JPH0566146A - Level sensor - Google Patents

Abstract

PURPOSE:To provide a level sensor regularly measurable without error and having good reproducibility in which dust and liquid drop are never left around a level detecting electrode even after the level sensor is repeatedly used. CONSTITUTION:A first separate space part 6 is formed between a lateral pair of level detecting window holes 5 arranged in the vertical direction of a level sensor 10, and a second separate space part 7 is formed between an electrode 3 group on a resistance film 2 side arranged on the left of the insulating base material of the level sensor and the electrode 3 group on the resistance film 2 side arranged on the right. Liquid drops by dust is prevented from being left between vertical and lateral electrode parts of the level detecting window holes 5, and a short-circuit between the electrodes is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact type liquid level sensor using a resistor.

[0002]

2. Description of the Related Art A contact-type liquid level sensor using a resistor is known as a liquid level sensor for measuring the liquid level of a liquid containing an electrolyte, that is, the water depth of the liquid. FIG. 10 shows the main configuration of this type of liquid level sensor used for urine measurement in hospitals and the like. In the figure, a pair of left and right carbon resistance films 2 are provided on the surface of a polyethylene terephthalate film substrate 1.
Are continuously formed in the vertical direction, and the carbon resistance film 2
A plurality of silver electrodes 3 are vertically arranged in a comb shape at regular intervals. The surfaces of the carbon film 2 and the silver electrode 3 are covered with the surface of the polyethylene terephthalate film substrate 1 by a water-repellent silicon water-repellent film 4, for example. The water repellent film 4 is provided with a liquid level detection window hole 5 at a position facing each of the silver electrodes 3. Note that the silver electrodes 3 are not bilaterally symmetric, and if the electrodes have the same pitch,
It is configured to be staggered by 1/2 pitch,
It is designed to double the detection sensitivity.

An outline of the liquid level measurement of a liquid (containing an electrolyte) using the liquid level sensor 10 having the above structure will be described. Liquid level sensor 10
Are arranged upright in a liquid measuring container (not shown). In this state, the resistance circuit of the liquid level sensor 10 is as shown in FIG. In the figure, the resistance (R) indicates the resistance of the pair of left and right resistance films 2 of the liquid level sensor 10 shown in FIG. 10, and the resistances (R) are connected to each other. The lead 11 corresponds to the silver electrode 3 which is conductively arranged in a comb shape on the resistance film 2. The resistor group arranged on the left side of the liquid level sensor 10 is connected to the external terminal A via the lead lead 12, and the resistor group arranged on the right side is similarly connected to the external terminal B via the lead lead 12. It is connected.

When the liquid level of the liquid injected into the liquid measuring container (not shown) in which the liquid level sensor 10 is vertically arranged reaches, for example, the CD plane, it is between the external terminals A and B. When a constant alternating current is applied, each electrode 3 below the C-D liquid level of the liquid level sensor 10 is short-circuited between the left and right electrodes, and the arrow K
Flows like A-C-D-B according to the path. When the liquid surface of the injected liquid is, for example, the EF surface,
The electric current flows along the arrow L along the route A-E-F-B.
Therefore, the resistance value of the path through which the current flows differs depending on the height of the liquid surface of the liquid (water depth). As shown in FIG. 8, the relationship between the resistance value and the water depth of the liquid increases as the water depth increases by the amount of one resistance (R) (actually, by the level difference between the left and right liquid level detection window holes 5). The resistance value changes stepwise. Thus, since the resistance value varies depending on the water depth, when a current is passed between the external terminals A and B, the voltage between the external terminals A and B varies depending on the water depth. Therefore, by detecting the voltage between the external terminals A and B, the liquid surface level of the liquid to be detected is obtained as a voltage value, and this liquid surface level value is amplified by the amplifier circuit 13 as shown in FIG. Is added to an arithmetic circuit (not shown),
The amount of urine excreted by the patient is obtained by performing a predetermined calculation process.

[0005]

However, since the liquid level sensor is repeatedly used many times, the measurement data is naturally required to have reproducibility. Therefore, after the liquid is measured, when the liquid is discharged from the liquid discharge hole (not shown) of the measurement container, droplets are formed above and below and to the left and right of the liquid level detection window hole 5 of the electrode 3 of the liquid level sensor 10. There should be no residual and no short circuit between the electrodes 3. As a countermeasure against this, as described above, a water-repellent film 4 such as a silicone resin or a fluorine resin, which is effectively water-repellent with respect to water or the like, is coated on the entire surface of the base material 1 excluding the liquid level detection window holes 5. , This water-repellent film 4 to the resistor 2, silver electrode 3
Although the method formed above is adopted, the water-repellent film 4 has a problem that the water-repellent effect is weak in the case of a liquid containing a high molecular organic substance, so-called water drainage is poor. Further, if dust or the like adheres to the periphery of the liquid level detection window hole 5, the liquid containing the electrolyte is likely to remain together with the dust, which may cause a short circuit between the electrodes 3 and the subsequent measurement. At this time, the voltage corresponding to the part between the left and right electrodes short-circuited by the residual liquid droplets is detected, which causes a malfunction of detecting the short-circuited electrode part regardless of the water depth of the liquid surface, which is a fatal defect in practical use There is a problem that it may occur.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to leave a droplet containing dust or the like around the detection electrode window hole even when the liquid level sensor is repeatedly used. There is no problem of short circuit between electrodes due to
An object of the present invention is to provide a liquid level sensor that can always perform normal measurement.

[0007]

In order to achieve the above object, the present invention is configured as follows. That is, in the liquid level sensor of the present invention, a pair of left and right resistance films are formed on the surface of the insulating base material by extending in the vertical direction, and the plurality of electrodes are spaced from each other by electrically connecting to each of the left and right corresponding resistance films. In the liquid level sensor arranged in the up-down direction, the electrode group on the resistance film side arranged between the electrodes arranged in the up-down direction or on the left side and the electrode on the resistance film side arranged on the right side A separate space portion is formed between the group and the group.

Further, a water-repellent film covering the resistance film and the electrodes is formed on the surface of the insulating base material, and the water-repellent film is provided with a liquid level detecting window hole at a position facing each electrode. It is also a characteristic configuration of the present invention that a protective layer covering the resistance film is formed on the surface of the insulating base material, and the electrode is exposed to the outside without being covered by the protective layer. There is.

[0009]

In the present invention having the above-described structure, since the separated space portion is formed between the pair of left and right liquid level detection window holes arranged in the vertical direction of the liquid level sensor, when the liquid level sensor is repeatedly used. Also, no liquid droplets are left on the upper and lower sides of the liquid level detection window due to dust or the like.

Further, a separation space portion is formed between the resistance film side electrode group arranged on the left side of the insulating base material of the liquid level sensor and the resistance film side electrode group arranged on the right side. Also in this case, no liquid droplets remain due to dust between the left and right electrodes.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same parts as those of the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted. FIG. 1 and FIG. 2 show the essential structure of the first embodiment. The configuration is similar to the liquid level sensor 10 of the conventional example,
The resistance film 2, the electrode 3, and the water repellent film 4 are formed on the surface of the insulating base material 1.
And a liquid level detection window hole 5 are formed.
The characteristic of the present embodiment is that the first separated space portions 6 are formed at regular intervals in the vertical direction of the liquid level detection window hole 5,
In addition, the second separated space portion 7 is formed between the pair of left and right electrode groups 8 and 9.

The first separated space 6 is formed by cutting out the base material between the liquid level detection window holes 5 arranged in the vertical direction. The space between the liquid level detection window holes 5 of the first separation space 6 is set to a size that allows complete drainage in consideration of the surface tension and viscosity of the liquid to be measured. Further, the second separated space portion 7 is formed by vertically cutting out between the left and right electrode groups 8 and 9 in consideration of water drainage similarly to the first separated space portion 6.

According to this embodiment, the first separation space portion 6 is formed in the vertical direction of the liquid surface detection window hole 5 of the liquid surface sensor 10, and the second separation space is formed between the left and right electrode groups 8 and 9. Since the portion 7 is formed, no droplets due to dust or the like remain between the upper and lower portions of the liquid level detection window hole 5. In addition, since no liquid droplets remain due to dust between the left and right electrodes, there is no short circuit between electrodes due to residual liquid droplets even when this liquid level sensor is repeatedly used, and normal measurement is always possible. Becomes

FIG. 3 shows the essential structure of the second embodiment. In the liquid level sensor 10 of the present embodiment, the resistance film 2 on the insulating substrate 1 and the inner portion 17 of the electrode 3 formed on the resistance film 2 are covered with the water repellent film 4, and a pair of left and right exposed to the outside. The water repellent film 4 is not formed on each electrode 3 group. Then, the left and right electrode groups 3 are exposed and function as liquid level detection electrodes. Separated space portions 6 and 7 are formed between the upper and lower sides or the left and right sides of the electrode 3 as in the first embodiment.

FIG. 4 shows the construction of the essential parts of the third embodiment. In this liquid level sensor 10, the resistance film 2 of the insulating substrate 1 is covered with a protective layer 16 such as an insulating resin sheet or film, and the left and right electrodes 3 are not covered with the protective layer 16 and are exposed to the outside. A space 6 is formed between the upper and lower sides of the electrode 3.

The present invention is not limited to the above-mentioned embodiments, and various embodiments can be adopted. For example, in the present embodiment, the shape of the first separated space portion 6 is a square shape, but it may be a rounded shape 14 as shown in FIG. With this rounded shape, when draining the liquid to be detected, the liquid in the separated space portion 6 easily flows out along the roundness, and even if dust is attached to the wall surface of the separated space portion 6, However, since this is discharged together with the flow of the liquid, the effect of preventing the adhesion and accumulation of dust is great.

Further, although the shape of the second separated space portion 7 is cut out into a strip shape, it may be formed by a punch hole as shown in FIG. 6, for example.

[0018]

According to the present invention, since the separated space portion is formed at least vertically between the pair of left and right liquid level detection window holes of the liquid level sensor or between the left and right electrode groups, this liquid level sensor is repeatedly used. Even at this time, the liquid level of the liquid can always be measured in a normal state without causing a short circuit between the electrodes due to the remaining of the liquid droplets due to dust or the like between the liquid level detection window holes.

[Brief description of drawings]

FIG. 1 is an enlarged explanatory view showing a main part configuration of a liquid level sensor according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an external configuration of a liquid level sensor according to the same embodiment.

FIG. 3 is an enlarged explanatory diagram showing a main part configuration of a liquid level sensor according to a second embodiment of the present invention.

FIG. 4 is an enlarged explanatory view showing a main part configuration of a liquid level sensor according to a third embodiment of the present invention.

FIG. 5 is an explanatory view of another shape of the separation space portion formed between the upper and lower sides of the liquid level detection window hole of the liquid level sensor of the embodiment.

FIG. 6 is an explanatory view of another shape of the separated space portion formed between the left and right electrode groups of the liquid surface sensor of the same embodiment.

FIG. 7 is a circuit diagram of a measurement system of the liquid level sensor.

FIG. 8 is a graph showing the relationship between the resistance value output of the liquid level sensor and the water depth.

FIG. 9 is a schematic explanatory diagram of a resistance circuit showing a liquid level detection principle of a conventional liquid level sensor.

FIG. 10 is an explanatory diagram of the same liquid level sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating base material 2 Resistive film 3 Electrode 4 Water repellent film 5 Liquid level detection window hole 6 First separation space part 7 Second separation space part

Claims (4)

[Claims] 1. A pair of left and right resistance films are formed on the surface of an insulating base material by extending in the vertical direction, and a plurality of electrodes are vertically connected to each other by electrically connecting to the pair of left and right corresponding resistance films. In the arrayed liquid level sensor, a separated space portion is formed between the electrodes arrayed in the vertical direction, the liquid level sensor. 2. A pair of left and right resistance films are formed on the surface of an insulating base material by extending in the vertical direction, and a plurality of electrodes are vertically connected to each other by electrically connecting to the pair of left and right corresponding resistance films. In the arrayed liquid level sensor, a space is formed between the resistance film side electrode group arranged on the left side and the resistance film side electrode group arranged on the right side. Liquid level sensor. 3. A water-repellent film that covers the resistance film and the electrodes is formed on the surface of the insulating base material, and the water-repellent film is provided with a liquid level detection window hole at a position facing each electrode. The liquid level sensor according to claim 1 or 2. 4. The liquid surface according to claim 1 or 2, wherein a protective layer covering the resistance film is formed on the surface of the insulating base material, and the electrode is exposed to the outside without being covered with the protective layer. Sensor.