Polarographic densitometer

• US 7,123,019 B2
• Filed: 05/25/2005
• Issued: 10/17/2006
• Est. Priority Date: 06/23/2004
• Status: Expired due to Fees

• Current Assignee: Tanita Corporation (Tanita)
• Original Assignee: Tanita Corporation (Tanita)
• Inventors: Harima, Shinichi
• Primary Examiner(s): Nguyen, Vincent Q.
• Assistant Examiner(s): Dole, Timothy J.
• Application Number:
  US11/136,576
• Publication Number:
  US 20050285599A1
• Time in Patent Office: 510 Days
• Field of Search: 324/464, 324/713, 399/74
• US Class Current: 324/464
• CPC Class Codes: G01N 27/4045 for gases other than oxygen

Abstract

A polarographic densitometer has a voltage applying circuit, a sensor unit, an impedance reduction circuit, and a current/density conversion unit. The voltage applying circuit applies specified voltage, and the sensor unit includes a group of electrodes to produce a current output in response to any reaction caused in a specimen when the specified voltage is applied by the voltage applying circuit. Furthermore, the impedance reduction circuit reduces impedance of the specimen between the electrodes of the group, and the current/density conversion unit converts the current output of the sensor unit when the impedance is reduced by the impedance reduction circuit into the density of specific material in the specimen.

Claims

1. A polarographic densitometer, comprising:

a voltage applying circuit;

a sensor unit;

an impedance reduction circuit; and

a current/density conversion unit, wherein said voltage applying circuit applies specified voltage, said sensor unit includes a group of electrodes to produce a current output in response to any reaction caused in a specimen when the specified voltage is applied by said voltage applying circuit, said impedance reduction circuit reduces impedance of the specimen between said electrodes of the group to stabilize the reaction caused in the specimen, and said current/density conversion unit converts the current output of said sensor unit when the impedance is reduced by said impedance reduction circuit into the density of specific material in the specimen.

2. A polarographic densitometer according to claim 1 in which if the specimen is liquid the densitometer further comprises an electric conductivity measurement unit, said conductivity measurement unit measures the electric conductivity of the liquid specimen between any of electrodes of the group, and

said current/density conversion unit converts the current output of said sensor unit in proportion to the electric conductivity measured by said electric conductivity measurement unit into the density of specific material in the liquid specimen.

3. A polarographic densitometer according to claim 1 in which if the specimen is liquid the densitometer further comprises:

an immersion measurement unit; and

an impedance reduction circuit switching unit, wherein

said immersion measurement unit determines that said sensor unit is immersed in the liquid between any of the electrodes of the group within a standby interval before said current/density conversion unit starts to convert the current output into the density of specific material, and

the impedance reduction circuit switching unit switches the impedance reduction circuit to no-connection mode for a period during which determination is done by said immersion measurement unit within the standby interval.

4. A polarographic densitometer according to claim 2 in which if the specimen is liquid the densitometer further comprises:

an immersion measurement unit; and

an impedance reduction circuit switching unit, wherein

said immersion measurement unit determines that said sensor unit is immersed in the liquid between any of the electrodes of the group within a standby interval before said current/density conversion unit starts to convert the current output into the density of specific material, and

the impedance reduction circuit switching unit switches the impedance reduction circuit to no-connection mode for a period during which determination is done by said immersion measurement unit within the standby interval.

5. A polarographic densitometer according to any one of claims 1 to 3 or 4 in which said group of electrodes consists of a counter/reference electrode to which the specified voltage is applied by said voltage applying circuit and a plurality of working electrodes each having different area to produce the current in response to any reaction caused in the specimen in conjunction with said counter/reference electrode,

said impedance reduction circuit reduces the impedance of the specimen between said counter/reference electrode and each of said working electrodes, and

a working electrode switching unit is provided for switching the connection of the plurality of working electrodes in such order that the working electrode having the smallest area is initially connected.

6. A polarographic densitometer according to any one of claims 1 to 3 or 4 in which said group of electrodes consists of a reference electrode by which a reference voltage is developed in the specimen for providing the specified voltage output from said voltage applying circuit, a counter electrode to which the specified voltage output from said voltage applying circuit is applied, and a plurality of working electrodes each having different area to produce the current in response to any reaction caused in the specimen in conjunction with said counter/reference electrode,

said impedance reduction circuit reduces the impedance of the specimen between said counter electrode and each of said working electrodes, and

a working electrode switching unit is provided for switching the connection of the plurality of working electrodes in such order that the working electrode having the smallest area is initially connected.

7. A polarographic densitometer according to any one of claims 1 to 3 or 4 in which said voltage applying circuit includes a voltage follower to which a basic voltage for said group of electrodes to only react with specific material of the specimen is input and from which the specified voltage is output, and

said group of electrodes consists of a counter/reference electrode to which the specified voltage is applied from the output of said voltage follower and a working electrode for providing the current in response to any reaction caused in the specimen in conjunction with said counter/reference electrode.

8. A polarographic densitometer according to any one of claims 1 to 3 or 4 in which said voltage applying circuit includes a voltage follower to which a basic voltage for said group of electrodes to only react with specific material of the specimen is input and from which the specified voltage is output, and

said group of electrodes consists of a reference electrode by which a reference voltage is developed in the specimen for providing the specified voltage output from said voltage applying circuit, a counter electrode to which the specified voltage output from said voltage follower is applied, and a working electrode for providing the current in response to any reaction caused in the specimen in conjunction with said counter electrode.

9. A polarographic densitometer according to any one of claims 1 to 3 or 4 in which said voltage applying circuit includes a potentiostat to which a basic voltage for said group of electrodes to only react with specific material of the specimen and a reference voltage developed in the specimen are input and from which the specified voltage is output, and

said group of electrodes consists of a reference electrode by which a reference voltage is developed in the specimen for providing the specified voltage output from said voltage applying circuit, a counter electrode to which the specified voltage output from said potentiostat is applied, and a working electrode for providing the current in response to any reaction caused in the specimen in conjunction with said counter/reference electrode.

10. A polarographic densitometer according to any one of claims 1 to 3 or 4 in which it further comprises an offset current calibration unit, said calibration unit calibrates any offset current that may be caused when the specified voltage is applied by said voltage applying circuit.

11. A polarographic densitometer according to any one of claims 1 to 3 or 4 in which it further comprises:

a current amplifier circuit; and

an amplifying factor control unit, wherein

said current amplifier circuit amplifies the current output from the sensor when the impedance is reduced by said impedance reduction circuit, and

said amplifying factor control unit controls the amplifying factor for the current from said current amplifier circuit.

12. A polarographic densitometer according to any one of claims 1 to 3 or 4 in which said voltage applying circuit applies the specified voltage that is variable, and the densitometer further comprises:

a selection unit; and

a specified voltage controller unit, wherein

said selection unit selects any density of specific material from among a plurality of densities, and

said specified voltage controller unit provides variable control to produce such specified voltage from said voltage applying circuit that causes reaction of said group of electrodes with the specimen in proportion to the density of specific material selected by said selection unit.