阅读说明：本技术 色谱仪装置以及负载开关电路 (Chromatograph device and load switch circuit ) 是由 石原悠悟 于 2019-11-01 设计创作，主要内容包括：本发明提供一种可减少突入电流,并且以低成本抑制零件发热的色谱仪装置及负载开关电路。色谱仪装置包括：多个动作部,构成色谱仪；及负载开关电路(11),开启及关闭直流电力的供给；多个动作部中的至少一个动作部作为负载电路(15)而与负载开关电路(11)连接,负载开关电路(11)包含：第一开关元件(Q1),连接在承受直流电压的第一节点(N1)与负载电路(15)之间,具有承受第二节点(N2)的电位的控制端子；电容元件(C1),连接在第一节点(N1)与第二节点(N2)之间；第一电阻元件(R1),连接在第一节点(N1)与第二节点(N2)之间；以及旁路电路(B1),在第一开关元件(Q1)的断开时使电流流入第一节点(N1)与第二节点(N2)之间。(The invention provides a chromatograph device and a load switch circuit, which can reduce inrush current and inhibit parts from heating at low cost. The chromatograph device includes: a plurality of operation units constituting a chromatograph; and a load switch circuit (11) that turns on and off the supply of the DC power; at least one of the plurality of operation units is connected to a load switch circuit (11) as a load circuit (15), and the load switch circuit (11) includes: a first switching element (Q1) connected between a first node (N1) receiving a DC voltage and a load circuit (15), and having a control terminal receiving the potential of a second node (N2); a capacitive element (C1) connected between the first node (N1) and the second node (N2); a first resistance element (R1) connected between a first node (N1) and a second node (N2); and a bypass circuit (B1) that causes a current to flow between the first node (N1) and the second node (N2) when the first switching element (Q1) is turned off.)

1. A chromatograph apparatus comprising:

a plurality of operation units constituting a chromatograph; and

a load switch circuit that turns on and off supply of the direct-current power;

at least one of the plurality of operation units is connected to the load switch circuit as a load circuit,

the load switch circuit includes:

a first switching element connected between a first node receiving a direct-current voltage and the load circuit, and having a control terminal receiving a potential of a second node;

a capacitive element connected between the first node and the second node;

a first resistive element connected between the first node and the second node; and

a bypass circuit that causes a current to flow between the first node and the second node when the first switching element is turned off.

2. The chromatograph apparatus of claim 1, wherein the bypass circuit comprises a directionally conducting circuit that causes current to flow from the first node to the second node when the first switching element is turned off.

3. The chromatograph apparatus of claim 2, wherein the load switch circuit further comprises a second resistive element connected between the second node and a third node, and

the unidirectional turn-on circuit comprises:

a third resistive element connected between the first node and the third node; and

a diode connected between the third node and the second node.

4. The chromatograph apparatus of claim 3, wherein the load switch circuit further comprises:

a second switching element connected between the third node and a fourth node set to a reference potential; and

a fourth resistive element connected between the anode of the diode and the second node.

5. The chromatograph apparatus according to any one of claims 1 to 4, wherein the chromatograph includes:

an analytical column;

a detector for detecting components of the sample separated by the analytical column; and

a power supply circuit;

the detector includes the load switch circuit and the load circuit, and

the load switch circuit is connected between the power supply circuit and the load circuit.

6. A load switch circuit for turning on and off supply of DC power to a load circuit of a chromatograph device, comprising:

a first switching element connected between a first node receiving a direct-current voltage and the load circuit, and having a control terminal receiving a potential of a second node;

a capacitive element connected between the first node and the second node;

a first resistive element connected between the first node and the second node; and

a bypass circuit that causes a current to flow between the first node and the second node when the first switching element is turned off.

Technical Field

The present invention relates to a chromatograph device and a load switch circuit.

Background

A detector such as an absorbance detector is used in a chromatograph such as a liquid chromatograph (for example, patent document 1). The detector used in the liquid chromatograph includes a light source such as a deuterium lamp, a motor for driving a shutter, a heater for adjusting the temperature of an optical system, and the like. A circuit for lighting the light source, a circuit for driving the motor, a circuit for driving the heater, and the like are load circuits to which dc power is supplied from a common power supply circuit. A load switch circuit is used to turn on and off the supply of dc power from a power supply circuit to a load circuit. In the load switch circuit, for example, a field effect transistor is used.

[ Prior art documents ]

[ patent document ]

[ patent document 1] International publication No. 2013/140617

Disclosure of Invention

[ problems to be solved by the invention ]

When the load circuit has a capacitance component such as a capacitor, an inrush current flows into the capacitance component of the load circuit when the field effect transistor is turned on at a high speed. In order to reduce the inrush current, a capacitor having a relatively large time constant is sometimes connected to the load switch circuit. This reduces the speed of turning on the field effect transistor. As a result, the peak current flowing into the field effect transistor can be reduced at the time of turning on the field effect transistor.

On the other hand, when a capacitor having a relatively large time constant is provided in the load switch circuit, the off time of the field effect transistor becomes long. When the field effect transistor is about to be turned off in a state where a large current is being supplied to the load circuit, a voltage between the drain and the source is generated, and heat generation of the field effect transistor temporarily increases. When the off time is long, the amount of heat generation increases, and therefore, a field effect transistor having a large rated current capacity must be used. This increases the cost of the parts.

The invention aims to provide a chromatograph device and a load switch circuit which can reduce inrush current and inhibit the heat generation of parts at low cost.

[ means for solving problems ]

A chromatograph apparatus according to a first aspect of the present invention includes: a plurality of operation units constituting a chromatograph; and a load switch circuit that turns on and off supply of the direct-current power; at least one of the plurality of operation units is connected to the load switch circuit as a load circuit, and the load switch circuit includes: a first switching element connected between a first node receiving a direct-current voltage and the load circuit, and having a control terminal receiving a potential of a second node; a capacitive element connected between the first node and the second node; a first resistive element connected between the first node and the second node; and a bypass circuit that causes a current to flow between the first node and the second node when the first switching element is turned off.

A load switch circuit according to a second aspect of the present invention is a load switch circuit that turns on and off supply of dc power to a load circuit of a chromatograph apparatus, including: a first switching element connected between a first node receiving a direct-current voltage and the load circuit, and having a control terminal receiving a potential of a second node; a capacitive element connected between the first node and the second node; a first resistive element connected between the first node and the second node; and a bypass circuit that causes a current to flow between the first node and the second node when the first switching element is turned off.

[ Effect of the invention ]

According to the first aspect of the present invention, it is possible to reduce inrush current in a chromatograph apparatus and suppress heat generation of parts at low cost.

According to the second aspect of the present invention, it is possible to reduce the inrush current in the load switch circuit and suppress the heat generation of the components at low cost.

Drawings

Fig. 1 is a block diagram mainly showing a configuration of a chromatography detector in a chromatograph apparatus according to an embodiment.

Fig. 2 is a circuit diagram showing a configuration of the load switch circuit of fig. 1.

Fig. 3 is a circuit diagram showing another example of the load switch circuit.

Fig. 4 is a circuit diagram showing a configuration of a load switch circuit according to the embodiment.

Fig. 5 is a circuit diagram showing a configuration of a load switch circuit of a comparative example.

Fig. 6 is a waveform diagram showing a simulation result of the load switch circuit of the embodiment.

Fig. 7 is a waveform diagram showing a simulation result of the load switch circuit of the comparative example.

Fig. 8 is a block diagram showing a configuration of a chromatograph apparatus including the chromatography detector of fig. 1.

[ description of symbols ]

10: chromatography detector

11. 11 a: load switch circuit

12: lamp lighting circuit

13: motor driving circuit

14: heater driving circuit

15: load circuit

16: lamp with a light source

17: stepping motor

18: DC heater

19: flow cell

20: light detector

30: detector control unit

50: analysis control unit

51: operation part

52: display unit

60: power supply circuit

100: chromatograph device

110: pump and method of operating the same

111: flow compatilizer

112: waste liquid container

120: sample introduction part

130: introducing port

140: analytical column

150: column box

B1: bypass circuit

C1, C2: capacitor with a capacitor element

D1: diode with a high-voltage source

GND: ground potential

L1, L11 dotted lines

L2, L12 solid lines

N1-N4: node point

PK1, PK2, PK11, PK 12: peak value

Q1, Q2: transistor with a metal gate electrode

R1-R6: resistance (RC)

SW: switching signal

Vcc: supply voltage

t 1-t 6, t 11-t 16: point in time

Detailed Description

Hereinafter, a chromatograph device and a load switch circuit used for the chromatograph device according to an embodiment will be described in detail with reference to the drawings.

(1) Structure of chromatographic detector

Fig. 1 is a block diagram mainly showing a configuration of a chromatography detector in a chromatograph apparatus according to an embodiment.

As shown in fig. 1, the chromatograph apparatus 100 includes a chromatograph detector 10 and a power supply circuit 60. The chromatographic detector 10 comprises: a load switch circuit 11, a lamp lighting circuit 12, a motor drive circuit 13, and a heater drive circuit 14. The lamp lighting circuit 12, the motor drive circuit 13, and the heater drive circuit 14 constitute a load circuit 15. The chromatographic detector 10 further comprises: a lamp 16, a stepping motor 17, a dc heater 18, a flow cell (flow cell)19, a light detector 20, and a detector control section 30.

The power supply circuit 60 converts ac power into dc power and generates a dc power supply voltage Vcc. The power supply voltage Vcc is, for example, 24V, but is not limited thereto. The load switch circuit 11 is connected between the power supply circuit 60 and the load circuit 15. The load switch circuit 11 turns on and off the supply of the dc power from the power supply circuit 60 to the load circuit 15. In the present embodiment, the load switch circuit 11 is connected to the lamp lighting circuit 12, the motor drive circuit 13, and the heater drive circuit 14.

The lamp lighting circuit 12 lights the lamp 16 by the dc power supplied through the load switch circuit 11. The motor drive circuit 13 drives the stepping motor 17 by the dc power supplied via the load switch circuit 11. The heater driving circuit 14 drives the dc heater 18 by the dc power supplied through the load switch circuit 11. The lamp lighting circuit 12, the motor drive circuit 13, and the heater drive circuit 14 have relatively large capacitance components. The lamp 16 is, for example, a deuterium lamp or a tungsten lamp. The stepper motor 17 moves a shutter and a filter arranged between the lamp 16 and the flow cell 19. The dc heater 18 adjusts the temperature of the optical system containing the flow cell 19.

The mobile phase and the sample supplied from the analytical column 140 shown in FIG. 8 described later flow into the flow cell 19. Light generated by the lamp 16 is directed to the flow cell 19. The light detector 20 detects the light transmitted through the flow cell 19. The detector control unit 30 receives an output signal of the photodetector 20 while controlling operations of the load switch circuit 11, the lamp lighting circuit 12, the motor drive circuit 13, and the heater drive circuit 14.

(2) Structure of load switch circuit 11

Fig. 2 is a circuit diagram showing a configuration of the load switch circuit 11 of fig. 1. The load switch circuit 11 includes: a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) (Metal-Oxide-Field-Effect Transistor; hereinafter, abbreviated as Transistor) Q1, an N-channel MOSFET (Metal-Oxide-Field-Effect Transistor; hereinafter, abbreviated as Transistor) Q2, a capacitor C1, and a resistor R1, a resistor R2, and a resistor R3.

The transistor Q1 is connected between a node N1 that receives the power supply voltage Vcc generated by the power supply circuit 60 and the load circuit 15. More specifically, the transistor Q1 has a source connected to the node N1 and a drain connected to the load circuit 15. The gate of transistor Q1 is connected to node N2. The capacitor C1 and the resistor R1 are connected in parallel between the node N1 and the node N2. The resistor R2 is connected between the node N2 and the node N3. The transistor Q2 is connected between the node N3 and the node N4 that receives the ground potential GND. Specifically, the transistor Q2 has a source connected to the node N4 and a drain connected to the node N3. The gate of the transistor Q2 is supplied with the switching signal SW by the detector control section 30 of fig. 1.

The resistor R3 is connected between the node N1 and the node N3. The diode D1 is connected between the node N2 and the node N3. Specifically, the diode D1 has an anode connected to the node N3 and a cathode connected to the node N2. The diode D1 and the resistor R3 constitute a bypass circuit B1. In this embodiment, the bypass circuit B1 is a unidirectional turn-on circuit that causes current to flow from the node N1 to the node N2 via the node N3.

If the switching signal SW becomes high level, the transistor Q2 is turned on. Thereby, the potential of the node N2 falls. If the voltage between node N1 and node N2 exceeds the gate threshold voltage, transistor Q1 turns on. Thereby, the dc power from the power supply circuit 60 is supplied to the load circuit 15. The resistor R1 and the resistor R2 limit the drain current of the transistor Q2 and determine the gate voltage of the transistor Q1. The capacitor C1 has a relatively large time constant. Therefore, the rising waveform of the drain voltage of the transistor Q1 is blunted by the time constant of the capacitor C1. This reduces the inrush current when the transistor Q1 is turned on.

If the switching signal SW goes low, the transistor Q2 is turned off. Thereby, the potential of the node N2 rises. If the voltage between node N1 and node N2 becomes less than the full gate threshold voltage, transistor Q1 turns off. Thereby, the load circuit 15 and the power supply circuit 60 are isolated. In this case, the potential of the node N2 rises to be close to the power supply voltage Vcc of the node N1 via the parallel circuit of the resistor R1 and the capacitor C1, and the potential of the node N2 rises to be close to the power supply voltage Vcc via the resistor R3 and the diode D1. The time constant of the bypass circuit B1, which includes the resistor R3 and the diode D1, is close to 0, so the gate of the transistor Q1 is charged quickly. Therefore, the off time of the transistor Q1 becomes short. As a result, when the transistor Q1 is turned off, heat generation due to the voltage between the source and the drain of the transistor Q1 is suppressed.

In addition, when the transistor Q1 is turned on, the diode D1 is reverse-biased, and thus the diode D1 is turned off. Therefore, the influence of the diode D1 and the resistor R3 on the turn-on speed can be ignored.

When the transistors Q1 and Q2 are turned on, current flows into the resistor R3, and thus power loss occurs. On the other hand, since the time constant of the bypass circuit B1 is ignored when the transistor Q1 is turned off, the influence of the value of the resistor R3 on the turn-off time is small. Therefore, the value of the resistor R3 can be set large so that the power loss due to the resistor R3 falls within the allowable range.

Fig. 3 is a circuit diagram showing another example of the load switch circuit 11. When the inter-terminal capacitance of the diode D1 is large, an inrush current may flow from the node N1 to the transistor Q2 through the capacitor C1 and the diode D1 when the transistor Q1 is turned on. Therefore, it is desirable that the inter-terminal capacitance of the diode D1 be small. In the example of fig. 3, a current limiting resistor R4 is added between the anode of the diode D1 and the resistor R2. Thus, even when the inter-terminal capacitance of the diode D1 is large, the inrush current flowing into the transistor Q2 is reduced.

(3) Simulation of

In order to evaluate the effects of the load switch circuit 11 of the present embodiment, simulations of the load switch circuits 11 of the examples and comparative examples were performed. Fig. 4 is a circuit diagram showing a configuration of a load switch circuit according to the embodiment. Fig. 5 is a circuit diagram showing a configuration of a load switch circuit of a comparative example.

The load switch circuit 11 of the embodiment of fig. 4 has the same configuration as the load switch circuit 11 of the embodiment of fig. 2 except for the following points. In the load switch circuit 11 of fig. 4, the switching signal SW is supplied to the gate of the transistor Q2 via the resistor R5. As the load circuit 15, a capacitor C2 and a resistor R6 are used. The capacitor C2 and the resistor R6 are connected in parallel between the drain of the transistor Q1 and the node N4.

The load switch circuit 11a of the comparative example of fig. 5 does not have the bypass circuit B1 of fig. 4. The structure of the other part of the load switch circuit 11a of the comparative example is the same as that of the load switch circuit 11 of the embodiment of fig. 4.

In the simulation, the power supply voltage Vcc was 24V. The capacitance of the capacitor C1 was 4.7 μ F, and the values of the resistors R1 and R2 were 100k Ω, respectively. The resistor R3 has a value of 10k Ω, and the resistor R5 has a value of 1k Ω. The capacitance value of the capacitor C2 of the load circuit 15 is 300 μ F, and the value of the resistor R6 is 6 Ω.

Fig. 6 is a waveform diagram showing a simulation result of the load switch circuit 11 of the embodiment. Fig. 7 is a waveform diagram showing a simulation result of the load switch circuit 11a of the comparative example.

In fig. 6 and 7, the horizontal axis represents time, the left vertical axis represents voltage, and the right vertical axis represents power loss, the waveforms of the gate-source voltage of the transistor Q1 are indicated by a dashed dotted line L1 and a dashed dotted line L11, and the waveforms of the power loss of the transistor Q1 are indicated by a solid line L2 and a solid line L12.

As shown in fig. 6, in the load switch circuit 11 of the embodiment, when the switching signal SW rises to the high level at the time point t1, the voltage between the gate and the source of the transistor Q1 rises in the form of a logarithmic function. The turning on of the transistor Q1 is started at a time point t2, and the transistor Q1 becomes fully on at a time point t 3. During the on period from the start of turning on the transistor Q1 to the full on, a peak PK1 of power loss due to an inrush current mainly occurs.

In addition, if the switching signal SW falls to the low level at the time point t4, the voltage between the gate and the source of the transistor Q1 falls in an exponential function. In this case, the potential of the gate of the transistor Q1 rapidly approaches the power supply voltage Vcc via the bypass circuit B1, and therefore the voltage between the gate and the source of the transistor Q1 rapidly decreases. The transistor Q1 starts to be turned off at a time point t5, and the transistor Q1 completely becomes an off state at a time point t 6. During the off period from the start of the off to the complete off of the transistor Q1, a peak PK2 of power loss mainly occurs due to the transient current flowing through the resistor R6.

As shown in fig. 7, in the load switch circuit 11a of the comparative example, when the switching signal SW rises to the high level at time t11, the voltage between the gate and the source of the transistor Q1 rises in the form of a logarithmic function. The turning on of the transistor Q1 is started at a time point t12, and the transistor Q1 becomes fully on at a time point t 13. During the on period from the start of turning on the transistor Q1 to the full on, a peak PK11 of power loss due to an inrush current mainly occurs.

In addition, if the switching signal SW falls to the low level at the time point t14, the voltage between the gate and the source of the transistor Q1 falls in an exponential function. In this case, since the potential of the gate of the transistor Q1 slowly rises due to the time constant of the capacitor C1, the voltage between the gate and the source of the transistor Q1 slowly falls. The transistor Q1 starts to be turned off at a time point t15, and the transistor Q1 completely becomes an off state at a time point t 16. During the off period from the start of the off to the complete off of the transistor Q1, a peak PK12 of power loss mainly occurs due to the transient current flowing through the resistor R6.

As described above, the off time of the transistor Q1 in the load switch circuit 11 of the embodiment is short as compared with the off time of the transistor Q1 in the load switch circuit 11a of the comparative example. Therefore, the transient current flowing into the transistor Q1 at the time of off in the load switch circuit 11 of the embodiment is smaller than the transient current flowing into the transistor Q1 at the time of off in the load switch circuit 11a of the comparative example.

On the other hand, the on time of the transistor Q1 in the load switch circuit 11 of the embodiment is substantially equal to the on time of the transistor Q1 in the load switch circuit 11a of the comparative example. Therefore, it is found that the bypass circuit B1 in the load switch circuit 11 of the embodiment hardly affects the on speed of the transistor Q1.

(4) Chromatograph device

Fig. 8 is a block diagram showing a configuration of a chromatograph apparatus including the chromatography detector 10 of fig. 1. The chromatograph apparatus 100 of fig. 8 is a liquid chromatograph apparatus.

The chromatograph apparatus 100 of fig. 8 includes: a pump 110 for mobile phase, a sample introduction part 120, an introduction port 130, an analytical column 140, a column box 150, and a chromatography detector 10. The analytical column 140 is disposed within a column housing 150. The column box 150 maintains the analytical column 140 at a set temperature.

The pump 110 sucks the mobile phase (eluent) in the mobile phase container 111 and supplies it to the analytical column 140. The sample introduction unit 120 includes, for example, an auto-sampler or a syringe, and introduces a sample to be analyzed into the mobile phase at the introduction port 130. The mobile phase and the sample having passed through the analytical column 140 flow in the flow cell 19 (fig. 1) of the chromatography detector 10 and then are discharged to the waste liquid container 112.

The chromatograph apparatus 100 includes: an analysis control unit 50, an operation unit 51, and a display unit 52. The operation unit 51 is used for a user to provide various instructions to the analysis control unit 50. The analysis controller 50 controls the pump 110, the sample introduction unit 120, the column box 150, and the chromatography detector 10. The analysis controller 50 generates a chromatogram from the output signal of the chromatography detector 10. The generated chromatogram is displayed on the display unit 52.

(5) Effects of the embodiments

In the load switch circuit 11 used in the chromatograph apparatus 100 according to the present embodiment, the on time of the transistor Q1 can be ensured, and the off time of the transistor Q1 can be shortened. This reduces the inrush current and reduces the amount of heat generated when the circuit is turned off. Accordingly, the transistor Q1 having a small rated current capacity can be used, and thus the cost and size of the transistor Q1 can be reduced. The resistor R3 and the diode D1 are less expensive than the transistor Q1. Therefore, the component cost and the component size of the load switch circuit 11 can be reduced. In addition, the parts cost of the chromatography detector 10 and the chromatograph apparatus 100 using the same can be reduced.

(6) Other embodiments

(6-1)

In the above embodiment, the load circuit 15 includes the lamp lighting circuit 12, the motor drive circuit 13, and the heater drive circuit 14, but the load circuit 15 may include a part of the lamp lighting circuit 12, the motor drive circuit 13, and the heater drive circuit 14.

(6-2)

In the above embodiment, the load switch circuit 11 is connected to the load circuit 15 in the chromatograph detector 10, but the load switch circuit 11 may be connected to another operation unit of the chromatograph apparatus 100. For example, the load switch circuit 11 may be connected to a motor drive circuit in the sample introduction unit 120, a heater drive circuit in the column box 150, or the like.

(6-3)

In the load switch circuit 11 of the above embodiment, another circuit element such as a resistor may be provided between the source of the transistor Q1 and the node N1. Further, another circuit element such as a resistor may be provided between the drain of the transistor Q1 and the load circuit 15. The capacitor C1 may also be connected between the node N1 and the node N2 via other circuit elements. The resistor R1 may be connected between the node N1 and the node N2 via other circuit elements. The resistor R2 may be connected between the node N2 and the node N3 via other circuit elements. The resistor R3 may be connected between the node N1 and the node N3 via other circuit elements. The diode D1 may also be connected between the node N2 and the node N3 via other circuit elements. The gate of the transistor Q1 may also be connected to the node N2 via other circuit elements. The transistor Q2 may also be connected between the node N3 and the node N4 via other circuit elements. The resistor R4 may be connected between the anode of the diode D1 and the node N3 via another circuit element.

(6-4)

In the above embodiment, the transistors Q1 and Q2 are MOSFETs, but other types of switching elements such as Bipolar transistors and Insulated Gate Bipolar Transistors (IGBTs) may be used as the first switching elements, and other types of switching elements such as Bipolar transistors and IGBTs may be used as the second switching elements.

(6-5)

In the above-described embodiment, the resistors R1 to R4 are used as the first to fourth resistor elements, but other circuit elements having resistance components may be used as the first to fourth resistor elements. In the above-described embodiment, the capacitor C1 is used as the capacitive element, but another circuit element having a capacitance component may be used as the capacitive element.

(6-6)

In the above embodiment, the bypass circuit B1 includes the resistor R3 and the diode D1, but the bypass circuit B1 may include a switching element such as a photocoupler or a transistor. In this case, the switching element is connected between the node N1 and the node N2 in place of the resistor R3 and the diode D1. The switching element is turned on by a control circuit such as the detector control unit 30 when the transistor Q1 is turned off.

(6-7)

In the above embodiment, the resistor R1, the resistor R2, and the transistor Q2 are provided to change the gate potential of the transistor Q1, but another gate potential control circuit may be provided instead of the resistor R2 and the transistor Q2.

(6-8)

In the above embodiment, the chromatograph apparatus 100 is a liquid chromatograph apparatus, but the chromatograph apparatus may be another chromatograph apparatus such as a supercritical fluid chromatograph apparatus.

(7) Correspondence between each constituent element of the technical means and each element of the embodiments

Hereinafter, examples of correspondence between each constituent element of the embodiments and each element of the embodiments will be described. In the above-described embodiment, the lamp lighting circuit 12, the motor drive circuit 13, or the heater drive circuit 14 is an example of an operating unit, the transistor Q1 is an example of a first switching element, the gate is an example of a control terminal, the capacitor C1 is an example of a capacitive element, the resistor R1 is an example of a first resistive element, the resistor R2 is an example of a second resistive element, the resistor R3 is an example of a third resistive element, and the resistor R4 is an example of a fourth resistive element. The transistor Q2 is an example of the second switching element, the power supply voltage Vcc is an example of a dc voltage, the ground potential GND is an example of a reference potential, and the nodes N1 to N4 are examples of the first to fourth nodes. In the above-described embodiment, various other elements having the structures and functions described in the claims may be used as the respective constituent elements of the claims.

(8) Form of the composition

Specific examples of the various illustrative embodiments in the following forms will be understood by those skilled in the art.

A chromatograph apparatus according to a first aspect includes:

a plurality of operation units constituting a chromatograph; and

a load switch circuit that turns on and off supply of the direct-current power;

at least one of the plurality of operation units is connected to the load switch circuit as a load circuit,

the load switching circuit may include:

a first switching element connected between a first node receiving a direct-current voltage and the load circuit, and having a control terminal receiving a potential of a second node;

a capacitive element connected between the first node and the second node;

a first resistive element connected between the first node and the second node; and

a bypass circuit that causes a current to flow between the first node and the second node when the first switching element is turned off.

According to the chromatograph apparatus described in the first item, when the first switching element in the load switching circuit is turned on, the first node receiving the dc voltage and the load circuit are electrically connected. Thereby, the supply of the dc power to the load circuit is turned on. In this case, the voltage waveform supplied to the load circuit is blunted by the time constant of the capacitive element. This reduces the inrush current when the first switching element is turned on.

If the first switching element is turned off, the first node bearing the direct-current voltage is isolated from the load circuit. Thereby, the supply of the dc power to the load circuit is shut off. At this time, a current flows between the first node and the second node through the bypass circuit. Thereby, the potential of the control terminal of the first switching element changes rapidly. Therefore, the off time of the first switching element becomes short. Therefore, since heat generation of the first switching element is suppressed when the first switching element is turned off, a large rated current capacity is not required for the first switching element. Thus, the cost of the first switching element can be reduced.

As a result, the inrush current can be reduced in the load switch circuit and the chromatograph apparatus, and heat generation of the components can be suppressed at low cost.

(item II)

In the chromatograph apparatus according to the first aspect,

the bypass circuit may also include a directionally conducting circuit that causes current to flow from the first node to the second node when the first switching element is turned off.

According to the chromatograph apparatus described in the second item, the potential of the control terminal of the first switching element can be changed rapidly at the time of turning off without affecting the operation of the first switching element at the time of turning on, by the one-way conduction circuit having a simple configuration.

(third item) the chromatograph device according to the second item,

the load switch circuit further includes a second resistance element connected between the second node and a third node, and

the unidirectional turn-on circuit may also include:

a third resistive element connected between the first node and the third node; and

a diode connected between the third node and the second node.

According to the chromatograph apparatus described in the third aspect, a current can be caused to flow from the first node to the second node at the time of disconnection by a simple configuration.

(fourth) the chromatograph device according to the third aspect,

the load switch circuit may further include:

a second switching element connected between the third node and a fourth node set to a reference potential; and

a fourth resistance element connected between the anode of the diode and the second node

According to the chromatograph device described in the fourth item, the first switching element is turned on or off in response to turning on or off of the second switching element. When the first switching element is turned on, even when an inrush current flows from the first node through the capacitor element and the diode, the inrush current flowing into the second switching element is reduced by the fourth resistor element. This does not require a large rated current capacity for the second switching element. As a result, the cost and size of the parts can be reduced.

(fifth) the chromatograph device according to any one of the first to fourth items,

the chromatograph includes:

an analytical column;

a detector for detecting components of the sample separated by the analytical column; and

a power supply circuit;

the detector includes the load switch circuit and the load circuit, and

the load switch circuit may also be connected between the power circuit and the load circuit.

A load switch circuit according to another aspect of the present invention is a load switch circuit for turning on and off supply of dc power to a load circuit of a chromatograph apparatus, and may include:

a first switching element connected between a first node receiving a direct-current voltage and the load circuit, and having a control terminal receiving a potential of a second node;

a capacitive element connected between the first node and the second node;

a first resistive element connected between the first node and the second node; and

a bypass circuit that causes a current to flow between the first node and the second node when the first switching element is turned off.

According to the load switch circuit described in the sixth aspect, when the first switching element is turned on, conduction is established between the first node receiving the dc voltage and the load circuit. Thereby, the supply of the dc power to the load circuit is turned on. In this case, the voltage waveform supplied to the load circuit is blunted by the time constant of the capacitive element. This reduces the inrush current when the first switching element is turned on.

If the first switching element is turned off, the first node bearing the direct-current voltage is isolated from the load circuit. Thereby, the supply of the dc power to the load circuit is shut off. At this time, a current flows between the first node and the second node through the bypass circuit. Thereby, the potential of the control terminal of the first switching element changes rapidly. Therefore, the off time of the first switching element becomes short. Therefore, since heat generation of the first switching element is suppressed when the first switching element is turned off, a large rated current capacity is not required for the first switching element. Thus, the cost of the first switching element can be reduced.

As a result, the inrush current can be reduced in the load switch circuit, and heat generation of the components can be suppressed at low cost.