JP2019163959A - State detection sensor and mass flow controller - Google Patents

Abstract

To detect a state of liquid in a transparent tube under a mild condition as compared to a conventional configuration.SOLUTION: The state detection sensor includes a light projection section 13 for projecting parallel light to a transparent tube 11, a light reception section 14 having a photo-detector, and a liquid existence determination section 151 for determining existence of transparent liquid in the transparent tube 11 according to a result of photo-detection by the light reception section 14. The photo-detector is disposed at a position corresponding to a focal position of the parallel light projected by the light projection section 13 and transmitted through the transparent tube 11, or at a distance from a position corresponding to the focal position with respect to the transparent tube 11 when the inside of the transparent tube 11 is filled with the transparent liquid, and the photo-detector receives the parallel light which is projected by the light projection section 13 and transmitted through the transparent tube 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a state detection sensor that detects the state of a liquid in a transparent tube, and a mass flow controller having the state detection sensor.

  2. Description of the Related Art Conventionally, there are known bubble detection sensors that detect whether bubbles are present in a transparent tube (see, for example, Patent Documents 1 and 2). Examples of the bubble detection sensor include an ultrasonic type sensor, an infrared LED type sensor, and a microwave type sensor.

JP, 2006-214793, A JP-A-9-99062

  However, the conventional bubble detection sensor has a problem that there is a condition that the presence / absence of bubbles cannot be detected. For example, in the conventional ultrasonic type state detection sensor, the presence / absence of bubbles cannot be detected in the state where bubbles are always present because the presence / absence of bubbles is detected by utilizing a change in conductivity. In addition, although the conventional infrared LED type state detection sensor is inexpensive, it detects the presence or absence of bubbles using the variation in the amount of transmitted light, and therefore cannot detect minute bubbles. Further, since the conventional microwave type state detection sensor generally detects the presence or absence of bubbles using the Doppler effect, the presence or absence of bubbles cannot be detected when the flow of liquid present in the transparent tube stops.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a state detection sensor capable of detecting the state of a liquid in a transparent tube under a looser condition than the conventional configuration. Yes.

  The state detection sensor according to the present invention has a light projecting unit that projects parallel light onto the transparent tube, and the light projecting unit transmits light through the transparent tube when the transparent tube is filled with a transparent liquid. A position corresponding to the focal position of parallel light, or a position far from the position corresponding to the focal position with respect to the transparent tube, and receives the parallel light projected by the light projecting unit and transmitted through the transparent tube. A light receiving unit having a light receiving device and a liquid presence / absence determining unit that determines whether a transparent liquid exists in the transparent tube based on a light reception result by the light receiving unit.

  According to this invention, since it comprised as mentioned above, the detection of the state of the liquid in a transparent pipe | tube is attained on conditions loose with respect to a conventional structure.

1A and 1B are diagrams showing a configuration example of a state detection sensor according to Embodiment 1 of the present invention, FIG. 1A is a top view, and FIG. 1B is a side view. It is a figure which shows the structural example of the state detection part in Embodiment 1 of this invention. It is a flowchart which shows the operation example of the state detection sensor which concerns on Embodiment 1 of this invention. FIG. 4A is a diagram illustrating an example of light transmitted through the transparent tube (when there is no liquid in the transparent tube), and FIG. 4B is a light receiving unit (when the image sensor is disposed at a position corresponding to the focal position). FIG. 4C is a diagram illustrating an example of the light reception distribution, and FIG. 4C is a diagram illustrating an example of the light reception distribution in the light receiving unit (when the image sensor is arranged far from the focal position). FIG. 5A is a diagram showing an example of light transmitted through the transparent tube (when the inside of the transparent tube is filled with liquid), and FIG. 5B is a light receiving unit (when the image sensor is arranged at a position corresponding to the focal position). FIG. 5C is a diagram illustrating an example of the light reception distribution in the light receiving unit (when the image sensor is arranged far from the focal position). 6A is a diagram illustrating an example of light transmitted through the transparent tube (when bubbles are present in the transparent tube), and FIG. 6B is a light receiving unit (when the image sensor is arranged at a position corresponding to the focal position). FIG. 6C is a diagram illustrating an example of the light reception distribution, and FIG. 6C is a diagram illustrating an example of the light reception distribution in the light receiving unit (when the image sensor is arranged far from the focal position). 7A and 7B are diagrams illustrating a configuration example of the mass flow controller according to the first embodiment of the present invention, FIG. 7A is a diagram illustrating an example of an appearance, and FIG. 7B is a diagram illustrating an example of an internal configuration. is there. 8A and 8B are diagrams illustrating an operation example of the mass flow controller according to Embodiment 1 (when the bubbles are small and do not affect the flow measurement), and FIG. 8A is a diagram illustrating an operation example of the bubble detection unit. FIG. 8B is a diagram illustrating an operation example of the flow rate measurement unit. 9A and 9B are diagrams illustrating an operation example of the mass flow controller according to Embodiment 1 (the bubbles are in a state that greatly affects the flow rate measurement and the flow rate measurement value is not held), and FIG. It is a figure which shows the operation example of a detection part, and FIG. 9B is a figure which shows the operation example of a flow volume measurement part. 10A and 10B are diagrams showing an operation example of the mass flow controller according to the first embodiment (when bubbles are in a state that greatly affects the flow rate measurement, but when the flow rate measurement value is held), FIG. It is a figure which shows the operation example of a bubble detection part, FIG. 10: B is a figure which shows the operation example of a flow volume measurement part.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
1 is a diagram showing a configuration example of a state detection sensor 1 according to Embodiment 1 of the present invention. In FIG. 1, a state detection unit 15 to be described later is not shown.
The state detection sensor 1 detects the state of the transparent liquid in the transparent tube 11. In addition, as this transparent liquid, water is mentioned, for example. As shown in FIG. 1, the state detection sensor 1 includes a transparent tube 11, a light shielding plate 12, a light projecting unit 13, a light receiving unit 14, and a state detection unit 15.

The transparent tube 11 is a tube through which a transparent liquid flows.
The light shielding plates 12 are arranged in contact with both side surfaces in the radial direction of the transparent tube 11 so as to sandwich the transparent tube 11 and block light.
In FIG. 1, the state detection sensor 1 is provided with a holding mechanism 16 that holds the transparent tube 11, and this holding mechanism 16 also functions as the light shielding plate 12.

  The light projecting unit 13 projects parallel light (for example, laser parallel light) onto the transparent tube 11. In FIG. 1, the light projecting unit 13 emits light from a light projecting substrate 131 provided on the main substrate 17, a light emitting element 132 such as a laser diode that is provided on the light projecting substrate 131 and emits light, and the light emitting element 132. And a collimating lens 133 that converts the emitted light into parallel light.

  The parallel light projected by the light projecting unit 13 is irradiated only with the parallel light transmitted through the transparent tube 11 on the light receiving unit 14 side from the transparent tube 11. In the example of FIG. 1, among the parallel light projected by the light projecting unit 13, the parallel light irradiated to the portion other than the transparent tube 11 is blocked by the light shielding plate 12, and only the parallel light irradiated to the transparent tube 11 is used. Is transmitted through the transparent tube 11 and irradiated to the light receiving unit 14 side. For example, without using the light shielding plate 12, the light projecting unit 13 sets the width of the parallel light to the same width (including substantially the same meaning) as the outer diameter of the transparent tube 11, and the transparent tube Only 11 may be projected with parallel light.

  The light receiving unit 14 is disposed with a gap with respect to the transparent tube 11, and includes an image sensor (light receiving device) 144 that receives the parallel light projected by the light projecting unit 13 and transmitted through the transparent tube 11. In FIG. 1, the light receiving unit 14 includes a mirror 141 that reflects incident light, an optical slit 142 that is a diaphragm disposed on the optical path before and after the mirror 141, and a light receiving substrate 143 provided on the main substrate 17. And an image sensor 144 that receives light incident on the optical slit 142 after being reflected by the mirror 141. In the example of FIG. 1, the image sensor 144 is disposed farther from the transparent tube 11 than the position corresponding to the focal position of the parallel light. The focal position of the parallel light is a focal position of the parallel light that is projected by the light projecting unit 13 and transmitted through the transparent tube 11 when the transparent tube 11 is filled with a transparent liquid. Information indicating the light reception result by the light receiving unit 14 is output to the state detection unit 15.

  The state detection unit 15 detects the state of the transparent liquid in the transparent tube 11 based on the light reception result by the light receiving unit 14. As shown in FIG. 2, the state detection unit 15 includes a liquid presence / absence determination unit 151, a bubble presence / absence determination unit 152, a position detection unit 153, and a size detection unit 154. The state detection unit 15 is realized by a processing circuit such as a system LSI (Large Scale Integration) or a CPU (Central Processing Unit) that executes a program stored in a memory or the like.

  The liquid presence / absence determination unit 151 determines whether a transparent liquid exists in the transparent tube 11 based on the light reception result by the light receiving unit 14. Information indicating the determination result by the liquid presence / absence determination unit 151 is output to the bubble presence / absence determination unit 152.

  When the liquid presence / absence determination unit 151 determines that there is a transparent liquid, the bubble presence / absence determination unit 152 determines whether there is a bubble in the transparent tube 11 based on the light reception result by the light receiving unit 14. Information indicating the determination result by the bubble presence / absence determination unit 152 is output to the position detection unit 153 and the size detection unit 154.

The position detection unit 153 detects the position of the bubble based on the light reception result by the light receiving unit 14 when the bubble presence / absence determination unit 152 determines that the bubble is present.
When the bubble presence / absence determination unit 152 determines that a bubble is present, the size detection unit 154 detects the size of the bubble based on the light reception result by the light receiving unit 14.

  In the example of FIG. 1, the state detection unit 15 includes a liquid presence / absence determination unit 151, a bubble presence / absence determination unit 152, a position detection unit 153, and a size detection unit 154. However, the present invention is not limited to this, and the bubble presence / absence determination unit 152, the position detection unit 153, and the size detection unit 154 are not essential components, and may be removed from the state detection unit 15.

Next, an operation example of the state detection sensor 1 according to the first embodiment will be described with reference to FIGS. In the following, the state detection sensor 1 shown in FIG. 1 is used and the image sensor 144 is arranged at a position 144a shown in FIGS.
Here, the transparent tube 11 filled with a transparent liquid can be regarded as a spherical convex lens. When the transparent tube 11 is irradiated with parallel light, the parallel light is condensed at the focal position due to the characteristics of the convex lens. Then, it diffuses uniformly (FIG. 5A). Further, when bubbles are present in the transparent tube 11, a state similar to a state in which a concave lens is present in the convex lens is obtained, and the diffused light is disturbed (FIG. 6A).
Therefore, in the first embodiment, using the above phenomenon, the image sensor 144 disposed farther than the focal position with respect to the transparent tube 11 acquires the distribution of parallel light transmitted through the transparent tube 11. Thus, the state of the transparent liquid in the transparent tube 11 is detected.

  In the operation example of the state detection sensor 1, as shown in FIG. 3, first, the light projecting unit 13 projects parallel light onto the transparent tube 11 (step ST1). Of the parallel light projected by the light projecting unit 13, the parallel light irradiated on the portion other than the transparent tube 11 is blocked by the light shielding plate 12, and only the parallel light irradiated on the transparent tube 11 passes through the transparent tube 11. The light is transmitted and irradiated to the light receiving unit 14 side.

  Next, the light receiving unit 14 receives the parallel light projected by the light projecting unit 13 and transmitted through the transparent tube 11 (step ST2).

Next, the liquid presence / absence determination unit 151 determines whether a transparent liquid exists in the transparent tube 11 based on the light reception result by the light receiving unit 14 (step ST3).
Here, as shown in FIGS. 4C and 5C, the shape of the light reception distribution in the light receiving unit 14 is different between the case where the transparent liquid is present in the transparent tube 11 and the case where the transparent liquid is not present. Therefore, the liquid presence / absence determination unit 151 can determine the presence / absence of a transparent liquid from the difference in the shape of the received light distribution.

  In step ST3, when the liquid presence / absence determination unit 151 determines that there is no transparent liquid, the sequence ends.

On the other hand, when the liquid presence / absence determination unit 151 determines that there is a transparent liquid in step ST3, the bubble presence / absence determination unit 152 has air bubbles in the transparent tube 11 based on the light reception result by the light receiving unit 14. Is determined (step ST4).
Here, as shown in FIG. 5C and FIG. 6C, when bubbles exist in the transparent tube 11, the amount of light at the location where the bubbles on the received light distribution are almost zero compared to the case where no bubbles are present. Become. Therefore, the bubble presence / absence determination unit 152 can determine the presence / absence of bubbles by checking whether there is a point at which the amount of light is almost zero within the range corresponding to the transparent tube 11 on the light reception distribution using the threshold value. It is. Even when foreign matter such as slurry is present in the transparent tube 11, the received light distribution is the same result as when the bubbles are present. Therefore, the bubble presence / absence determination unit 152 can also determine the presence / absence of foreign matter.

In step ST4, when the bubble presence / absence determining unit 152 determines that a bubble is present, the position detecting unit 153 detects the position of the bubble based on the light reception result by the light receiving unit 14 (step ST5). The size detection unit 154 detects the size of the bubbles based on the light reception result by the light receiving unit 14 (step ST6).
Here, as described above, when bubbles exist in the transparent tube 11, the light amount of the portion where the bubbles on the light reception distribution exist is almost zero. Therefore, the position detection unit 153 can detect the position of the bubble from the point where the light amount becomes almost zero within the range corresponding to the transparent tube 11 on the light reception distribution. In addition, the size detection unit 154 can detect the size of the bubble from the range in which the amount of light is substantially zero within the range corresponding to the transparent tube 11 on the light reception distribution.

  In step ST4, when the bubble presence / absence determining unit 152 determines that there is no bubble, the processes in steps ST5 and ST6 are skipped, and the sequence ends.

  Here, in the state detection sensor 1 according to the first embodiment, since the state detection is performed by the light reception distribution in the light receiving unit 14, it is possible to detect the presence / absence of bubbles even when bubbles are always present in the transparent tube 11. is there. Further, in the state detection sensor 1 according to the first embodiment, since the state detection is performed by the light reception distribution in the light receiving unit 14, it is possible to detect the presence / absence of bubbles even when there are minute bubbles in the transparent tube 11. is there. Further, in the state detection sensor 1 according to the first embodiment, since the state detection is performed by the light reception distribution in the light receiving unit 14, the presence or absence of bubbles is detected even when the flow of the transparent liquid existing in the transparent tube 11 is stopped. It can be detected. Furthermore, the state detection sensor 1 according to the first embodiment can detect not only the presence / absence of bubbles but also the position and size of bubbles.

  Further, in the state detection sensor 1 according to the first embodiment, since it is not necessary to fix the sensors (the light projecting unit 13 and the light receiving unit 14) to the transparent tube 11, it can be configured in various shapes at low cost.

  The image sensor 144 enlarges the image to be formed as the distance from the focal position with respect to the transparent tube 11 increases. Therefore, the state detection sensor 1 can easily detect the state even when the accuracy of the light receiving unit 14 is low by disposing the image sensor 144 sufficiently far from the position corresponding to the focal position with respect to the transparent tube 11. It becomes. For example, the image sensor 144 is disposed at a distance of 3 to 4 times the focal position. The location where the image sensor 144 is arranged is appropriately set based on, for example, desired resolution, the size of the light receiving surface of the image sensor 144, the outer diameter of the transparent tube 11, and the like.

In the above description, the image sensor 144 is disposed farther from the transparent tube 11 than the position corresponding to the focal position (position 144a shown in FIGS. 4 to 6).
However, the present invention is not limited to this, and when the state detection unit 15 determines the presence or absence of a transparent liquid in the transparent tube 11, the image sensor 144 is positioned corresponding to the focal position (the positions shown in FIGS. 4 to 6). 144b). In this case, as shown in FIG. 4B and FIG. 5B, the amount of light at a position corresponding to the focal position on the light reception distribution when there is a transparent liquid and when there is no transparent liquid in the transparent tube 11. Is different. Therefore, the liquid presence / absence determination unit 151 can determine the presence / absence of a transparent liquid by checking the amount of light at a position corresponding to the focal position on the light reception distribution using the threshold value. In this case, the light receiving device is not limited to the image sensor 144, and a photodiode may be used.

  In the above description, the position of the image sensor 144 is fixed. However, the present invention is not limited thereto, and the state detection sensor 1 may be provided with a moving mechanism that allows the image sensor 144 to move. As a result, the moving mechanism can dispose the image sensor 144 farther than the position corresponding to the focal position and the transparent tube 11.

  In the above description, the case where a single image sensor 144 is used as the light receiving device is shown. However, the present invention is not limited to this, and a photodiode may be used as a light receiving device in addition to the image sensor 144. In this case, the image sensor 144 is disposed farther than the position corresponding to the focal position with respect to the transparent tube 11, and the photodiode is disposed at a position corresponding to the focal position. As described above, by using the image sensor 144 and the photodiode as the light receiving device, it is possible to simultaneously acquire the light receiving distribution far from the focal position and the light receiving distribution at the focal position.

  The state detection sensor 1 can be applied to a mass flow controller, for example. In a mass flow controller that measures and controls the flow rate of a liquid, if bubbles exist in the liquid, an error occurs in the measured value, the control performed based on the measured value becomes incorrect, and correct flow rate control cannot be performed. Therefore, by externally attaching or incorporating the state detection sensor 1 in this mass flow controller, measurement output by the mass flow controller can be temporarily stopped when bubbles are present.

  Here, FIG. 7 shows a configuration example of the mass flow controller 2 in which the state detection sensor 1 according to Embodiment 1 is incorporated. The mass flow controller 2 shown in FIG. 7 includes a liquid inflow part 21, a bubble detection part 22, a flow rate measurement part 23, a valve 24, a liquid outflow part 25, a main control part (control part) 26, and an interface part (I / F part) 27. It has.

  The liquid inflow portion 21 is a portion where a transparent liquid flows into the mass flow controller 2.

  The bubble detection unit 22 detects the state of transparent liquid (presence / absence of transparent liquid, presence / absence of bubbles, position and size of bubbles) in the transparent tube 11 having one end communicating with the liquid inflow unit 21. As the bubble detection unit 22, the state detection sensor 1 according to the first embodiment is used. The state detection sensor 1 detects whether or not the bubble is close to the sensing portion of the flow rate measurement unit 23 in detecting the position of the bubble. The bubble detection unit 22 includes a signal output unit in addition to the configuration included in the state detection sensor 1. This signal output unit determines that bubbles are applied to the sensing portion of the flow rate measurement unit 23 based on the detection results of the position detection unit 153 and the size detection unit 154 when the bubble presence / absence determination unit 152 determines that bubbles are present. In this case, an output hold signal is output to the flow rate measurement unit 23. The output hold signal is a signal for instructing to temporarily hold the measurement output from the flow rate measurement unit 23 during the period in which the detected bubble flows in the measurement region of the flow rate measurement unit 23.

  The flow rate measurement unit 23 measures the flow rate of the transparent liquid in a tube having one end communicating with the other end of the transparent tube 11. Further, when the flow rate measurement unit 23 receives the output hold signal from the bubble detection unit 22, the flow rate measurement unit 23 temporarily holds the measurement output for the period according to the output hold signal.

The liquid outflow portion 25 is a portion that is communicated with the other end of the pipe and through which a transparent liquid flows out.
The valve 24 controls the outflow amount of the transparent liquid in the liquid outflow portion 25 by opening and closing the valve.
The main control unit 26 controls the valve 24 based on the flow rate measurement result by the flow rate measurement unit 23.

Here, in the conventional mass flow controller, in the normal state shown in FIG. 8 (when the bubble is small and does not affect the flow measurement), in the abnormal state shown in FIG. 9 (when the bubble greatly affects the flow measurement). In the flow rate measuring unit, erroneous measurement of the flow rate due to bubbles occurs, and the control of the valve by the main control unit also fluctuates greatly, greatly disturbing the flow rate. 8 and 9, for ease of explanation, the case where the bubble detection unit 22 does not hold the flow rate measurement value in the mass flow controller 2 according to the first embodiment is shown. This corresponds to the operation of a conventional mass flow controller that does not have. Moreover, the broken line shown in FIG. 9 has shown the case of a normal state. Moreover, the arrow shown in FIG. 9 has shown the movement time of the bubble.
In contrast, as shown in FIG. 10, in the mass flow controller 2 according to the first embodiment, the bubble detection unit 22 determines that the flow rate measurement in the flow rate measurement unit 23 has an influence from the position and size of the detected bubble. In this case, an output hold signal is output to the flow rate measurement unit 23. And according to this output hold signal, the flow measurement part 23 can suppress disturbance of the measured value of the flow rate by temporarily holding the measurement output (output value output) for the corresponding period. As a result, the occurrence of abnormal control over the valve 24 by the main control unit 26 can be suppressed, and the flow rate disturbance can be suppressed. In addition, the arrow shown in FIG. 10 has shown the movement time of the bubble from the measurement area | region in the bubble detection part 22 to the measurement area | region in the flow volume measurement part 23. FIG.

In the above description, the configuration example and the operation example of the mass flow controller 2 including the state detection sensor 1 have been described. However, the same applies to the case where the state detection sensor 1 is externally attached to the mass flow controller.
Moreover, the state detection sensor 1 is applicable to a liquid application apparatus, for example. In a liquid application apparatus that applies liquid while dripping, if there are bubbles in the liquid, application unevenness occurs. Therefore, by incorporating or externally attaching the state detection sensor 1 to this liquid application device, it is possible to temporarily stop the application of liquid by the liquid application device when bubbles are present.

  As described above, according to the first embodiment, the light projecting unit 13 that projects parallel light to the transparent tube 11 and the light projecting unit 13 when the transparent tube 11 is filled with a transparent liquid. It is disposed at a position corresponding to the focal position of the parallel light that has been projected and transmitted through the transparent tube 11, or farther from the position corresponding to the focal position with respect to the transparent tube 11, and is projected by the light projecting unit 13. A light receiving unit 14 having a light receiving device that receives the parallel light transmitted through the transparent tube 11 and a liquid presence / absence determining whether a transparent liquid exists in the transparent tube 11 based on a light reception result by the light receiving unit 14 Since the determination unit 151 is provided, it is possible to detect the state of the liquid in the transparent tube under a looser condition than the conventional configuration.

  In the present invention, any constituent element of the embodiment can be modified or any constituent element of the embodiment can be omitted within the scope of the invention.

DESCRIPTION OF SYMBOLS 1 State detection sensor 2 Mass flow controller 11 Transparent tube 12 Light-shielding plate 13 Light projection part 14 Light reception part 15 State detection part 16 Holding mechanism 17 Main board 21 Liquid inflow part 22 Bubble detection part 23 Flow measurement part 24 Valve 25 Liquid outflow part 26 Main Control unit (control unit)
27 Interface Unit 131 Light Emitting Substrate 132 Light Emitting Element 133 Collimating Lens 141 Mirror 142 Optical Slit 143 Light Receiving Substrate 144 Image Sensor (Light Receiving Device)
151 Liquid presence / absence determination unit 152 Bubble presence / absence determination unit 153 Position detection unit 154 Size detection unit

Claims (8)

A light projecting unit that projects parallel light onto the transparent tube;
When the inside of the transparent tube is filled with a transparent liquid, the position corresponding to the focal position of parallel light projected by the light projecting unit and transmitted through the transparent tube, or at the focal position with respect to the transparent tube A light receiving unit that is disposed farther than the corresponding position and has a light receiving device that receives the parallel light that is projected by the light projecting unit and transmitted through the transparent tube;
A state detection sensor comprising: a liquid presence / absence determination unit that determines whether a transparent liquid is present in the transparent tube based on a light reception result by the light reception unit. The light receiving device is an image sensor disposed farther than a position corresponding to the focal position with respect to the transparent tube,
When the liquid presence / absence determination unit determines that there is a transparent liquid, the liquid presence / absence determination unit includes a bubble presence / absence determination unit that determines whether bubbles exist in the transparent tube based on a light reception result of the light receiving unit. The state detection sensor according to claim 1. The state according to claim 2, further comprising a position detection unit that detects a position of the bubble based on a light reception result by the light receiving unit when the bubble presence / absence determination unit determines that a bubble is present. Detection sensor. The size detection part which detects the size of the said bubble based on the light reception result by the said light-receiving part when the bubble presence determination part determines with a bubble existing is provided. The claim 2 or Claim characterized by the above-mentioned. 3. The state detection sensor according to 3. The state detection sensor according to any one of claims 2 to 4, further comprising a moving mechanism that allows the light receiving unit to move. The said light-receiving part has a photodiode which is arrange | positioned in the position corresponded to the said focus position, and receives the parallel light which was projected by the said light projection part and permeate | transmitted the said transparent tube. Item 5. The state detection sensor according to any one of Items4. 7. The light-shielding plate according to claim 1, wherein the light-shielding plate is disposed in contact with both side surfaces in the radial direction of the transparent tube so as to sandwich the transparent tube, and blocks light. The state detection sensor described in the item. A liquid inflow section into which a transparent liquid flows, and
A light projecting portion for projecting parallel light to a transparent tube having one end communicating with the liquid inflow portion;
With respect to the transparent tube, when the inside of the transparent tube is filled with a transparent liquid, it is disposed farther from the position corresponding to the focal position of the parallel light projected by the light projecting unit and transmitted through the transparent tube, A light receiving unit having an image sensor that receives parallel light projected by the light projecting unit and transmitted through the transparent tube;
A flow rate measuring unit for measuring a flow rate of a transparent liquid in a tube having one end communicating with the other end of the transparent tube;
A liquid outflow portion that is communicated with the other end of the tube and through which a transparent liquid flows out;
A valve for controlling the amount of transparent liquid flowing out of the liquid outflow portion;
Based on the measurement result by the flow rate measurement unit, a control unit for controlling the valve;
A liquid presence / absence determining unit that determines whether a transparent liquid exists in the transparent tube based on a light reception result by the light receiving unit;
When it is determined by the liquid presence / absence determination unit that a transparent liquid is present, a bubble presence / absence determination unit that determines whether bubbles exist in the transparent tube based on a light reception result by the light receiving unit;
A position detection unit that detects a position of the bubble based on a light reception result by the light receiving unit when the bubble presence determination unit determines that a bubble is present;
When it is determined by the bubble presence / absence determination unit that a bubble is present, a size detection unit that detects a size of the bubble based on a light reception result by the light receiving unit;
When it is determined by the bubble presence / absence determination unit that the bubble is present, the bubble is detected in the measurement region of the flow rate measurement unit based on the detection results of the position detection unit and the size detection unit. A signal output unit that outputs an output hold signal instructing to temporarily hold the measurement output by the flow rate measurement unit in the flowing period;
The mass flow controller, wherein the flow rate measurement unit temporarily holds a measurement output in accordance with the output hold signal.

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