developed. However, when these detection outputs are digitally processed using a TV microcomputer, a five-way converter is often required as an interface, which is rarely complicated.

Therefore, the present invention provides a detection device using a compact piezoelectric vibrator having a small detection NIK' which can be directly digitally processed.

EMBODIMENT OF THE INVENTION Hereinafter, one implementation of the present invention will be explained based on aspect II.

In Fig. 1, P is a crystal vibrator which is a piezoelectric vibrator, and on one side there are two pairs of single-sided driving tortoises 4Nmm112>l.
and Wel and 1ast are formed, and the electrodes 111*ll- and lll5 are formed, respectively.
On the back of the
Ih 'r shadow formation 0 sled? Electrode Ill m IIs K BtlA 2 O-hiMO8 inverter v1. Resistance R1j?
and load capacitance '1ieOtsk continues to generate fi circuit 0
A qC-MO8 elevator, a resistor R3, and a load capacitor t0shOsnk are connected to the electrode E11゜1■ to form a single oscillation path Oamk. M is for mixer.

In the above #, since one surface of the crystal glass P is a free image, the equivalent circuit of 1tRjII+area 1eAl is expressed as 5th-. That is, the double-sided moving type equal 1111I-path Km resistor 8 and the capacitor 08 are connected in series. This resistance R8 is formed by 1 to the electrical resistance of the back electrode B formed on the free surface, so it depends on the resistance value of the back electrode B, so each swing IIJ1
The stroke frequency a in the iI region changes as shown in No. 4- Therefore, the sensor material 2 that changes the IE electrical resistance in response to a specific detection blur is used for either the back turtle @B> or B1, and the other 1 to use something that does not have any sensitivity to the above detection target! l1%q! The target can be detected from the difference η in the excavation frequencies of the rMjR working region.

First, we will discuss the case of using it as an optical sensor.The %D of the photoconductive effect type optical sensor that utilizes the internal photoelectric effect of the conductor changes its a resistance depending on the amount of light. I wanted to,
For example, the material for the back 111k B* is ca day, 06B
m, PbEl, pbs=, nkAs, nk sb.

Hg1-x Odz Te (X-electron α2)elF", the resistance changes depending on the amount of light as shown in Figure 5. In other words, the excavation circuit 0 in Figure 2 depends on the
The excavation frequency of the town changes 〇 On the other hand, as the back electrode B, the shadow caused by the light II! By using hair that does not receive IR, the firing circuit OS1゜08
It is possible to detect the amount of light from the difference in the number of snow peaks tlL. That is, the amount of light can be detected by counting the output frequency r from mixer M' in FIG.

Next, when using it as a magnetic center, a magnetoresistive element using a ■-■ group compound semiconductor such as Lnoc with high electron mobility may be used for the back electrode B1.
n indicates magneto-resistance characteristics as shown in FIG. - For 1kBm, there are 11 AUs etc. that are not affected by magnetism.
-#4Vh is sufficient.

Also, when used as a temperature MIL sensor, L
Materials for nermistors and posisters whose resistance changes
hlt etc. may be used as the electrode B1, and the frame U may be used as the back electrode B and the frame U.

In addition, when used as a single gas sensor, the rear camera memory B
This can be done by using an n-type semiconductor or a p-type conductor as 1. In other words, the gas resistance characteristics of an n-type semiconductor become like the 7th curve due to the a-layer of the cyclic gas, and the adsorption of oxidized squares becomes 1 and the 7th curve becomes 1 snow. 0 Also, in the case of a P-type semiconductor, the resistance increases due to the adsorption of the reduced gas, and the resistance decreases by 1 due to the adsorption of the acclimatized gas. Bird B, as for AU
If you use %AjL etc.

Also, when used as a humidity sensor, finol
The resistance of t changes depending on the humidity.

9 showing the humidity-resistance characteristics of 8n01 is shown in FIG. In this case, the back electrode B11/c has a water-based coating kJii and 2C and L Jim uK, but any substance may be used.0 In this case, water j! If a Y-cut transducer is used as the IfEIIJ element, its resonance station yLIIL changes directly with temperature, so the temperature [k is detected] At the same time, the humidity R' can be detected from the output frequency of the mixer M.

As described above, according to the present invention, there are two
＠A substance whose electrical resistance changes in response to the object to be detected is used as the back electrode of one of the oscillation regions to form the oscillation region of the oscillation region. Since the object was detected based on the difference in number ρ, a detection device with an extremely small and simple configuration [111- could be provided!] ＞'' Digital processing can be performed without going through a 4μ-D converter. Also, since the change in electrical resistance due to the object to be detected is extremely significant, it is possible to detect 1IIIl degrees of force.

Furthermore, since two ridge-cut regions are formed on the same piezoelectric vibrator, the frequency-temperature-temporality of each striation region is the same.Therefore, the difference in excavation frequency is Hot fIL
0, which will not be included in the error component due to fluctuations

[Brief explanation of the drawing]

FIG. 1 is a top view and rear view of a piezoelectric transducer according to an embodiment of the invention, and FIG. 2 is an electrical diagram of an embodiment of the invention using the piezoelectric transducer of FIG. 1. Fig. 3 is an equivalent circuit diagram of a single-sided true sea bream-shaped crystal m1 IJ, Fig. 4 is a time diagram showing the relationship between the resistance of the back surface and the frequency, and the fifth fusion light amount and light guide effect. @gIA1 with resistance of shaped material! -Boneity diagram shown in Figure 6 is a characteristic diagram showing magnetic field-resistance bone property of magnetoresistive element, Figure 7 is a bone diagram showing gas concentration-resistance bone property of an-type semiconductor, Figure 8 is the g1 degree-resistance characteristic r of 81103
The characteristic diagram shown is O P...Piezoelectric vibrator "11 m"11 m m11 m m11 """
Single-sided driving electric current......Witling area BlmBM...Back electrode O8,,08m......Spring circuit...Mixer Figure 1 Fig. 2 S2 Fig. 3 Fig. 4 → R5 Fig. 5 Fig. 7 factor

Claims (1)

[Scope of Claims] Two pairs of single-sided drive IILs are formed on one side of the piezoelectric vibrator to form a 21-point horizontal rectangle τ on the piezoelectric vibrator, and one pair of single-sided drive IILs is formed on one side of the piezoelectric vibrator. The electrical resistance changes in response to the detection target on the back side of the electrode. The electrode hair is formed, and the above-mentioned stroking areas are used to form two almost radial channels, and the detection strategy is to detect the difference in the output frequency of each oscillating 1gl channel, and the piezoelectric vibration is used to wait for an order of magnitude. Detection using child fe llk
.