Automated analysis device

Abstract

The present invention relates to an automatic analysis device. The object is to improve the accuracy of liquid level detection. The means for solving the problem is that the automatic analysis device according to the embodiments has a probe and a liquid level detection mechanism. The liquid level detection mechanism is electrically connected to the probe and detects contact of the probe with the liquid level. The liquid level detection mechanism includes an adjustment unit that adjusts the electrostatic capacity of a capacitor of an electric circuit for the liquid level.

Description

[0001] Cross-references to related applications:

[0002] This application is based on and enjoys priority of Japanese Patent Application 2021-042301, filed on March 16, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments of the present invention relate to an automatic analysis device. Background Technology

[0004] Conventionally, liquid level detection circuits are known in automated analysis devices for detecting contact between a probe and a liquid surface. These circuits use differentially input signals to detect the liquid level. For example, one of the differential inputs of the liquid level detection circuit is connected to the probe, while the other is open. Liquid level detection is performed by detecting changes in the amplitude and phase of the signal generated by the impedance change accompanying the probe's contact with the liquid surface. Furthermore, these liquid level detection circuits sometimes include an automatic phase-shifting circuit that treats the differentially input signal as zero when the probe is not in contact with the liquid surface. This automatic phase-shifting circuit enables the output to be zero when the probe is not in contact with the liquid surface.

[0005] However, while the aforementioned automatic phase-shifting circuit can absorb output deviations related to the individual probe, it does not take into account the equipment used with the probe. These devices include, for example, perforated needles that make holes in the container lid, and heaters that heat the reagent in the probe. If these devices are connected to the liquid level detection circuit, the automatic phase-shifting circuit alone may not be able to absorb the output deviations, leading to a decrease in the accuracy of liquid level detection.

[0006] Existing technical documents:

[0007] Japanese Patent Application Publication No. 63-259420 Summary of the Invention

[0008] The problem to be solved by this invention is to improve the accuracy of liquid level detection.

[0009] The automated analysis apparatus according to the embodiment includes a probe and a liquid level detection mechanism. The liquid level detection mechanism is electrically connected to the probe and detects the contact between the probe and the liquid surface. The liquid level detection mechanism includes an adjustment section for adjusting the electrostatic capacitance of the capacitor in the circuit used for the liquid surface.

[0010] The purpose of the invention is to improve the accuracy of liquid level detection. Attached Figure Description

[0011] Figure 1 This is a diagram illustrating the functional configuration of the automatic analysis device according to the first embodiment.

[0012] Figure 2 This is an example Figure 1 A diagram showing the structure of the analytical organization.

[0013] Figure 3 This is a diagram illustrating the configuration of the liquid level detection circuit in the first embodiment.

[0014] Figure 4 This is a diagram illustrating the sample dispensing probe and perforation needle in the first embodiment.

[0015] Figure 5 This is an example Figure 4 The diagram shows the movement of the sample dispensing probe and the perforating needle.

[0016] Figure 6 This is a diagram illustrating the connection of the bridge circuit, capacitor adjustment circuit, perforation needle, and sample dispensing probe in the first embodiment.

[0017] Figure 7 This is a diagram illustrating the configuration of the liquid level detection circuit in the second embodiment.

[0018] Figure 8 This is a diagram illustrating the first reagent dispensing probe and heater in the second embodiment.

[0019] Figure 9 This is a diagram illustrating the connection of the bridge circuit, capacitor adjustment circuit, heating shroud, and first reagent dispensing probe in the second embodiment.

[0020] Figure 10 This is a diagram illustrating the connection between the bridge circuit and the capacitor adjustment circuit in the third embodiment.

[0021] Figure 11 This is an existing diagram illustrating the configuration of a liquid level detection circuit.

[0022] Figure 12 This is an existing diagram illustrating the connection between the bridge circuit and the sample dispensing probe.

[0023] Figure 13 This is an example Figure 11 The existing diagram shows the configuration of the automatic phase-shifting circuit.

[0024] Explanation of reference numerals in the attached figures

[0025] 1…Automatic analysis device, 2…Analytical mechanism, 3…Analytical circuit, 4…Drive mechanism, 5…Input interface, 6…Output interface, 7…Communication interface, 8…Storage circuit, 9…Control circuit, 21, 21A, LDC…Liquid level detection circuit, 100…Reagent container, 201…Reaction tray, 2011…Reaction vessel, 202…Thermostatic section, 203…Rack sampler, 2031…Sample holder, 2032…Sample container, 20321…Lid, 204…First reagent storage, 205… 2nd reagent storage, 206…sample dispensing arm, 207…sample dispensing probe, 2071…perforation needle, 208…first reagent dispensing arm, 209…first reagent dispensing probe, 2091…heating shroud, 2092…heater, 210…second reagent dispensing arm, 211…second reagent dispensing probe, 212…electrode unit, 213…photometer unit, 214…cleaning unit, 215…stirring unit, 330, 330A…differential amplifier circuit, 360, 360A…amplifier circuit. Detailed Implementation

[0026] The automated analysis apparatus according to the embodiment includes a probe and a liquid level detection mechanism. The liquid level detection mechanism is electrically connected to the probe and detects the contact between the probe and the liquid surface. The liquid level detection mechanism includes an adjustment section for adjusting the electrostatic capacitance of the capacitor in the circuit used for the liquid surface.

[0027] Hereinafter, embodiments of the automatic analysis device will be described in detail with reference to the accompanying drawings.

[0028] (First Embodiment)

[0029] Figure 1 This is a diagram illustrating the functional configuration of the automatic analysis device 1 according to the first embodiment. Figure 1 The automatic analysis device 1 includes an analysis mechanism 2, an analytical circuit 3, a drive mechanism 4, an input interface 5, an output interface 6, a communication interface 7, a storage circuit 8, and a control circuit 9. The automatic analysis device 1 measures the components within the test object by measuring the mixture of the test object and the sample.

[0030] The analysis unit 2 mixes a standard sample or a test sample (also referred to as the test object) with reagents used in the various tests specified for that sample. The analysis unit 2 measures the mixture of sample and reagents, generating standard data and test data, for example, expressed as absorbance. Furthermore, the analysis unit 2 has a liquid level detection circuit 21 (liquid level detection mechanism). A detailed description of the liquid level detection circuit 21 will be provided later.

[0031] The parsing circuit 3 is a processor that parses the standard data and test data generated by the analysis unit 2 to generate calibration data and analytical data. The parsing circuit 3 reads the parsing program from the storage circuit 8 and generates calibration data and analytical data according to the read parsing program. For example, based on the standard data, the parsing circuit 3 generates calibration data that represents the relationship between the standard data and a pre-set standard value for a standard sample. Additionally, based on the test data and the calibration data for the corresponding test item, the parsing circuit 3 generates analytical data, expressed as concentration values ​​and enzyme activity values. The parsing circuit 3 outputs the generated calibration data and analytical data to the control circuit 9.

[0032] The drive mechanism 4, under the control of the control circuit 9, drives the analysis mechanism 2. The drive mechanism 4 is implemented, for example, by gears, stepper motors, conveyor belts, and lead screws.

[0033] Input interface 5, for example, receives settings for analytical parameters of various examination items related to the sample to be measured, either from the operator or via the hospital's intranet NW. Input interface 5 is implemented, for example, by a mouse, keyboard, or touchpad for inputting instructions via a touch operating surface. Input interface 5 is connected to control circuit 9, converts the operation instructions input by the operator into electrical signals, and outputs the electrical signals to control circuit 9.

[0034] Furthermore, in this specification, the input interface 5 is not limited to interfaces with physical operating components such as a mouse, keyboard, and touchpad. For example, a processing circuit that accepts electrical signals corresponding to operating instructions input from an external input device that is separately located relative to the automatic analysis device 1, and outputs such electrical signals to the control circuit 9, is also included in the example of the input interface 5.

[0035] Output interface 6 is connected to control circuit 9 and outputs signals supplied from control circuit 9. Output interface 6 may be implemented by, for example, a display circuit, a printing circuit, and a sound device. The display circuit may include, for example, a CRT monitor, a liquid crystal display (LCD), an organic EL monitor, an LED monitor, and a plasma display. Furthermore, the display circuit may also include processing circuitry that converts data representing the displayed object into video signals and outputs the video signals externally. The printing circuit may include, for example, a printer. Furthermore, the printing circuit may also include output circuitry that outputs data representing the printed object to externally. The sound device may include, for example, a speaker. Furthermore, the sound device may also include output circuitry that outputs sound signals to externally.

[0036] Communication interface 7 is connected, for example, to the hospital intranet NW. Communication interface 7 communicates with the HIS (Hospital Information System) via the hospital intranet NW. Furthermore, communication interface 7 can also communicate with the HIS via the Laboratory Information System (LIS) connected to the hospital intranet NW.

[0037] The storage circuit 8 includes a recording medium that can be read by a processor, such as a magnetic recording medium, an optical recording medium, or a semiconductor memory. Furthermore, the storage circuit 8 does not necessarily need to be implemented using a single storage device. For example, the storage circuit 8 can also be implemented using multiple storage devices.

[0038] In addition, storage circuit 8 stores the analysis program executed by analysis circuit 3, as well as the control program used to implement the functions of control circuit 9. Storage circuit 8 stores the analysis data generated by analysis circuit 3 for each examination item. Storage circuit 8 stores examination instructions input by the operator, or examination instructions received via the hospital intranet NW through communication interface 7.

[0039] The control circuit 9 is a processor that functions as the central hub of the automatic analysis device 1. The control circuit 9 executes the control program stored in the storage circuit 8 to perform the functions corresponding to the executed control program. Furthermore, the control circuit 9 may also have a storage area for storing at least a portion of the data stored in the storage circuit 8.

[0040] Figure 2 This is an example Figure 1 The diagram shows the composition of the analysis unit 2. Figure 2 The analytical unit 2 shown includes a reaction plate 201, a temperature control unit 202, a rack sampler 203, a first reagent storage compartment 204, and a second reagent storage compartment 205. Additionally, the analytical unit 2 includes a sample dispensing arm 206, a sample dispensing probe 207, a first reagent dispensing arm 208, a first reagent dispensing probe 209, a second reagent dispensing arm 210, a second reagent dispensing probe 211, an electrode unit 212, a photometric unit 213, a cleaning unit 214, and a stirring unit 215.

[0041] The following will first describe the reaction tray 201, the constant temperature section 202, the rack sampler 203, the first reagent storage 204, and the second reagent storage 205.

[0042] The reaction disk 201 holds multiple reaction vessels 2011 arranged in a ring. The reaction disk 201 transports the multiple reaction vessels 2011 along a predetermined path. Specifically, the reaction disk 201 is driven by a drive mechanism 4 to alternately rotate and stop at predetermined time intervals (hereinafter referred to as one cycle), for example, at 4.5 seconds or 9.0 seconds. The reaction vessels 2011 are formed, for example, of glass, polypropylene (PP), or acrylic.

[0043] The thermostatic unit 202 stores a heat medium set to a predetermined temperature and immerses the reaction vessel 2011 in the stored heat medium, thereby raising the temperature of the mixture stored in the reaction vessel 2011.

[0044] The rack-type sampler 203 supports the sample holder 2031 in a movable manner. The sample holder 2031 can hold multiple sample containers 2032 that hold the samples to be measured. Figure 2 The example shown illustrates a sample holder 2031 capable of holding five sample containers 2032 side by side.

[0045] The rack-type sampler 203 includes a transport area for moving the sample holder 2031 from its placement position to its recovery position after measurement. Within this transport area, multiple sample holders 2031, neatly arranged along their shorter side, move in direction D1 via a drive mechanism 4.

[0046] Furthermore, in the rack sampler 203, a pull-in area is provided to move the sample container 2032 held by the sample holder 2031 towards a predetermined sample attraction position. This pulls the sample holder 2031 from the transport area. The sample attraction position is, for example, located where the rotation trajectory of the sample dispensing probe 207 intersects with the movement trajectory of the opening of the sample container 2032, supported by the rack sampler 203 and held by the sample holder 2031. In the pull-in area, the transported sample holder 2031 moves in direction D2 via the drive mechanism 4.

[0047] Additionally, the rack-type sampler 203 includes a return area for returning the sample holder 2031, which holds the sample container 2032 that has been attracted, to the transport area. In the return area, the sample holder 2031 moves in direction D3 via the drive mechanism 4.

[0048] The first reagent storage 204 refrigerates multiple reagent containers 100 storing the first reagent, which reacts with specified components contained in standard samples and test samples. Figure 2Not shown in the diagram, the first reagent storage compartment 204 is covered by a removable reagent cover. Inside the first reagent storage compartment 204, reagent trays are rotatably arranged. The reagent trays hold multiple reagent containers 100 arranged in a circular pattern. The reagent trays are rotated by a drive mechanism 4.

[0049] A first reagent aspiration position is set at a predetermined location on the first reagent storage 204. The first reagent aspiration position is, for example, set at the position where the rotation trajectory of the first reagent dispensing probe 209 intersects with the movement trajectory of the opening of the reagent container 100 arranged in a ring on the reagent holder.

[0050] The second reagent storage 205 refrigerates multiple reagent containers 100 storing the second reagent, which is paired with the first reagent to form a dual-reagent system. Figure 2 Not shown in the diagram, the second reagent storage compartment 205 is covered by a removable reagent cover. Inside the second reagent storage compartment 205, reagent racks are arranged in a rotatable manner. The reagent racks arrange and hold multiple reagent containers 100 in a circular shape. Furthermore, the second reagent refrigerated in the second reagent storage compartment 205 and the first reagent refrigerated in the first reagent storage compartment 204 can be reagents of the same composition and concentration.

[0051] A second reagent aspiration position is set at a predetermined location on the second reagent storage 205. The second reagent aspiration position is, for example, set at the position where the rotation trajectory of the second reagent dispensing probe 211 (described later) intersects with the movement trajectory of the opening of the reagent container 100 arranged in a ring on the reagent holder.

[0052] Next, the sample dispensing arm 206, sample dispensing probe 207, first reagent dispensing arm 208, first reagent dispensing probe 209, second reagent dispensing arm 210, second reagent dispensing probe 211, electrode unit 212, photometric unit 213, cleaning unit 214 and stirring unit 215 will be described.

[0053] The sample dispensing arm 206 is positioned between the reaction plate 201 and the rack sampler 203. The sample dispensing arm 206 is configured to move freely up and down in the vertical direction and rotate freely in the horizontal direction via the drive mechanism 4. The sample dispensing arm 206 holds the sample dispensing probe 207 at one end.

[0054] The sample dispensing probe 207 rotates along an arc-shaped trajectory, accompanying the rotation of the sample dispensing arm 206. The opening of the sample container, held by the sample holder 2031 on the rack sampler 203, is located on this rotation trajectory.

[0055] In addition, a sample ejection position is provided on the rotation trajectory of the sample dispensing probe 207 to eject the sample attracted by the sample dispensing probe 207 into the reaction vessel 2011. The sample ejection position is equivalent to the intersection of the rotation trajectory of the sample dispensing probe 207 and the movement trajectory of the reaction vessel 2011 held on the reaction plate 201.

[0056] In addition, the sample dispensing probe 207 is driven by the drive mechanism 4 to move directly above the opening of the sample container held by the sample holder 2031 on the rack sampler 203, or to move in the vertical direction at the sample ejection position.

[0057] Additionally, the sample dispensing probe 207, under the control of the control circuit 9, draws the sample from the sample container located directly below. Furthermore, under the control of the control circuit 9, the sample dispensing probe 207 ejects the drawn sample towards the reaction vessel 2011 located directly below the sample ejection position. For example, the sample dispensing probe 207 performs a series of dispensing actions, including one draw and one ejection, during one cycle.

[0058] The first reagent dispensing arm 208 is disposed, for example, between the reaction plate 201 and the first reagent reservoir 204. The first reagent dispensing arm 208 is configured to be able to move freely up and down in the vertical direction and rotate freely in the horizontal direction via the drive mechanism 4. The first reagent dispensing arm 208 holds the first reagent dispensing probe 209 at one end.

[0059] The first reagent dispensing probe 209 rotates along an arc-shaped trajectory, accompanying the rotation of the first reagent dispensing arm 208. A first reagent aspiration position is provided along this trajectory. Furthermore, a first reagent ejection position is set along the rotation trajectory of the first reagent dispensing probe 209 to eject the reagent aspirated by the probe 209 into the reaction vessel 2011. This first reagent ejection position corresponds to the intersection of the rotation trajectory of the first reagent dispensing probe 209 and the movement trajectory of the reaction vessel 2011 held by the reaction disk 201.

[0060] The first reagent dispensing probe 209 is driven by the drive mechanism 4, moving vertically along its rotational trajectory at either the first reagent aspiration position or the first reagent ejection position. Furthermore, under the control of the control circuit 9, the first reagent dispensing probe 209 aspirates the first reagent from the reagent container located directly below the first reagent aspiration position. Additionally, under the control of the control circuit 9, the first reagent dispensing probe 209 ejects the aspirated first reagent towards the reaction vessel 2011 located directly below the first reagent ejection position.

[0061] The second reagent dispensing arm 210 is, for example, disposed between the reaction plate 201 and the second reagent reservoir 205. The second reagent dispensing arm 210 is configured to be able to move freely up and down in the vertical direction and rotate freely in the horizontal direction via the drive mechanism 4. The second reagent dispensing arm 210 holds the second reagent dispensing probe 211 at one end.

[0062] The second reagent dispensing probe 211 rotates along an arc-shaped trajectory, accompanying the rotation of the second reagent dispensing arm 210. A second reagent aspiration position is provided along this trajectory. Furthermore, a second reagent ejection position is set along the rotation trajectory of the second reagent dispensing probe 211 to eject the reagent aspirated by the second reagent dispensing probe 211 into the reaction vessel 2011. The second reagent ejection position corresponds to the intersection of the rotation trajectory of the second reagent dispensing probe 211 and the movement trajectory of the reaction vessel 2011 held by the reaction disk 201.

[0063] The second reagent dispensing probe 211 is driven by the drive mechanism 4, moving vertically along its rotational trajectory at either the second reagent aspiration position or the second reagent ejection position. Furthermore, under the control of the control circuit 9, the second reagent dispensing probe 211 aspirates the second reagent from the reagent container located directly below the second reagent aspiration position. Additionally, under the control of the control circuit 9, the second reagent dispensing probe 211 ejects the aspirated second reagent towards the reaction vessel 2011 located directly below the second reagent ejection position.

[0064] The above describes the composition of the automatic analysis device and analysis mechanism. Next, we will use... Figure 11 Explain the existing liquid level detection circuitry of the analysis unit.

[0065] Figure 11 This is an existing diagram illustrating the configuration of a liquid level detection circuit (LDC). Figure 11 The liquid level detection circuit LDC shown includes an oscillation circuit 310, a bridge circuit 320, a differential amplifier circuit 330, a synchronous detector circuit 340, an integrator circuit 350, an amplifier circuit 360, a comparator circuit 370, and an automatic phase shifting circuit 380. The automatic phase shifting circuit 380 includes a sample-and-hold circuit 381 and a reference signal generation circuit 382.

[0066] The liquid level detection circuit LDC is electrically connected to the sample dispensing probe 207. The liquid level detection circuit LDC detects the contact between the sample dispensing probe 207 and the liquid surface and outputs the detected information (detection information) to the control circuit 9. The detection information includes, for example, information about the instant of contact with the liquid surface and information about the duration of contact. Additionally, the liquid level detection circuit LDC receives a zero adjustment signal from the control circuit 9 as a trigger for adjusting the liquid level detection circuit. The liquid level detection circuit LDC has the following function: if a zero adjustment signal is input, it automatically adjusts the deviation so that the output of the state where the sample dispensing probe 207 is not in contact with the liquid surface becomes zero. The deviation here includes, for example, deviations caused by the electrostatic capacitance of the fixed capacitor C0 included in the bridge circuit 320, and deviations caused by changes in the inherent capacitance resulting from the movement of the sample dispensing probe 207.

[0067] The oscillation circuit 310 generates an oscillation signal at a specified frequency. The oscillation circuit 310 outputs the oscillation signal to the bridge circuit 320 and the automatic phase-shifting circuit 380.

[0068] The bridge circuit 320 receives an oscillation signal from the oscillation circuit 310. Additionally, the bridge circuit 320 is electrically connected to the sample dispensing probe 207. The bridge circuit 320 outputs the voltage difference between the two connection points in the circuit to the differential amplifier circuit 330. Hereinafter, it will be used... Figure 12 Explain the specific structure of the bridge circuit 320.

[0069] Figure 12 This is a conventional diagram illustrating the connection between the bridge circuit 320 and the sample dispensing probe 207. The bridge circuit 320 includes four resistors R1 to R4 and a fixed capacitor C0. The four resistors R1 to R4 each have the same resistance value. The fixed capacitor C0 has an electrostatic capacitance that balances the electrostatic capacitance generated by the sample dispensing probe 207 in its normal state. The normal state is when the sample dispensing probe 207 is not in contact with the liquid surface. That is, the bridge circuit 320 maintains a balanced input to the differential amplifier circuit 330 by using the fixed capacitor C0 to cancel out the electrostatic capacitance generated by the sample dispensing probe 207 in its normal state. The electrostatic capacitance of the fixed capacitor C0 is, for example, 3.3 pF. Furthermore, for ease of explanation, the points where components are connected to each other will be referred to as connection points. Additionally, the bridge circuit 320 has four connection points P1 to P4.

[0070] At connection point P1, one end of the oscillation circuit 310, one end of resistor R1, and one end of resistor R4 are connected. The other end of the oscillation circuit 310 is grounded. The other end of resistor R1 is connected to connection point P2. The other end of resistor R4 is connected to connection point P4.

[0071] At connection point P2, the other end of resistor R1, one end of resistor R2, and one end of fixed capacitor C0 are connected. The other end of resistor R2 and the other end of fixed capacitor C0 are connected to connection point P3. That is, resistor R2 and fixed capacitor C0 are connected in parallel. In addition, connection point P2 is connected to the first input of differential amplifier circuit 330.

[0072] At connection point P3, the other end of resistor R2, the other end of fixed capacitor C0, and the other end of resistor R3 are connected and grounded.

[0073] At connection point P4, one end of resistor R3, the other end of resistor R4, and sample dispensing probe 207 are connected. Additionally, connection point P4 is connected to the second input of differential amplifier circuit 330.

[0074] The bridge circuit 320 configured as described above can detect whether the sample dispensing probe 207 is in contact with the liquid surface based on the voltage difference between connection points P2 and P4. The electrostatic capacitance of the fixed capacitor C0 is set so that the potential difference is zero when the sample dispensing probe 207 is in its normal state.

[0075] The differential amplifier circuit 330 receives the voltage signal representing the potential difference between connection points P2 and P4 from the bridge circuit 320. The differential amplifier circuit 330 outputs the differential amplified signal, generated by differentially amplifying the input voltage signal, to the synchronous detector circuit 340.

[0076] The synchronous detection circuit 340 receives a differential amplified signal from the differential amplifier circuit 330 and a reference signal from the automatic phase shifter circuit 380. The synchronous detection circuit 340 operates to selectively extract only the differential amplified signal with the same frequency components as the reference signal. Specifically, the synchronous detection circuit 340 outputs the synchronous detection signal, generated by full-wave rectification according to the polarity of the reference signal synchronized with the differential amplified signal, to the integrator circuit 350.

[0077] When the sample dispensing probe 207 is not in contact with the liquid surface, the synchronous detection signal output by the synchronous detection circuit 340 is zero because the phase difference between the differential amplified signal and the reference signal is set to 90 degrees. Furthermore, even if a slight deviation occurs in the differential amplified signal, the synchronous detection signal output by the synchronous detection circuit 340 is also zero because the phase of the reference signal is adjusted by the automatic phase shifting circuit 380.

[0078] The integrator circuit 350 receives a synchronous detection signal from the synchronous detection circuit 340. The integrator circuit 350 outputs a low-pass signal to the amplifier circuit 360, which is generated by truncating the frequency components above a specified frequency of the synchronous detection signal and allowing other frequency components to pass.

[0079] Amplifier circuit 360 receives a low-pass signal from integrator circuit 350. Amplifier circuit 360 outputs the output signal generated by amplifying the low-pass signal to comparator circuit 370 and automatic phase shifter circuit 380.

[0080] The comparator circuit 370 receives an output signal from the amplifier circuit 360. The comparator circuit 370 compares the output signal with a preset detection level to generate detection information. For example, by inputting the output signal to a differentiating circuit (not shown) and then inputting the output of the differentiating circuit to a comparator (not shown), information about the instant of contact with the liquid surface, contained in the detection information, is obtained. Alternatively, for example, by inputting the output signal to a comparator (not shown), information about the duration of contact with the liquid surface, contained in the detection information, is obtained. The comparator circuit 370 outputs the detection information to the control circuit 9.

[0081] The automatic phase-shifting circuit 380 receives an oscillation signal from the oscillation circuit 310, an output signal from the amplifier circuit 360, and a zero-adjustment signal from the control circuit 9. Using the zero-adjustment signal as a trigger, the automatic phase-shifting circuit 380 generates a reference signal based on the oscillation signal and the input signal. The automatic phase-shifting circuit 380 then outputs the reference signal to the synchronous detector circuit 340.

[0082] If a zero adjustment signal is input, the sample-and-hold circuit 381 holds the amplified signal generated by the error amplifier circuit (not shown) amplifying the output signal. The sample-and-hold circuit 381 then outputs the held amplified signal to the reference signal generation circuit 382.

[0083] If an amplified signal is input from the sample-and-hold circuit 381, the reference signal generation circuit 382 generates a reference signal based on the oscillation signal and the amplified signal. At this time, the phase difference between the reference signal and the oscillation signal is 90 degrees. Hereinafter, using... Figure 13 This section describes the more specific configuration of the automatic phase-shifting circuit 380.

[0084] Figure 13 This is an example Figure 11 The existing diagram shows the configuration of the automatic phase-shifting circuit 380. The automatic phase-shifting circuit 380 includes a sample-and-hold circuit 381 and a reference signal generation circuit 382. The reference signal generation circuit 382 includes a multiplication circuit 3821, a phase delay circuit 3822, a phase lead circuit 3823, and an adder circuit 3824.

[0085] The phase delay circuit 3822 generates a phase-delayed signal by assigning a predetermined phase delay to the oscillating signal. The phase delay circuit 3822 outputs the phase-delayed signal to the multiplication circuit 3821.

[0086] The multiplier circuit 3821 generates a multiplied signal by multiplying the amplified signal with the phase-delayed signal. The multiplier circuit 3821 outputs the multiplied signal to the adder circuit 3824.

[0087] The phase lead circuit 3823 generates a phase lead signal by giving the oscillation signal a predetermined phase lead. The phase lead circuit 3823 outputs the phase lead signal to the adder circuit 3824.

[0088] The adder circuit 3824 receives a multiplication signal from the multiplier circuit 3821 and a phase-lead signal from the phase-lead circuit 3823. The adder circuit 3824 generates a reference signal by adding the multiplication signal and the phase-lead signal. The adder circuit 3824 then outputs the reference signal to the synchronous detector circuit 340.

[0089] As described above, the existing liquid level detection circuit LDC, through the automatic phase shifting circuit 380, can absorb deviations in the output when the sample dispensing probe 207 is not in contact with the liquid surface to a certain extent. For example, even if the electrostatic capacitance of the fixed capacitor C0 mounted on the bridge circuit 320 deviates from 3.3pF, the liquid level detection circuit LDC can absorb changes within ±4pF. Furthermore, for example, the liquid level detection circuit LDC can also absorb changes in the inherent capacitance that occur with the movement of the sample dispensing probe 207.

[0090] In other words, the existing liquid level detection circuit LDC can detect the changes in amplitude and phase of the signal generated by the impedance change that accompanies the probe contacting the liquid surface, and adjust the voltage value based on the above signal to a specified value when the probe is not in contact with the liquid surface.

[0091] However, under conditions of extremely large deviations, existing liquid level detection circuits (LDCs) cannot absorb the output deviations. For example, when the output of the sample-and-hold circuit 381 is above a first voltage value (e.g., +15V) or below a second voltage value (e.g., -15V), the liquid level detection circuit (LDC) struggles to adjust automatically to the reference signal and cannot absorb the deviation. This situation sometimes occurs, for example, due to the electrical connection between the sample dispensing probe 207 and the equipment (e.g., a perforating needle) used with the sample dispensing probe 207. That is, this is because the capacitance on the probe side becomes extremely large, making it impossible to maintain the balance of the differential input using only the fixed capacitor C0.

[0092] The above uses Figures 11 to 13 This describes the existing liquid level detection circuitry available in the analytical apparatus. Furthermore, while the above description uses a sample dispensing probe as an example, the same applies to other probes (such as reagent dispensing probes).

[0093] Next, use Figure 3The liquid level detection circuit in the first embodiment will be described. The liquid level detection circuit in the first embodiment is configured to detect the contact between the sample dispensing probe and the liquid surface. Furthermore, the sample dispensing probe in the first embodiment is configured to be used in conjunction with a perforating needle.

[0094] Figure 3 This is a diagram illustrating the configuration of the liquid level detection circuit 21 in the first embodiment. Figure 3 The liquid level detection circuit 21 shown includes an oscillation circuit 310, a bridge circuit 320, a differential amplifier circuit 330, a synchronous detector circuit 340, an integrator circuit 350, an amplifier circuit 360, a comparator circuit 370, an automatic phase-shifting circuit 380, and a capacitor adjustment circuit 390 (adjustment section). The automatic phase-shifting circuit 380 includes a sample-and-hold circuit 381 and a reference signal generation circuit 382.

[0095] The liquid level detection circuit 21 has an added capacitor adjustment circuit 390, which is similar to... Figure 11 The liquid level detection circuit 21 differs from the LDC used in this case. The liquid level detection circuit 21 is electrically connected to the sample dispensing probe 207. Additionally, the liquid level detection circuit 21 is also electrically connected to the perforation needle 2071. The following will use… Figure 4 and Figure 5 The perforation needle 2071 is described below.

[0096] Figure 4 This is a diagram illustrating the sample dispensing probe 207 and the perforating needle 2071 in the first embodiment. Figure 4 (a) shows the sample dispensing probe 207 housed within the perforating needle 2071. Figure 4 The cross-section is shown in (b). The perforating needle 2071 is formed of a cylindrical tube that is longer in the vertical direction, allowing the sample dispensing probe 207 to enter. The upper end of the perforating needle 2071 has an opening, and its lower end is needle-shaped. The perforating needle 2071 is used to perforate the cap 20321 of the sample container 2032.

[0097] Figure 5 This is an example Figure 4 A diagram illustrating the operation of the sample dispensing probe 207 and the perforating needle 2071. (See diagram for reference.) Figure 5 As shown in (a), the piercing needle 2071 moves in the direction D11 directly above the sample container 2032 via the drive mechanism 4. After the piercing needle 2071 moves in the direction D11 to pierce the cover 20321 of the sealed sample container 2032, as... Figure 5 As shown in (b), the sample dispensing probe 207 moves in direction D12 to enter the interior of the perforating needle 2071. Thereafter, as... Figure 5 As shown in (c), the sample dispensing probe 207 draws the sample stored in the sample container 2032 through the perforating needle 2071.

[0098] The automatic phase-shifting circuit 380 then outputs the amplified signal used when generating the reference signal to the capacitor adjustment circuit 390. Specifically, the sample-and-hold circuit 381 of the automatic phase-shifting circuit 380 outputs the amplified signal to the capacitor adjustment circuit 390 when a zero adjustment signal is input from the control circuit 9.

[0099] The capacitor adjustment circuit 390 is electrically connected to the bridge circuit 320. The capacitor adjustment circuit 390 receives an amplified signal from the automatic phase-shifting circuit 380. The capacitor adjustment circuit 390 adjusts the capacitance connected to the bridge circuit 320 accordingly to the voltage value of the amplified signal. In other words, the capacitor adjustment circuit 390 adjusts the electrostatic capacitance of the capacitor used in the circuit for liquid level detection. Hereinafter, [the circuit will be used...] Figure 6 Explain the specific structure of the capacitor adjustment circuit 390.

[0100] Figure 6 This diagram illustrates the connections of the bridge circuit 320, capacitor adjustment circuit 390, perforation needle 2071, and sample dispensing probe 207 in the first embodiment. The following description is related to... Figure 12 The differences.

[0101] The capacitor adjustment circuit 390 includes a judgment circuit 391, a switch control circuit 392, multiple switches SWs1 to SWsN, and multiple capacitors Cs1 to CsN. Furthermore, N is a design value and can be any number.

[0102] The judgment circuit 391 compares the value of the amplified signal with a threshold. Specifically, when the threshold is set to zero, the judgment circuit 391 determines whether the value of the amplified signal is zero. If the value of the amplified signal is not zero, the judgment circuit 391 generates a judgment signal corresponding to the value of the amplified signal. Then, the judgment circuit 391 outputs the generated judgment signal to the switch control circuit 392.

[0103] The switch control circuit 392 receives a judgment signal from the judgment circuit 391. Based on the judgment signal, the switch control circuit 392 generates control signals to control the multiple switches SWs1 to SWsN respectively. The switch control circuit 392 outputs the control signals to the multiple switches SWs1 to SWsN respectively.

[0104] One end of each of the multiple switches SWs1 to SWsN is connected to connection point P2, and the other end of each of the multiple switches SWs1 to SWsN is connected to one end of each of the multiple capacitors Cs1 to CsN. Control signals are input to the multiple switches SWs1 to SWsN from the switch control circuit 392. Then, the multiple switches SWs1 to SWsN switch between on and off states according to the control signals.

[0105] One end of each of the multiple capacitors Cs1 to CsN is connected to the other end of each of the multiple switches SWs1 to SWsN, and the other end of each of the multiple capacitors Cs1 to CsN is grounded. The multiple capacitors Cs1 to CsN can each have different capacitances, or at least two of them can have the same capacitance.

[0106] At connection point P2 of the bridge circuit 320, one end of each of multiple switches SWs1 to SWsN is connected. Additionally, a perforating needle 2071 is connected at connection point P4 of the bridge circuit 320. Connecting the perforating needle 2071 at connection point P4 causes an increase in the electrostatic capacitance generated by the perforating needle 2071. Therefore, the capacitance adjustment circuit 390 controls multiple switches to balance the electrostatic capacitance of the sample dispensing probe 207 and the perforating needle 2071, virtually adjusting the capacitance of the fixed capacitor C0.

[0107] For example, if the capacitance at connection point P4 becomes approximately 10pF due to the connection of the perforating pin 2071, the capacitance of the fixed capacitor C0 at connection point P2 alone (e.g., 3.3pF) is insufficient to maintain the balance of the two outputs of the bridge circuit 320. Therefore, in the first embodiment, the capacitance at connection point P2 is increased by using the capacitor adjustment circuit 390, thereby balancing the two outputs of the bridge circuit 320.

[0108] As explained above, the automatic analysis device according to the first embodiment is electrically connected to the sample dispensing probe, detects the contact between the sample dispensing probe and the liquid surface, and adjusts the electrostatic capacitance of the capacitor in the circuit used for liquid surface detection. Therefore, the automatic analysis device according to the first embodiment can improve the accuracy of liquid surface detection, thus enabling inspections with higher reliability than before. Furthermore, this automatic analysis device can also absorb deviations caused by the aging of perforated needles, etc.

[0109] Furthermore, the automatic analysis apparatus according to the first embodiment detects the contact between the sample dispensing probe and the liquid surface, but is not limited thereto. For example, a perforated probe can also be used to detect the liquid surface. This allows for a reduction in the diameter of the sample dispensing probe.

[0110] (Second Implementation)

[0111] In the first embodiment, it is described that connecting a capacitance adjustment circuit increases the electrostatic capacitance on the surface of the fixed capacitor C0 mounted on the bridge circuit. In the second embodiment, it is described that connecting a capacitance adjustment circuit increases the electrostatic capacitance generated with respect to the probes connected to the bridge circuit.

[0112] The following uses Figure 7The liquid level detection circuit in the second embodiment will be described. The liquid level detection circuit in the second embodiment is configured to detect the contact between the reagent dispensing probe and the liquid surface. Furthermore, the reagent dispensing probe in the second embodiment is configured to be used in conjunction with a heater.

[0113] Figure 7 This is a diagram illustrating the configuration of the liquid level detection circuit 21A in the second embodiment. Figure 7 The liquid level detection circuit 21A shown includes an oscillation circuit 310A, a bridge circuit 320A, a differential amplifier circuit 330A, a synchronous detector circuit 340A, an integrator circuit 350A, an amplifier circuit 360A, a comparator circuit 370A, an automatic phase-shifting circuit 380A, and a capacitor adjustment circuit 390A. The automatic phase-shifting circuit 380A includes a sample-and-hold circuit 381A and a reference signal generation circuit 382A.

[0114] Furthermore, the oscillation circuit 310A, differential amplifier circuit 330A, synchronous detector circuit 340A, integrating circuit 350A, amplifier circuit 360A, comparator circuit 370A, and automatic phase shifting circuit 380A are substantially the same as the oscillation circuit 310, differential amplifier circuit 330, synchronous detector circuit 340, integrating circuit 350, amplifier circuit 360, comparator circuit 370, and automatic phase shifting circuit 380, respectively, and their descriptions are omitted.

[0115] The liquid level detection circuit 21A detects the contact between the first reagent dispensing probe 209 and the liquid surface, which is consistent with... Figure 3 The liquid level detection circuit 21 is different. The liquid level detection circuit 21A is electrically connected to the first reagent dispensing probe 209. In addition, the liquid level detection circuit 21A is also electrically connected to the heating shroud 2091 of the heater.

[0116] Figure 8 This is a diagram illustrating the first reagent dispensing probe 209 and heater 2092 in the second embodiment. Figure 8 (a) shows the first reagent dispensing probe 209 housed within a heating shroud 2091 to which the heater 2092 is wound. Figure 8 (b) shows its cross-section. The heating cover 2091 is a conductive component formed by a cylindrical tube that is longer in the vertical direction. In addition, the heating cover 2091 allows the first reagent dispensing probe 209 to enter. The heater 2092 and the heating cover 2091 are used to heat the first reagent held by the first reagent dispensing probe 209.

[0117] Figure 9 This diagram illustrates the connection of the bridge circuit 320A, the capacitor adjustment circuit 390A, the heating cover 2091, and the first reagent dispensing probe 209 in the second embodiment. The following description is related to... Figure 6 The differences and with Figure 12The differences.

[0118] The bridge circuit 320A receives an oscillation signal from the oscillation circuit 310A. Furthermore, the bridge circuit 320A is electrically connected to the first reagent dispensing probe 209 and the heating cover 2091. The bridge circuit 320A outputs the voltage of the potential difference between the two connection points in the circuit to the differential amplifier circuit 330. Additionally, the first reagent dispensing probe 209 and the heating cover 2091 are configured to be non-conductive to each other.

[0119] Specifically, the bridge circuit 320A includes four resistors R1A to R4A and a fixed capacitor C0A. The four resistors R1A to R4A each have the same resistance value. The fixed capacitor C0A has an electrostatic capacitance that balances with the normal state of the first reagent dispensing probe 209. The normal state is when the first reagent dispensing probe 209 is not in contact with the liquid surface. Additionally, the bridge circuit 320A has four connection points P1A to P4A.

[0120] At connection point P1A, one end of the oscillator circuit 310A, one end of resistor R1A, and one end of resistor R4A are connected. The other end of the oscillator circuit 310A is grounded. The other end of resistor R1A is connected to connection point P2A. The other end of resistor R4A is connected to connection point P4A.

[0121] At connection point P2A, the other end of resistor R1A, one end of resistor R2A, and one end of fixed capacitor C0A are connected. The other end of resistor R2A and the other end of fixed capacitor C0A are connected to connection point P3A. That is, resistor R2A and fixed capacitor C0A are connected in parallel. In addition, connection point P2A is connected to the first input of differential amplifier circuit 330A.

[0122] At connection point P3A, the other end of resistor R2A, the other end of fixed capacitor C0A, and the other end of resistor R3A are connected and grounded.

[0123] At connection point P4A, one end of resistor R3A and the other end of resistor R4A are connected. Additionally, connection point P4A is connected to the second input of differential amplifier circuit 330A.

[0124] The bridge circuit 320A configured as described above can detect whether the first reagent dispensing probe 209 is in contact with the liquid surface based on the voltage difference between connection points P2A and P4A. The electrostatic capacitance of the fixed capacitor C0A is set to be zero when considering only the first reagent dispensing probe 209.

[0125] The capacitor adjustment circuit 390A includes a judgment circuit 391A, a switch control circuit 392A, multiple switches SWp1 to SWpM, and multiple capacitors Cp1 to CpM. Furthermore, M is a design value and can be any number.

[0126] The judgment circuit 391A compares the value of the amplified signal with a threshold. Specifically, when the threshold is set to zero, the judgment circuit 391A determines whether the value of the amplified signal is zero. If the value of the amplified signal is not zero, the judgment circuit 391A generates a judgment signal corresponding to the value of the amplified signal. Then, the judgment circuit 391A outputs the generated judgment signal to the switch control circuit 392A.

[0127] The switch control circuit 392A receives a judgment signal from the judgment circuit 391A. Based on the judgment signal, the switch control circuit 392A generates control signals to control the multiple switches SWp1 to SWpM respectively. The switch control circuit 392A outputs the control signals to the multiple switches SWp1 to SWpM respectively.

[0128] One end of each of multiple switches SWp1 to SWpM is connected to connection point P4A, and the other end of each of multiple switches SWp1 to SWpM is connected to one end of each of multiple capacitors Cp1 to CpM. Control signals are input to the multiple switches SWp1 to SWpM respectively from the switch control circuit 392A. Then, the multiple switches SWp1 to SWpM switch between on and off states according to the control signals.

[0129] One end of each of the multiple capacitors Cp1 to CpM is connected to the other end of each of the multiple switches SWp1 to SWpM, and the other end of each of the multiple capacitors Cp1 to CpM is grounded. The multiple switches SWp1 to SWpM can each have different capacitances, or at least two of them can have the same capacitance.

[0130] A heating shield 2091 is also connected to connection point P2A of the bridge circuit 320A. Additionally, one end of each of multiple switches SWp1 to SWpM is connected to connection point P4A of the bridge circuit 320A. Connecting the heating shield 2091 to connection point P2A causes an increase in the electrostatic capacitance generated by the heating shield 2091. Therefore, the capacitance adjustment circuit 390A controls multiple switches to balance the electrostatic capacitance with respect to the heating shield 2091, virtually adjusting the electrostatic capacitance generated by the first reagent dispensing probe 209.

[0131] For example, when the capacitance at connection point P2A becomes approximately 190 pF due to the connection of the heating shroud 2091, the electrostatic capacitance generated by the first reagent dispensing probe 209 (e.g., approximately 3.3 pF) alone is insufficient to maintain the balance of the two outputs in the bridge circuit 320A. Therefore, in the second embodiment, by using the capacitor adjustment circuit 390A, the capacitance at connection point P4A is increased, thereby balancing the two outputs of the bridge circuit 320A.

[0132] As explained above, the automatic analysis device according to the second embodiment is electrically connected to the first reagent dispensing probe, detects the contact between the first reagent dispensing probe and the liquid surface, and adjusts the electrostatic capacitance of the capacitor in the circuit used for liquid surface detection. Therefore, the automatic analysis device according to the second embodiment can improve the accuracy of liquid surface detection, thus enabling inspections with higher reliability than before. Furthermore, in the automatic analysis device according to the second embodiment, the capacitor adjustment circuit can be designed according to the performance of the heater, thus allowing the use of heaters with high temperature rise performance that were previously difficult to use. In addition, this automatic analysis device can also absorb deviations caused by aging of the heater, etc.

[0133] Furthermore, in the second embodiment, the first reagent dispensing probe 209 and the heating cover 2091 are configured to be non-conductive, but this is not a limitation. If the first reagent dispensing probe 209 and the heating cover 2091 are conductive, the heating cover 2091 can be connected at connection point P4A and the capacitor adjustment circuit 390A can be connected at connection point P2A.

[0134] Furthermore, while the above description indicates the use of a heater for the first reagent dispensing probe 209, it is not limited to this. For example, a heater may also be used for the second reagent dispensing probe 211.

[0135] (Third Implementation)

[0136] In the first and second embodiments, it was described that a capacitor adjustment circuit was connected to either the side connected to the fixed capacitor or the side connected to the probe. In the third embodiment, it was described that a capacitor adjustment circuit was connected to both sides.

[0137] Figure 10 This diagram illustrates the connection between the bridge circuit 320B and the capacitor adjustment circuit 390B in the third embodiment. Furthermore, in Figure 10 The diagrams of the probe and the equipment used with the probe (such as the piercing needle and heater) are omitted.

[0138] Bridge circuit 320B has the following features: Figure 6 Bridge circuit 320 and Figure 9The bridge circuit 320B has a configuration largely the same as that of the bridge circuit 320A. Specifically, the bridge circuit 320B includes four resistors R1B to R4B and a fixed capacitor C0B. The four resistors R1B to R4B each have the same resistance value. The fixed capacitor C0B has an electrostatic capacitance that balances the normal state of the probe (not shown). The normal state is when the probe is not in contact with the liquid surface. Additionally, the bridge circuit 320B has four connection points P1B to P4B. Furthermore, the connection relationship between the four resistors R1B to R4B and the fixed capacitor C0B is the same as the connection relationship between the four resistors R1A to R4A and the fixed capacitor C0A, therefore, the description is omitted.

[0139] The capacitor adjustment circuit 390B includes a judgment circuit 391B, a switch control circuit 392B, multiple switches SWs1 to SWsN, multiple capacitors Cs1 to CsN, multiple switches SWp1 to SWpM, and multiple capacitors Cp1 to CpM. Furthermore, N and M are design values ​​and can be of any quantity.

[0140] The judgment circuit 391B compares the value of the amplified signal with a threshold. Specifically, when the threshold is set to zero, the judgment circuit 391B determines whether the value of the amplified signal is zero. If the value of the amplified signal is not zero, the judgment circuit 391B generates a judgment signal corresponding to the value of the amplified signal. Then, the judgment circuit 391B outputs the generated judgment signal to the switch control circuit 392B.

[0141] The switch control circuit 392B receives a judgment signal from the judgment circuit 391B. Based on the judgment signal, the switch control circuit 392B generates a control signal to control at least one of the multiple switches SWs1 to SWsN and the multiple switches SWp1 to SWpM. The switch control circuit 392B outputs the control signal to at least one of the multiple switches SWs1 to SWsN and the multiple switches SWp1 to SWpM.

[0142] One end of each of the multiple switches SWs1 to SWsN is connected to the connection point P2B, and the other end of each of the multiple switches SWs1 to SWsN is connected to one end of each of the multiple capacitors Cs1 to CsN. Furthermore, the multiple capacitors Cs1 to CsN are the same as in the first embodiment, therefore description is omitted.

[0143] One end of each of the multiple switches SWp1 to SWpM is connected to the connection point P4B, and the other end of each of the multiple switches SWp1 to SWpM is connected to one end of each of the multiple capacitors Cp1 to CpM. Furthermore, the multiple capacitors Cp1 to CpM are the same as in the second embodiment, therefore description is omitted.

[0144] Based on the above configuration, the automatic analysis device according to the third embodiment can balance the two outputs of the bridge circuit 320B regardless of which connection point P2B or connection point P4B is connected when the perforated needle or heating cover is connected to the bridge circuit 320B. Furthermore, the automatic analysis device according to the third embodiment can achieve higher precision control compared to the first and second embodiments by combining and controlling multiple switches SWs1 to SWsN and multiple switches SWp1 to SWpM.

[0145] (Other implementation methods)

[0146] In the automatic analysis apparatus according to the first to third embodiments, a fixed capacitor is mounted on the bridge circuit to achieve balance with the probe, but the apparatus is not limited to this. The automatic analysis apparatus according to these embodiments may also not be equipped with a fixed capacitor, but may use a capacitor adjustment circuit to achieve balance with the probe.

[0147] Furthermore, in the automatic analysis apparatus according to the first to third embodiments, the threshold is set to zero during the comparison in the judgment circuit, but this is not a limitation. The automatic analysis apparatus according to these embodiments may also set the threshold according to the relationship between the output of the sample-and-hold circuit and the output of the bridge circuit during liquid level detection, corresponding to the output of the sample-and-hold circuit where the output of the bridge circuit is the largest. For example, the threshold may be approximately 0.4V.

[0148] According to at least one of the embodiments described above, the accuracy of liquid level detection can be improved.

[0149] Several embodiments have been described above, but these embodiments are provided as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, modifications, and combinations of embodiments are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope or spirit of the invention and in the scope of the invention as described in the patent claims and its equivalents.

Claims

1. An automatic analysis device, wherein, have: probe; and A liquid level detection mechanism, electrically connected to the probe, detects the contact between the probe and the liquid surface. The liquid level detection mechanism includes a bridge circuit and an adjustment unit. The bridge circuit is used for liquid level detection, and the adjustment unit adjusts the electrostatic capacitance of the capacitor connected to the bridge circuit. The adjustment unit adjusts the electrostatic capacitance by switching the capacitor connected to the bridge circuit. The bridge circuit includes a fixed capacitor connected in parallel with a resistor. This fixed capacitor has an electrostatic capacitance balanced with the state in which the probe is not in contact with the liquid surface. The bridge circuit has, in sequence, a first connection point connected to the fixed capacitor, a third connection point connected to the probe and the adjustment unit, and a fourth connection point between each resistor. An oscillation signal is input between the third connection point and the fourth connection point. The liquid level detection mechanism detects the contact between the probe and the liquid surface based on the potential difference between the first connection point and the second connection point.

2. An automatic analysis device, wherein, have: probe; and A liquid level detection mechanism, electrically connected to the probe, detects the contact between the probe and the liquid surface. The liquid level detection mechanism includes a bridge circuit and an adjustment unit. The bridge circuit is used for liquid level detection, and the adjustment unit adjusts the electrostatic capacitance of the capacitor connected to the bridge circuit. The adjustment unit adjusts the electrostatic capacitance by switching the capacitor connected to the bridge circuit. The bridge circuit includes a fixed capacitor connected in parallel with a resistor. This fixed capacitor has an electrostatic capacitance balanced with the state in which the probe is not in contact with the liquid surface. The bridge circuit has a first connection point, a third connection point, a second connection point, and a fourth connection point connected sequentially between each resistor and the fixed capacitor. An oscillation signal is input between the third connection point and the fourth connection point. The probe is connected to the second connection point. The adjustment part is connected to the first connection point and the second connection point. The liquid level detection mechanism detects the contact between the probe and the liquid surface based on the potential difference between the first connection point and the second connection point of the bridge circuit.

3. The automatic analysis device as described in claim 1 or 2, wherein, It also has: A perforating needle is used to pierce the lid of the sample container, allowing the probe to enter the interior; and The driving mechanism drives the perforating needle. The adjustment unit adjusts the deviation of electrostatic capacitance caused by the perforating needle.

4. The automatic analysis device as described in claim 1 or 2, wherein, It also has: A heater is used to heat the liquid inside the probe; and A conductive component is disposed between the heater and the probe. The adjustment unit adjusts the deviation of the electrostatic capacitance caused by the conductive component.

5. The automatic analysis device as described in claim 1 or 2, wherein, The liquid level detection mechanism detects the changes in amplitude and phase of the signal generated by the impedance change accompanying the probe contacting the liquid surface, and adjusts the voltage value based on the signal to a predetermined value when the probe is not in contact with the liquid surface.

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