JP2010151737A - Pressure transducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a viscometer in responsibility even when carrying out a liquid chromatograph operation at a low flow rate. <P>SOLUTION: A pressure transducer 50 is provided, which includes: a diaphragm 60 containing a magnetic body; coils disposed on both sides of the diaphragm; a displacement detecting means for magnetically detecting a state of the diaphragm being close to and/or spaced from the coils; and a displacement suppressing means which applies displacement suppressing current to any one of the coils in accordance with the displacement of the diaphragm, wherein a portion of the diaphragm is made of a hard magnetic material. Furthermore, the viscometer including the transducer is obtained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pressure transducer. In particular, the present invention relates to a pressure transducer used in a liquid chromatograph viscometer.

  In order to analyze a polymer substance contained in the eluent of a liquid chromatograph, it is usually necessary to use an analytical column packed with a porous gel or the like that can separate the polymer substance according to the hydrodynamic size of the molecule, etc. A refractive index detector or an ultraviolet absorption detector is widely used.

  By the way, the hydrodynamic size of a polymer substance depends not only on its molecular weight but also on the shape of the molecule such as the degree of spatial expansion and the hardness of the molecule, but there are differences in physical properties depending on the size. .

  In general, ultraviolet absorbance and refractive index depend on the polymer weight concentration, and viscosity depends on the polymer weight concentration and molecular size, so UV absorbance and viscosity or refractive index and viscosity are measured simultaneously. Thus, information on the size can be extracted. Therefore, if the molecular weight is known, information on the shape and hardness of the molecule can be obtained from the size information. Conversely, if the shape and hardness are known, information on molecular weight can be obtained.

  By the way, when it is necessary to continuously measure the viscosity in a minute amount as in the eluate of the liquid chromatograph apparatus, a viscometer using a capillary bridge is used (Patent Documents 1 and 2). A block diagram of a viscometer using a capillary bridge is shown in FIG. The viscometer (10) is basically composed of four capillaries (21, 22, 23, 24) having the same length and inner diameter connected in a bridge shape (FIG. 1). ). Depending on the difference between the viscosity of the sample liquid and the viscosity of the carrier liquid between the flow of the carrier liquid to each capillary and the flow of the sample liquid (usually a liquid containing a polymer substance in the carrier liquid) The pressure generated at both ends of the plate changes. When the viscosity is continuously measured, the sample liquid is retained or diluted between the rear-stage tube (24) and the midpoint (32) of either one of the series pair capillaries, and flows through the front-stage tube. A dilution tube or a delay tube (40) is installed to prevent the liquid from flowing directly into the downstream capillary during the viscosity measurement period. When the eluate eluted from the analytical column is allowed to flow into the inflow channel A, the pressure generated at both ends of the pre-stage tubule (21) and the both ends of the pre-stage tubule (22) until the sample liquid reaches the middle point (31, 32). Since the generated pressure changes equally, there is no pressure difference at the midpoint (31, 32) of the bridge. On the other hand, since the sample liquid does not flow into the downstream capillary tube (24) while the sample fluid passes through the downstream capillary tube (23), the pressure generated at both ends of the downstream capillary tube (23) and the both ends of the downstream capillary tube (24). A difference occurs in the generated pressure. As a result, a difference occurs in the pressure at the midpoint (31, 32) of the bridge. Since the magnitude of the pressure difference depends on the difference between the viscosity of the sample liquid and the viscosity of the carrier liquid, the viscosity of the sample liquid can be obtained from the pressure difference at the midpoint (31, 32). A diaphragm pressure transducer (50) is often used to measure the pressure at the midpoint.

  When the viscometer using the capillary bridge shown in FIG. 1 is used as the liquid chromatograph viscometer, the inner diameter of the thin tubes (21, 22, 23, 24) is 0.2 to 0.4 mm, and the length is several tens. A stainless steel tube or a polyether ether ketone (PEEK) tube of cm to several meters is used. The flow rate flowing through the viscometer varies depending on the size of the analytical column and the like, but is usually 0.2 to 3 mL / min.

  When a variable reluctance type pressure transducer is used as the diaphragm type pressure transducer (50), normally, an inductance coil (91, 92) wound around an E type core (91, 92) on both sides of a diaphragm (60) made of a magnetic material. 93, 94) are arranged close to each other in the vertical direction (FIG. 2A). Further, the peripheral portion of the diaphragm has a pleat shape (62) so that the disk portion (61) at the center of the diaphragm (60) can be easily translated by the differential pressure while maintaining a flat surface (see FIG. 2 (B)). When a differential pressure is generated on both sides of the diaphragm, the disk portion (61) of the diaphragm moves from a maximum of 0.025 to 0.05 mm, and the distance between the coils (93, 94) and the disk portion (61) of the diaphragm changes. Then reluctance changes. An AC voltage of about 5 V (effective value) and 3 to 5 kHz is applied to both ends of both coils connected in series. When there is no difference between the reluctances of both coils, no AC voltage is generated at the connection point of both coils. However, when there is a difference in reluctance, an AC voltage is output according to the difference value.

  Generally, in a variable reluctance type pressure transducer, the diaphragm (60) is made of a soft magnetic material with low hysteresis. Then, by changing the elasticity of the diaphragm by changing the shape and thickness of the pleat portion, the displacement amount of the diaphragm with respect to a predetermined differential pressure can be changed, and the detection sensitivity of the differential pressure can be adjusted.

  By the way, in recent years, in liquid chromatographs, in order to cope with a small amount of sample, reduce the consumption of eluent, and shorten the analysis time, the particle diameter packed in the analytical column and the analytical column have been reduced in size. Progressing. For this reason, analysis has been increasing at an eluent flow rate of 0.2 to 0.3 mL / min or less.

  When the flow rate of the eluent is reduced in the liquid chromatograph, when a capillary having the same diameter as that of the conventional apparatus is used for the capillary bridge, the pressure generated between both ends of the capillary is reduced. Therefore, in order to generate a pressure that can be detected with a small flow rate, it is necessary to use a narrower diameter tube, a pressure transducer with higher sensitivity, or a combination of both. However, it became clear that the peak of the viscosity signal tails when a thin tube having a diameter of 0.2 mm or less is used. On the other hand, when a detector such as a differential refractometer was connected downstream of the viscometer, it was found that tailing of the viscosity signal was not due to the spread of the peak component.

  Even if a method of increasing the sensitivity of the pressure transducer by thinning the diaphragm, installing more pleats around the diaphragm, or making the diaphragm with a material rich in elasticity, the diameter of the narrow tube It was revealed that the peak of the viscosity signal tails in the same manner as when the value was reduced.

JP 59-160740 A Japanese National Patent Publication No. 11-514744

In order to solve the problems of the prior art, the inventors previously
A liquid inflow path and a liquid outflow path, and four capillaries having substantially the same flow path resistance,
Two thin tubes connected in series, a series pair of the thin tubes connected in parallel to the inflow channel and the outflow channel, and the equilibrium bridge type viscosity in which the midpoint of each series pair is pressure-connected via a diaphragm In total
Installed between the downstream tube and the middle point of either one of the series pair capillaries, the liquid flowing in via the front tube, staying while the sample liquid passes through the rear tube of the other serial pair capillaries, or A standard viscosity adjusting means for diluting and introducing a standard viscosity liquid into the latter capillary,
A mutation detection means for detecting a mutation relative to a reference position of the diaphragm;
A displacement restraining means for applying a displacement restraining force to the diaphragm so as to reduce the displacement of the diaphragm;
Viscosity calculation means for calculating the viscosity of the liquid from the displacement suppression force value by the displacement suppression means;
Has been invented, and the apparatus is capable of suppressing tailing of the viscosity signal and detecting a highly accurate change in viscosity at a small flow rate (Japanese Patent Application No. 2007-310186).

  However, in the device, the diaphragm is made of the same soft magnetic material as in the prior art. Therefore, when a direct current, which is a displacement suppression current, is applied to the coil to suppress the displacement of the diaphragm, the force acting on the diaphragm is only an attractive force, and a repulsive force cannot be applied. In addition, since the magnitude of the force is proportional to the square of the current, the feedback gain (the phase detector gain with respect to the differential pressure, the gain of the amplifier for passing the current, and the magnetic pressure applied to the diaphragm when the current is passed are all multiplied. Value) was proportional to the differential pressure input, and when the differential pressure was small, feedback could not be satisfactorily applied. Further, since the feedback gain is proportional to the differential pressure input, the amount of error between the differential pressure and the feedback magnetic pressure becomes a value proportional to the square root of the differential pressure value. Therefore, in order to obtain a signal proportional to the differential pressure, it is necessary to obtain the differential pressure signal using a square circuit or a digital arithmetic unit.

  An object of the present invention is to further improve the responsiveness of a viscometer even when a liquid chromatograph is carried out at a small flow rate.

The present invention made in view of the above problems includes the following inventions:
A first invention is a diaphragm including a magnetic material;
Coils disposed on both sides of the diaphragm;
Mutation detection means for magnetically detecting whether the diaphragm is close to and / or away from the coil;
A displacement suppression means for applying a displacement suppression current to any of the coils according to the displacement of the diaphragm;
A pressure transducer comprising:
The pressure transducer according to claim 1, wherein a part of the diaphragm is made of a hard magnetic material.

  A second invention is the pressure transducer according to the first invention, wherein the coil is wound around a core disposed on both sides of the diaphragm.

A third invention is the pressure transducer according to the first or second invention, wherein the diaphragm is at least
A disk part having a structure in which a flat plate made of hard magnetic material is sandwiched between two thin plates made of soft magnetic material,
Pleats surrounding the disk portion,
A fixed part on the outside of the pleat part,
The pressure transducer is characterized by comprising:

  According to a fourth aspect of the present invention, the coil for detecting the proximity and / or separation of the diaphragm and the coil for applying the displacement suppression current are the same coil. A pressure transducer as described.

  According to a fifth aspect, in the first to third aspects, the coil for detecting the proximity and / or separation of the diaphragm is different from the coil to which the displacement suppression current is applied. Pressure transducer.

  A sixth invention is a viscometer for liquid chromatography including the pressure transducer described in the first to fifth inventions.

  Hereinafter, the present invention will be described in detail.

  The diaphragm in the pressure transducer according to the present invention includes a disk part, a pleat part surrounding the disk part, and a fixed part outside the pleat part, and at least a part of the disk part is made of a hard magnetic material. The region made of a hard magnetic material in the disk portion only needs to include at least the center of the disk portion, but the displacement suppression current (DC current) is arranged perpendicularly to and in close proximity to the diaphragm. A region that is larger than the outer diameter of the central core of the E-type core that houses the coil for flowing the gas and smaller than the inner diameter of the outer core of the E-type core is preferable. Examples of the hard magnetic material include materials used for permanent magnets such as hard ferrite, AlNiCo, SmCo, NdFeB, PrCo, and PtFe. In particular, rare earth magnets such as SmCo and NdFeB have a high saturation magnetic flux density and a strong coercive force. Therefore, they can be said to be a preferable hard magnetic material in the diaphragm used in the present invention in that they can generate a large magnetic flux even if they are thin. In addition, when the differential pressure to be measured is small, it is not necessary to generate a large magnetic force. Therefore, in addition to the materials described above, magnetic stainless steel such as ferritic stainless steel (for example, SUS430) and martensitic stainless steel (for example, SUS410) is made hard magnetic. It may be used as a material.

  As one mode of the diaphragm (60) in the pressure transducer of the present invention, a flat plate in which the disk portion (61) is made of a hard magnetic material (100) shown in FIG. A diaphragm having a structure sandwiched between (111, 112) and the disk portion (61) shown in FIG. 3 (B) has a central portion made of a hard magnetic material (100) and a periphery made of a soft magnetic material (113). The diaphragm which consists of a structure which pinched | interposed the plane board comprised by a part with the two thin plates (116, 117) which consist of nonmagnetic materials can be illustrated. The material of the thin plates (111, 112) and the peripheral portion (113) made of the soft magnetic material is preferably a material having a saturation magnetic flux density larger than the external magnetic flux density of a permanent magnet made of the hard magnetic material, and considering corrosion resistance. Then, soft magnetic stainless steel such as electromagnetic stainless steel (for example, K-M31 (made by Tohoku Special Steel Co., Ltd.)) is particularly preferable. In addition, when using a material with insufficient corrosion resistance such as a magnetic steel sheet as the material of the thin plate (111, 112), the surface of the material is plated with a metal having high corrosion resistance such as gold, painted, or fluorine. It can be used as the material of the thin plate by improving the corrosion resistance by coating with a resin or the like. As the material of the thin plates (116, 117) made of the nonmagnetic material, nonmagnetic stainless steel having excellent spring properties and corrosion resistance can be used. Examples of the nonmagnetic stainless steel include spring stainless steel (for example, SUS301, SUS304, SUS304L) and a highly durable austenitic stainless steel (for example, SUS316). In FIGS. 3A and 3B, when the flat plate is sandwiched between the two thin plates, the flat plate and the thin plate are preferably in close contact with each other in order to withstand high line pressure. In addition, when a hollow part (120) is generated when the flat plate is sandwiched, the hollow part (120) is filled with a non-magnetic material (for example, non-magnetic resin, adhesive, or nonmagnetic stainless steel). Good.

As another embodiment of the diaphragm (60) in the pressure transducer of the present invention, in FIGS. 3 (A) and (B), a flat plate (FIG. 4 (A)) made of a hard magnetic material (100), or a hard magnetic material ( 100) and a flat plate (FIG. 4B) composed of a peripheral portion made of a soft magnetic material (113) is sandwiched between two soft magnetic materials or covered with a soft magnetic material, A diaphragm having a structure sandwiched between two thin plates (116, 117) made of a non-magnetic material can be given (FIGS. 4A and 4B).
The diaphragm shown in FIGS. 3B, 4A and 4B is independent of the soft magnetic material used to impart soft magnetism and the nonmagnetic material used to impart springiness and corrosion resistance. Therefore, the degree of freedom in material selection is improved as compared with the diaphragm shown in FIG.

  Although the DC current generation source in the pressure transducer of the present invention is not particularly limited, a circuit or device capable of setting a current flowing through the coil in proportion to the input signal is preferable, and a circuit in which a series resistor is connected to the output of the voltage amplification circuit A current output amplifier circuit that can regulate the output current in proportion to the input voltage, a constant voltage power source and a constant current power source that can control the output voltage and output current with an external signal can be exemplified. In addition, when an offset is set at the feedback operating point and only one of attractive force and repulsive force should be applied, a source that generates a voltage or current in a single direction can be used. It is more preferable that the output voltage or current can take both a positive value and a negative value depending on the polarity of the input signal because feedback can be applied without setting an offset. In the present invention, the direct current does not always mean a constant current, but means a constant current with respect to an alternating current of about several KHz used for measuring reluctance, and a change in differential pressure. In response to this, the direction of current flow and the magnitude of the current change.

  The coil through which a direct current flows in the pressure transducer of the present invention may be the same coil as the alternating current for detecting the differential pressure, or a coil different from the coil may be newly prepared. When direct current and alternating current are passed through the same coil, it is preferable to separate the direct current component and the alternating current component with a capacitor or choke coil so as not to couple each other. In addition, the coil which sends a direct current may be installed only in the one side of a diaphragm, and may be installed in both sides. In the former case, an attractive force or a repulsive force acts between the coil and the diaphragm depending on the direction in which the current flows. In the latter case, an attractive force acts between one coil and the diaphragm and a repulsive force acts between the other coil and the diaphragm by flowing the current in the reverse direction. Conversely, when a repulsive force acts between one coil and the diaphragm, an attractive force acts between the other coil and the diaphragm. Furthermore, the coil for passing the direct current can be incorporated inside the pressure transducer of the present invention, and by adopting the configuration, the transducer can generate a force even with a small current. Note that when a magnetic force is applied to the diaphragm from the outside of the transducer, the distance from the diaphragm becomes long, so that a stronger magnetic field needs to be generated. However, the problem can be solved by using a large electromagnet. Further, when the coil for passing the direct current is installed outside the transducer, there is an advantage that heat generated by passing the current is not directly transmitted to the pressure transducer. In any of the above cases, the magnitude of the current and the force applied to the transducer are substantially proportional.

  In a conventional diaphragm made of a soft magnetic material, a force could be applied to the diaphragm by passing an electric current through the coil. However, the force was always an attractive force, which was a strength proportional to almost the square of the current. In other words, since no repulsive force could be applied, it was necessary to install a coil for passing a direct current on both sides of the diaphragm, and it was necessary to switch the coil for passing a direct current when the direction of the force changed. Further, since the force is approximately proportional to the square of the current, the feedback gain is proportional to the differential pressure input, and the displacement of the diaphragm cannot be suppressed where the differential pressure is small. In addition, when the current was close to zero, the coil that constantly passed a direct current switched when noise was present. If the pressure transducer of the present invention is used, the force changes linearly with respect to the current, so that a constant feedback gain can be obtained. Further, since the current flowing through one coil continuously changes from negative to positive and from positive to negative, feedback can be satisfactorily applied even near zero.

  As an embodiment of the viscometer including the transducer of the present invention, the viscometer shown in FIG. 1 can be given. The viscometer (10) includes four capillaries (21, 22, 23, 24). The capillaries of capillaries 21 and 23, and the capillaries of 22 and 24 are connected in series to the inflow path and the outflow path, respectively. ing. A viscosity adjusting tube (40) made of a dilution tube or a delay tube is disposed between the thin tube 22 and the thin tube 24. Here, as the dilution tube, a hollow cylindrical tube having a sufficiently large internal volume and in which the internal liquid is stirred with a stirrer is used, and as the delay tube, a cylinder filled with glass beads having a particle size of several hundreds μm, etc. Many tubes (columns) are used. A bridge is formed between the midpoint 31 of the flow path from the thin tube 21 to the thin tube 23 and the midpoint 32 of the flow path from the thin tube 22 to the thin tube 24. The bridge has a midpoint of the present invention. A pressure transducer (50) is arranged. The volume of the liquid part in the viscosity adjusting tube (40) is selected so as to be larger than the volume of the eluent (carrier liquid) necessary for eluting the analyte. When the pressure loss of the viscosity adjusting tube (40) is not negligible, the pressure adjusting tube (40) is adjusted so that the pressure loss of the thin tube 24 and the pressure loss of the thin tube 23 are equal. With such a viscosity adjusting tube (40), the sample liquid flowing in through the thin tube 22 does not flow into the thin tube 24 during the detection period, and the reference viscosity fluid (usually the carrier liquid) flows into the thin tube 24, or the sample The liquid is sufficiently diluted and adjusted to have the same viscosity as that of the carrier liquid and flows into the thin tube 24.

  When the sample liquid is flowed from the inflow path A, the pressure loss of the thin tubes 21 and 22 changes equally until the polymer substance dissolved in the carrier liquid reaches the midpoint (31, 32), while the pressure loss of the thin tubes 23 and 24 also changes. Since they are equal, there is no pressure difference between the midpoints (31, 32). However, when the polymer material passes through the midpoints (31, 32), in section B, the pressure loss of the capillary tube 23 changes due to the viscosity derived from the polymer material, whereas in section C, the polymer material adjusts the viscosity. Since pressure loss does not occur until it stays in the tube (40) and reaches the thin tube 24, a differential pressure is generated between the midpoints (31, 32).

  Then, based on the displacement detection of the diaphragm (60) by the pressure transducer (50), the displacement suppression means (70) applies a suppression force to the diaphragm (60) so as to suppress the displacement, and the viscosity is determined based on the suppression force value. The computing means (80) outputs the viscosity at that time.

  The pressure transducer of the present invention is characterized in that a part of the diaphragm is made of a hard magnetic material. In the pressure transducer of the present invention, the magnetic force applied to the diaphragm is proportional to the magnitude of the applied direct current including the sign. As a result, feedback is effective from a weak differential pressure to a large differential pressure, and the linearity between the differential pressure and the output signal is improved. Furthermore, in the prior art, when the differential pressure is close to zero, the coil through which the current flows is switched. Therefore, when the signal becomes inaccurate or there is only one coil through which the direct current flows, the feedback system offset is Although necessary, the above-mentioned problem was solved by using the pressure transducer of the present invention, and the differential pressure can be measured more precisely.

  By applying feedback to suppress the displacement of the diaphragm using the pressure transducer of the present invention, a viscometer using an inner diameter of about 0.1 mm and a narrower tube than the conventional one and / or a diaphragm with high sensitivity and easy displacement. Even with the viscometer used, a highly symmetrical signal can be obtained without tailing the viscosity signal. Therefore, the viscometer including the pressure transducer of the present invention is particularly preferable as a viscometer for a semi-micro liquid chromatograph in which a small flow rate is passed.

  Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

Example 1 Transducer of the Present Invention (Part 1)
One embodiment of the transducer (50) of the present invention is shown in FIG. The E core (91, 92) is made of soft ferrite, the outer diameter of the central core is 8.0 mm, and the inner diameter of the outer core is 15 mm. The disk portion (61) of the diaphragm (60) has a flat plate (100) having a thickness of 0.8 mm and a diameter of 12 mm made of an NdFeB magnet at the center, and the flat plate is made of soft magnetic stainless steel thin plates (111, 112). ). The distance between the two stainless steel plates (111, 112) is constant from the center to a diameter of 19 mm, and is bonded to the outside. The gap (120) with the flat plate (100) is filled with a non-magnetic material such as resin or non-magnetic stainless steel so as to withstand high line pressure. Coils (93, 94) are wound around bobbins (not shown) on the left and right E cores (91, 92), respectively, and direct current and alternating current are superimposed and flowed. Here, the choke coil and the capacitor are appropriately separated so that the DC circuit and the AC circuit are not coupled. Each coil may be connected in series to the DC supply source or may be connected in parallel. Moreover, you may send a direct current to two coils using a positive / negative direct current supply source. In either case, a current is passed so that the magnetic poles created by the two coils face each other like NN or SS.

  When the diaphragm (60) is displaced, a difference occurs in the electrical characteristics of the reluctance detection coils (93, 94), so that the voltage between the transformer midpoint (161) and the coil midpoint (162) is phase amplified. Thus, an error signal can be taken out. The error signal is further amplified by a DC supply source or the like, and a current is passed through the coil in a direction to reduce the error signal. As for the viscosity signal, the voltage or current may be extracted from the output of the current supply source as shown in FIG. 6, or the output voltage of the phase amplification circuit may be extracted as shown in FIG.

Example 2 Transducer of the Present Invention (Part 2)
Another embodiment of the transducer (50) of the present invention is shown in FIG. The E core (91, 92) and the diaphragm (60) are the same as in the first embodiment. Two sets of coils (93, 94, 95, 96) are wound around bobbins (not shown) on the left and right E cores (91, 92), respectively, and reluctance detection is performed on one set of coils (93, 94). For this purpose, an alternating current is applied, and a direct current is applied to the other set of coils (95, 96). Each coil may be connected in series (FIG. 9) or connected in parallel (FIG. 10) to the DC supply source. Moreover, you may send a direct current to two coils using a positive / negative direct current supply source. In either case, the current may be passed so that the magnetic poles formed by the two coils face each other like NN or SS.

  When the diaphragm (60) is displaced, a difference occurs in the electrical characteristics of the reluctance detection coils (95, 96), so that the voltage between the transformer midpoint (161) and the coil midpoint (162) is phase-amplified. Thus, an error signal can be taken out. The error signal is further amplified by a DC supply source or the like, and a current is passed through the coil in a direction to reduce the error signal. As in the first embodiment, the viscosity signal may be amplified by extracting the output voltage of the phase amplification circuit, or the voltage or current may be extracted from the output of the current supply source.

Example 3 Viscometer of the present invention (Part 1)
An example in which the viscometer of the present invention equipped with the transducer described in Example 1 is applied to a liquid chromatograph is shown below.

A schematic configuration of a liquid chromatograph apparatus (180) to which the present invention is applied is shown in FIG. 11 includes an analysis column (181), a detector (182) arranged on the downstream side of the column (181), and an eluent (carrier liquid) (183) in the analysis column (181). And a pump (184) for supplying the sample and an injection valve (185) capable of injecting a sample upstream of the analytical column (181). And the viscometer (10) of this invention is installed between the analysis column (181) and the detector (182).

  The viscometer (10) has the same configuration as that of FIG. 1 except that the pressure transducer (50) has the configuration of the first embodiment. When a differential pressure is generated between the midpoints (31, 32) of the narrow tube, the diaphragm (60) tries to displace due to the differential pressure, but the magnetic force also acts in the direction to suppress the displacement, so the displacement of the diaphragm (60) Is suppressed. When the gain of the feedback system is set so that the feedback gain becomes 100, the displacement amount of the diaphragm is suppressed to 1/100, and as a result, the peak tailing in the liquid chromatography is suppressed to be small.

Example 4 Viscometer of the Present Invention (Part 2)
An example in which the viscometer of the present invention equipped with the transducer described in Example 2 is applied to a liquid chromatograph is shown below.

FIG. 11 shows a schematic configuration (180) of a liquid chromatograph apparatus to which the present invention is applied. The viscometer (10) has the same configuration as that of FIG. 1 except that the pressure transducer (50) has the configuration of the second embodiment. Although the coil for supplying the direct current is provided separately from the coil for supplying the alternating current, the tailing of the peak in the liquid chromatography can be kept small as in the third embodiment.

In size exclusion chromatography, the output of the viscometer depends on the concentration and the hydrodynamic size of the molecule. On the other hand, the ultraviolet absorption detector and the differential refractive index detector are proportional to the concentration. In addition, by using the present invention, peak tailing does not occur even in liquid chromatography performed under conditions where the flow rate of the eluent is low. Therefore, by combining a viscometer with an ultraviolet absorption detector or a differential refractive index detector, it is possible to extract a small amount of information on the size of the analyte, and from the size information, the molecular weight, the shape of the molecule, Information on hardness and the like can be obtained.

The block diagram of the viscometer which concerns on this invention. The block diagram of the pressure transducer in a prior art. The diaphragm used for the pressure transducer of the present invention. The diaphragm used for the pressure transducer of the present invention. The block diagram of the pressure transducer of this invention. The circuit diagram of the pressure transducer of the present invention. The circuit diagram of the pressure transducer of the present invention. The block diagram of the pressure transducer of this invention. The circuit diagram of the pressure transducer of the present invention. The circuit diagram of the pressure transducer of the present invention. The block diagram of the liquid chromatograph apparatus to which the viscometer which concerns on this invention is applied.

Explanation of symbols

10: Viscometer
21, 22, 23, 24: narrow tubes 31 and 32: midpoint 40 of each bridge: viscosity adjusting tube 50: pressure transducer 60: diaphragm 61: diaphragm disk portion 62: diaphragm fold portion 70: displacement suppressing means 80: viscosity Calculation means 91, 92: E core 93, 94, 95, 96: Coil 97, 98: Choke coil 100: Hard magnetic material 111, 112, 113, 114, 115: Soft magnetic material 116, 117: Nonmagnetic material 120: Hollow part 130: Oscillator 140: Transformer 151: Difference amplification circuit 152: Phase detection circuit 153: Amplification circuit 161, 162: Midpoint 171: Reluctance signal 172: Viscosity signal 173: Reference voltage 180: Liquid chromatograph 181: Analysis column 182: Detector 183: Eluent (carrier liquid)
184: Pump 185: Injection valve

Claims (6)

A diaphragm including a magnetic material;
Coils disposed on both sides of the diaphragm;
Mutation detection means for magnetically detecting whether the diaphragm is close to and / or away from the coil;
A displacement suppression means for applying a displacement suppression current to any of the coils according to the displacement of the diaphragm;
A pressure transducer comprising:
The pressure transducer according to claim 1, wherein a part of the diaphragm is made of a hard magnetic material. The pressure transducer according to claim 1, wherein the coil is wound around a core disposed on both sides of the diaphragm. The pressure transducer according to claim 1 or 2, wherein the diaphragm is at least
A disk part having a structure in which a flat plate made of hard magnetic material is sandwiched between two thin plates made of soft magnetic material,
Pleats surrounding the disk portion,
A fixed part on the outside of the pleat part,
The pressure transducer comprising: 4. The pressure transducer according to claim 1, wherein a coil for detecting proximity and / or separation of the diaphragm and a coil to which the displacement suppression current is applied are the same coil. 5. The pressure transducer according to claim 1, wherein a coil for detecting proximity and / or separation of the diaphragm and a coil to which the displacement suppression current is applied are different coils. A liquid chromatograph viscometer comprising the pressure transducer according to claim 1.

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