JP4950752B2 - Density measuring device - Google Patents

Description

  The present invention relates to a density measuring apparatus having a surface acoustic wave element for measuring the density of a liquid object to be measured.

  In general, a surface acoustic wave element includes a piezoelectric substrate, and an input electrode and an output electrode composed of comb-like electrode fingers provided on the piezoelectric substrate. In the surface acoustic wave element, when an electric signal is input to the input electrode, an electric field is generated between the electrode fingers, and the surface acoustic wave is excited by the piezoelectric effect and propagates on the piezoelectric substrate. Among these surface acoustic waves, detection of various substances and physical property values using surface acoustic wave elements that use a shear surface acoustic wave (SH-SAW) that is displaced in a direction perpendicular to the propagation direction Elastic wave sensors for making measurements have been studied.

  In a surface acoustic wave element, when a liquid object to be measured is loaded on a piezoelectric substrate, the propagation speed of the surface acoustic wave decreases with an increase in the mass of the object to be measured. A mass load effect is known in which the resonance frequency of a surface acoustic wave element changes. When a concavo-convex structure is formed on the propagation path between the input electrode and the output electrode of the surface acoustic wave element, and the object to be measured is loaded in the concave portion, the loaded object to be measured forms a pseudo film. This film is excited together with the piezoelectric substrate, and the density of the object to be measured can be obtained by utilizing the fact that the resonance frequency changes based on the mass of the film (see Patent Document 1 and Non-Patent Document 1).

  9A is an explanatory diagram of the density measuring apparatus 100 shown in Patent Document 1, and FIG. 9B is an end view of IXB-IXB in FIG. 9A. The density measuring apparatus 100 includes a first surface acoustic wave element 10 and a second surface acoustic wave element 20. The first surface acoustic wave element 10 includes an input electrode 12 and an output electrode 14, and a short-circuit propagation path 16 is formed between the input electrode 12 and the output electrode 14. The second surface acoustic wave element 20 includes an input electrode 22 and an output electrode 24, and an uneven structure is formed between the input electrode 22 and the output electrode 24 in a direction perpendicular to the propagation direction of the surface acoustic wave output from the input electrode 22. A propagation path 26 is formed. The short-circuit propagation path 16 and the convex portion 28 of the concavo-convex structure are provided on a metal film 44 formed on the surface of the piezoelectric substrate 42.

  The measurement of the density of the object to be measured in the density measuring apparatus 100 is performed by inputting the same signal to the input electrodes 12 and 22 while the object to be measured 46 is loaded on the short-circuit propagation path 16 and the propagation path 26. The density of the object to be measured is obtained by measuring the phase difference between the signals output from the output electrodes 14 and 24.

Japanese Patent No. 3248683 Satoshi Kondo and Shoko Shiokawa, “Separate measurement of density and viscosity of liquids using a slip surface acoustic wave sensor”, IEICE Technical Report, IEICE, November 2000

  However, as shown in FIG. 9B, in the propagation path 26, the object to be measured 46 is loaded on the concave portion 30, and the surface acoustic wave output from the input electrode 22 is loaded on the convex portion 28 and the concave portion 30. It propagates through a different medium such as the measurement object 46 and is output from the output electrode 24. Therefore, the surface acoustic wave propagating through the convex portion 28 and the surface acoustic wave propagating through the object to be measured 46 loaded in the concave portion 30 are vector-synthesized at the output electrode 24, and both surface acoustic waves may cancel each other. As a result, a measurement error of the density of the object to be measured may occur.

  The present invention has been made in consideration of the above-described problems, and an object of the present invention is to provide a density measuring apparatus capable of accurately measuring the density of a liquid object to be measured.

  The density measuring apparatus according to the present invention outputs a first surface acoustic wave element having a short-circuit propagation path electrically short-circuited between an input electrode and an output electrode, and outputs from the input electrode between the input electrode and the output electrode. And a second surface acoustic wave element having a lattice-shaped propagation path in which a concavo-convex structure is formed in a direction parallel to the propagation direction of the surface acoustic wave to be electrically short-circuited, and the first surface acoustic wave element and the second surface acoustic wave element The surface acoustic wave element is arranged in parallel, and the same signal is input to each of the input electrodes in a state where a liquid measurement object is loaded on the short-circuit propagation path and the lattice-shaped propagation path, and the output electrodes The density of the object to be measured is obtained from the phase difference between the output signals output from.

  Another density measuring apparatus according to the present invention includes a first surface acoustic wave device having an open propagation path electrically opened between an input electrode and an output electrode, and the input electrode and the output electrode. A first surface acoustic wave device, comprising: a second surface acoustic wave device having a lattice-shaped propagation path in which an uneven structure is formed in a direction parallel to a propagation direction of the surface acoustic wave output from the input electrode; And the second surface acoustic wave element are arranged in parallel, and in the state where a liquid object to be measured is loaded on the open propagation path and the lattice propagation path, the same signal is input to each input electrode, The density of the object to be measured is obtained from the phase difference between the output signals output from the output electrodes.

  According to the present invention, the output electrode is provided by providing a grid-like propagation path having a concavo-convex structure formed in a direction parallel to the propagation direction of the surface acoustic wave output from the input electrode between the input electrode and the output electrode. It is possible to prevent the occurrence of measurement errors due to the vector synthesis of surface acoustic waves in and to accurately measure the density of the liquid object to be measured.

  Further, another density measuring apparatus according to the present invention includes a first surface acoustic wave element having a short-circuit propagation path electrically short-circuited between an input electrode and an output electrode, and a checkered lattice between the input electrode and the output electrode. And a second surface acoustic wave element having a checkered lattice-shaped propagation path that is electrically short-circuited, and the first surface acoustic wave element and the second surface acoustic wave element are arranged in parallel. In the state where the liquid measurement object is loaded on the short circuit propagation path and the checkered lattice propagation path, the same signal is input to each input electrode, and the level of each output signal output from each output electrode The density of the object to be measured is obtained from the phase difference.

  Furthermore, another density measuring apparatus of the present invention includes a first surface acoustic wave element having an open propagation path electrically opened between an input electrode and an output electrode, and a checkered pattern between the input electrode and the output electrode. A second surface acoustic wave element having a checkered lattice-shaped propagation path formed with a lattice-shaped uneven structure, and the first surface acoustic wave element and the second surface acoustic wave element are arranged in parallel. In the state where a liquid object to be measured is loaded on the open propagation path and the checkered lattice propagation path, the same signal is input to each input electrode, and each output signal output from each output electrode The density of the object to be measured is obtained from the phase difference.

  According to the present invention, by providing a checkered lattice-shaped propagation path in which a checkered lattice-shaped uneven structure is formed between an input electrode and an output electrode, measurement errors caused by vector synthesis of surface acoustic waves at the output electrode are reduced. Generation | occurrence | production can be prevented and the density of a liquid to-be-measured object can be measured correctly.

  Furthermore, the object to be measured is preferably alcohol.

  According to the present invention, the lattice-shaped propagation path or the checkered lattice-shaped propagation path in which an uneven structure is formed between the input electrode and the output electrode in a direction parallel to the propagation direction of the surface acoustic wave output from the input electrode. By providing, it is possible to prevent measurement errors caused by vector synthesis of surface acoustic waves at the output electrode, and to accurately measure the density of the liquid object to be measured.

  Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of a configuration of a density measuring device 40 according to the embodiment of the present invention. 2A and 2C are end views of IIA-IIA in FIG. 1, FIG. 2A is a diagram showing a state before loading the object to be measured, and FIG. 2C is loaded with the object to be measured. It is a figure which shows a back state. 2B and 2D are end views of IIB-IIB in FIG. 1, FIG. 2B is a diagram showing a state before loading the object to be measured, and FIG. 2D is loaded with the object to be measured. It is a figure which shows a back state. In addition, the same code | symbol is attached | subjected to the component same as the density measuring apparatus 100 shown to FIG. 9A and FIG. 9B.

  As shown in FIG. 1, the density measuring device 40 distributes the electric signal from the first surface acoustic wave element 10, the second surface acoustic wave element 20, an oscillator 48 that generates a high-frequency electric signal, and the oscillator 48. And a phase difference detector 52 that measures the phase difference of the surface acoustic waves propagating through the first surface acoustic wave element 10 and the second surface acoustic wave element 20. The first surface acoustic wave element 10 includes an input electrode 12 and an output electrode 14, and a short-circuit propagation path 16 is formed between the input electrode 12 and the output electrode 14. The second surface acoustic wave element 20 includes an input electrode 22 and an output electrode 24, and a lattice propagation path 32 is formed between the input electrode 22 and the output electrode 24. Further, the first surface acoustic wave element 10 and the second surface acoustic wave element 20 are arranged in parallel on the piezoelectric substrate 42.

  The input electrodes 12 and 22 are composed of comb-shaped electrodes for exciting surface acoustic waves by an electric signal input from an oscillator 48 via a distributor 50. The output electrodes 14 and 24 are composed of comb-shaped electrodes for receiving the surface acoustic waves excited and propagated by the input electrode 12 or 22.

  The short-circuit propagation path 16 and the lattice-shaped propagation path 32 are formed of a metal film 44 deposited on the piezoelectric substrate 42, and the metal film 44 is electrically short-circuited (see FIGS. 1A and 1B). Further, the metal film 44 is commonly grounded in order to improve measurement accuracy. The material of the metal film 44 is not particularly limited, but is preferably formed of gold that is chemically stable with respect to the measurement object 46.

  In the lattice-shaped propagation path 32, convex portions 34 formed in a direction perpendicular to the propagation direction of the surface acoustic wave output from the input electrode 22 (the arrow X direction in FIG. 1) are equally spaced in the X direction. The measured object 46 to be measured is loaded on the concave portion 36 formed between the adjacent convex portions 34 (see FIG. 2D). In other words, the lattice-shaped propagation path 32 is formed with a concavo-convex structure 38 composed of convex portions 34 and concave portions 36 in the X direction. By forming the concavo-convex structure 38 and loading and confining the measurement object 46 in the concave portion 36, an output signal based on the mass load effect described later can be obtained.

  In addition, it is preferable that the space | interval of convex parts 34 is shorter than wavelength (lambda) of the surface acoustic wave to propagate, More preferably, it is (lambda) / 8. Further, it is preferable that the depth of the recess 36 is formed as deep as possible in order to increase the detection accuracy of the mass load effect.

The piezoelectric substrate 42 is not particularly limited as long as it can propagate a sliding surface acoustic wave, but is preferably a 36-degree rotated Y-plate X-propagating LiTaO ₃ .

  Next, density measurement of the measurement object 46 using the density measuring device 40 will be described.

  First, the DUT 46 to be measured is loaded on the short-circuit propagation path 16 and the lattice-shaped propagation path 32. The short-circuit propagation path 16 is loaded on the metal film 44 (see FIG. 2C), and the lattice-shaped propagation path 32 is formed with the concavo-convex structure 38 composed of the convex part 34 and the concave part 36, so 46 is mainly loaded in the recess 36 (see FIG. 2D).

  Next, the electric signal is distributed by the distributor 50 from the oscillator 48, and the same signal is input to the input electrodes 12 and 22. In the input electrode 12, a surface acoustic wave is excited based on the input signal, propagates on the short-circuit propagation path 16, and is received by the output electrode 14. Similarly, at the input electrode 22, a surface acoustic wave is excited based on the input signal, propagates on the lattice propagation path 32, and is received by the output electrode 24.

  In the lattice-shaped propagation path 32, the concavo-convex structure 38 is formed in the X direction, and the electrical lengths of the propagation paths are equal. Therefore, the phase of the surface acoustic wave is equal between the arbitrary paths PP parallel to the X direction. Become. As a result, the surface acoustic waves propagated through different paths can be prevented from being received by the output electrode 24 and canceling each other.

  Both output signals extracted from the surface acoustic waves received by the output electrodes 14 and 24 are compared by a phase difference detector 52 to detect a phase difference. The output signal from the output electrode 14 includes a signal component based on the density viscosity product, and the output signal from the output electrode 24 includes a signal component based on the density viscosity product and the mass load effect. Therefore, the difference signal detected from both the output signals is a signal based on the mass load effect, and the density of the DUT 46 is calculated based on the phase difference detected from this signal. The specific density is calculated by a calculation formula described below.

From the sensor sensitivity equation for mass load, the velocity change (ΔV / V) _m at the convex portion 34 and the propagation velocity change (ΔV / V) _l at the concave portion 36 are expressed by equations (1) and (2). Is done. Here, the subscript m corresponds to the convex portion 34, the subscript l corresponds to the concave portion 36, ρ is the density of the load film, μ is the Lame constant, S _m is the cross-sectional area of the convex portion 34, and S _l is the concave portion 36. , S is the sum of the cross-sectional area of the projection 34 parallel to the metal film 44 and the bottom area of the recess 36. Further, A is a material constant. For example, in 36-degree Y-plate X-propagating LiTaO ₃ , A = 5.249 × 10 ⁻⁹ Ω.

In the case of a liquid, since ρ _l >> μ _l / V ² , the equation (2) becomes the following equation (3).

Next, the speed change (ΔV / V) _s in the first surface acoustic wave element 10 and the speed change (ΔV / V) _g in the second surface acoustic wave element 20 are expressed by equations (4) and (5). The Here, (ΔV / V) _liquid represents perturbation by Newtonian fluid.

  If the speed change in the measured object 46 is expressed with ', it is expressed as Expression (4) and Expression (5).

Substituting equation (6) into equation (7) yields equation (8). Here, ρ _l is the density of the loaded film of the standard solution, and ρ _l ′ is the density of the loaded film of the object to be measured 46.

  Accordingly, the relational expression of the density of the object to be measured 46 is the expression (9).

By substituting the phase difference of the output signal detected by the phase difference detector 52 into (ΔV / V) _g − (ΔV / V) _s in Expression (9), the density ρ _l ′ of the object to be measured 46 is obtained. be able to.

  In the second surface acoustic wave element 20 shown in FIG. 2B, the concavo-convex structure 38 composed of the convex portions 34 and the concave portions 36 is formed in the X direction. It is good also as the checkered lattice-shaped propagation path 54 which added the structure.

  As shown in FIG. 3A, the checkered lattice-shaped propagation path 54 may have a quadrangular cross section parallel to the metal film 44 of the recess 36A, and the projecting portion 34A and the recess 36A may be used as an uneven structure 38A. Further, as shown in FIG. 3B, the cross section of the recess 36B parallel to the metal film 44 may be circular, and the concavo-convex structure 38B may be formed from the protrusion 34B and the recess 36B. Furthermore, as shown in FIG. 3C, the cross section of the concave portion 36C parallel to the metal film 44 may be formed in a rhombus shape so that the concave and convex structure 38C is formed from the convex portion 34C and the concave portion 36C. The shape of the cross section of the recess parallel to the metal film 44 is not limited to these shapes as long as a checkered lattice propagation path can be formed.

  In the checkered lattice-shaped propagation path 54, since the uneven structure is formed in the horizontal and vertical directions with respect to the X direction, the electrical lengths of the propagation paths in the X direction are equal. Therefore, similarly to the lattice-shaped propagation path 32, the surface acoustic waves received by the output electrode 24 can be prevented from canceling each other.

  When the propagation path formed in the second surface acoustic wave element 20 is a checkered lattice, the lattice propagation path 32 is compared, and the effect of confining the object to be measured 46 in the recesses 36A to 36C increases. The measurement accuracy of the density of the object 46 can be further increased.

  As described above, the density measuring apparatus 40 according to this embodiment includes the first surface acoustic wave element 10 having the short-circuit propagation path 16 that is electrically short-circuited between the input electrode 12 and the output electrode 14, and the input electrode. A second surface acoustic wave having a lattice-shaped propagation path 32 in which a concavo-convex structure 38 is formed in a direction parallel to the propagation direction of the surface acoustic wave output from the input electrode 22 between the output electrode 24 and the output electrode 24. The device 20 is provided. In the state where the first surface acoustic wave element 10 and the second surface acoustic wave element 20 are arranged in parallel and the object to be measured 46 is loaded on the short-circuit propagation path 16 and the lattice-shaped propagation path 32, the same as the input electrodes 12 and 22. The density of the DUT 46 can be obtained from the phase difference between the output signals output from the output electrodes 14 and 24.

  In the density measuring apparatus 40, the concave-convex structure 38 is formed in a direction parallel to the propagation direction of the surface acoustic wave, and the lattice-shaped propagation path 32 that is electrically short-circuited is provided, thereby causing the vector synthesis of the surface acoustic wave at the output electrode 24. It is possible to prevent the occurrence of measurement error and to accurately measure the density of the object to be measured 46.

  In the density measuring apparatus 40 according to this embodiment, the first surface acoustic wave element 10 having the short-circuit propagation path 16 electrically short-circuited between the input electrode 12 and the output electrode 14, the input electrode 22, and the output electrode And a second surface acoustic wave element 20 having a checkered lattice-shaped propagation path 54 in which a concavo-convex structure 38 </ b> A (concavo-convex structure 38 </ b> B, 38 </ b> C) is formed and electrically short-circuited.

  In the density measuring apparatus 40, by providing the checkered lattice-shaped propagation path 54 in which the concavo-convex structure 38 </ b> A (concavo-convex structure 38 </ b> B, 38 </ b> C) is formed in the propagation direction of the surface acoustic wave and is electrically short-circuited, It is possible to prevent measurement errors due to vector synthesis and accurately measure the density of the object to be measured 46.

  Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is an explanatory diagram of a configuration of a density measuring apparatus 40A according to the second embodiment of the present invention. 5A and 5C are VA-VA end views of FIG. 4, and FIG. 5A is a diagram showing a state before the object to be measured is loaded, and FIG. 5C is a state in which the object to be measured is loaded. It is a figure which shows a back state. 5B and 5D are VB-VB end views of FIG. 4, FIG. 5B is a diagram showing a state before loading the object to be measured, and FIG. 5D is a state in which the object to be measured is loaded. It is a figure which shows a back state.

  The density measuring device 40 </ b> A includes a first surface acoustic wave element 10 </ b> A and a second surface acoustic wave element 20 </ b> A as in the case of the density measuring device 40, and the first surface acoustic wave element 10 with respect to the density measuring device 40. The short propagation path 16 in the inside is an open propagation path 60, and the lattice propagation path 32 in the second surface acoustic wave element 20 is a lattice propagation path 70. In addition, the same code | symbol is attached | subjected to the component same as the density measuring apparatus 40. FIG.

  The open propagation path 60 includes an open region 62 and a convex portion 64. The open region 62 is a region where the metal film 44 is peeled off, and the convex portion 64 is a portion that remains without being peeled off by the metal film 44.

  The lattice-shaped propagation path 70 is provided with recesses 72 formed at regular intervals in the X direction so that the piezoelectric substrate 42 is exposed by peeling a part of the metal film 44 in a direction perpendicular to the X direction. A convex portion 74 is formed between adjacent concave portions 72. In other words, the lattice-shaped propagation path 70 is formed with a concavo-convex structure 76 composed of a concave portion 72 and a convex portion 74 in the X direction, and the concave portion 72 where the piezoelectric substrate 42 is exposed is in an electrically open state. Yes.

  The sum of the areas of the regions 62 a and 62 b constituting the open region 62 is formed to be equal to the sum of the bottom areas of all the recesses 72 in the concavo-convex structure 76.

The protrusion 74 is formed as a part of the metal film 44, but is not limited to a metal, and may be an insulating film such as SiO ₂ or a resin.

  Next, density measurement of the measurement object 46 using the density measuring device 40A will be described. Basically, this is the same as the density measurement by the density measuring device 40.

  First, the measurement object 46 to be measured is loaded on the open propagation path 60 and the lattice propagation path 70. In the open propagation path 60, the load is applied to the open area 62 (see FIG. 5C), and in the lattice-shaped propagation path 70, the load is applied to the recess 72 (see FIG. 5D).

  Next, the electric signal is distributed by the distributor 50 from the oscillator 48, and the same signal is input to the input electrodes 12 and 22. In the input electrode 12, a surface acoustic wave is excited based on the input signal, propagates on the open propagation path 60, and is received by the output electrode 14. Similarly, at the input electrode 22, a surface acoustic wave is excited based on the input signal, propagates on the lattice propagation path 70, and is received by the output electrode 24.

  Both output signals extracted from the surface acoustic waves received by the output electrodes 14 and 24 are compared by a phase difference detector 52 to detect a phase difference. The output signal from the output electrode 14 includes a signal component based on the electrical characteristics and the density viscosity product, and the output signal from the output electrode 24 includes the signal component based on the electrical characteristics, the density viscosity product, and the mass load effect. It is included. Therefore, the difference signal detected from both the output signals is a signal based on the mass load effect, and the density of the DUT 46 is calculated based on the phase difference detected from this signal.

  Here, the electrical characteristics are characteristics based on electrical opening and appear corresponding to the area of the electrically opened area. Therefore, by making the sum of the area of the open region 62 and the bottom area of all the recesses 72 equal, the electrical characteristics are excluded from the difference signal detected from both output signals. The specific density is calculated based on the formulas (1) to (9) in the same manner as the density measuring device 40.

  In the second surface acoustic wave element 20A shown in FIG. 5B, the concavo-convex structure 76 composed of the concave portions 72 and the convex portions 74 is formed in the X direction. It is good also as the checkered lattice-shaped propagation path 78 which added the structure.

  As the checkered lattice-shaped propagation path 78, as shown in FIG. 6A, the cross section parallel to the metal film 44 of the concave portion 72A may be a square shape, and the concave and convex structure 76A may be formed from the concave portion 72A and the convex portion 74A. Further, as shown in FIG. 6B, the cross section of the recess 72B parallel to the metal film 44 may be circular, and the recess / protrusion 72B and the protrusion 74B may be a concavo-convex structure 76B. Further, as shown in FIG. 6C, the cross section of the recess 72C parallel to the metal film 44 may be formed in a rhombus shape so that the recess / protrusion 72C and the protrusion 74C form a concavo-convex structure 76C. The shape of the cross section of the recess parallel to the metal film 44 is not limited to these shapes as long as a checkered lattice propagation path can be formed.

  As described above, the density measuring apparatus 40A according to this embodiment includes the first surface acoustic wave element 10A having the open propagation path 60 that is electrically opened between the input electrode 12 and the output electrode 14, and the input electrode. A second surface acoustic wave having a lattice-shaped propagation path 70 in which a concavo-convex structure 76 is formed in a direction parallel to the propagation direction of the surface acoustic wave output from the input electrode 22 between the output electrode 24 and the output electrode 24. The device 20A is provided. In the state where the first surface acoustic wave element 10A and the second surface acoustic wave element 20A are arranged in parallel and the object to be measured 46 is loaded on the open propagation path 60 and the lattice propagation path 70, they are the same as the input electrodes 12 and 22. The density of the DUT 46 can be obtained from the phase difference between the output signals output from the output electrodes 14 and 24.

  Further, in the density measuring apparatus 40A according to this embodiment, the first surface acoustic wave element 10A having the open propagation path 60 opened electrically between the input electrode 12 and the output electrode 14, the input electrode 22 and the output electrode 24 may be provided with a second surface acoustic wave element 20A having a checkered lattice-shaped propagation path 78 in which a concavo-convex structure 76A (concavo-convex structure 76B, 76C) is formed and electrically opened.

  The uneven structure 76 is not limited to the case where the uneven structure 76 is formed on the piezoelectric substrate 42 as shown in FIG. 5B as long as the mass load effect can be detected.

  FIG. 7 is an explanatory diagram of a configuration of a density measuring device 40B that is a modification of the density measuring device 40A according to the second embodiment of the present invention. 8A and 8C are end views of VIIIA-VIIIA in FIG. 7, and FIG. 8A is a diagram showing a state before loading the object to be measured, and FIG. 8C is a state in which the object to be measured is loaded. It is a figure which shows a back state. 8B and 8D are end views of VIIIB-VIIIB in FIG. 7, FIG. 8B is a diagram showing a state before loading the object to be measured, and FIG. 8D is loaded with the object to be measured. It is a figure which shows a back state.

  The density measuring device 40B includes a first surface acoustic wave element 10B and a second surface acoustic wave element 20B as in the case of the density measuring device 40A, and the first surface acoustic wave element 10A is different from the density measuring device 40A. The open propagation path 60 in the middle is an open propagation path 80, and the lattice-shaped propagation path 70 in the second surface acoustic wave element 20 </ b> B is a lattice-shaped propagation path 84. In addition, the same code | symbol is attached | subjected to the component same as the density measuring apparatus 40A.

  As shown in FIG. 8A, the open propagation path 80 includes a flat open region 82 where the piezoelectric substrate 42 is exposed. Further, as shown in FIG. 8B, the lattice-shaped propagation path 84 is provided with recesses 86 formed in the direction perpendicular to the X direction on the surface of the piezoelectric substrate 42 at equal intervals in the X direction. A convex part 88 is formed therebetween, and a concave-convex structure 90 composed of a concave part 86 and a convex part 88 is provided.

  The liquid object to be measured is not particularly limited, and may be either a pure solution or a mixed solution, and is particularly effective when measuring the density of alcohol such as methanol and ethanol. is there.

  Note that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted without departing from the gist of the present invention.

It is explanatory drawing of a structure of the density measuring apparatus which concerns on 1st Embodiment of this invention. 2A and 2C are end views of IIA-IIA in FIG. 1, and FIG. 2A is a diagram illustrating a state before loading the object to be measured, and FIG. 2C is a diagram after loading the object to be measured. 2B and FIG. 2D are end views of IIB-IIB in FIG. 1, and FIG. 2B is a diagram showing a state before loading the object to be measured. It is a figure which shows the state after loading a to-be-measured object. 3A to 3C are explanatory diagrams of a checkered lattice-shaped propagation path. It is explanatory drawing of a structure of the density measuring apparatus which concerns on 2nd Embodiment of this invention. 5A and 5C are VA-VA end views of FIG. 4, and FIG. 5A is a diagram illustrating a state before loading the object to be measured, and FIG. 5C is a diagram after loading the object to be measured. FIG. 5B and FIG. 5D are VB-VB end views of FIG. 4, and FIG. 5B is a diagram showing a state before loading the object to be measured, and FIG. It is a figure which shows the state after loading a to-be-measured object. 6A to 6C are explanatory diagrams of a checkered lattice-shaped propagation path. FIG. 7 is an explanatory diagram of a configuration of a modified example according to the second embodiment. 8A and 8C are end views of VIIIA-VIIIA in FIG. 7, in which FIG. 8A is a diagram showing a state before loading the object to be measured, and FIG. 8C is a view after loading the object to be measured. 8B and FIG. 8D are end views of VIIIB-VIIIB in FIG. 7, and FIG. 8B is a diagram showing a state before loading the object to be measured, and FIG. It is a figure which shows the state after loading a to-be-measured object. FIG. 9A is an explanatory diagram of a conventional density measuring device, and FIG. 9B is an end view of IXB-IXB in FIG. 9A.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 10A, 10B ... 1st surface acoustic wave element 12, 22 ... Input electrode 14, 24 ... Output electrode 16 ... Short-circuit propagation path 20, 20A, 20B ... 2nd surface acoustic wave element 26 ... Propagation paths 28, 34, 34A to 34C, 64, 74, 74A to 74C, 88 ... convex portions 30, 36, 36A to 36C, 72, 72A to 72C, 86 ... concave portions 32, 70, 84 ... lattice-like propagation paths 38, 38A to 38C, 76 , 76A to 76C, 90 ... Uneven structure 40, 40A, 40B, 100 ... Density measuring device 42 ... Piezoelectric substrate 44 ... Metal film 46 ... Object to be measured 48 ... Oscillator 50 ... Distributor 52 ... Phase difference detector 54, 78 ... Checkered propagation path 60, 80 ... Open propagation path 62, 82 ... Open area 62a, 62b ... Area

Claims (5)

A first surface acoustic wave device having a short-circuit propagation path electrically short-circuited between the input electrode and the output electrode;
A second surface acoustic wave element having a lattice-shaped propagation path in which a concavo-convex structure is formed between the input electrode and the output electrode in a direction parallel to the propagation direction of the surface acoustic wave output from the input electrode and electrically short-circuited; With
The first surface acoustic wave element and the second surface acoustic wave element are arranged in parallel,
In a state where a liquid measurement object is loaded on the short-circuit propagation path and the lattice-shaped propagation path,
A density measuring apparatus, wherein the same signal is input to each input electrode, and the density of the object to be measured is obtained from the phase difference between the output signals output from the output electrodes. A first surface acoustic wave device having an open propagation path electrically opened between the input electrode and the output electrode;
A second surface acoustic wave element having a lattice-shaped propagation path in which an uneven structure is formed between the input electrode and the output electrode in a direction parallel to the propagation direction of the surface acoustic wave output from the input electrode, With
The first surface acoustic wave element and the second surface acoustic wave element are arranged in parallel,
In a state where a liquid measurement object is loaded on the open propagation path and the lattice propagation path,
A density measuring apparatus, wherein the same signal is input to each input electrode, and the density of the object to be measured is obtained from the phase difference between the output signals output from the output electrodes. A first surface acoustic wave device having a short-circuit propagation path electrically short-circuited between the input electrode and the output electrode;
A second surface acoustic wave device having a checkered lattice-shaped propagation path in which a checkered lattice-shaped uneven structure is formed between the input electrode and the output electrode and is electrically short-circuited,
The first surface acoustic wave element and the second surface acoustic wave element are arranged in parallel,
In a state where a liquid object to be measured is loaded on the short-circuit propagation path and the checkered lattice propagation path,
A density measuring apparatus, wherein the same signal is input to each input electrode, and the density of the object to be measured is obtained from the phase difference between the output signals output from the output electrodes. A first surface acoustic wave device having an open propagation path electrically opened between the input electrode and the output electrode;
A second surface acoustic wave element having a checkered lattice-shaped propagation path in which a checkered lattice-shaped uneven structure is formed between the input electrode and the output electrode,
The first surface acoustic wave element and the second surface acoustic wave element are arranged in parallel,
In a state where a liquid object to be measured is loaded on the open propagation path and the checkered lattice propagation path,
A density measuring apparatus, wherein the same signal is input to each input electrode, and the density of the object to be measured is obtained from the phase difference between the output signals output from the output electrodes. In the density measuring device according to any one of claims 1 to 4,
The density measuring apparatus, wherein the object to be measured is alcohol.

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