JP6910813B2 - Measuring equipment, measuring methods, computer programs and storage media - Google Patents

Description

The present invention relates to a technical field of a measuring device, a measuring method, a computer program, and a storage medium that irradiate light to measure information about an object to be measured.

As a device of this type, a device that irradiates a measurement target with light and receives scattered light to measure information about the measurement target is known. For example, Patent Document 1 discloses an artificial dialysis apparatus that measures blood concentration and flow rate.

Patent No. 5586476

When irradiating the object to be measured with light, it is desirable to maintain the irradiated portion at an appropriate temperature in order to suppress, for example, mode hop. The temperature control of the irradiation unit can be realized, for example, by performing feedback control so as to bring the temperature detected by a temperature sensor or the like closer to the target temperature.

The temperature of the irradiation unit is preferably detected as close to the irradiation unit as possible in order to detect an accurate temperature. However, due to the structure of the device, the distance between the irradiation unit (temperature control target), the heat transfer unit (Pelche element), and the temperature sensor may be unavoidable. In such a case, there is a technical problem that a difference occurs between the detected temperature (that is, the temperature used for feedback control) and the actual temperature of the irradiated portion, and appropriate temperature control cannot be performed. Occurs.

Examples of the problems to be solved by the present invention include the above. An object of the present invention is to provide a measuring device, a measuring method, a computer program, and a storage medium capable of suitably controlling the temperature of an irradiation unit.

The measuring device for solving the above problems includes a first irradiation unit that irradiates the object to be measured with light, a heat transfer unit that transfers the heat generated by the first irradiation unit to the heat dissipation unit, and the first irradiation unit. Around the first temperature detection unit that detects the first temperature around the temperature, the target temperature setting unit that sets the second target temperature based on the first temperature and the first temperature target information, and the heat transfer unit. A second temperature detection unit that detects the second temperature of the above, and a control unit that controls the heat transfer unit based on the second temperature and the second target temperature are provided.

A measurement method for solving the above problems includes a measuring device including a first irradiation unit that irradiates the object to be measured with light, and a heat transfer unit that transfers the heat generated by the first irradiation unit to the heat dissipation unit. The measurement method to be used is to set the second target temperature based on the first temperature detection step of detecting the first temperature around the first irradiation unit and the first temperature and the first temperature target information. A control step of controlling the heat transfer unit based on a target temperature setting step, a second temperature detection step of detecting a second temperature around the heat transfer unit, and the second temperature and the second target temperature. And, including.

A computer program for solving the above problems is a measuring device including a first irradiation unit that irradiates the object to be measured with light, and a heat transfer unit that transfers the heat generated by the first irradiation unit to the heat dissipation unit. In the computer program to be used, the second target temperature is set based on the first temperature detection step of detecting the first temperature around the first irradiation unit and the first temperature and the first temperature target information. A control step of controlling the heat transfer unit based on a target temperature setting step, a second temperature detection step of detecting a second temperature around the heat transfer unit, and the second temperature and the second target temperature. To the measuring device.

The storage medium for solving the above problems stores the above-mentioned computer program.

It is a schematic block diagram which shows the structure of the measurement block of the measuring apparatus which concerns on Example. It is a graph which shows the power spectrum of an optical beat signal when the flow rate of a fluid is used as a parameter. It is a graph which shows the relationship between the fluid concentration and the amount of transmitted light. It is a schematic block diagram which shows the structure of the temperature control block of the measuring apparatus which concerns on Example. It is a flowchart which shows the flow of the temperature error calculation operation by the measuring apparatus which concerns on Example. It is a flowchart which shows the flow of the temperature target output operation by the measuring apparatus which concerns on Example. It is a flowchart which shows the flow of the Perche control operation by the measuring apparatus which concerns on Example.

<1>
In the measuring device according to the present embodiment, the heat transfer that transfers the generated heat to the first irradiation unit that irradiates the object to be measured with light and the heat radiation unit that dissipates the heat generated by the first irradiation unit. A target temperature setting unit that sets a second target temperature based on the unit, a first temperature detection unit that detects a first temperature around the first irradiation unit, and the first temperature and the first temperature target information. A second temperature detection unit that detects a second temperature around the heat transfer unit, and a control unit that controls the heat transfer unit based on the second temperature and the second target temperature. ..

During the operation of the measuring device according to the present embodiment, the object to be measured is irradiated with light from the first irradiation unit. The light to be irradiated is, for example, laser light, and is irradiated using a Fabry-Perot type (FP) laser light source or the like. The heat generated in the first irradiation unit by irradiating the light is transferred to the heat dissipation unit by the heat transfer unit. The heat transfer unit includes, for example, a Perche element, and has a configuration capable of controlling the heat flow rate transmitted to the heat radiation unit.

In this embodiment, in particular, the second target temperature is set based on the first temperature around the first irradiation unit and the preset first temperature target information. Then, the heat transfer unit is controlled based on the second temperature around the heat transfer unit and the set second target temperature (that is, the degree of heat flow rate transferred to the heat radiation unit is adjusted). As a result, the temperature of the first irradiation unit is maintained at an appropriate temperature based on the first temperature target information. The "first temperature target information" is information indicating an appropriate temperature (in other words, a target temperature of the first temperature) for operating the first irradiation unit. The "second target temperature" is a temperature that is a target of the second temperature.

As described above, the first temperature around the first irradiation unit and the second temperature around the heat transfer unit are detected as different temperatures from each other. In this case, for example, when the distance between the first irradiation unit and the heat transfer unit becomes large, a large difference occurs between the first temperature and the second temperature due to the heat transfer delay due to the thermal resistance. Under such circumstances, if the heat transfer unit is controlled based only on the second temperature, the second temperature is as large as the first temperature (that is, a value close to the actual temperature of the first irradiation unit). Due to the divergence, accurate temperature control may not be possible. Specifically, even if the second temperature is controlled to be an appropriate value, the first temperature may not be an appropriate value.

However, in the present embodiment, as described above, the second target temperature is first set based on the first temperature and the first temperature target information. Here, the second target temperature is set as a value for reducing the influence of the difference between the first temperature and the second temperature. Specifically, the second target temperature is set as a value such that the first temperature approaches the temperature indicated by the first target temperature when the second temperature is controlled to approach the second target temperature. Therefore, by controlling the heat transfer unit based on the second temperature and the second target temperature, the first temperature (that is, the temperature around the first irradiation unit) can be brought closer to the temperature indicated by the first target temperature information. can.

Therefore, according to the measuring device according to the present embodiment, the temperature of the first irradiation unit can be maintained at an appropriate temperature even when there is a difference between the first temperature and the second temperature. Therefore, even if it is unavoidable to adopt a device configuration that causes a relatively large difference between the first temperature and the second temperature, the temperature of the first irradiation unit is maintained at an appropriate temperature. can do.

<2>
In one aspect of the measuring device according to the present embodiment, as the first temperature target information, a storage unit that previously stores information indicating the temperature for operating the first irradiation unit in the single mode is further provided.

According to this aspect, the generation of mode hops in the first irradiation unit can be suitably suppressed by controlling the heat transfer unit. Therefore, it is possible to prevent the measurement accuracy from being lowered due to the occurrence of the mode hop.

<3>
In another aspect of the measuring device according to the present embodiment, the first irradiation unit can adjust the optical axis of the light to be irradiated.

According to this aspect, the distance between the first irradiation part and the heat transfer part may be increased due to the structure that allows the optical axis of the first irradiation part to be adjusted (for example, the arrangement of a special jig). There is sex. Therefore, there is a possibility that a large difference may occur between the first temperature and the second temperature.

However, in this embodiment, as described above, the second target temperature is set based on the first temperature and the first temperature target information, and the heat transfer unit is controlled based on the second temperature and the second target temperature. NS. Therefore, even when there is a difference between the first temperature and the second temperature, the temperature of the first irradiation unit can be maintained at an appropriate temperature.

<4>
In another aspect of the measuring device according to the present embodiment, the object to be measured is a fluid, and among the light emitted from the first irradiation unit, the light scattered by the fluid is used to flow the flow rate of the fluid. A flow rate measuring unit for measuring the above is further provided.

When trying to measure the flow rate of the fluid, it is preferable that the light of the first irradiation unit is obliquely irradiated to the object to be measured at a predetermined angle. However, in order to irradiate light from the first irradiation unit at an appropriate angle, it is required to adopt, for example, a configuration in which the optical axis can be adjusted as described above. In addition, the arrangement of each member is restricted so that the irradiation light is not blocked by other members or the like. As a result, the distance between the first irradiation unit, the heat transfer unit, and the heat radiation unit becomes large, and there is a high possibility that a large difference will occur between the first temperature and the second temperature.

However, in this embodiment, as described above, the second target temperature is set based on the first temperature and the first temperature target information, and the heat transfer unit is controlled based on the second temperature and the second target temperature. NS. Therefore, even when there is a difference between the first temperature and the second temperature, the temperature of the first irradiation unit can be maintained at an appropriate temperature.

<5>
The measurement method according to the present embodiment uses a measuring device including a first irradiation unit that irradiates the object to be measured with light and a heat transfer unit that transfers the heat generated by the first irradiation unit to the heat dissipation unit. A target temperature for setting a second target temperature based on a first temperature detection step of detecting a first temperature around the first irradiation unit and the first temperature and the first temperature target information. A setting step, a second temperature detection step of detecting a second temperature around the heat transfer section, a control step of controlling the heat transfer section based on the second temperature and the second target temperature, and a control step of controlling the heat transfer section. including.

According to the measurement method according to the present embodiment, similarly to the measurement device according to the present embodiment described above, adopt an apparatus configuration such that a relatively large difference occurs between the first temperature and the second temperature. Even when there is no choice but to maintain the temperature of the first irradiation unit at an appropriate temperature.

In the measurement method according to the present embodiment, it is possible to adopt various aspects similar to the various aspects in the measuring device according to the above-described embodiment.

<6>
The computer program according to the present embodiment is a computer used for a measuring device including a first irradiation unit that irradiates the object to be measured with light and a heat transfer unit that transfers the heat generated by the first irradiation unit to the heat dissipation unit. In the program, the target temperature for setting the second target temperature based on the first temperature detection step of detecting the first temperature around the first irradiation unit and the first temperature and the first temperature target information. A setting step, a second temperature detection step of detecting a second temperature around the heat transfer section, a control step of controlling the heat transfer section based on the second temperature and the second target temperature, and a control step of controlling the heat transfer section. Is executed by the measuring device.

According to the computer program according to the present embodiment, by causing the measuring device to execute the same process as the measurement method according to the present embodiment described above, a relatively large difference is generated between the first temperature and the second temperature. The temperature of the first irradiation unit can be maintained at an appropriate temperature even when it is unavoidable to adopt a device configuration that causes the problem.

In the computer program according to the present embodiment, it is possible to adopt various aspects similar to the various aspects in the measuring device according to the above-described embodiment.

<7>
The storage medium according to the present embodiment stores the above-mentioned computer program.

According to the storage medium according to the present embodiment, the apparatus configuration is such that a relatively large difference is generated between the first temperature and the second temperature by executing the computer program according to the above-described embodiment. Even when it has to be adopted, the temperature of the first irradiation unit can be maintained at an appropriate temperature.

The operation of the measuring device, the measuring method, the computer program and the storage medium, and other gains according to the present embodiment will be described in more detail in the following examples.

In the following, examples of the measuring device, the measuring method, the computer program, and the storage medium will be described in detail with reference to the drawings. In the following, the description will be given by taking as an example a case where the measuring device is applied to a device that measures information on blood flow rate and concentration.

<Measurement block>
First, with reference to FIG. 1, the configuration of the measurement block of the measurement device according to the present embodiment and the basic operation of each part will be described. FIG. 1 is a schematic configuration diagram showing a configuration of a measurement block of a measuring device according to an embodiment. The measuring device according to this embodiment is used, for example, in a hemodialysis device.

As shown in FIG. 1, the measuring device according to the present embodiment includes semiconductor lasers 121, 122, and 123 capable of irradiating a laser beam toward a transparent tube 200, which is a blood flow path. The transparent tube 200 constitutes a flow path on the blood removal side and a flow path on the blood return side. The semiconductor laser is configured as, for example, a Fabry-Perot type laser element. The semiconductor laser 121 is driven by the first drive control unit 111, and irradiates the laser light toward the blood flow path on the blood removal side mainly in order to obtain the reflected light from the blood. The semiconductor laser 122 is driven by the second drive control unit 112, and irradiates the laser light toward the blood flow path on the blood removal side mainly in order to obtain the transmitted light from the blood. The semiconductor laser 123 is driven by the third drive control unit 113, and irradiates the laser light toward the flow path on the blood return side mainly in order to obtain the transmitted light from the blood.

The reflected light generated by the irradiation light from the semiconductor laser 121 is received by the first light receiving element 131. The transmitted light generated by the irradiation light from the semiconductor laser 122 is received by the second light receiving element 132. The transmitted light generated by the irradiation light from the semiconductor laser 123 is received by the third light receiving element 133. The first light receiving element 131, the second light receiving element 132, and the third light receiving element 133 are configured as, for example, a photodiode, and output a detection current according to the intensity of the received light, respectively.

The first detection current output from the first light receiving element 131 is converted into the first detection voltage by the first IV conversion unit 141. The first detection voltage output from the first IV conversion unit 141 is amplified by the first BPF amplifier 151 while removing unnecessary high-frequency components and low-frequency components including noise, and the first reflected signal. Is output as. The first reflected signal is quantized by the first A / D conversion unit 161 and input to the flow rate concentration estimation unit as the first reflected light amount.

The second detection current output from the second light receiving element 132 is converted into the second detection voltage by the second IV conversion unit 142. The second detection voltage output from the second IV conversion unit 142 is amplified by the first LPF amplifier 152 while removing an unnecessary high frequency component including noise, and is output as a first transmission signal. The first transmitted signal is quantized by the second A / D conversion unit 162 and input to the flow rate concentration estimation unit as the first transmitted light amount.

The third detection current output from the third light receiving element 133 is converted into the third detection voltage by the third IV conversion unit 143. The third detection voltage output from the third IV conversion unit 143 is amplified by the second LPF amplifier 153 while removing an unnecessary high frequency component including noise, and is output as a second transmission signal. The second transmitted signal is quantized by the third A / D conversion unit 163 and input to the flow rate concentration estimation unit as the second transmitted light amount.

The flow rate concentration estimation unit 300 estimates and outputs the flow rate Q1 of the blood to be measured by frequency-analyzing the input first reflected light amount. Specifically, the flow rate Q1 is estimated by calculating the average frequency of the optical beat signal from the frequency analysis result of the first reflected light amount which is the optical beat signal generated by the laser Doppler action. The flow rate concentration estimation unit 300 estimates and outputs the blood concentration Ht2 on the blood removal side from the input first transmitted light amount. The flow rate concentration estimation unit 300 estimates and outputs the blood concentration Ht3 on the blood return side from the input second transmitted light amount.

Here, a method for calculating the flow rate and concentration of blood will be described with reference to FIGS. 2 and 3. FIG. 2 is a graph showing the power spectrum of the optical beat signal when the flow rate of the fluid is used as a parameter. Further, FIG. 3 is a graph showing the relationship between the fluid concentration and the amount of transmitted light.

As shown in FIG. 2, when the flow rate of blood flowing through the transparent tube 200 is low, the power spectrum P1 (f) of the first reflected light amount becomes a large value when the frequency is low and a small value when the frequency is high. Become. On the contrary, when the blood flow rate is high, the power spectrum P2 (f) of the first reflected light amount becomes a smaller value when the frequency is low and a larger value when the frequency is high as compared with P1 (f). .. As a result, when the flow rate is low, the average frequency corresponding to the center of gravity of the power spectrum is lower than when the blood flow rate is high. The flow rate concentration estimation unit 300 estimates the blood flow rate Q1 from the average frequency of the power spectrum by utilizing such a relationship.

As shown in FIG. 3, when the concentration of blood flowing in the transparent tube 200 (that is, the hematocrit value) increases, the amount of transmitted light is exponentially attenuated. The flow rate concentration estimation unit 300 uses such a relationship to estimate the blood concentrations Ht2 and Ht3 from the amount of transmitted light, respectively.

<Temperature control block>
Next, with reference to FIG. 4, the configuration of the temperature control block of the measuring device according to the present embodiment and the basic operation of each part will be described. FIG. 4 is a schematic configuration diagram showing a configuration of a temperature control block of the measuring device according to the embodiment.

As shown in FIG. 4, the first semiconductor laser 121 irradiates the transparent tube 200, which is a flow path, with a laser beam at a predetermined angle in order to measure the blood flow velocity by utilizing the optical Doppler shift. It is configured to be possible. Specifically, the first semiconductor laser 121 is configured so that the angle of the optical axis of the laser beam can be adjusted. The first semiconductor laser 121 is thermally coupled to the heat transfer plate 50 via the heat conductive material 55. The second semiconductor laser 122 and the third semiconductor laser 123 are also thermally coupled to the heat transfer plate 50. Since the second semiconductor laser 122 and the third semiconductor laser 123 need only be able to irradiate the transparent tube 200 with the laser beam perpendicularly, they are not provided with the optical axis adjusting function unlike the first semiconductor laser 121.

The heat transfer plate 50 is configured to contain, for example, a metal having high thermal conductivity, and is arranged so as to thermally bond to one surface of the Pelche element 60, which is a heat transfer element. Further, on the other surface of the Pelche element 60, a heat radiating plate 70 for releasing heat to the outside is arranged so as to thermally bond. Here, in particular, the first semiconductor laser 121 so that the Perche element 60 and the heat radiating plate 70 do not block the laser light emitted from the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123. , The second semiconductor laser 122, and the third semiconductor laser 123 are arranged at positions apart from each other. The perche element 60 and the heat radiating plate 70 are specific examples of the "heat transfer part" and the "heat radiating part", respectively.

The first thermistor 81 is arranged so as to thermally bond with the first semiconductor laser 121 in the heat transfer plate 50 in order to detect the temperature around the first semiconductor laser 121. The first thermistor 81 constitutes a bridge circuit in cooperation with a resistance element and a constant voltage source, which are components of the first temperature detection unit 410 (not shown). The first temperature detection unit 410 outputs the temperature detection voltage V1 by differentially amplifying the midpoint voltage of the bridge circuit. The temperature detection voltage V1 is quantized by the A / D conversion unit 420 and input to the CPU 430. The CPU 430 executes an operation for estimating the temperature T1 of the first thermistor 81 from the output value of the A / D conversion unit 420. The CPU 430 sends temperature target value data to the D / A conversion unit 450 in order to change the temperature target value of the second thermistor 82, which will be described later, according to the difference between the estimated temperature T1 and the target temperature T1ref acquired from the memory 440. Output. The D / A conversion unit 450 generates a temperature target voltage T2v according to the temperature target value data and supplies it to one input of the temperature control unit 520.

The second thermistor 82 is arranged so as to be thermally coupled to the heat transfer plate 50 near the perche element 60 in order to detect the temperature around the perche element 60. The second thermistor 82 constitutes a bridge circuit in cooperation with a resistance element and a constant voltage source, which are components of the second temperature detection unit 510 (not shown). The second temperature detection unit 510 outputs the temperature detection voltage V2 by differentially amplifying the midpoint voltage of the bridge circuit. The temperature detection voltage V2 is supplied to the other input of the temperature control unit 520.

The temperature control unit 520 generates a control output voltage VC2 according to the difference between the temperature target voltage T2v and the temperature detection voltage V2, and outputs the control output voltage VC2 to the drive circuit 530. The drive circuit 530 generates a drive current corresponding to the control output voltage VC2 and drives the Pelche element 60. The Pelche element 60 absorbs the heat generated by the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123 from the heat transfer plate 50 according to the drive current, and moves the heat to the heat dissipation plate 70. The heat radiating plate 70 dissipates the heat transferred by the Pelche element 60 to the outside. That is, the heat transfer plate 50, the Perche element 60, and the heat dissipation plate 70 cooperate to cool the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123.

Each of the first thermistor 81, the first temperature detection unit 410, the A / D conversion unit 420, the CPU 430, and the D / A conversion unit 450 cooperate with each other to form the first temperature control loop. The first temperature control loop forms a first negative feedback control that controls the temperature target voltage T2v according to the temperature target value T1ref.

Each of the second thermistor 82, the second temperature detection unit 510, the temperature control unit 520, the drive circuit 530, and the Pelche element 60 cooperate to form the second temperature control loop. The second temperature control loop forms a second negative feedback control that controls the temperature around the Perche element 60 according to the temperature target voltage T2v.

The second temperature detection unit 510, the temperature control unit 520, and the drive circuit 530, which are the components of the second temperature control loop, may be configured by the same analog control LSI. In this case, the substrate area is reduced, and the device can be downsized.

Further, the output voltage V2 of the second temperature detection unit 510 is quantized by the A / D converter, and the CPU 430, which is a component of the first temperature control loop, executes the operation of the temperature control unit 520 by digital signal processing. You may. In this case, instead of the target voltage T2v of the second temperature control loop, the target value of the second temperature control loop is input to the second temperature control loop as a digital value. As a result, the D / A converter 450 of the first temperature control loop can be omitted, and the cost can be reduced.

<Problems caused by heat transfer>
Next, problems caused by heat transfer will be described with reference to FIG.

As shown in FIG. 4, the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123 are attached to the same heat transfer plate 50 for thermal coupling, and are attached to the heat transfer plate 50 as a single unit. The Pelche element 60 is attached for thermal coupling. Further, the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123, and the perche element 60 and the heat radiating plate 70 are arranged at different positions with a distance from each other. By arranging in this way, the emitted light of the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123 is not blocked by the perche element 60 and the heat sink 70, which require a relatively large volume. can do.

In this embodiment, in particular, as described above, despite the fact that the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123, the perche element 60, and the heat sink 70 are arranged apart from each other. By interposing a common heat transfer plate 50, mutual thermal coupling is realized. Therefore, the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123 can be suitably cooled. However, due to the existence of a certain distance between the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123, and the Perche element 60 and the heat sink 70, a heat transfer delay occurs between them. Resulting in. Specifically, the amount of heat generated by the irradiation of the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123 is transmitted through the heat transfer plate 50 and reaches the second thermistor 82. It takes some time.

If the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123, which are heat sources, are arranged close to the Pelche element 60 in order to eliminate this heat transfer delay, the emitted light is blocked. There is no choice but to make it a structure. Therefore, this heat transfer delay becomes an unavoidable problem when a plurality of light sources are cooled by a single Perche element 60 and a heat sink 70, and at the same time, each optical path is to be secured. In order to solve such a problem, the measuring device according to the present embodiment executes a temperature control operation using two control loops (that is, a first temperature control loop and a second temperature control loop). ..

<Temperature control operation>
Next, the temperature control operation executed by the measuring device according to the present embodiment will be described with reference to FIGS. 5 to 7. FIG. 5 is a flowchart showing the flow of the temperature error calculation operation by the measuring device according to the embodiment. FIG. 6 is a flowchart showing the flow of the temperature target output operation by the measuring device according to the embodiment. FIG. 7 is a flowchart showing the flow of the Perche control operation by the measuring device according to the embodiment.

As shown in FIG. 5, during the operation of the measuring device according to the present embodiment, the CPU 430 acquires the A / D conversion value of the temperature detection voltage V1 which is the output of the first temperature detection unit 410 (step S101). Subsequently, the CPU 430 calculates the temperature T1 of the first thermistor 81 from the A / D conversion value of the first temperature detection unit 410 by executing an exponential function calculation or the like using, for example, the thermistor B constant (step S102). .. Subsequently, the CPU 430 reads the target temperature T1ref of the temperature T1 of the first thermistor 81 (that is, the temperature of the first semiconductor laser 121) from the memory 440 (step S103). Subsequently, the CPU 430 subtracts the current temperature T1 of the first thermistor 81 from the target temperature T1ref to calculate the temperature error Err1 (step S104).

As shown in FIG. 6, the CPU 430 calculates the phase delay compensation Eq1 with the temperature error Err1 as an input (step S201). Specifically, a digital filter operation having a low boost filter characteristic is executed in order to execute phase lag compensation, and the output thereof is output as phase lag compensation Eq1. Subsequently, the CPU 430 multiplies the phase delay compensation Eq1 by the loop gain K1 and outputs the value as the control output value DA to the conversion unit 450 to the D / A (step S202). The D / A conversion unit 450 generates and outputs a temperature target voltage T2v according to the control output value DA input from the CPU 430 (step S203).

As shown in FIG. 7, the temperature control unit 520 has a control error due to the difference between the temperature detection voltage V2, which is the output of the second temperature detection unit 510, and the temperature target voltage T2v input from the D / A conversion unit 450. Calculate Err2 (step S301). Specifically, differential amplification is performed by an Op amplifier. Subsequently, the temperature control unit 520 calculates the phase lag advance compensation Eq2 with the control error Err2 as an input (step S302). Specifically, the analog filter calculation using the calculation function by the Op amplifier is executed, and the phase lag advance compensation Eq2 is output. Subsequently, the temperature control unit 520 multiplies the phase delay advance compensation Eq2 by the loop gain K2 to calculate the control output voltage VC2 (step S303). Specifically, the amplification function of the Op amplifier is used. The drive circuit 530 generates a drive current according to the control output voltage VC2 to drive the Pelche element 60.

<Effect of this example>
Next, the technical effect of this embodiment obtained by the above-mentioned temperature control operation will be described. In the following, the effect of this example will be clarified by comparing with a comparative example having a configuration different from that of this example.

When performing temperature control, it is conceivable to omit the second thermistor 82 and perform negative feedback control using the first thermistor 81 as a component of the second temperature control loop instead of the second thermistor 82 (first comparison). example). However, in the first comparative example, due to the heat transfer delay described above, a long wasted time element is included in the control loop. Due to this wasted time, it is impossible to increase the control band in principle. As a result, it becomes difficult to suppress the disturbance due to the change in the ambient temperature and stabilize the temperature, which is unsuitable as a control characteristic. In addition, since the control band cannot be secured in a high band, the settling time at the time of turning on the power becomes long, and problems such as difficulty in starting measurement occur.

On the other hand, in the measuring device according to the present embodiment, the component of the detection system of the second temperature control loop is the second thermistor 82, which is arranged in the vicinity of the perche element 60. Therefore, since it has a configuration capable of minimizing the heat transfer delay, the control band can be made higher in principle.

Contrary to the first comparative example, it is conceivable that the first thermistor 81 is omitted and the target voltage of the second temperature control loop is set to a fixed voltage (second comparative example). In the second comparative example, it is relatively easy to increase the band of the second temperature control loop to improve the disturbance suppression performance due to the change in ambient temperature. However, there is a temperature difference between the temperature near the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123 and the temperature near the second thermistor 82. The reason is that although they are thermally coupled via the heat transfer plate 50, they have a relatively large thermal resistance due to the distance between them.

Since the heat flow rate of this temperature difference fluctuates depending on the state of disturbance due to the change in ambient temperature, the temperature near the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123 due to the action of the above-mentioned thermal resistance. It is difficult to accurately maintain the desired temperature under the condition that the disturbance is applied, and as a result, the oscillation state of the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123 is not good. Become stable. More specifically, the oscillation wavelengths of the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123 become unstable, so-called mode hops occur, and in particular, due to laser Doppler shift utilizing the coherence of light. Not suitable for flow rate detection.

On the other hand, in the measuring device according to the present embodiment, the component of the detection system of the second temperature control loop is the second thermistor 82, which is arranged in the vicinity of the perche element 60. Therefore, at the same time as having a configuration capable of minimizing the heat transfer delay, the target temperature of the second temperature control loop is not a fixed value but the first semiconductor laser 121, the second semiconductor laser 122, and the like. And, it changes appropriately depending on the application state of the disturbance with respect to the vicinity temperature of the third semiconductor laser 123. The reason is the difference between the temperature T1 detected by the first thermistor 81 arranged in the vicinity of the first semiconductor laser 121, the second semiconductor laser 122, and the third semiconductor laser 123 and the target temperature T1ref stored in the memory 440. This is because the target temperature voltage T2v of the second temperature control loop is negatively fed back controlled by the first temperature control loop having the control error of.

As described above, the measuring device according to the present embodiment is configured to have a double negative feedback control loop. As a result, when a plurality of luminous fluxes are emitted from a plurality of light sources for a plurality of measurement targets, even if the temperature is controlled by using a single thermoelectric element 60 and a heat sink 70, the thermoelectric cooling element 60 and the heat sink 70 are used. Does not block each light source. At the same time, even if there is a heat transfer delay due to the distance between the light source that is the temperature control target and the heat transfer element (Pelche element 60) that is the heat control element, the second thermistor 82 arranged near the heat transfer element is used for the second. By minimizing the heat transfer delay of the temperature control loop of the above, the control band of the second temperature control loop by the Perche element 60 and the second thermistor 82 is increased, and the target temperature to be finally controlled is set near the light source. By detecting using the first thermistor 81 arranged in, the target temperature of the second temperature control loop, which is the control amount of the first temperature control loop, can be appropriately changed, so that the temperature of the light source can be set to the target temperature. It is possible to maintain the temperature accurately.

The present invention is not limited to the above-described embodiment, and can be appropriately modified within the scope of claims and within a range not contrary to the gist or idea of the invention that can be read from the entire specification. Measuring methods, computer programs and storage media are also included in the technical scope of the present invention.

50 Heat transfer plate 60 Perche element 70 Heat sink 81 1st thermistor 82 2nd thermistor 121 1st semiconductor laser 122 2nd semiconductor laser 123 3rd semiconductor laser 200 Transparent tube 300 Flow concentration estimation unit 410 1st temperature detection unit 420 A / D converter 430 CPU
440 Memory 450 D / A conversion unit 510 Second temperature detection unit 520 Temperature control unit 530 Drive circuit

Claims (7)

The first irradiation unit that irradiates the object to be measured with light,
A heat transfer unit that is arranged at a position away from the first irradiation unit so as to thermally bond with the first irradiation unit via a heat transfer plate, and transfers heat generated by the first irradiation unit to the heat dissipation unit. When,
A first temperature detection unit that detects the first temperature around the first irradiation unit, and
A target temperature setting unit that sets a second target temperature based on the first temperature and the first temperature target information,
A first temperature control loop composed of
A second temperature detection unit that detects the second temperature around the heat transfer unit, and
A control unit that controls the heat transfer unit based on the second temperature and the second target temperature,
A second temperature control loop composed of
A measuring device characterized by having a double temperature control loop. The measuring device according to claim 1, further comprising a storage unit that previously stores information indicating a temperature for operating the first irradiation unit in a single mode as the first temperature target information. The measuring device according to claim 1 or 2, wherein the first irradiation unit can adjust the optical axis of the light to be irradiated. The object to be measured is a fluid.
Any of claims 1 to 3, further comprising a flow rate measuring unit for measuring the flow rate of the fluid using the light scattered by the fluid among the light emitted from the first irradiation unit. The measuring device according to item 1. The first irradiation unit that irradiates the object to be measured with light and the first irradiation unit are arranged so as to be thermally coupled to the first irradiation unit via a heat transfer plate at a position away from the first irradiation unit. It is a measurement method using a measuring device including a heat transfer unit that transfers the heat generated by the unit to the heat dissipation unit.
A first temperature detection step for detecting a first temperature around the first irradiation unit, and
A target temperature setting process for setting a second target temperature based on the first temperature and the first temperature target information, and
A first temperature control loop composed of
A second temperature detection step for detecting the second temperature around the heat transfer unit, and
A control step for controlling the heat transfer unit based on the second temperature and the second target temperature, and
A second temperature control loop composed of
A measurement method comprising a double temperature control loop of. The first irradiation unit that irradiates the object to be measured with light and the first irradiation unit are arranged so as to be thermally coupled to the first irradiation unit via a heat transfer plate at a position away from the first irradiation unit. A computer program used for a measuring device including a heat transfer unit that transfers heat generated by the unit to a heat dissipation unit.
A first temperature detection step for detecting a first temperature around the first irradiation unit, and
A target temperature setting process for setting a second target temperature based on the first temperature and the first temperature target information, and
A first temperature control loop composed of
A second temperature detection step for detecting the second temperature around the heat transfer unit, and
A control step for controlling the heat transfer unit based on the second temperature and the second target temperature, and
A second temperature control loop composed of
A computer program characterized by causing the measuring device to execute the double temperature control loop of the above. A storage medium for storing the computer program according to claim 6.

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