JPS62243421A - Detector - Google Patents

Abstract

PURPOSE:To attain easy and sure fault check by bringing a detection circuit section into the state equivalent to the state that an object to be sensed comes in response to the check mode designation. CONSTITUTION:When a switch 32 of the mode designation section 30 is turned on or an L signal is impressed from an external terminal 31, the check mode designation is attained, a transistor (TR) Q41 is turned on and a node (a) goes to H. Then a TR Q42 is turned on, a TR Q42 is turned off to disconnect a parallel resistor R47, the adjusting resistor is increased, aud so long as no fault is caused, and the oscillation is stopped. A signal in response to the presence of the oscillation stop is outputted to a fault check output circuit 20 via a comparator 21, an integration circuit 22, a waveform shaping circuit 23 and a TR Q21 to check the presence of a fault of a detector for the proximity switch easily and surely.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention provides a proximity switch having an operation check function;
It relates to a detection device (sensor switch) such as a photoelectric switch.

(B) Conventional technology In general, a conventional proximity switch includes a detection circuit whose operating state changes depending on when an object to be detected arrives and when it does not arrive, and a detection circuit that receives a signal from this detection circuit and processes the signal to detect an object. It is equipped with a signal processing section that outputs an on/off signal from an output terminal depending on the presence or absence of a detection object.

The detection circuit section specifically includes a high frequency oscillation circuit,
Oscillation stops when the detected object approaches.

The signal processing section detects the oscillation output from the detection circuit section,
It compares it with a reference level using a comparator, and then shapes the waveform and outputs an on/off signal depending on the presence or absence of oscillation, that is, the presence or absence of an object to be detected approaching. - (c) Problems to be solved by the invention When detecting the arrival of an object using a detection device such as a proximity switch and turning on or off an external device based on the detection output,
A high degree of reliability is required, especially when a sensing object is in close proximity to be reliably detected and responded to. Therefore, the detection device must always be confirmed to be operating normally, or must be able to be checked to confirm that it is operating properly whenever necessary.

However, the conventional proximity switch described above does not have a function to check the operation when the detected object arrives, and if the detected object does not actually arrive, the device will not function properly when the detected object arrives. It was not possible to check whether or not it was working properly. Therefore, it is not possible to ensure sufficient reliability, and when many detection devices are used in one system, it is extremely troublesome to check the operation of each detection device when the detected object arrives. was there.

In view of the above, it is an object of the present invention to provide a detection device whose operation can be checked when a detected object arrives at a required time and whose reliability is improved.

(d) Means for Solving the Problems The detection device of the present invention includes a detection circuit section (10) whose operating state changes depending on when an object to be detected arrives and when it does not arrive, and a signal from this detection circuit section. a signal processing unit (20) configured to receive and process the detected object and output an output signal from an output terminal according to the presence or absence of the detected object, and a designation unit (30) for externally designating a check mode; circuit means (40) for forcing the detection circuit section into a state equivalent to the arrival of a detected object in response to the check mode designation by the designation means; It is characteristically equipped with a failure check output means (50) that outputs a signal indicating the presence or absence of a failure by a logic output.

(E) Function In this detection device, when a signal specifying the check mode is inputted from the outside by the specifying means, the circuit means responds to the signal specifying the check mode to detect the arrival of the object to be detected. Regardless, the detection circuit section is forced into a state equivalent to when the detected object has arrived. Therefore, if the detection circuit section is normal, a signal similar to that when the detected object has arrived is applied to the signal processing section. If the signal processing section is normal, a signal indicating that it is normal is outputted from the failure check output means based on the output of the signal processing section and the logical output of the check mode designation signal. On the other hand, if the signal processing section is abnormal, for example, the failure check output means outputs a signal indicating that there is a failure.

(f) Examples The present invention will now be explained in more detail with reference to Examples.

<Embodiment 1> FIG. 1 is a circuit diagram of a proximity switch according to a first embodiment. This proximity switch 1 includes a detection circuit section 10, a signal processing circuit section 20, a mode specifying section 30 for specifying a check mode, a circuit section 40 for forcing the detection circuit section 10 into an operating state when a detected object arrives, and a check mode. and a failure check output circuit 50 that outputs whether or not there is a failure.

The detection circuit section 10 includes a current feedback circuit 1 consisting of a bias current source 11, a voltage shift circuit 12, a detection coil L1, a resonant capacitor C3, and transistors Q1, Q12, Q, and 3.
3 and an adjustment resistor R11.

In other words, the proximity switch 1 is a high frequency oscillation type proximity switch.

The signal processing circuit section 20 includes a comparator 21 and an integrating circuit 2.
2. Consisting of a waveform shaping circuit 23 and an output transistor Q□, a high signal indicating the presence or absence of detection from the output terminal 24;
Alternatively, the detection circuit section 10 and the signal processing circuit section 20 that output the low signal are already known parts.

The mode specifying section 30 includes a terminal 31 for inputting a check mode signal from the outside and a check mode setting switch 32.

The circuit section 40 includes transistors Q a 1. Q a t
, Q a s, the emitter of the transistor Q41 is connected to the power supply terminal 25, and the collector is connected to the resistors R43, R
The base is connected to the first power supply terminal 26 through a resistor R44, and the base thereof is connected to the second power supply terminal 25 through a resistor R41, and to the terminal 31 through a resistor R4t% diode d41. Further, the base of the transistor Q4° is connected to the connection point of the resistors R43 and R44, the emitter is connected to the one power supply terminal 26, and the collector is connected to the connection point of the resistors R43 and R44.
It is connected to the base of 3.

Transistor Q4. The emitter of is connected to one power supply terminal 26, and the collector is connected to a transistor Q through a resistor R4'l.
It is connected to the emitter of ll. In other words, the adjustment resistance R
0 in parallel. Transistor Q4. The base of
46 to one power supply terminal 26, respectively.

The failure check output circuit unit 50 includes an AND circuit 51, a light emitting diode 52 for failure indication, a transistor QS1 for failure output, and the like. The output terminal 24 is connected to one end of the input of the AND circuit 51, and the collector (point a) of the transistor Q41 is connected to the other end of the input.

The output terminal of the AND circuit 51 is connected to the base of the transistor Q,1 via the light emitting diode 52. The emitter of the transistor Q51 is connected to the first power supply terminal 26, and the collector is connected to the failure output terminal 53 and also to the second power supply terminal 25 via a resistor R5I.

Next, the operation of this proximity switch 1 will be explained.

In the normal mode, that is, when the mode setting switch 32 is not turned on and no check mode signal is input from the outside to the terminal 31, the transistor Q41 is not turned on, and therefore the potential at point a is at a low level, and the transistor Qn
z is on, transistor Q43 is also on, resistor R4'1 is connected in parallel to adjustment resistor R11, and detection circuit section 1
0 is in an oscillation state when there is no object to be detected, and inputs an oscillation output signal to the signal processing circuit section 20. Then, the waveform shaping circuit 23 outputs a low signal, and the transistor Q
! Turn off I. Therefore, a higher signal is output from the output terminal 24. On the other hand, since the input signal of the AND circuit 51 is "high" and "low", the output signal becomes low, the light emitting diode 52 does not light up, and the transistors Q and I do not turn on. Therefore, a high signal (
Normal) is output.

When the object to be detected reaches the detection area, the detection circuit section 10
The conductance of the detection coil Lll decreases and oscillation stops. Therefore, the waveform shaping circuit 23 outputs a high signal, and the transistor Q! Turn on l. This results in
A low signal (detection signal) is output from the output terminal 24.

In this case, since the input signal of the AND circuit 51 is "low", the output signal is also low, and the light emitting diode 52 does not light up and the transistors Q and 1 do not turn on either.

Then, a high signal indicating normality is output from the failure output terminal 53.

When the check mode setting switch 32 is turned on or when a low (ground level) signal is input to the terminal 31, the check mode is entered. In check mode, terminal 3
1 becomes low level, transistor Q41 turns on, point a becomes high level, and transistor Q4!
turns on, and transistor Q43 turns off accordingly. For this reason, resistor R4 in parallel with resistor R11? is disconnected, the adjustment resistance becomes large, and the oscillation of the detection circuit section 10 stops under normal conditions. In other words, the state is the same as if the object to be detected had arrived. When the oscillation stops, the output of the signal processing circuit section 20 becomes high, the transistor Qt is turned on, and a low signal is output from the output terminal 24. On the other hand, since the AND circuit 51 receives a high signal from point a and a low signal from the collector of the transistor Q□, its output is also low. Therefore, the light emitting diode 52 is turned off, the transistor QSI is also turned off, and a high signal (normal) is output from the failure output terminal 53.

Next, in this check mode, if there is a fault in the circuit,
For example, if the coil 13 is disconnected, the comparator 21
The input to the waveform shaping circuit 23 becomes high, and the output of the waveform shaping circuit 23 becomes low. Therefore, the transistor Glt+ is off and the output terminal 24 becomes high.

Furthermore, even if the detection circuit section 10 is normal and the input to the comparator 21 is low, there is an abnormality in the signal processing circuit section 20 and a low signal is output from the waveform shaping circuit 23, or the transistor Q0 is destroyed. If transistor Q2. is off, and the output terminal 24 becomes high. Since point a is high, in these cases, the input power of the AND circuit 51 is "high" and "high", and its output is also high.

Therefore, the light emitting diode 52 lights up, the transistor Q,1 turns on, and a low signal indicating a failure is output from the failure output terminal 53.

<Embodiment 2> FIG. 2 is a circuit diagram of a proximity switch which is a second embodiment. This proximity switch 2 is characterized by the circuit configuration of the circuit unit 40 that forces the operating state when the detected object arrives,
The other parts are the same as the first embodiment. Also in the circuit section 40, transistors Q41. The circuit section of Qa□ is also similar to that of the first embodiment. In this embodiment, the circuit section of transistor Q43 is omitted, and instead, the collector of transistor Q4t is connected to the connection point of parallel capacitor C0 and voltage shift circuit 12 via capacitor C41. In other words, turn on transistor Q4□.
By turning off, capacitor C4+ is connected or disconnected in parallel to capacitor C11.

In this proximity switch 2, in the normal mode, the mode setting switch 32 is not turned on, and the terminal 3 is not turned on from the outside.
No check mode signal is input to transistor Q
41, Q4t remains off and capacitor C4I
is separated from capacitor C11. Therefore, the detection circuit section 10 oscillates at a frequency determined by the coil 13 and the capacitor C11.

The normal operation is the same as that of the first embodiment, so a description thereof will be omitted.

In the check mode, the mode setting switch 32 is turned on, or a low signal is input to the terminal 31. Therefore, transistors Q a t and Q4□ are turned on, and a
The point becomes high level. Furthermore, when the transistor (Lx) is turned on, the capacitor C41 is connected in parallel to the capacitor Ctt. Therefore, the oscillation frequency decreases, the conductance g of the circuit increases, and the oscillation tends to stop.

Furthermore, since the transistor Q4t allows current to flow in only one direction, the oscillation amplitude immediately becomes zero. Therefore, a low signal is input to the comparator 2.111, and if the signal processing circuit section 20 is normal, the transistor Q! Since a low signal is input to + to turn it on, the output terminal 24 outputs a low signal. In addition, the collector side of the transistor Qt+ is low, the point a is high (1), the output side of the AND circuit 51 is low, the light emitting diode 52 remains off, the transistor QSI is also off, and a high signal is output to the failure output terminal 53. be done.

This operation is the same as that of the first embodiment.

If there is an abnormality in the circuit, transistor Q2I is off, the collector side becomes high, and the input of AND circuit 51 becomes "
"High" becomes "high" and the output also becomes high. Therefore, the light emitting diode 52 lights up, the transistor Q,1 turns on, and a low signal (fault) is output to the fault output terminal 53. Also, for example, if the coil L11 is disconnected,
After the capacitor Car is charged, the voltage across the resistor R11 rises.

Therefore, a high signal is input to the comparator 21, a low signal is input to the transistor Q1, and the transistor Q! Since the output of l becomes high, the light emitting diode 52 is turned on in the same way as above, and a low signal indicating a failure is also output to the failure output terminal 53.

<Embodiment 3> FIG. 3 is a circuit diagram of a proximity switch according to a third embodiment. This proximity switch 3 also has a feature in the circuit configuration of the circuit section 40, and other parts are the same as the first embodiment. Further, in the circuit section 40, the transistor Q4. The circuit section is also the same as in the first embodiment. The collector of the transistor Q41 is connected to one power supply terminal 26 via Raw, and a series circuit of the resistor R411, points C and D of the diode bridge 41, and the reference voltage source 42 is connected to both ends of the resistor R4m. Also, A of the diode bridge 41
, 8 are connected with a series circuit of a coupling coil L4 and a resistor Raq.

In this proximity switch 3, in the normal mode, the mode setting switch 32 is not turned on, the check mode signal is not inputted to the terminal 31 from the outside, the transistor Q41 is turned off, and the potential at point a is low. Therefore, points C and D of the diode bridge 41 are reverse biased by the reference voltage source 42, and points A and B are in an oven state, so no current flows through the coupling coil L41 and the capacitor in the coil L1 It does not have any influence on the resonant circuit consisting of C0. In normal times, the arrival of the object to be detected is detected by the same operation as in the first embodiment.

In the check mode, the mode setting switch 32 is turned on or a low signal is input to the terminal 31, the transistor Q4I is turned on, and the potential at point a becomes high level. The potential at this point, that is, the voltage across resistor R42, is
It is applied to the diode bridge 41 as a forward bias. As a result, points A and B are short-circuited equally, and the voltage induced in the coupled coil L41 is passed as a current through the resistor R49, causing a loss to the coil L11 in the same way as when the object to be detected is present. , changes the conductance g, and stops the oscillation of the detection circuit section 10.

The operations of this proximity switch 3 in normal and abnormal conditions in the check mode are the same as those in the first and second embodiments, so a description thereof will be omitted.

In each of the above embodiments, if you want to check for a failure in the state when the detected object arrives, regardless of whether the detected object has arrived, you can manually set the mode setting switch 32.
This can be executed whenever necessary by turning on the switch or by applying a low signal to the terminal 31 from the outside.

Although each of the above embodiments uses a proximity switch as an example,
This invention can also be applied to other detection devices such as photoelectric switches.

(G) Effects of the Invention According to the present invention, there is provided a designating means for externally designating the check mode, and in response to the designation of the check mode by the designating means, the detection circuit section is placed in a state equivalent to the arrival of the object to be detected. It is characterized by a circuit means for forcing the detection circuit to perform a fault check, and a fault check output means for outputting a signal indicating the presence or absence of a fault based on the check mode designation signal and the logical output of the output of the signal processing section. The area can be brought into the same state as when the detected object arrived. Furthermore, in a system in which a large number of detection devices are installed, if a check mode signal is inputted from the control section as a specifying means, it is possible to check whether or not a large number of detection devices are malfunctioning during detection operation.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a proximity switch showing a first embodiment of the invention, FIG. 2 is a circuit diagram of a proximity switch showing a second embodiment of the invention, and FIG. 3 is a circuit diagram of a proximity switch showing a second embodiment of the invention. FIG. 7 is a circuit diagram of a proximity switch showing a third embodiment. 10: Detection circuit section, 20: Signal processing circuit section, 30: Mode specifying section, 40: Circuit section, 50: Failure check output circuit section.

Claims (1)

[Claims] (1) A detection circuit whose operating state changes depending on whether or not a detected object has arrived, and which receives and processes a signal from this detection circuit and outputs a signal depending on whether or not the detected object has arrived. A detection device comprising: a signal processing section that outputs a signal from an output terminal, a specifying means for externally specifying a check mode; and a signal processing section for specifying a check mode from the outside; and a failure check output means for outputting a signal indicating the presence or absence of a failure based on the check mode designation signal and the logical output of the output of the signal processing section. Device.