JPH01170218A - Proximity switch - Google Patents

Abstract

PURPOSE:To allow each illuminant individually to light, to discriminate in which range an object to be detected resides depending on a potential of each output terminal and to output the result as an electric signal by devising the switch such that each comparator produces an output individually in response to a distance of the object to be detected with respect to a sensing element. CONSTITUTION:The switch consists of the sensing element 3 producing an output of a level corresponding to a distance with respect to an object to be detected, >=two comparators 4, 5 with different threshold levels connected to the sensing element 3, >=2 illuminants 7, 10 with different illuminant color lighted depending on the output of the comparators 4, 5, and >=2 output terminals 13, 14 from which a level discriminating the output state of each comparator is outputted. That is, it is discriminated in such a way that the object to be detected resides in a danger range with a sensing output terminal 14 at a low level and with a danger output terminal 13 at a low level arisen respectively, the object to be detected is in the optimum range with the terminal 14 at a low level and the terminal 13 at a high level and the object to be detected is at the outside of the said ranges with the terminal 14 at a high level.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to detecting the position of a piston of a fluid pressure cylinder such as a pneumatic cylinder or a hydraulic cylinder from outside the cylinder, or detecting the approach of an article conveyed by a conveyor. In particular, proximity switches are used to separate the distance from the object to be detected into two or more ranges, turn on light emitters of different colors, and use the electric potential of two or more output terminals to separate the distance from the object to the object to be detected. The present invention relates to a proximity switch that can determine in which range the distance is within.

Prior Art and Problems to be Solved by the Invention Conventional proximity switches of this type include a sensing element that produces an output of a magnitude corresponding to the distance to the object to be detected, and two comparators each having a different threshold value. and two light emitters that emit light in green and red respectively depending on the output of each comparator, and when the object to be detected is in a certain optimum range closest to the sensing element, the green light emitter is emitted in the optimum range. When the sensor is in a certain danger range on both sides of the cylinder, red light emitters are turned on.For example, when the cylinder is positioned on the outer periphery of a hydraulic cylinder to detect the piston position, the green light emitter is turned on. When the piston is located inside the danger range on both sides including the optimum range, a certain output voltage is generated and input to the sequencer etc. There is a problem in that it is only possible to confirm whether the proximity switch is within the range or the dangerous range by visually observing the light emitting body of the proximity switch, and it is not possible to determine in which range it is by the output voltage. Ta.

Means for Solving the Problems The proximity switch of the present invention, as a means for solving such problems, includes a sensing element that generates an output of a magnitude corresponding to the distance to the detected object, and the sensing element. connected to
Two or more comparators each having a different threshold value, two or more light emitters with different colors that light up depending on the output of each comparator, and two or more outputs that output potentials that can be used to determine the output state of each comparator. The configuration consists of a terminal.

Functions and Effects of the Invention The present invention has the above-mentioned configuration, and each comparator generates an output separately according to the distance corresponding to the sensing element of the object to be detected, so that each light emitting body lights up separately, and each output terminal It has the effect of being able to determine which range the detected object is in based on the potential and output it as an electrical signal.
For example, it is possible to issue an alarm when the detected object is within a certain dangerous range.

Example An embodiment of the present invention will be described below with reference to the accompanying drawings.

The proximity switch according to the first embodiment of the present invention shown in FIG.
is connected to the comparator 4 and the second comparator 5,
Each comparator 4.5 is connected to a reference level setting circuit 6, the first comparator 4 producing a high potential output when the output of the magnetic sensor 3 becomes higher than a certain high reference level; The comparators 5 are each designed to generate a high potential output when the output of the magnetic sensor 3 becomes higher than a certain low level of 3 lvl, and a green wire is connected between the output terminal of the first comparator 4 and the ground wire 2. In addition to the light emitting diode 7 provided, its output terminal is connected to one output terminal of the AND circuit 9 via the NOT circuit 8, and the output terminal of the second comparator 5 is connected to the other output terminal of the AND circuit 9. It is connected to the base of the transistor 12 interposed between the input terminal, the detection output terminal 14, and the ground line 2,
A red light emitting diode IO is interposed between the output terminal of the AND circuit 9 and the ground line 2, and the output terminal of the AND circuit 9 is a transistor 11 interposed between the dangerous output terminal 13 and the ground line 2. connected to the base of.

In this embodiment, when a detected object (not shown) to which a permanent magnet is attached gradually approaches the magnetic sensor 3 and then moves away again, the strength of the magnetic field acting on the magnetic sensor 3 gradually increases until it reaches its maximum value. , gradually decreases, and the output of the magnetic sensor 3 changes in proportion to this, and that output becomes the second
When the voltage becomes higher than the reference level set in the second comparator 5, the output of the second comparator 5 becomes high potential, conduction occurs between the collector and emitter of the transistor 12, and the potential of the detection output terminal 14 decreases, so that the object to be detected is detected. When entering a certain detection range is detected and the output of the magnetic sensor 3 is lower than the high reference level set to the first comparator 4, the output of the first comparator 4 is at a low potential, The high potential output inverted by the NOT circuit 8 and the high potential output of the second comparator 5 are input to the AND circuit, and the output becomes a high potential, so that the red light emitting diode IO lights up and the collector of the transistor 11 is turned on. When conduction occurs between the emitters and the potential of the dangerous output terminal 13 decreases, it is determined that the object to be detected is in the dangerous range outside the optimum range, and the object to be detected is closer to the magnetic sensor 3. The output of the magnetic sensor 3 is the first
When the voltage becomes higher than the high reference voltage of the first comparator 4, the output of the first comparator 4 becomes a high potential, which lights up the green light emitting diode 7, and the low potential inverted by the NOT circuit 8 is input to the AND circuit 9. That AN
The output of the D circuit 9 becomes a low potential, and the red light emitting diode I
O goes out, the collector and emitter of the transistor 11 are cut off, the dangerous output terminal +3 becomes a high potential, and the detection output terminal 14 is at a low potential, so it is determined that the object to be detected is within the optimum range. be. Zunawara,
When the detection output terminal 14 is at a low potential and the dangerous output terminal 13 is at a low potential, the object to be detected is in the dangerous range, and the detection output terminal 14 is at a low potential.
It is determined that the detected object is within the optimal range when the voltage is low and the dangerous output terminal 13 is high potential, and it is determined that the object is outside these ranges when the detection output terminal 14 is high potential. By connecting the output terminals 13 and 14 to the sequencer, the position of the object to be detected is input to the sequencer as a potential signal, and proper control is performed.

Next, the proximity switch according to the second embodiment of the present invention shown in FIG. The comparator 4 of the transistor 16 is connected to the optimum output terminal 15.
The structure is the same as the first embodiment above except that it is directly connected to the base of the sensor, and when the object to be detected enters the detection range, the red light emitting diode IO lights up and the detection output terminal 14 becomes low potential, so that the detection output terminal 14 is at a low potential. When it enters, the red light emitting diode 10 is turned off, the green light emitting diode 7 is turned on, and the optimum output terminal 15 is set to a low potential. That is, when the detection output terminal 14 is at a low potential and the optimum output terminal 15 is at a high potential, the object to be detected is in the dangerous range, and when the detection output terminal 14 is at a low potential and the optimum output terminal 15 is at a low potential, the object to be detected is at a low potential. is within the optimum range, and when the detection output terminal 14 is at a high potential, it is determined that it is outside these ranges.

Note that the present invention can be applied to a case where the number of comparators, light emitting diodes, and output terminals is three or more each, and various sensing elements such as a high frequency type or a capacitance type can be used instead of the magnetic sensor 3. Can be done.

[Brief explanation of the drawing]

FIGS. 1 and 2 are circuit configuration diagrams of first and second embodiments of the present invention, respectively. 1: Power line 2: Ground line 3: Magnetic sensor 4.5: Comparator 6: Reference level setting device 7, lO: Light emitting diode 8: NOT circuit 9: AND circuit l! ,
12.16: Transistor 13: Hazardous output terminal ■4
: Detection output terminal 15: Optimal output terminal

Claims (1)

[Claims] A sensing element that generates an output of a size corresponding to the distance to the object to be detected, two or more comparators connected to the sensing element and each having a different threshold value, and a color that lights up individually depending on the output of each comparator. A proximity switch comprising two or more light emitting bodies with different values, and two or more output terminals that output potentials that can determine the output state of each of the comparators.