JP2007336683A - Power unit and electrophoresis apparatus equipped with the power unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the influence on the current measured values due to the current for making the transistor of a discharge circuit actuated, in a power unit equipped with a discharge circuit. <P>SOLUTION: The discharge circuit comprises a bipolar transistor Q1, which is connected in parallel with potential dividing resistors R1 and R2 and a photovolatic photocoupler PC1 which receives the input of the output signal of a comparator circuit 4, when set voltage is lower than feedback voltage and generates a base current as a control signal for actuating the bipolar transistor Q1, and is connected so that a control signal returns to the photocoupler PC1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to, for example, a power supply device for applying a voltage to a sample injection channel or a separation channel of an electrophoresis device, and an electrophoresis device including such a power supply device.

  In an electrophoresis device, the sample is moved to the separation medium by applying an electric field to the sample enclosed in the electrophoresis medium (for example, sol), and the sample is separated into components by using the difference in the movement speed due to the molecular size. To do. In a chip-type electrophoresis apparatus, an electric field is also applied when a sample is introduced into the analysis chip or when the sample is moved within the chip. The electric field is controlled by controlling the voltage of the high-voltage power source connected to the separation medium and the separation channel.

  In order to operate the sample at a high speed in order to control the introduction of the sample and the start of electrophoresis, it is necessary to control the voltage of the high voltage power source at a high speed. The chip-type electrophoresis device applies an electric field to the sample injection channel to move the sample to the intersection with the separation channel, and then switches the power supply device to apply an electric field to the separation channel to separate the sample at the intersection. Inject into the channel. However, if switching the power supply device, that is, it takes time to fall the voltage applied to the injection channel, the sample injected into the separation channel diffuses and the separation performance (theoretical plate number) deteriorates. was there. Therefore, it is preferable to use a power supply device having a short voltage fall time as a power supply device used for an electrophoresis apparatus or the like. However, in order to convert an AC voltage into a smooth DC voltage, the power supply device is usually configured with a rectifying and smoothing circuit composed of a diode and a capacitor. Even if the set voltage value input to the power supply device is lowered, There is a problem that it takes time for the output voltage to fall due to the electric charge accumulated in the capacitor.

  As a method for shortening the voltage fall time, it is conceivable to quickly discharge the charge accumulated in the capacitor provided in the rectifying and smoothing circuit of the power supply device. As a configuration for quickly discharging the electric charge accumulated in the capacitor of the rectifying and smoothing circuit, for example, as shown in FIG. 5, a method of providing a charge discharging circuit including a bipolar transistor Q1 connected in parallel to the voltage dividing resistors R1 and R2 There is. In this power supply device, the bipolar transistor Q1 is operated by a control signal from the comparison circuit 4. The comparison circuit 4 compares the set voltage of the setting unit 2 with the feedback voltage corresponding to the output voltage, and when the set voltage is higher than the feedback voltage, supplies an electric signal to the inverter 6 side to boost the transformer T1, the rectifying and smoothing circuit A voltage corresponding to the set voltage is output to the output terminal 10 via 8, and when the set voltage is lower than the feedback voltage, the bipolar transistor Q1 is operated by passing a base current. When the bipolar transistor Q1 is activated, the electric charge accumulated in the smoothing capacitors C1, C2 of the rectifying / smoothing circuit 8 is discharged to the ground between the collector and the emitter of the bipolar transistor Q1 and through the current detection resistor R3. Thereby, when the output voltage falls, the charges accumulated in the smoothing capacitors C1 and C2 are quickly discharged, so that the output voltage falls quickly.

  As shown in FIG. 6, the power supply device of FIG. 5 is connected to the upstream end A and the downstream end B of the separation channel 16 of the microchip type electrophoresis apparatus 14 to control the voltage applied to the separation channel 16. Think about the case you want to. The power supply device is provided with a current measurement resistor R3 between the voltage dividing resistors R1 and R2 of the power supply device and the ground terminal 11 in order to satisfy the demand for measuring a high-voltage current flowing through the separation channel 16. The current flowing through the current measuring resistor R3 can be measured by the current measuring unit 12. This is because the current flowing through the separation channel 16 cannot be measured on the microchip 14. This also applies to an injection channel (not shown) orthogonal to the separation channel 16 for injecting a sample into the separation channel 16.

  For example, in order to apply a voltage of 1000 V between the upstream end A and the downstream end B of the separation channel 16, a voltage of 1000 V is applied from a power supply device connected to the upstream end A (hereinafter referred to as an upstream power supply device). And outputs a voltage of 0 V from a power supply device connected to the downstream end B (hereinafter referred to as a downstream power supply device). That is, the inverter 6 is stopped by setting the set voltage of the downstream power supply device to 0V. Thereby, the current output from the upstream power supply device flows into the downstream power supply device via the separation channel 16. The current flowing into the downstream power supply device passes through the voltage dividing resistors R1 and R2 and the current measuring resistor R3 and flows out from the ground terminal 11 to the ground. However, a voltage drop occurs due to the current flowing through these resistors, and the comparison circuit The feedback voltage detected at 4 increases. Since the set voltage of the downstream power supply device is 0V, the feedback voltage becomes higher than the set voltage, the base signal is supplied to the bipolar transistor Q1, and the bipolar transistor Q1 operates. As a result, the current flowing into the downstream power supply device passes between the collector and emitter of the bipolar transistor Q1 connected in parallel with the voltage dividing resistors R1 and R2, and then flows out from the ground terminal 11 to the ground via the current measuring resistor R3. Thus, the voltage drop due to the voltage dividing resistors R1 and R2 disappears, and the potential of the output unit 10 of the downstream power supply apparatus approaches zero. The resistance value of the current measuring resistor R3 is set to be extremely smaller than the resistors R1 and R2, and the voltage drop due to the resistor R3 can be ignored.

  However, in the configuration shown in FIG. 6, the current from the comparison circuit 4 of the downstream power supply device passes through between the base and emitter of the bipolar transistor Q1, and then flows out to the ground through the resistor R3. Therefore, the current value detected by the current measuring unit 12 includes the base current of the bipolar transistor Q1, and in this configuration, only the current flowing through the separation channel 16 cannot be measured accurately. Furthermore, the base current may instantaneously be in the order of mA (milliampere), which is a fatal error particularly when a current in the order of μA (microampere) or less is detected.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate an influence on a current measurement value due to a current for operating a transistor of a charge discharge circuit in a power supply device including the charge discharge circuit.

  The power supply device of the present invention is connected between the output terminal and the ground terminal, and inputs a feedback voltage and a set voltage, a series circuit including a voltage dividing resistor and a current measuring resistor that divides the output voltage to create a feedback voltage. A comparison circuit, an oscillation circuit that operates according to an output signal of the comparison circuit when the set voltage is higher than the feedback voltage, a step-up transformer that uses the output signal of the oscillation circuit as a primary side input, and a secondary side of the step-up transformer A power supply circuit having a rectifying / smoothing circuit connected to the output terminal and supplying a power supply voltage to the output terminal, a transistor connected in parallel to the voltage dividing resistor, and an output signal of the comparison circuit when the set voltage is lower than the feedback voltage And a charge discharge circuit including a photovoltaic photocoupler that generates a control signal that is input to generate a control signal, and is connected so that the control signal returns to the photocoupler.

  A bipolar transistor can be used as the transistor connected in parallel with the voltage dividing resistor. In that case, the control signal from the photocoupler is supplied to the base electrode of the transistor, and the base current is connected so as to return to the photocoupler.

  Further, a field effect transistor can be used as a transistor connected in parallel to the voltage dividing resistor. In this case, the photocoupler is connected so that the electromotive force of the photocoupler is applied between the gate and the source of the field effect transistor.

  A plurality of charge discharge circuits may be connected in series. In that case, the connection is made so that the control signal returns to the photocoupler in each charge discharge circuit.

  An example of a preferred application of the power supply device of the present invention is an electrophoresis device. In that case, the power supply device of the present invention is connected to both ends of the electrophoresis path of the electrophoresis medium provided with the electrophoresis path in which the sample is electrophoresed from one end of the flow path to the other end of the flow path. Used to apply voltage.

  In the power supply device of the present invention, the photovoltaic power generating the control signal for operating the transistor by inputting the output signal of the comparison circuit when the set voltage is lower than the feedback voltage and the transistor connected in parallel to the voltage dividing resistor A charge discharging circuit including a type photocoupler and connected so that a control signal is returned to the photocoupler, the current through the transistor and the control signal for operating the transistor are not discharged together from the ground terminal. Therefore, since the control signal is not detected together with the current detected by the current measuring resistor through the transistor, the current value can be accurately detected by the current measuring resistor.

FIG. 1 is a circuit diagram showing an embodiment of a power supply device of the present invention.
A series circuit including voltage dividing resistors R1 and R2 and a current measuring resistor R3 connected between the output terminal 10 and the ground terminal 11 is configured. A comparison circuit 4 is provided for comparison by inputting a feedback voltage and a set voltage corresponding to the output voltage output to the output terminal 10 by the voltage dividing resistors R1 and R2, and the comparison circuit when the set voltage is higher than the feedback voltage is provided. Inverter 6 as an oscillation circuit operated by an output signal, step-up transformer T1 using the output signal of inverter 6 as a primary side input, and rectifying / smoothing connected to the secondary side of step-up transformer T1 and supplying a power supply voltage to output terminal 10 A power supply circuit including the circuit 8 is configured. Further, a bipolar transistor Q1 connected in parallel to the voltage dividing resistors R1 and R2, and a base as a control signal for operating the bipolar transistor Q1 by inputting the output signal of the comparison circuit 4 when the set voltage is lower than the feedback voltage. A charge discharge circuit including a photovoltaic photocoupler PC1 that generates current and connected so that a control signal returns to the photocoupler PC1 is configured.

  The rectifying / smoothing circuit 8 includes smoothing capacitors C1 and C2 and diodes D1 and D2. The charge discharge circuit is a circuit for discharging the electric charge accumulated in the smoothing capacitors C1 and C2 from the ground terminal to the ground when the output voltage is lowered. During the discharge, the bipolar transistor Q1 is activated and the collector-emitter is connected. Through the bipolar transistor Q1, the electric charge accumulated in the smoothing capacitors C1 and C2 flows to the ground terminal 11 side and is discharged.

The operation of the power supply device of this embodiment will be described.
When the output voltage rises, the comparison circuit 4 detects that the set voltage is higher than the feedback voltage corresponding to the output voltage by the voltage dividing resistors R1 and R2, and generates an electric signal on the inverter 6 side to generate an AC voltage. generate. The AC voltage generated by the inverter 6 is boosted by the step-up transformer T1, converted to a smooth DC voltage by the rectifying and smoothing circuit 8, and a DC voltage corresponding to the set voltage is output from the output unit 10.

  When the output voltage falls, the comparison circuit 4 detects that the set voltage is lower than the feedback voltage corresponding to the output voltage by the voltage dividing resistors R1 and R2, and generates an electric signal on the photocoupler PC1 side. The photocoupler PC1 receives the electrical signal from the comparison circuit 4 on the primary side to emit light from the light emitting diode, and receives light from the light emitting diode with the secondary side photodiode. An electromotive force is generated in the photodiode that receives light, and a potential is applied to the base of the bipolar transistor Q1 to generate a base current, thereby operating the bipolar transistor Q1. Due to the operation of the bipolar transistor Q1, the charges accumulated in the smoothing capacitors C1 and C2 of the rectifying and smoothing circuit 8 are discharged from the ground terminal 11 to the ground through the collector-emitter of the bipolar transistor Q1. The base current for operating the bipolar transistor Q1 returns to the photocoupler PC1 again through the base-emitter.

FIG. 2 is a circuit diagram showing an example of a configuration of a power supply device connected to a microchip type electrophoresis apparatus. In this figure, the illustration of the injection channel for injecting the sample into the separation channel is omitted.
In this embodiment, the output terminal 10 of the power supply device shown in FIG. 1 is connected to the upstream end A and the downstream end B of the separation channel 16 of the microchip 14. Hereinafter, the power supply device connected to the upstream end A is referred to as an upstream power supply device, and the power supply device connected to the downstream end B is referred to as a downstream power supply device.

  For example, when a voltage of 1000 V is applied to the separation channel 16, a voltage of 1000 V is output from the upstream power supply device, and a voltage of 0 V is output from the downstream power supply device. That is, the inverter 6 is stopped by setting the set voltage of the downstream power supply device to 0V. In this case, the current output from the upstream power supply device flows into the downstream power supply device through the separation channel 16. The current flowing into the downstream power supply device flows to the ground from the ground terminal via the voltage dividing resistors R1 and R2 and the current measuring resistor R3. However, these resistors R1 and R2 (using a high resistance such as 10 MΩ) are still used. ) And the voltage drop of R3, the potential of the output unit 10 does not become 0V. However, since the feedback voltage to the comparison circuit 4 of the downstream power supply device becomes higher than the set voltage due to the voltage drop due to these resistors, it is detected that the potential of the output unit is higher than the set voltage, and an electric signal is sent to the photocoupler PC1. To operate the bipolar transistor Q1. When the bipolar transistor Q1 is operated, the current flowing into the downstream power supply device passes between the collector and the emitter of the bipolar transistor Q1, and then flows from the ground terminal to the ground through the current measuring resistor R3. Therefore, the voltage generated by the resistors R1 and R2 The drop disappears and the potential of the output unit 10 drops and approaches 0V. However, the voltage drop due to the current measuring resistor R3 becomes an error, but can be ignored by setting the resistance value of the current measuring resistor R3 to be extremely smaller than other resistors.

  The power supply device used here is configured so that the base current for operating the bipolar transistor Q1 passes between the base and the emitter of the bipolar transistor Q1 and then returns to the photocoupler PC1. The current does not pass through the current measuring resistor R3 together with the current. Therefore, since the base current is not detected by the current measuring unit 12, the current flowing through the separation channel 16 in the current measuring unit 12 can be accurately measured.

  Next, consider the case of outputting a voltage exceeding the withstand voltage of the transistor that controls the opening and closing of the charge discharge circuit. For example, it may be necessary to output a voltage of 3000 V to the separation channel of the chip type electrophoresis apparatus. However, the withstand voltage between the collector and the emitter of a commercially available bipolar transistor is as high as about 1800V, and a charge discharge circuit using only one such transistor is a charge discharge circuit in a power supply device that outputs a voltage of 3000V. Can not fulfill the function.

  Therefore, in order to reduce the voltage applied to one transistor, for example, as shown in FIG. 7, it is conceivable to arrange two bipolar transistors Q1 and Q2 in stages as transistors for opening and closing the charge discharge circuit. In such a power supply device, bleeder resistors R6 and R7 having equal resistance values are provided so that collector voltages applied to the bipolar transistors Q1 and Q2 are equal. However, when the bipolar transistors Q1 and Q2 are arranged in stages, the emitter potential of the bipolar transistor Q2 is close to 0, so that the bipolar transistor Q2 can be operated only by applying a low voltage from the comparison circuit 4 to the base. However, the emitter potential of the bipolar transistor Q1 is the same as the collector potential of the bipolar transistor Q2, and in order to operate the bipolar transistor Q1, it is necessary to apply a high voltage to the base. For this purpose, a separate high voltage power supply is provided. Is necessary.

  Further, in the configuration of the power supply device shown in FIG. 7, since the base current when the bipolar transistors Q1 and Q2 are operated flows to the ground terminal 11 through the current measurement resistor R3, the downstream of the microchip. When the set voltage is set to 0 V using the side power supply device, the current flowing from the output unit 10 cannot be accurately measured by the current measuring unit 12.

FIG. 3 is a circuit diagram showing an embodiment of a power supply device configured to output a high voltage.
A series circuit including voltage dividing resistors R1 and R2 and a current measuring resistor R3 connected between the output terminal 10 and the ground terminal 11 is configured. A comparison circuit 4 is provided for comparison by inputting a feedback voltage and a set voltage corresponding to the output voltage output to the output terminal 10 by the voltage dividing resistors R1 and R2, and the comparison circuit when the set voltage is higher than the feedback voltage is provided. Inverter 6 as an oscillation circuit operated by an output signal, step-up transformer T1 using the output signal of inverter 6 as a primary side input, and rectifying / smoothing connected to the secondary side of step-up transformer T1 and supplying a power supply voltage to output terminal 10 A power supply circuit including the circuit 8 is configured. In addition, the bipolar transistors Q1 and Q2 connected in parallel to the voltage dividing resistor, the base current as a control signal for operating the bipolar transistor Q1 by inputting the output signal of the comparison circuit 4 when the set voltage is lower than the feedback voltage Photovoltaic photocoupler PC1 and photocoupler PC1 that generate the photocurrent that generates the base current as a control signal for operating the bipolar transistor Q2 by inputting the output signal of the comparison circuit 4 when the set voltage is lower than the feedback voltage A charge discharge circuit is configured that includes a power type photocoupler PC2 and is connected so that the control signal generated by the photocoupler PC1 returns to the photocoupler PC1 and the control signal generated by the photocoupler PC2 returns to the photocoupler PC2. In order to supply the output signal of the comparison circuit 4 to the photocouplers PC1 and PC2 with an appropriate current, current limiting resistors R8 and R9 are provided between the comparison circuit 4 and the photocouplers PC1 and PC2. Further, bleeder resistors R6 and R7 having equal resistance values are provided so that collector voltages applied to the bipolar transistors Q1 and Q2 are equal.

The operation of the power supply device of this embodiment will be described.
When the output voltage rises, the comparison circuit 4 detects that the set voltage is higher than the feedback voltage corresponding to the output voltage by the voltage dividing resistors R1 and R2, and generates an electric signal on the inverter 6 side to generate an AC voltage. generate. The AC voltage generated by the inverter 6 is boosted by the step-up transformer T1, converted to a smooth DC voltage by the rectifying and smoothing circuit 8, and a DC voltage corresponding to the set voltage is output from the output unit 10.

  When the output voltage falls, the comparison circuit 4 detects that the set voltage is lower than the feedback voltage, and generates an electrical signal on the photocouplers PC1 and PC2 side. Each of the photocouplers PC1 and PC2 receives the electric signal from the comparison circuit 4 on the primary side to emit light from the light emitting diode, and the secondary side photodiode receives light from the light emitting diode. An electromotive force is generated in the photodiode that has received the light, a base current is generated in the bipolar transistors Q1 and Q2, and the bipolar transistors Q1 and Q2 are operated. By the operation of the bipolar transistors Q1 and Q2, the charges accumulated in the smoothing capacitors C1 and C2 of the rectifying and smoothing circuit 8 are discharged from the ground terminal 11 to the ground through the collectors and emitters of the bipolar transistors Q1 and Q2. The base current for operating the bipolar transistor Q1 returns to the photocoupler PC1 again through the base-emitter, and the base current for operating the bipolar transistor Q2 returns to the photocoupler PC2 again through the base-emitter.

  Since the emitter potential of the bipolar transistor Q1 is the same as the collector potential of the bipolar transistor Q2, it is necessary to apply a higher potential to the base than the collector potential of the bipolar transistor Q2 in order to operate the bipolar transistor Q1. However, in the power supply device of this embodiment, the electromotive force side of the photocoupler PC1 is connected so as to have the same potential as the collector potential of the bipolar transistor Q2, and the secondary side photodiode receives light so that the bipolar transistor Q2 Since an electromotive force is further generated based on the same potential as the collector potential, bipolar is generated by an electric signal from the comparison circuit 4 without providing a separate power source for applying a high potential to the base of the bipolar transistor Q1. Transistors Q1 and Q2 can be activated.

  A charge discharge circuit for quickly discharging the charges accumulated in the smoothing capacitors C1 and C2 of the rectifying and smoothing circuit 8 to the ground when the output voltage falls is configured using the two bipolar transistors Q1 and Q2 as switching elements. Since the voltages applied to the bipolar transistors Q1 and Q2 are distributed by the bleeder resistors R6 and R7, the voltage applied to the bipolar transistors Q1 and Q2 at the time of charge discharge is from the output section when the charge discharge is not performed. Since the output voltage is smaller than the output voltage, a voltage exceeding the breakdown voltage of the bipolar transistors Q1 and Q2 can be output.

  In the power supply device of this embodiment, the base currents for operating the bipolar transistors Q1 and Q2 are configured to return to the photocouplers PC1 and PC2, respectively. Therefore, the base current does not flow through the current measurement resistor R3, and the output unit 10 Therefore, when the current flowing into the power supply device is measured, accurate measurement can be performed without being affected by the base current.

  In the power supply device of the present invention, field effect type (MOS type) transistors Q3 and Q4 can be used as switching elements of the discharge circuit, instead of the bipolar transistors Q1 and Q2, for example, as shown in FIG. In this case, since no current flows from the gate electrodes of the MOS transistors Q3 and Q4 to the source side, the currents generated in the photocouplers PC1 and PC2 are consumed, and the resistors R4 and R5 are connected to the photocoupler PC1 in order to shorten the OFF time. And Q2 are connected in parallel to the photodiodes on the secondary side. The current output from the photodiode of the photocoupler PC1 is returned to the photocoupler PC1 again through the resistor R4, and the current output from the photodiode of the photocoupler PC2 is connected to return to the photocoupler PC2 again through the resistor R5. .

  Also in the power supply device shown in FIG. 4, the current generated by the photocouplers PC1 and PC2 is configured to return again to the photocouplers PC1 and PC2, respectively, and the current generated by the photocouplers PC1 and PC2 may flow through the current measurement resistor R3. Therefore, when measuring the current flowing from the output unit 10 into the power supply device, accurate measurement can be performed without being affected by the current generated by the photocouplers PC1 and PC2.

It is a circuit diagram which shows one Example of a power supply device. It is a circuit diagram which shows one Example of the power supply device connected to the electrophoresis apparatus. It is a circuit diagram which shows the further another Example of a power supply device. It is a circuit diagram which shows the further another Example of a power supply device. It is a circuit diagram which shows the structural example of the power supply device provided with the charge discharge circuit. It is a circuit diagram which shows the structure of the example which connected the power supply device provided with the charge discharge circuit to the electrophoresis apparatus. It is a circuit diagram which shows the structural example of the power supply device comprised so that a high voltage might be output.

Explanation of symbols

2 Setting part 4 Comparison circuit 6 Converter 8 Rectification smoothing circuit 10 Output part 11 Grounding part 12 Current measuring part T1 Step-up transformer C1, C2 Smoothing capacitor D1, D2 Diode PC1, PC2 Photocoupler Q1, Q2, Q3, Q4 Transistors R1, R2, R3, R4, R5, R6, R7, R8, R9 resistance

Claims (5)

A series circuit consisting of a voltage dividing resistor and a current measuring resistor connected between the output terminal and the ground terminal and dividing the output voltage to create a feedback voltage;
A comparison circuit for inputting and comparing the feedback voltage and the set voltage;
An oscillation circuit that operates according to an output signal of the comparison circuit when a set voltage is higher than a feedback voltage, a step-up transformer that uses the output signal of the oscillation circuit as a primary side input, and a secondary side of the step-up transformer that is connected to the secondary circuit A power supply circuit including a rectifying and smoothing circuit for supplying a power supply voltage to the output terminal;
A transistor connected in parallel to the voltage dividing resistor, and a photovoltaic photocoupler for generating a control signal for operating the transistor by inputting an output signal of the comparison circuit when a set voltage is lower than a feedback voltage A charge discharge circuit connected to return the control signal to the photocoupler;
Power supply unit with The transistor is a bipolar transistor,
The power supply device according to claim 1, wherein a control signal from the photocoupler is supplied to a base electrode of the transistor, and the base current is connected so as to return to the photocoupler. The transistor is a field effect transistor,
The power supply device according to claim 1, wherein the photocoupler is connected so that an electromotive force of the photocoupler is applied between a gate and a source of the transistor. A plurality of the charge discharge circuits are connected in series,
4. The power supply apparatus according to claim 1, wherein the control signal is connected so as to return to the photocoupler in each charge discharge circuit. An electrophoresis medium provided with an electrophoresis path through which a sample is electrophoresed from one end of the flow path to the other end;
The power supply device according to any one of claims 1 to 4, which is connected to both ends of the electrophoresis path, and applies an electrophoresis voltage to the electrophoresis path.
An electrophoretic apparatus comprising:

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