JP3237005B2 - Liquid detector and control device using the liquid detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detector for optically detecting the presence or absence of a liquid such as water or kerosene. The present invention relates to a detector used for detecting the presence or absence of fuel, and a control device using the detector.

[0002]

2. Description of the Related Art FIG. 6 shows an example of a conventional optical liquid detector. Reference numerals 1, 2, and 3 denote lead terminals, and an end face of the lead terminal 1 among these lead terminals. 1a, the light emitting element 4 is fixed by a conductive adhesive so as to connect one electrode, and the light receiving element 5 is similarly connected to the end face 3a of the lead terminal 3 by connecting the one electrode. It is fixed by the material. Then, the light emitting element 4 and the light receiving element 5
The other electrode is connected to the lead terminal 2 by the conductive wires 6 and 7.
Is connected to the end face 2a. These lead terminals 1,
A part of the light emitting element 4, a part of the light receiving element 5, and a part of the conductive lines 6, 7 are provided inside a hemispherical lens 8 formed of a transparent resin material.

The above-described liquid detector supplies power to the lead terminals 1 and 2 to cause the light emitting element 4 to emit light. The emitted light diverges, but when the hemispherical lens 8 is in contact with air, the ratio of the refractive index of the hemispherical lens 8 to the refractive index of air is relatively large. Is reflected at the boundary surface of the light receiving element 5, and the reflected light at the position of the zenith 10 of the hemispherical lens 8 enters the light receiving element 5. When the hemispheric lens 8 is in a liquid having the same refractive index as the hemispheric lens 8,
The emitted light is not reflected on the interface between the hemispherical lens 8 and the liquid and does not enter the light receiving element 5.

Accordingly, by appropriately processing the photocurrent output from the light receiving element 5 based on the presence or absence of incident light, a detection signal as to whether or not the hemispherical lens 8 is in contact with the liquid can be obtained.

FIG. 7 shows a conventional example using another prism 9 in place of the hemispherical lens 8. The prism 9 is tapered toward the tip, and is a prism having a roof-shaped right-angled surface. This liquid detector emits light emitted from the light-emitting element 4 in the same manner as the liquid detector shown in FIG. 6, but a part of the light emits when the prism 9 is in contact with air. Then, the light is reflected by the reflection surface 11 and then reflected by the second reflection surface 12 and enters the light receiving element 5.

At this time, the angle of incidence of light on the reflecting surfaces 11 and 12 is 45 °, and the refractive index of air is 1, so if the refractive index of the prism 9 is about 1.4 or more, the light is emitted. Light emitted from the element 4 is totally reflected by the reflecting surfaces 11 and 12. When the prism 9 is in the liquid, no light is incident on the light receiving element 5 like the liquid detector shown in FIG. 6, and no photocurrent is output from the light receiving element 5.

FIG. 8 shows an example of an operation circuit of these liquid detectors. Here, reference numeral 13 denotes a liquid detector composed of the light emitting element 4, the light receiving element 5, and the lead terminals 1, 2, and 3 described above. One electrode of the light emitting element 4 is connected to a power supply + V via a lead terminal 1 and a stable resistor R1. The other electrode of the light emitting element 4 is connected to a power supply -V via a lead terminal 2 serving as a common terminal.

One of the electrodes of the light receiving element 5 is a lead terminal 3,
Connected to the power supply + V via the load resistor R2. The other electrode of the light receiving element 5 is connected to the power supply -V via the lead terminal 2. Further, a detection signal Vo is output from a connection point between the lead terminal 3 and the load resistor R2.

The light emitted from the light-emitting element 4 of the circuit having the above-described configuration enters the light-receiving element 5 when the liquid detector 13 is in the air, and sets the detection signal Vo at which the photocurrent flows to a low level L. When the liquid detector 13 is in the liquid, the light emitted from the light emitting element 4 does not enter the light receiving element 5, so that no photocurrent flows and the detection signal Vo becomes high level H.

FIG. 9 shows an example of a control device using such a liquid detector 13. Reference numeral 37 denotes a container for containing a liquid 34 as an object to be detected. Reference numeral 38 denotes a lid provided on the upper part of the container 37. The liquid detector 13 is attached to the lid 38 using a holder 39 with the lead terminal facing upward. Reference numeral 35 denotes a transfer pipe for transferring the liquid 34 in the container 37. 36 is a pump for transferring the liquid.

The pump 36 is driven by the high level H of the detection signal Vo. Therefore, when the liquid 34 is filled in the container 37 and the liquid detector 13 is submerged in the liquid, the detection signal Vo becomes high level H, the pump 36 is driven, and the liquid 34 in the container 37 is discharged. It is sent out of the container 37 through the transfer pipe 35. The above operation is continued, and the liquid level 34a of the liquid 34 in the container 37 is changed to the liquid level 34.
When the pressure drops to b, the liquid detector 13 is exposed to air, the detection signal Vo becomes a low level L, and the driving of the pump 36 is stopped.

For example, when the above-described control device is used for an oil stove, the liquid 34 becomes kerosene, and a burner (not shown) is attached to a terminal of the transfer pipe 35 to burn the kerosene. . Many such devices use a pump 36
Is driven such that kerosene always exists inside the pump 36 when the pump is driven. This is because many of the pumps for transferring liquid use the transferred liquid as a lubricant for the mechanism.

[0013]

The liquid transfer control device using the above liquid detector has the following problems. This liquid transfer control device has no problem when the function of the liquid detector 13 is working normally.
When the pump fails, the pump 36 is
Will continue to drive. For this reason, the drive of the pump 36 without the liquid to function as a lubricant is performed by the pump 3
6 will be damaged.

That is, there are two types of failures of the liquid detector 13, that is, a short circuit and a disconnection of the light emitting element 4, and two types of a short circuit and a disconnection of the light receiving element 5. The detection signal Vo in these cases by the circuit of FIG. 8 is as follows. First, when the light emitting element 4 is short-circuited or disconnected, no light current flows through the light receiving element 5 regardless of whether the light emitting element 4 is in liquid or air because the light emitting element 4 does not emit light, and the detection signal Vo is the same as the power supply voltage. Potential. That is, the detection signal Vo becomes high level H.

Next, when the light receiving element 5 is disconnected, no photocurrent flows as in the above case, and the detection signal Vo becomes the power supply voltage, that is, the high level H. Further, when the light receiving element 5 is short-circuited,
Regardless of whether the liquid detector 13 is in the liquid or in the air, the detection signal Vo becomes zero voltage, that is, the low level L.

Here, the detection signal Vo must be at the high level H only when the liquid detector 13 is in the liquid. However, as described above, the detection signal Vo has the high level at the fault. In the case of, the detection signal Vo also becomes high level H when the liquid detector 13 is in the air,
Even if there is no liquid 34 inside, the pump 36 for transferring the liquid 34 will continue to be driven. In the case of a failure in which the detection signal Vo becomes the low level L, the driving of the pump 36 for transferring the liquid 34 is stopped.

In the case of the above-described apparatus for transferring the liquid 34 in the container 37 to another apparatus for use, when the above-described failure occurs, the operation of this apparatus and other related apparatuses is performed. It cannot be stopped immediately to ensure safety.

[0018]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of a liquid detector and a control device using the liquid detector. And light receiving element and a lead for energizing these elements
A part of the terminal is disposed inside a package formed of a transparent material, and when the outer surface of the package is in the air, the light emitted from the light emitting element is flush with the outer surface of the package. In the liquid detector having a shape which is reflected one or more times and is incident on the light receiving element, the light emitted from the light emitting element is incident on the light receiving element through a light path different from the light path reflected by the outer surface of the package. A liquid detector characterized in that a reflecting mirror is arranged inside the package is proposed. The liquid detector configured as described above can determine whether or not the function of the liquid detector is normal even when the liquid detector is in the liquid.

According to a second aspect of the present invention, the above-mentioned liquid detector has at least one of three strip-shaped lead terminals arranged in a plane in order and sandwiching at least one of the lead terminals. A light-emitting element and a light-receiving element are separately mounted on one end of the lead terminal in a plane, and are sandwiched between two lead terminals on which the light-emitting element and the light-receiving element are mounted. One end of one lead terminal has reflectivity, and this lead terminal
A liquid detector is characterized in that one end having reflectivity of the terminal is bent in the same direction as the direction of the light-emitting axis of the light-emitting element to provide the above-mentioned reflecting mirror. With this configuration, it is possible to provide a reflector different from the outer surface of the package without using a special member.

According to a third aspect of the present invention, in the control device using the liquid detector, the control based on the detection signal Vo of the liquid detector is such that the detection signals Vo of the liquid detector are arranged in the order of A, B, C, and D. , E, and when the detection signal Vo is between C and D, this signal corresponds to the fact that the liquid detector is in the air, and the detection signal Vo is B, When the signal is between C, this signal corresponds to the fact that the liquid detector is in the liquid. When the detection signal Vo is between A and B or between D and E, the normal operation is changed to the emergency operation. The present invention proposes a control device using a liquid detector, which is characterized in that the control is performed in a controlled manner. By controlling the control device with the signal thus obtained, the control device can be safely operated without being damaged.

[0021]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a simplified front view showing the configuration of the present liquid detector. FIG. 2 is a simplified bottom view of the liquid detector. In these drawings, the same members are denoted by the same reference numerals.

As shown in these drawings, as shown in FIG.
The light emitting element 23 is fixed to one end of the lead terminal 22 with a conductive adhesive so as to connect to one electrode, and one end of the lead terminal 22 is connected to one electrode. Thus, the light receiving element 24 is fixed with a conductive adhesive. The other electrode of the light emitting element 23 and the other electrode of the light receiving element 24 are wired to one end of the lead terminal 21 by conductive wires 25 and 26, respectively.

These light emitting element 23, light receiving element 24,
The lead terminals 20, 21, 22 and the conductive wires 25, 26 are buried in a package 28 made of a transparent material such as epoxy resin except for a part of the lead terminals 20, 21, 22. As shown in FIG. 2, the shape of the package 28 is such that the front side (the surface shown in FIG. 1) has a roof shape of two surfaces 29 and 30, and the two surfaces 29 and 30 are This is a liquid detection unit.

Further, reference numeral 27 shown in FIGS.
Is a reflecting mirror that constantly reflects light. The package 28 in which the reflecting mirror 27 is located at a predetermined position can be obtained by dividing a transparent material such as epoxy resin at the position of the reflecting mirror 27 and forming it twice. Liquid detector 3 configured as above
1 supplies power to the lead terminals 20 and 21 to cause the light emitting element 23 to emit light.

When the package 28 is in the air, a part of the emitted light is transmitted along the optical path indicated by a dashed line 32 to the light receiving element 24.
Incident on. When the package 28 is in a liquid, since the refractive index of the liquid and the refractive index of the package 28 are equal or similar, light is emitted on the two surfaces 29 and 30 of the package 28. No light is incident on the light receiving element 24 without reflection.

The reflecting mirror 27 always controls the light emitting element 2 regardless of whether the liquid detector 31 is in the air or liquid.
The emitted light of No. 3 is incident on the light receiving element 24 through an optical path indicated by a dotted line 33 in FIG.

FIG. 3 shows an example of a detection circuit when the present liquid detector is used. In the two-dot chain line, a liquid detector 31 is shown, 23 is a light emitting element such as an LED, 24 is a photodiode, and 24 is a photodiode. It is a light receiving element such as a phototransistor. R1 is a resistor for stabilizing the current flowing through the light emitting element 23. R2 is a load resistance of the light receiving element 24;
The detection signal Vo is output from the connection point with the reference numeral 4.

Here, when a power supply is connected between Va and Vb, the light emitting element 23 emits light. When the liquid detector 31 is in the air as described above, the light emitted from the two light paths indicated by 32 and 33 in FIGS.
Incident on. The detection signal Vo at this time is set to Vcb.
2 and 3 when the liquid detector 31 is in the liquid.
Only the light from the optical path indicated by 33 enters the light receiving element 24. The detection signal Vo at this time is set to Vbc.

Next, the electric damage of the liquid detector 31 is caused by the disconnection and short circuit of the light emitting element 23 and the light receiving element 24 as described above.
Disconnection and short circuit. First, when the light emitting element 23 is disconnected or short-circuited, the light emitting element 23 does not emit light and there is no light incident on the light receiving element 24. Therefore, the internal resistance of the light receiving element 24 becomes high, and the detection signal Vo becomes the power supply voltage Va or a value Vab very close to Va.

In the case of disconnection of the light receiving element 24, the internal resistance of the light receiving element 24 becomes infinite and the detection signal Vo becomes the power supply voltage Va, similarly to the disconnection and short circuit of the light emitting element 23. When the light receiving element 24 is short-circuited, the internal resistance of the light receiving element 24 becomes zero or a value close to zero, and the detection signal Vo
Is the power supply voltage Ve or a value Vde very close to Ve.

The above detection voltages are arranged in the order close to the power supply voltage Va and are listed below. Power supply voltage Va Light-emitting element disconnection, short-circuit, light-receiving element disconnection Vab In liquid (liquid detection) Vbc In air (liquid not detected) Vcd Light-receiving element short-circuit Vde Power supply zero Ve

The above-described detection voltages vary depending on environmental conditions such as a power supply voltage, a refractive index of a liquid, and an ambient temperature. Therefore, when such a liquid detector 31 is actually used, it is necessary to consider the fluctuation range in the determination of the detection signal.

From the detection signals, a first reference value B is set between Vab and Vbc, a second reference value C is set between Vbc and Vcd, and a third reference value D is set between Vcd and Vde. Are set, the power supply voltage Va is set to A, and the power supply voltage Ve is set to E.
The above fluctuation range can be provided as shown below.

Disconnection of light emitting element, short circuit, disconnection of light receiving element AB When in liquid (detection of liquid) BC When in air (not detecting liquid) C to D Short circuit of light receiving element D to E

As described above, the value of the detection signal corresponding to the situation of the object to be detected is determined, and the present liquid detector 31 is mounted on the liquid transfer control device shown in FIG. 9 in place of the conventional liquid detector 13. Will be described. FIG. 4 shows an example of a signal processing circuit of this apparatus. Reference numeral 40 denotes a detection circuit shown in FIG. The detection signal Vo output from this circuit is input to the window comparators 41, 42, 43, and 44 that output signals in the set area.

The wind comparator 41 outputs a detection signal Vo.
Is output between the reference values A and B described above. This signal is designated as J. Similarly, the window comparator 42 outputs the signal K when the value of the detection signal Vo is between the reference values BC. The window comparator 43 outputs a signal L when the value of the detection signal Vo is C to D. The window comparator 44 outputs a signal M when the value of the detection signal Vo is between D and E.

Here, the signal K is the signal of the container 37 shown in FIG.
Is present when the liquid 34 is present, and the display device 47 shown in FIG. The signal L is a signal when there is no liquid 34 in the container 37 shown in FIG. 9, and indicates "out of fuel" on the display device 48 shown in FIG.

Next, the signals J and M are signals when the liquid detector 31 has failed. These two signals indicate "failure" on the display device 46 by the output N of the OR circuit 45. Further, the signal N indicating the failure and the signal L indicating the exhaustion of the fuel operate the shutoff circuit 50 for shutting off the power supply of the motor 51 of the transfer pump 36 by the output P of the OR circuit 49, and cut off the power supply to set the transfer pump 36 Stop the operation of.

In the liquid transfer control device configured as described above, the safety of the device can be maintained without damaging the device due to the accidental failure of the liquid detector 31.
The use of the signal when the liquid detector 31 has failed is not limited to the stop of the pump 36 for transferring the liquid 34, and the operation of the device for operating the liquid as the object to be detected or the operation of the related device is not limited to the stop. It can be used as a changing signal.

FIG. 5 shows another example of the lead terminal 21 and the reflecting mirror 27 of the liquid detector 31 shown in FIGS. 1 and 2.
FIG. 3 is a perspective view in which a package 28 is omitted. 2 shown in FIG.
Reference numerals 0 and 22 are lead terminals, 23 is a light-emitting element, 24 is a light-receiving element, and 25 and 26 are conductive wires, which are the same as those shown in FIGS.

The lead terminal 60 shown in FIG.
5 and 26 are wired, and have the same electrical function as the lead terminal 21 shown in FIGS. The back surface 60a, which is one end of the lead terminal 60, has a reflecting surface having a light reflecting function with respect to the drawing, and the reflecting mirror 2 shown in FIGS.
7 is a reflecting mirror having the same optical function.

The one end 60a as the above-mentioned reflecting mirror is formed by bending the lead terminal 60 at a predetermined position. A dotted line 61 indicates an optical path where the light emitted from the light emitting element 24 is reflected by the reflecting mirror at the one end 60a and enters the light receiving element 24, and is the same optical path as the dotted line 33 shown in FIG.

According to the above construction, it is not necessary to provide the reflecting mirror 27 shown in FIGS. 1 and 2 as a separate member, and complicated steps such as dividing the package 28 and forming it twice. It is not necessary to perform the process, and the cost can be reduced and the mass production efficiency can be increased.

The two surfaces 29 and 30 shown in FIG. 2 are not limited to the shapes shown in the figure, but may be, for example, one flat surface or one as proposed by the present inventor in Japanese Patent Application No. 89030/1996. Various surface shapes can be set according to the refractive index, concentration, and the like of the liquid to be detected, such as one or two curved surfaces having a light condensing function.

In implementing the liquid detector of the present invention, when an infrared light emitting element, an ultraviolet light emitting element or the like is used as the light emitting element 23, the package 28 is made of a transparent material for the emission wavelength. To form Further, the term “air” in the above text is not limited to actual air, but may be a gas such as nitrogen, or may be a medium having a refractive index smaller than the refractive index of the liquid to be detected.

[Brief description of the drawings]

FIG. 1 is a simplified front view of a liquid detector of the present invention.

FIG. 2 is a simplified bottom view of the liquid detector.

FIG. 3 is a detection circuit diagram using the liquid detector.

FIG. 4 is a block diagram showing an example of a circuit for processing a detection signal of an apparatus using the liquid detector.

FIG. 5 is a perspective view showing another configuration example of a lead terminal of the liquid detector.

FIG. 6 is a simplified front view of a conventional liquid detector.

FIG. 7 is a simplified front view showing another example of a conventional liquid detector.

FIG. 8 is a detection circuit diagram using a conventional liquid detector.

FIG. 9 is a configuration diagram illustrating a liquid transfer control device using a liquid detector.

[Explanation of symbols]

 20, 21, 22 lead terminal 23 light emitting element 24 light receiving element 25, 26 conductive wire 27 reflecting mirror 28 package 29, 30 reflecting surface provided in package 31 liquid detector 32, 33 optical path 60 lead Terminal 61 Optical path

Continuation of the front page (56) References JP-A-9-196737 (JP, A) JP-A-56-157819 (JP, A) JP-A-63-238452 (JP, A) JP-A-59-64535 (JP, A) , U) Jingo 5-24013 (JP, Y2) Patent 3134218 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01F 23/28

Claims (3)

(57) [Claims] 1. A light emitting element, a light receiving element, and a part of a lead terminal for energizing these elements are arranged inside a package formed of a transparent material, and an outer surface of the package is provided. A liquid detector in which light emitted from the light emitting element is reflected once or a plurality of times by the outer surface of the package and is incident on the light receiving element when is in the air; A liquid detector characterized in that a reflecting mirror for making the light emitted from the light emitting element incident on the light receiving element in an optical path different from the optical path reflected by the light receiving element is disposed inside the package. 2. A light emitting element is provided at one end of at least one of the at least one strip-shaped lead terminal among at least three strip-shaped lead terminals arranged sequentially in a plane. And a light receiving element are separately mounted in a plane, and one end of one lead terminal sandwiched between two lead terminals on which the light emitting element and the light receiving element are mounted is provided. 2. A structure according to claim 1, wherein said reflecting mirror is provided by forming a reflective end of said lead terminal, said reflective end being bent in the same direction as the light emitting axis direction of said light emitting element. Liquid detector. 3. The control device using a liquid detector according to claim 1, wherein the control based on the detection signal Vo of the liquid detector is such that the permutation of the detection signal Vo of the liquid detector is A,
B, C, D, and E are compared with the five reference values, and when the detection signal Vo is between C and D, this signal is assumed to correspond to that the liquid detector is in the air, and the detection is performed. When the signal Vo is between B and C, this signal corresponds to the fact that the liquid detector is in the liquid. When the detection signal Vo is between A and B or between D and E, A control device using a liquid detector, wherein the operation is controlled to an emergency operation.