System for measuring a physical variable

• US 8,353,210 B2
• Filed: 10/30/2007
• Issued: 01/15/2013
• Est. Priority Date: 12/01/2006
• Status: Active Grant

• Current Assignee: Tecan Trading AG (Tecan Group AG)
• Original Assignee: Tecan Trading AG (Tecan Group AG)
• Inventors: Kamm, Lars, Hinn, Werner, Baumann, Roman
• Primary Examiner(s): Williams, Hezron E
• Assistant Examiner(s): NGUYEN, HOANG T
• Application Number:
  US12/516,491
• Publication Number:
  US 20100071459A1
• Time in Patent Office: 1,904 Days
• Field of Search: 733/04.R, 733/04.C, 324649-724
• US Class Current: 73/304.C
• CPC Class Codes: G01D 3/036 on measuring arrangements themselves
• CPC Class Codes: G01D 5/24 by varying capacitance
• CPC Class Codes: G01L 1/144 with associated circuitry G01L1/146 and G01L1/148 take precedence
• CPC Class Codes: G01L 1/146 for measuring force distributions, e.g. using force arrays G01L1/148 takes precedence
• CPC Class Codes: G01R 27/2605 Measuring capacitance capacitive sensors G01D5/24
• CPC Class Codes: G06F 2203/04107 Shielding in digitiser, i.e. guard or shielding arrangements, mostly for capacitive touchscreens, e.g. driven shields, driven grounds
• CPC Class Codes: G06F 3/044 by capacitive means

Abstract

The invention relates to a system for measuring a physical variable using a plurality of measuring sensors (20). Said system is characterized in that an inverting measuring signal amplifier (17; 17.1, 17.2) is connected downstream of every measuring sensor (20), one output of a sensor (20) each being connected to an inverting input of the measuring signal amplifier (17; 17.1, 17.2) connected downstream of the measuring sensor (20).

Claims

1. A system for measuring a physical value having multiple capacitive measuring sensors (20) and an inverting measuring signal amplifier (17;

17.1, 17.2) being connected downstream from each measuring sensor (20), one output of a measuring sensor (20) being connected to an inverting input of the inverting measuring signal amplifier (17;

17.1, 17.2) connected downstream from the measuring sensor (20) in each case, characterized in that

a reference sensor (21) is associated with each measuring sensor (20), whereby an inverting reference signal amplifier (22) is connected downstream of said reference sensor 21, one output of the reference sensor (21) being connected to an inverting input of the inverting reference signal amplifier (22),

a signal generator (26) is associated with each measuring sensor (20) and reference sensor (21),

and means for subtracting the output signal of the inverting reference signal amplifier (22) from the output signal of the inverting measuring signal amplifier (17;

17.1, 17.2) in order to output a differential signal (V_out1) as output signal.

2. The system according to claim 1, characterized in that the receiver electrodes (E;

E1, E2, E3, E4) are situated in a spatial plane and no shielding is provided in the spatial plane between the receiver electrodes (E;

E1, E2, E3, E4).

3. The system according to claim 1, characterized in that an integrator (19;

23) is connected downstream from each inverting measuring signal amplifier (17;

17.1, 17.2), to whose inverting input an output signal of the inverting measuring signal amplifier (17;

17.1, 17.2) is applied, wherein the differential signal (V_out1) of the integrator (23) forms the integrated difference of the output signal of the inverting measuring signal amplifier (17;

17.1, 17.2) and the output signal of the inverting reference signal amplifier (22).

4. The system according to claim 1, characterized in that an integrator (25) is connected downstream from the inverting reference signal amplifier (22), to whose inverting input an output signal of the inverting reference signal amplifier (22) is applied.

5. The system according to claim 4, characterized in that an output signal of the inverting measuring signal amplifier (17;

17.1, 17.2), to which the measuring sensor (20) is connected downstream, with which the reference sensor (21) is associated, to which the inverting reference signal amplifier (22) is connected downstream, is applied to the non-inverting input of the integrator (25) downstream from the inverting reference signal amplifier (22).

6. The system according to claim 1, characterized in that the inverting measuring signal amplifier (17;

17.1, 17.2) and/or the inverting reference signal amplifier (22) are each implemented as a high-pass filter.

7. The system according to claim 1, characterized in that the multiple measuring sensors (20) are formed by a transmitter electrode (S) and multiple receiver electrodes (E;

E1, E2, E3, E4), the receiver electrodes (E;

E1, E2, E3, E4) being situated spaced apart from the transmitter electrode (S).