JP3741509B2 - Tube liquid sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tube liquid sensor, and more particularly, to a sensor that detects the presence or absence of liquid or bubbles in a fine tube that feeds liquid.
[0002]
[Prior art]
Conventionally, this type of sensor is used, for example, to determine whether or not a liquid exists in a liquid feeding tube of an analyzer. A light-transmitting tube is provided between the light-emitting element and the light-receiving element, and the light-receiving element is installed at a specific position by utilizing the fact that the refraction of light transmitted through the tube varies depending on the presence or absence of liquid, that is, Irradiates light to a specific position on the tube, receives light from the tube when there is no liquid in the tube, and places the light receiving element at a position where it does not receive light from the tube when there is liquid. An arrangement is known in which the presence or absence of liquid in the tube is detected (see, for example, Japanese Patent Laid-Open Nos. 4-42022 and 1-96515).
[0003]
[Problems to be solved by the invention]
However, if the size of the tube is smaller than the size of the light emitting part of the light emitting element or the light receiving part of the light receiving element, the light emitting element irradiates a specific position of the tube or the light transmitted through the tube only when no liquid is present. It becomes difficult to arrange at a position to receive light. That is, there is a problem that even if the position of the light receiving element is adjusted, the change in the amount of received light with respect to the presence or absence of liquid is small, so that it becomes difficult for the light receiving element to clearly determine the presence or absence of liquid.
[0004]
This invention was made in consideration of such circumstances, and by installing appropriate slit members before and after the tube, even if the tube is a fine size relative to the size of the light emitting and receiving elements, A liquid sensor capable of clearly detecting the presence or absence of liquid in a tube is provided.
[0005]
[Means for Solving the Problems]
The present invention relates to a light emitting and receiving element provided opposite to each other so that a translucent tube is disposed in an optical path from the light emitting element to the light receiving element, and between the light emitting element and the tube and between the tube and the light receiving element. Each of the slit members is arranged to selectively pass light from the light emitting element that passes through the tube to the light receiving element according to the presence or absence of liquid in the tube. And
Emitting element side of the slit member is disposed the light from the light emitting element to irradiate light to the offset portion from the center of the tube provided with a light-emitting element side slit for guiding the tube, the slit member of the light-receiving element side A light receiving element side slit for guiding light from the tube to the light receiving element, and the light receiving element side slit is stepped so that the slit width at a predetermined position away from the tube is smaller than the slit width on the tube side. And a tube liquid sensor provided with a light-shielding portion formed by the step .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
For example, a commercially available light emitting diode (LED) or laser diode can be used as the light emitting element in the present invention, and a photodiode or phototransistor can be used as the light receiving element.
[0007]
The slit member of the present invention includes a slit (gap) part that is installed in the optical path and allows a part of the light in the optical path to pass therethrough, and a light shielding part that blocks the passage of other light.
The liquid to be detected by the sensor of the present invention may be any liquid that has a refractive index different from that of air or that shields light, such as water.
[0008]
The tube for supplying the liquid to be detected by the sensor of the present invention is not particularly limited as long as it is translucent (transparent to translucent). For example, a synthetic resin tube such as a Teflon tube or a glass tube is used. Used.
[0009]
The size of the tube may be not more than the size of the light emitting part of the light emitting element and the light receiving part of the light receiving element (usually 5 to 4 mmφ), for example, the outer diameter may be 1 to 4 mm.
[0010]
In this invention, the slit members disposed between the light emitting element and the tube and between the tube and the light receiving element respectively select light from the light emitting element that passes through the tube in accordance with the presence or absence of liquid in the tube. Thus, the light receiving element is arranged so as to shield light.
The slit member on the light receiving element side may be arranged to shield light from the light emitting element when liquid is present in the tube and to allow light from the light emitting element to pass when no liquid is present in the tube.
In addition, the slit member on the light receiving element side may be arranged to allow light from the light emitting element to pass when liquid is present in the tube and to block light from the light emitting element when no liquid is present in the tube. Good.
[0011]
The arrangement will be described next. As shown in FIG. 1, when a translucent tube 3 is arranged in the optical path from the light emitting element 1 to the light receiving element, and a liquid exists in the tube 3, the tube 3 and the liquid generally have substantially the same refractive index. The tube 3 acts like a convex lens, and the light from the light emitting element 1 refracts relatively simply as shown in FIG.
[0012]
On the other hand, when there is no liquid in the tube 3 as shown in FIG. 2, the refraction of the light passing through the hollow portion of the tube and the light not passing through the hollow portion is greatly different. The light refracts in a complicated manner and reaches the light receiving element 2. As a result, in either case of FIG. 1 or FIG. 2, the light receiving element 2 receives substantially the same amount of light.
[0013]
Therefore, in the present invention, as shown in FIGS. 3 and 4, the slit member 4 is provided between the light emitting element 1 and the tube 3, and the slit member 5 is provided between the tube 3 and the light receiving element.
[0014]
In this case, the slit member 4 is preferably arranged so that the light from the light emitting element 1 irradiates one side from the axis of the tube 3, and the light from the light emitting element 1 is on one side of the axis of the tube 3 and the tube 3. More preferably, it is arranged so as to be incident only on the hollow portion.
[0015]
And when the liquid exists in the hollow part of the tube 3, the slit member 5 shields the light which permeate | transmitted the tube 3 from the light receiving element 2, as shown in FIG. 3, and there is no liquid in the hollow part of the tube 3 In some cases, as shown in FIG. 4, the light transmitted through the tube 3 is arranged to pass to the light receiving element 2.
As a result, the light receiving element 2 can clearly detect the presence or absence of liquid in the tube 3. Further, when an opaque liquid is present in the tube, the light is shielded by the liquid, so that the presence or absence of the liquid can be clearly detected regardless of whether the liquid is transparent or opaque.
[0016]
As shown in FIGS. 5 and 6, when the liquid exists in the hollow portion of the tube 3, the slit member 6 allows the light transmitted through the tube 3 to pass through the light receiving element 2 and allows the liquid to pass through the hollow portion of the tube 3. The light passing through the tube 3 may be arranged so as to be shielded from the light receiving element 2 when no light is present. However, in this case, it may be impossible to detect an opaque liquid.
[0017]
Embodiment Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. This does not limit the invention.
7 and 8 are a top view and a side view showing a liquid sensor for a fine tube according to one embodiment of the present invention, and FIG. 9 is a cutaway sectional view of a main part of FIG.
[0018]
In these drawings, the holders 14 and 15 are fastened together with screws 17 and 18 having an outer diameter of 3 mm so as to form a through-angle hole 16 at the center thereof, and the tube 13 is held through the through-angle hole 16. . The light emitting diode 11 is inserted and bonded to the recess 19 of the holder 14, and the phototransistor 12 is inserted and bonded to the recess 20 of the holder 15.
[0019]
The light emitting diode 11 and the phototransistor 12 are arranged on a straight line orthogonal to the axis of the tube 13 so as to face each other. The recess 19 and the through hole 16 are communicated with each other through a slit 21, and the through hole 16 and the recess 20 are connected through a slit 22.
[0020]
Here, the holders 14 and 15 are manufactured by machining using a polyacetal resin, and the light-emitting diode 11 and the phototransistor 12 have a TLN101A type (outside diameter D1 = 4.7 mm) and TPS601A, respectively, manufactured by Toshiba. (Outer diameter D2 = 4.7 mm) is used, and the tube 13 is a transparent Teflon tube having an outer diameter of 2.0 mm and an inner diameter of 1.2 mm.
As shown in FIG. 10, the slit 21 has a width W1 = 0.6 mm and a length L2 = 3 mm, and is formed away from the center of the square hole 16 by a distance L1 = 0.1 mm.
[0021]
The slit 22 has a width W2 = 0.8 mm and a length L3 = 3 mm, is formed along the inner wall surface of the square hole 16, and has a step of L5 = 0.5 mm at a distance L4 from the phototransistor 12 side. The width W2 is expanded to 1.3 mm and communicates with the square hole 16. That is, the slits 21 and 22 are configured to correspond to the slits of the slit members 4 and 5 in FIG.
[0022]
FIG. 11 is a drive circuit diagram of the sensor of this embodiment. When the switch S is turned on, a DC voltage 12V is supplied from the power source E to the light emitting diode 11 through the resistor R1, and to the phototransistor 12 through the resistor R2. The voltage Vs across the resistor R2 is obtained as an output of the sensor.
[0023]
In such a configuration, the resistance R1 is set so that a current of 51 mA flows through the light emitting diode 11, and the voltage Vs is measured when the tube 13 has water and when there is water, and when water is present, Vs = 0. In the absence, Vs = 4.0V was obtained, and it was confirmed that this sensor can clearly detect the presence or absence of water in the tube.
[0024]
Incidentally, when the step 22 is eliminated in the slit 22 of FIG. 10 and the width W2 is 1.3 mm over the length L3, Vs = 3.2V when water is present in the tube, and Vs = 4. 0V was obtained, and it was found that it was difficult to detect the presence or absence of water. This is because light is reflected on the left wall surface of the slit 22 and reaches the phototransistor 12 even when there is water in the tube.
[0025]
Instead of providing a step in the slit 22, the left inner wall surface may be a sawtooth uneven surface. As a result, light in the case where liquid is present in the tube is reflected by the uneven surface, and light incident on the phototransistor 12 is removed.
[0026]
Further, in this embodiment, the through hole is formed for a tube having an outer diameter of 2 mm. However, in order to use this sensor for a tube having a smaller diameter, for example, an outer diameter of 1.8 mm, the projection protrudes from the outside. A screw projecting into a through-angle hole whose length can be adjusted may be provided, and the center of the through-square hole and the axis of the tube may be aligned with the screw to hold the small-diameter tube.
[0027]
Furthermore, in the present invention, a single element is used as the light receiving element, but a CCD line sensor comprising a plurality of minute light receiving elements can also be used. In this case, if the CCD line sensor recognizes the pattern of light incident on the light receiving element shown in FIGS. 1 and 2, the slit member can be dispensed with.
[0028]
【The invention's effect】
According to the present invention, since the slit members are provided between the light emitting element and the tube and between the tube and the light receiving element, even if the tube is smaller than the size of the light emitting element and the light receiving element, It is possible to reliably detect the presence or absence of the liquid inside.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram for explaining the principle of the present invention;
FIG. 2 is an explanatory diagram for explaining the principle of the present invention.
FIG. 3 is an explanatory diagram for explaining the principle of the present invention;
FIG. 4 is an explanatory diagram for explaining the principle of the present invention;
FIG. 5 is an explanatory diagram for explaining the principle of the present invention;
FIG. 6 is an explanatory diagram for explaining the principle of the present invention.
FIG. 7 is a top view showing a liquid sensor according to one embodiment of the present invention.
FIG. 8 is a side view showing a liquid sensor according to one embodiment of the present invention.
FIG. 9 is a cutaway cross-sectional view showing a main part of a liquid sensor according to an embodiment of the present invention.
10 is an enlarged view of a main part of FIG. 9;
FIG. 11 is a drive circuit diagram of a liquid sensor according to one embodiment of the present invention.
[Explanation of symbols]
11 Light-emitting diode 12 Phototransistor 13 Tube 14 Holder 15 Holder 16 Through-angle hole 17 Screw 18 Screw 19 Recess 20 Recess 21 Slit 22 Slit

Claims (4)

A light emitting and receiving element provided opposite to each other so that a translucent tube is disposed in an optical path from the light emitting element to the light receiving element, and between the light emitting element and the tube and between the tube and the light receiving element Each of the slit members is arranged to selectively pass light from the light emitting element that passes through the tube to the light receiving element according to the presence or absence of liquid in the tube,
Emitting element side of the slit member is disposed the light from the light emitting element to irradiate light to the offset portion from the center of the tube provided with a light-emitting element side slit for guiding the tube, the slit member of the light-receiving element side A light receiving element side slit for guiding light from the tube to the light receiving element, and the light receiving element side slit is stepped so that the slit width at a predetermined position away from the tube is smaller than the slit width on the tube side. A tube liquid sensor having a light-shielding portion formed by the step .   The slit member on the light receiving element side is arranged to block light from the light emitting element when liquid is present in the tube, and to allow light from the light emitting element to pass when no liquid is present in the tube. The liquid sensor for tubes according to 1.   The slit member on the light receiving element side is disposed so as to allow light from the light emitting element to pass when liquid is present in the tube and to block light from the light emitting element when no liquid is present in the tube. The liquid sensor for tubes according to 1. The light emitting element side of the slit member is provided with a light-emitting element side slit for passing light from the light emitting element to the tube, the slit member of the light-receiving element side in the tube of the light from the light emitting element transmitted through the tube light-receiving element side slit for in response to the presence or absence of the liquid passing to selectively receiving element is formed, according to claim 1 with the axis of the light emitting element side slit and the axis of the light receiving element side of the slit do not match The liquid sensor for tubes according to any one of to 3 .

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