Automatic analysis device

Abstract

To provide an automatic analysis device capable of stirring a sample and a reagent by ultrasonic waves having a stable sound pressure regardless of a variation in characteristics of a piezoelectric element.SOLUTION: In an automatic analysis device for stirring a sample and a reagent by ultrasonic waves generated by driving a piezoelectric element, an amplifier for driving the piezoelectric element includes a voltage detection part for detecting voltage applied to the piezoelectric element, a current detection part for detecting current flowing to the piezoelectric element, a calculation part for calculating effective power on the basis of a detection voltage detected by the voltage detection part and a detection current detected by the current detection part, and for determining an adjustment signal by using the calculated effective power and predetermined target power, and an impedance matching circuit for adjusting output power of the amplifier by changing reactance components on the basis of the adjustment signal determined by the calculation part.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an automatic analyzer. [Background technology]

[0002] A technology has been developed that uses ultrasonic waves to irradiate a reaction solution in a reaction vessel, generating a flow in the sample and reagents contained in the reaction solution, thereby stirring the sample and reagents. This technology has already been implemented in automated analyzers. This ultrasonic stirring method can stir the reaction solution without contact, thereby avoiding carryover of sample and reagents and the introduction of wash water, which can occur when using a stirrer rod or other device. However, ultrasonic stirring methods can be problematic due to variations in the resonant frequency of the piezoelectric element that generates the ultrasonic waves, resulting in variations in the intensity of the generated ultrasonic waves, which can make it difficult to achieve stable stirring. Therefore, for example, Patent Document 1 discloses an automated analyzer that applies a frequency-modulated voltage within a desired frequency range to a piezoelectric element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO 01 / 63300 Summary of the Invention [Problem to be solved by the invention]

[0004] To cover the low frequency side by modulating the frequency around the nominal value of the resonant frequency, as in the technology described in Patent Document 1, the frequency must be expanded to a maximum frequency deviation of ΔF or more. However, when using an output frequency above ΔF, the time ratio during which the piezoelectric element is driven at a frequency other than the resonant frequency increases, resulting in a decrease in efficiency.

[0005] An object of the present invention is to provide an automatic analyzer that can agitate samples and reagents using ultrasonic waves with a stable sound pressure, regardless of variations in the characteristics of piezoelectric elements. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention provides an automatic analyzer that agitates a sample and a reagent by ultrasonic waves generated by driving a piezoelectric element, wherein the amplifier that drives the piezoelectric element includes a voltage detection unit that detects a voltage applied to the piezoelectric element, a current detection unit that detects a current flowing through the piezoelectric element, a calculation unit that calculates an active power based on the detected voltage detected by the voltage detection unit and the detected current detected by the current detection unit, and determines an adjustment signal using the calculated active power and a predetermined target power, and an impedance matching circuit that adjusts the output power of the amplifier by changing a reactance component based on the adjustment signal determined by the calculation unit. [Effects of the Invention]

[0007] According to the present invention, an automatic analyzer can be provided that is capable of agitating samples and reagents using ultrasonic waves with a stable sound pressure, regardless of variations in the characteristics of piezoelectric elements. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic configuration diagram of an automatic analyzer according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the configuration of the stirring unit, and the amplifier and mechanism control unit connected thereto. [Figure 3] FIG. 2 is a diagram showing the electrical circuit of the amplifier and the stirring unit and mechanism control unit connected thereto. [Figure 4] 3 is a diagram showing the configuration of a voltage detection unit, a current detection element, a current detection unit, and a calculation unit in the amplifier according to the first embodiment. FIG. [Figure 5] 10 is an example of a table that stores target power values ​​according to the first embodiment. [Figure 6] FIG. 1 is a diagram showing the configuration of a variable reactance impedance matching circuit according to a first embodiment. [Figure 7] 10 is a flowchart showing an initial setting process performed by a calculation unit. [Figure 8] 10 is a flowchart showing a power adjustment process performed by a calculation unit. [Figure 9]1 is a timing diagram showing the timing of a training sequence. [Figure 10] 10 is an example of a table that stores target power values ​​according to the second embodiment. [Figure 11] FIG. 10 is a diagram showing the configuration of a variable reactance impedance matching circuit according to a third embodiment. [Figure 12] FIG. 10 is a diagram showing the configuration of a voltage detection unit, a current detection element, a current detection unit, and a calculation unit in an amplifier according to a fourth embodiment. [Figure 13] 10 is a flowchart showing the process of initial setting of frequency search power adjustment by a calculation unit. [Figure 14] FIG. 2 illustrates a power adjustment module used in frequency search power adjustment. [Figure 15] 10 is a flowchart showing a process of adjusting frequency search power by a calculation unit. [Figure 16] 10 is a timing chart showing timings for performing power adjustment. [Figure 17] FIG. 4 is a diagram showing a signal sent from a mechanism control unit to an amplifier. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] Fig. 1 is a schematic diagram of an automatic analyzer according to this embodiment. As shown in Fig. 1, the automatic analyzer includes a sample storage section 101, a reagent storage section 102, a reaction section 103, stirring sections 104 to 109, an analysis section 110, a washing section 111, a sample dispensing mechanism 113, and a reagent dispensing mechanism 115. Although not shown in Fig. 1, the automatic analyzer further includes a mechanism control section 4 (host computer) that is configured from electronic circuits and a storage device, and this mechanism control section 4 controls the operation of each section and mechanism.

[0011] The sample storage unit 101 stores sample containers such as test tubes, and the sample containers contain samples 112. The reaction unit 103 is composed of a rotatable reaction disk, and reaction containers 114 (reaction cells) are arranged circumferentially on the reaction disk. The reaction disk also has a thermostatic bath that holds constant-temperature water at a specified temperature. The constant-temperature water circulating in the thermostatic bath comes into contact with the reaction containers 114, thereby maintaining the reaction containers 114 at a predetermined temperature. The sample dispensing mechanism 113 aspirates an amount of sample 112 required for analysis from the sample container and dispenses the aspirated sample 112 into the reaction containers 114 on the reaction unit 103. The reagent dispensing mechanism 115 aspirates an amount of reagent 116 required for analysis from the reagent storage unit 102 and dispenses the aspirated reagent 116 into the reaction containers 114. Multiple mixing units 104 to 109 are arranged along the outer periphery of the reaction disk, and each mixes the sample 112 and reagent 116 dispensed into the reaction containers 114. The analysis unit 110 analyzes the components of the reaction solution of the sample 112 and the reagent 116, whose reaction has been promoted, by measuring its absorbance. The cleaning unit 111 cleans the reaction vessel 114 after the absorbance measurement has been completed. The next sample 112 is dispensed by the sample dispensing mechanism 113 into the reaction vessel 114 cleaned by the cleaning unit 111, and the same sequence is repeated thereafter.

[0012] Here, the agitators 104 to 109 irradiate the reaction vessel 114 with ultrasonic waves, and utilize vibration, acoustic streaming, acoustic radiation pressure, etc. to agitate the sample 112 and the reagent 116 in a non-contact manner. By providing multiple agitators, the sample 112 and the reagent 116 are efficiently agitated, achieving high processing capacity. In this embodiment, constant temperature water is used as the liquid that transmits the sound waves, but water other than constant temperature water or a liquid other than water may also be used. Furthermore, sound waves other than ultrasonic waves may be used as long as they can impart vibrations, etc. to the sample 112 and the reagent 116.

[0013] Fig. 2 shows the configuration of the stirring unit, and the amplifier and mechanism control unit connected thereto. Fig. 2 mainly shows a vertical cross section of stirring unit 104 along the radial direction of reaction unit 103, and the specific configuration of amplifier 2 is shown in Fig. 3 and subsequent figures. In the following, stirring unit 104 will be described as an example, but the same applies to stirring units 105 to 109.

[0014] 2, the stirring unit 104 includes a piezoelectric element 202 that generates ultrasonic waves, a jig 203 for attaching the piezoelectric element 202 to the thermostatic bath 117, a reflector 223 that reflects ultrasonic waves transmitted through the reaction vessel 114 and the like back toward the reaction vessel 114, and a connector 201 that electrically connects the piezoelectric element 202 to the amplifier 2. The piezoelectric element 202 also has split electrodes 204 and 209 that are provided on one surface (the air side) and in contact with the air, and a constant-temperature water-side electrode 205 that is provided on the other surface (the constant-temperature water side) and in contact with the constant-temperature water 208. A portion of the constant-temperature water-side electrode 205 is folded back toward the air side along the lower end face of the piezoelectric element 202.

[0015] The divided electrodes 204, 209 are divided into multiple electrodes at different height positions. In this embodiment, an example in which 13 divided electrodes are provided (only a portion is shown in FIG. 2 etc.) will be described, but the number of divided electrodes is not limited to 13. The dimensions and shape of each divided electrode can be designed individually and arbitrarily, but in this embodiment, the first to twelfth divided electrodes 204 from the top all have the same shape (same width and length), and only the thirteenth (bottom) divided electrode 209 is formed slightly longer than the other divided electrodes 204. Each divided electrode is connected to a respective pin of the connector 201 in a one-to-one relationship.

[0016] The amplifier 2 is provided with an interface unit 221 that connects to the mechanism control unit 4, and the mechanism control unit 4 controls the amplifier 2 via this interface unit 221. The amplifier 2 is also connected to the stirring unit 104 via a connector 201. Furthermore, a relay group 213 is arranged between the amplifier 2 and the connector 201. The relay group 213 includes a plurality of switches, and the opening and closing of each switch is controlled by commands from the mechanism control unit 4. In other words, the relay group 213 functions as a switch device that switches the connection between the amplifier 2 and each of the segmented electrodes 204, 209.

[0017] The mechanism control unit 4 detects the liquid level position (liquid level height) of the liquid in the reaction vessel 114. Furthermore, the mechanism control unit 4 selects one or more of the divided electrodes 204, 209 at appropriate positions according to the liquid level position, and controls the relay group 213 to apply a voltage to the selected divided electrodes 204, 209. In this way, the irradiation position of the ultrasonic waves on the reaction vessel 114 is adjusted.

[0018] In this way, the mechanism control unit 4 of this embodiment applies a voltage to each of the divided electrodes 204, 209 via the amplifier 2. When a voltage is applied to each of the divided electrodes 204, 209, the piezoelectric element 202 is driven to generate an ultrasonic wave.

[0019] Next, we will explain the configuration of the electrical circuit of the amplifier 2. Figure 3 is a diagram showing the electrical circuit of the amplifier and the stirring unit and mechanism control unit connected thereto. As shown in Figure 3, the amplifier 2 includes a switching amplifier 16, a transformer 19, a variable reactance impedance matching circuit 11, a voltage detection unit 13, a current detection unit 14, and a calculation unit 12.

[0020] The switching amplifier 16 transmits the drive frequency Frs of the piezoelectric element 202. The transformer 19 converts the output of the switching amplifier 16 in accordance with the turns ratio. Here, the switching amplifier 16 can increase its output when the load impedance at the drive frequency Frs (the impedance seen from the primary side of the transformer 19 to the secondary side) is low. On the other hand, the impedance of the piezoelectric element 202 varies depending on its material, and may be several hundred ohms at the drive frequency Frs, which may be too high for the load of the switching amplifier 16. Therefore, in this embodiment, a variable reactance impedance matching circuit 11 is inserted between the transformer 19 and the piezoelectric element 202 to lower the impedance on the piezoelectric element 202 side.

[0021] The voltage detection unit 13 detects the voltage applied to the piezoelectric element 202 and outputs the detected voltage to the calculation unit 12. The current detection unit 14 detects the current flowing through the piezoelectric element 202 and outputs the detected current to the calculation unit 12. The calculation unit 12 calculates active power based on the detected voltage and current, and determines an adjustment signal using the calculated active power and a predetermined target power. The variable reactance impedance matching circuit 11 is connected to the secondary side of the transformer 19 and adjusts the output power of the amplifier 2 by changing the reactance component based on the reactance adjustment signal 15. Details of the method for calculating active power and the method for adjusting output power will be described later.

[0022] Specific examples of the amplifier 2 will be described below using Examples 1 to 7. [Example]

[0023] FIG. 4 is a diagram illustrating the configuration of a voltage detection unit, a current detection element, a current detection unit, and a calculation unit in the amplifier according to the first embodiment.

[0024] The voltage detection unit 13 has an input amplifier 22, an anti-aliasing filter 23, and an AD converter 24. The input amplifier 22 linearly amplifies the voltage applied to the piezoelectric element 202 and outputs the amplified voltage to the anti-aliasing filter 23. The anti-aliasing filter 23 has a cutoff frequency equal to or greater than twice the drive frequency Frs, and removes a frequency band that becomes an alias for the AD converter 24. The AD converter 24 AD-converts the voltage signal from which the alias components have been removed, and outputs the resulting signal to the voltage input register 31 of the calculation unit 12.

[0025] The current detection element 21 is an element that clamps the input cable of the piezoelectric element 202 and detects the current. The current detection unit 14 has a preamplifier 25, an anti-aliasing filter 26, and an AD converter 27. The preamplifier 25 converts the current detected by the current detection element 21 into a voltage and outputs it to the anti-aliasing filter 26. The AD converter 27 performs AD conversion on the current signal from which the alias component has been removed, and outputs it to the current input register 32 of the calculation unit 12.

[0026] The calculation unit 12 has a voltage input register 31, a current input register 32, a multiplier 33, a VI product register 34, and a power register 35. The voltage input register 31 and the current input register 32 synchronously output data to the multiplier 33, and the multiplier 33 outputs the product of that data to the VI product register 34. The VI product register 34 shifts the product data, and after a time Ts seconds sufficient for power calculation has elapsed, outputs the sum Psum of the product data to the power register 35.

[0027] In this way, the calculation unit 12 can calculate the effective power Prp=Psum / Ts supplied to the piezoelectric element 202. That is, when the piezoelectric element voltage is V(t) and the piezoelectric element current is I(t), the effective power Prp can be calculated by the following (Equation 1).

[0028] Prp=[∫{(V(t)×I(t))}dt] / Ts…(Equation 1) Furthermore, the amplifier 2 of this embodiment controls the effective power Prl supplied to the piezoelectric element 202 so that it approaches a predetermined target power. Here, the target power has different values ​​stored in a table 51 for each frequency and each type of piezoelectric element 202. The table 51 is stored in a storage unit (not shown).

[0029] FIG. 5 is an example of a table storing target power values ​​related to Example 1. The automated analyzer of this example can use different types of piezoelectric elements; that is, the amplifier 2 of this example can drive piezoelectric elements 202 made of materials with different characteristics. In FIG. 5, for example, the material of piezoelectric element A is PZT (lead zirconate titanate), and the material of piezoelectric element B is LN (lithium niobate). The gain of amplifier 2 can be set to one of three levels: maximum gain Gmax, intermediate gain Gmid, and minimum gain Gmin. The frequency of amplifier 2 has multiple channels with a minimum frequency FLw, a center frequency Fcn, and a maximum frequency Fhi, and for example, a band of 1.0 MHz to 1.5 MHz is used. As an example, when piezoelectric element A is driven with an intermediate gain Gmid and a center frequency Fcn, the target power Ptg is 6.7 W.

[0030] Next, the operation of the variable reactance impedance matching circuit 11 will be described. Fig. 6 is a diagram showing the configuration of the variable reactance impedance matching circuit according to the first embodiment. The variable reactance impedance matching circuit 11 of this embodiment has an inductor (toroidal cores 41, 42), a capacitor 43, and a variable capacitance diode (varactor diode 44). The varactor diode 44 is connected in parallel to the capacitor 43.

[0031] The toroidal cores 41, 42 and the capacitor 43 convert the impedance of several hundred ohms of the piezoelectric element 202 into a low impedance, thereby matching the impedance with the switching amplifier 16. When the calculation unit 12 outputs a capacitance adjustment signal 45 to bring the active power closer to the target power stored in the above-mentioned table 51, the capacitance value of the varactor diode 44 changes, and therefore the impedance seen from the primary side of the transformer 19 changes. In this embodiment, by utilizing this principle, the change in impedance caused by a shift in the resonant frequency of the piezoelectric element 202 can be corrected by adjusting the capacitance of the varactor diode 44.

[0032] Next, a method for controlling the variable reactance impedance matching circuit 11 by the calculation unit 12 will be described with reference to FIGS.

[0033] First, the initial setting will be described. FIG. 7 is a flowchart showing the initial setting process performed by the calculation unit. When the automatic analyzer is powered on, the calculation unit 12 reads information about the type of piezoelectric element 202 connected to the amplifier 2 (e.g., piezoelectric element A or piezoelectric element B) from the storage unit (step S101). The calculation unit 12 also reads the gain setting values ​​(e.g., Gmax, Gmid, Gmin) of the amplifier 2 from the storage unit (step S102). The calculation unit 12 also reads the frequency setting values ​​(e.g., FLw, Fcn, Fhi) of the amplifier 2 from the storage unit (step S103). Thereafter, the calculation unit 12 refers to table 51 shown in FIG. 5 based on the setting information read in steps S101 to S103, and substitutes the corresponding value into the target power Ptg (step S104). For example, if the piezoelectric element type is piezoelectric element A, the Gain setting value is Gmid, and the frequency setting value is Fcn, then 6.7 is substituted for the target power Ptg.

[0034] Next, the calculation unit 12 reads from the storage unit ΔVt, which is the increase / decrease step amount when changing the capacitance adjustment signal 45 (Vt) (step S105). This increase / decrease step amount ΔVt is determined in advance in the storage unit based on the amount of change in the active power Prl supplied to the piezoelectric element 202 when the voltage applied to the varactor diode 44 in the variable reactance impedance matching circuit 11 is changed.

[0035] Finally, the calculation unit 12 outputs the initial value Vit of the capacitance adjustment signal 45 (Vt) to the variable reactance impedance matching circuit 11 (step S106), thereby completing the initial setting process. Here, it is desirable that the initial value Vit of the capacitance adjustment signal 45 (Vt) be set to, for example, the median value of the applied voltage range of the varactor diode 44 so that it can respond to the amount of change in the active power Prl supplied to the piezoelectric element 202.

[0036] Next, power adjustment will be described. Fig. 8 is a flowchart showing the processing of power adjustment by the calculation unit. First, the calculation unit 12 starts voltage detection by the voltage detection unit 13 (step S111) and starts current detection by the current detection unit 14 (step S112). Thereafter, the calculation unit 12 calculates the active power Prl by the method described above with reference to Fig. 4 (step S113).

[0037] Next, the calculation unit 12 compares the active power Prl with the target power Ptg (step S114). If the active power Prl is smaller than the target power Ptg, the calculation unit 12 adds an increase / decrease step amount Δt to the current capacity adjustment signal, and sets the result as a new capacity adjustment signal (step S115). The calculation unit 12 calculates the active power Prl based on the voltage and current when the capacitance of the varactor diode 44 is changed by the new capacity adjustment signal (step S116). Then, the calculation unit 12 again compares the active power Prl with the target power (step S117). If the active power Prl is equal to or greater than the target power Ptg, the power adjustment process ends. However, if the active power Prl is smaller than the target power Ptg, steps S115 to S117 are repeated. It is assumed that there is a positive correlation between the capacity adjustment signal and the active power, i.e., the higher the adjustment signal, the greater the active power.

[0038] In step S114 described above, if the active power Prl is equal to or greater than the target power Ptg, the calculation unit 12 subtracts the increase / decrease step amount Δt from the current capacity adjustment signal and sets the result as a new capacity adjustment signal (step S118). The calculation unit 12 calculates the active power Prl based on the voltage and current when the capacitance of the varactor diode 44 changes due to the new capacity adjustment signal (step S119). Then, the calculation unit 12 again compares the active power Prl with the target power (step S120). If the active power Prl is smaller than the target power Ptg, the power adjustment process ends, but if the active power Prl is equal to or greater than the target power Ptg, steps S118 to S120 are repeated.

[0039] The above power adjustment allows the effective power Prl to approach the target power Ptg. Therefore, even if the characteristics of the piezoelectric element 202 vary, such as the resonance frequency shifting due to changes over time, the desired power is supplied to the piezoelectric element 202. When stable power is supplied, the variation in the output sound pressure from the piezoelectric element 202 is suppressed, resulting in stable stirring of the sample and reagent. Furthermore, even if the piezoelectric element 202 already installed in the automatic analyzer is replaced with one of a type with different characteristics, for example, if it is replaced from a material containing lead (e.g., PZT) to a material not containing lead (e.g., LN), the above-mentioned power adjustment allows the piezoelectric element 202 to be driven by the same amplifier 2.

[0040] Next, the power adjustment training sequence will be described. Figure 9 is a timing chart showing the timing of the training sequence. As shown in Figure 9, when the operator turns on the power of the automatic analyzer, the mechanism control unit 4 performs initialization settings for the entire device. At this time, the initial value Vit and the increase / decrease step ΔVt of the capacity adjustment signal 45 (Vt) described above are also set.

[0041] Thereafter, the operator mounts the piezoelectric element 202 for power calibration on the automatic analyzer. The piezoelectric element 202 for calibration is an individual having standard characteristics, for example, an individual having a standard resonance frequency that is consistent with that of the piezoelectric element A. The piezoelectric element 202 for power calibration may also be mounted in advance at a specific position on the outer periphery of the reaction disk.

[0042] The mechanism control unit 4 starts the training sequence and sends a calibration start signal to the calculation unit 12. The calculation unit 12 updates the table 51 shown in FIG. 5 by calculating each effective power when the gain setting value and frequency setting value of the amplifier 2 are changed. When the updating of the table 51 is complete, the calculation unit 12 sends a normal completion signal to the mechanism control unit 4. When the mechanism control unit 4 receives the normal completion signal 206, it determines that the training sequence has ended and starts the analysis operation, including mixing the sample and reagent.

[0043] In this way, by updating the target power table at the timing of calibration of the automatic analyzer, which is performed after power-on and before the start of analysis, it becomes possible to perform subsequent power adjustments normally. Note that the piezoelectric element 202 attached for calibration may also be used for actual stirring as is. [Example]

[0044] FIG. 10 is an example of a table storing target power values ​​for Example 2. As described above, in the automated analyzer according to an embodiment of the present invention, the electrodes of the piezoelectric element 202 are configured with multiple divided electrodes 204 (#1 to #12). Here, the voltage-current characteristics may differ for each divided electrode 204. Therefore, in this example, a different target power Ptg value is stored in table 52 for each divided electrode 204. Furthermore, when voltage is simultaneously applied to multiple divided electrodes 204, a different target power Ptg value is stored in table 52 for each combination of divided electrodes 204. For example, when divided electrodes 204 #5 and #6 are connected in parallel, the gain setting is the middle gain Gmid, and the frequency setting is the center frequency Fcn, the target power Ptg is 6.1 W. According to this example, even when the piezoelectric element 202 is configured with multiple electrodes, the power supplied to each electrode can be stabilized by approximating the target power set for each electrode and its combination, thereby suppressing variations in output sound pressure. [Example]

[0045] 11 is a diagram showing the configuration of a variable reactance impedance matching circuit according to Example 3. The variable reactance impedance matching circuit 11 of this example includes inductors (toroidal cores 61 and 62), a capacitor 63, and a 4-bit binary capacitor array 64. The 4-bit binary capacitor array 64 is connected in parallel to the capacitor 63, and is an element that can change the capacitance between its terminals by turning on / off an 8421-weighted capacitor in response to a capacitance adjustment 4-bit signal 65.

[0046] 6 of the first embodiment, toroidal cores 61 and 62 and capacitor 63 convert the impedance of several hundred ohms of piezoelectric element 202 into a low impedance to match the impedance with switching amplifier 16. However, in this embodiment, in order to bring the active power closer to target power Ptg, calculation unit 12 outputs a 4-bit capacitance adjustment signal 65. When a capacitor that is turned on among the multiple capacitors constituting 4-bit binary capacitor array 64 is changed, the capacitance value changes, and therefore the impedance seen from the primary side of transformer 19 also changes. In this embodiment, by utilizing this principle, impedance changes caused by a shift in the resonant frequency of piezoelectric element 202 can be digitally corrected by adjusting the capacitance of 4-bit binary capacitor array 64. [Example]

[0047] 12 is a diagram illustrating the configuration of a voltage detection unit, a current detection element, a current detection unit, and a calculation unit in the amplifier according to Example 4. Only differences from the configuration shown in FIG. 4 of Example 1 will be described below.

[0048] The voltage detection unit 13 of this embodiment further includes a voltage zero cross detector 71 (comparator) in addition to the input amplifier 22, the anti-aliasing filter 23, and the AD converter 24. The current detection unit 14 of this embodiment further includes a current zero cross detector 76 (comparator) in addition to the preamplifier 25, the anti-aliasing filter 26, and the AD converter 27. The calculation unit 12 of this embodiment further includes a voltage input register 31, a V 2 A sum calculation unit 78, a voltage effective value calculation unit 79, a current input register 32, I 2 It includes a sum calculation unit 83 , a current effective value calculation unit 84 , a period calculation unit 72 , a V counter 73 , an I counter 77 , a phase difference calculation unit 74 and an active power calculation unit 75 .

[0049] When the AD converter 24 of the voltage detection unit 13 outputs the voltage AD converted value to the voltage input register 31, V 2 The sum calculation unit 78 squares and sequentially adds the voltage AD converted values ​​to obtain V 2The voltage effective value calculation unit 79 calculates the sum of V 2 The square root of the sum is calculated, and the calculation result is output as the voltage effective value Vrms to the active power calculation unit 75. The voltage zero cross detector 71 detects the crossing points of the output of the input amplifier 22 with 0 volts, and outputs a voltage zero cross signal 81 to the period calculation unit 72 and the V counter 73. The period calculation unit 72 calculates one period of the voltage signal from the voltage zero cross signal 81.

[0050] On the other hand, when the AD converter 27 of the current detection unit 14 outputs the current AD converted value to the current input register 32, I 2 The sum calculation unit 83 squares and sequentially adds the current AD converted values, and calculates I 2 The current effective value calculation unit 84 calculates the sum of I 2 The square root of the sum is calculated, and the calculation result is output as the effective current value Irms to the active power calculation unit 75. The current zero cross detector 76 detects the crossing point of the output of the preamplifier 25 with 0 volts, and outputs a current zero cross signal 82 to the I counter 77.

[0051] The phase difference calculation unit 74 of the calculation unit 12 is synchronized with the period calculation unit 72, V counter 73, and I counter 77, and calculates the phase difference time ΔT from the count value of the V counter 73 and the count value of the I counter 77. Using one period T output by the period calculation unit 72, the phase difference Δθ is calculated by the following equation.

[0052] Phase difference Δθ=ΔT / T…(Formula 2) The active power calculation unit 75 of the operation unit 12 calculates the active power Prl from the output Vrms of the voltage effective value calculation unit 79, the output Irms of the current effective value calculation unit 84, and the output Δθ of the phase difference calculation unit 74 using the following formula:

[0053] Active power Prl = (Vrms × Irms) × cosΔθ…(Equation 3) In this way, the effective power Prl supplied to the piezoelectric element 202 can be calculated from the voltage applied to the piezoelectric element 202 and the current flowing therethrough. [Example]

[0054] The fifth embodiment will be described with reference to Figures 13 to 15. In the first embodiment, only the power adjustment is performed as described with reference to Figures 7 and 8, but in this embodiment, not only the power adjustment but also the adjustment of the drive frequency Fdr for driving the piezoelectric element 202 is performed, that is, a frequency search power adjustment is performed.

[0055] FIG. 13 is a flowchart showing the processing for initial setting of frequency search power adjustment by the calculation unit. When the power of the automatic analyzer is turned on, first, the calculation unit 12 executes processing similar to the initial setting shown in FIG. 7 of the first embodiment. Next, the calculation unit 12 reads the center frequency Fc of the piezoelectric element (which may be the nominal drive frequency of the piezoelectric element) from the storage unit (step S301). The calculation unit 12 also reads the difference ΔFLw between the center frequency Fc and the minimum frequency FLw at which the amplifier 2 can drive the piezoelectric element from the storage unit (step S302). Furthermore, the calculation unit 12 reads the frequency increase / decrease step ΔFdr used when increasing / decreasing the drive frequency Fdr from the storage unit (step S303). The center frequency Fc, minimum frequency FLw, center frequency Fc, frequency increase / decrease step ΔFdr, etc. are predefined in the storage unit for each type of piezoelectric element, for example.

[0056] Fig. 14 is a diagram showing a power adjustment module used in frequency search power adjustment. The power adjustment module shown in Fig. 14 corresponds to the part after step S114 in the power adjustment process shown in Fig. 8 of the first embodiment.

[0057] 15 is a flowchart showing the processing of frequency search power adjustment by the calculation unit 12. First, the calculation unit 12 substitutes the center frequency Fc-ΔFLw as the drive frequency Fdr (step S311).

[0058] Next, the calculation unit 12 performs steps S111 to S113 in the same manner as the power adjustment process shown in FIG. 8 of the first embodiment, and then performs the process of the power adjustment module shown in FIG.

[0059] The calculation unit 12 stores the active power Prl after adjustment by the power adjustment module in the storage unit (step S312), and also stores the current drive frequency Fdr in the storage unit (step S313). Thereafter, the calculation unit 12 adds the frequency increase / decrease step ΔFdr to the current drive frequency Fdr, sets the resulting value as the new drive frequency Fdr (step S314), and compares it with the center frequency Fc (step S315).

[0060] If the drive frequency Fdr is equal to or lower than the center frequency Fc, the process returns to the processing of the power adjustment module shown in Fig. 14, and steps S312 to S315 are repeated. If the drive frequency Fdr becomes higher than the center frequency Fc, the calculation unit 12 sets the reactance adjustment voltage (capacity adjustment signal) stored in the storage unit when the active power is maximized as the reactance adjustment voltage after frequency search adjustment (step S316), and sets the drive frequency at that time as the drive frequency after frequency search adjustment (step S317).

[0061] In this way, by changing the driving frequency of the piezoelectric element stepwise within a certain range and successively calculating the effective power, the frequency at which the effective power is maximized can be found. By driving the piezoelectric element at this frequency, it is possible to increase the output sound pressure.

[0062] Furthermore, the characteristics of a piezoelectric element include a resonant frequency where the impedance is minimal and an anti-resonant frequency in a higher frequency range where the impedance is maximal. Therefore, as in this embodiment, searching by increasing the frequency stepwise from a low frequency has the advantage of making it easier to find the resonant frequency. Then, by driving the piezoelectric element at the resonant frequency, the displacement of the piezoelectric element is maximized, allowing for efficient generation of powerful ultrasonic waves. [Example]

[0063] The sixth embodiment will be described with reference to Fig. 16. Fig. 16 is a timing chart showing the timing of power adjustment. The process from when the operator turns on the power of the automatic analyzer, to when the training sequence is executed and the analytical operation starts, is the same as that described above with reference to Fig. 9 in the first embodiment.

[0064] In this embodiment, the amplifier 2 adjusts the output power every time a predetermined time has elapsed. Specifically, after the calculation unit 12 determines the capacitance adjustment signal, power adjustment is not performed until the time Ttn has elapsed. This makes it possible to avoid unnecessary power adjustment. The time Ttn is determined taking into consideration the time (e.g., one month) over which the piezoelectric element may change over time. Furthermore, the timing for power adjustment may be determined based on whether a predetermined number of samples (e.g., 100,000 samples) has been reached, instead of whether the predetermined time has elapsed. [Example]

[0065] The seventh embodiment will be described with reference to Fig. 17. Fig. 17 is a diagram showing signals sent from the mechanism control unit to the amplifier.

[0066] As described above, the reaction vessels 114 containing samples and reagents are sequentially moved to the front of the stirring unit 104 by repeatedly rotating and stopping the reaction disk. If the piezoelectric element is driven to generate ultrasonic waves in front of the stirring unit 104, i.e., when no reaction vessels 114 containing samples or the like are present at the stirring position, the piezoelectric element may be damaged by reflection. Therefore, in this embodiment, when the reaction disk is at a predetermined rotational position and the reaction vessels 114 are at the stirring position, the mechanism control unit 4 transmits a reaction vessel facing signal 401 to the calculation unit 12 of the amplifier 2. The calculation unit 12 performs power adjustment only when it receives the reaction vessel facing signal 401 from the mechanism control unit 4. Furthermore, the calculation unit 12 terminates power adjustment after determining the reactance adjustment signal.

[0067] The signal sent from the mechanism control unit 4 to the amplifier 2 may include information indicating whether or not an analysis is in progress. The calculation unit 12 may adjust the power only when the automatic analyzer is performing an analysis, because adjusting the power when the automatic analyzer is not performing an analysis would be pointless.

[0068] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. It is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0069] 2: Amplifier, 4: Mechanical control unit, 11: Variable reactance impedance matching circuit, 12: Calculation unit, 13: Voltage detection unit, 14: Current detection unit, 15: Reactance adjustment signal, 16: Switching amplifier, 19: Transformer, 21: Current detection element, 22: Input amplifier, 23, 26: Anti-aliasing filter, 24, 27: AD converter, 25: Preamplifier, 31: Voltage input register, 32: Current input register, 33: Multiplier ,34: VI product register, 35: power register, 41, 42, 61, 62: toroidal core, 43, 63: capacitor, 44: varactor diode, 45: capacitance adjustment signal, 64: 4-bit binary capacitor array, 65: capacitance adjustment 4-bit signal, 71: voltage zero cross detector, 72: period calculation unit, 73: V counter, 74: phase difference calculation unit, 75: active power calculation unit, 76: current zero cross detector, 77: I counter, 78: V 2 Sum calculation unit, 79: voltage effective value calculation unit, 81: voltage zero cross signal, 82: current zero cross signal, 83: I 2Sum calculation unit, 84: current effective value calculation unit, 51, 52: table, 101: sample storage unit, 102: reagent storage unit, 103: reaction unit, 104-109: stirring unit, 110: analysis unit, 111: cleaning unit, 112: sample, 113: sample dispensing mechanism, 114: reaction vessel, 115: reagent dispensing mechanism, 116: reagent, 117: constant temperature bath, 201: connector, 202: piezoelectric element, 203: jig, 204: split electrode, 205: constant temperature water side electrode, 208: constant temperature water, 209: split electrode (lower side), 213: relay group, 223: reflector, 221: interface unit, 401: reaction vessel facing signal

Claims

1. In an automatic analyzer that stirs samples and reagents by ultrasonic waves generated by driving a piezoelectric element, The amplifier that drives the piezoelectric element includes: a voltage detection unit that detects a voltage applied to the piezoelectric element; a current detection unit that detects a current flowing through the piezoelectric element; a calculation unit that calculates an active power based on the detected voltage detected by the voltage detection unit and the detected current detected by the current detection unit, and determines an adjustment signal using the calculated active power and a predetermined target power; an impedance matching circuit that adjusts the output power of the amplifier by changing a reactance component based on the adjustment signal determined by the calculation unit; An automatic analyzer equipped with:

2. The automatic analyzer according to claim 1, The automatic analyzer is characterized in that the target power has different values ​​stored in a table for each frequency.

3. The automatic analyzer according to claim 2, The automatic analyzer is characterized in that the target power stored in the table is a different value for each type of piezoelectric element.

4. The automatic analyzer according to claim 3, The automatic analyzer is characterized in that the types of the piezoelectric elements include PZT elements and LN elements.

5. The automatic analyzer according to claim 2, An automatic analyzer characterized in that after power is turned on and before analysis begins, the calculation unit updates the table by calculating each effective power of the amplifier when the gain setting value and frequency setting value of the amplifier are changed.

6. The automatic analyzer according to claim 1, The automatic analyzer is characterized in that the impedance matching circuit includes a variable capacitance diode and an inductor.

7. The automatic analyzer according to claim 1, The automatic analyzer is characterized in that the calculation unit calculates the active power based on the sum of the products of the AD-converted value of the detected voltage and the AD-converted value of the detected current.

8. The automatic analyzer according to claim 2, The piezoelectric element has a plurality of electrodes at different height positions, The automatic analyzer is characterized in that the target power has a different value stored in the table for each of the electrodes or each combination thereof.

9. The automatic analyzer according to claim 1, The automatic analyzer is characterized in that the impedance matching circuit comprises a capacitor array in which each capacitor can be selectively turned on or off, and an inductor.

10. The automatic analyzer according to claim 1, the calculation unit calculates the active power based on an effective voltage value calculated from an AD converted value of the detected voltage, an effective current value calculated from an AD converted value of the detected current, and a phase difference calculated from the detected voltage and the detected current.

11. The automatic analyzer according to claim 1, The automatic analyzer is characterized in that the calculation unit changes the drive frequency that drives the piezoelectric element and determines the adjustment signal and the drive frequency using the effective power calculated for each drive frequency.

12. The automatic analyzer according to claim 11, An automatic analyzer characterized in that the drive frequency changed by the calculation unit is in a range from the nominal drive frequency or center frequency of the piezoelectric element to the lowest frequency at which the piezoelectric element can be driven.

13. The automatic analyzer according to claim 12, The automatic analyzer is characterized in that, when changing the drive frequency, the calculation unit increases the drive frequency in steps from the minimum frequency.

14. The automatic analyzer according to claim 1, The automatic analyzer is characterized in that the amplifier adjusts the output power at predetermined time intervals.

15. The automatic analyzer according to claim 1, a mechanism control unit for controlling a rotatable reaction disk on which reaction vessels containing samples and reagents are arranged, The automatic analyzer is characterized in that the amplifier adjusts the output power when it receives information from the mechanism control unit that the reaction vessel is in a stirring position or that analysis is in progress.

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