JPS6034291B2 - Detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detection device configured to actuate an actuator in response to a detection of a detected object, and its purpose is to enable use over a wide range of power supply voltages. It is an object of the present invention to provide a detection device that can achieve the following effects, such as reducing the number of parts and realizing miniaturization.

Hereinafter, an embodiment in which the present invention is applied to a reflective photoelectric switch will be described with reference to the drawings.

In FIG. 1, 1 is a bridge type full-wave rectifier circuit, both input terminals of which are connected to power supply terminals 2a and 2b, respectively.
Both output ends are connected to bus bars 4 and 5 through a smoothing circuit 3 consisting of a protective resistor R and a smoothing capacitor C, respectively. Therefore, a smooth DC output is applied between the bus bars 4 and 5 so that the bus bar 4 side has a high potential regardless of the type of power source (AC, DC) connected between the power supply terminals 2a and 2b. 6 is a chopper type switching regulator which acts as a constant voltage circuit, and will be described below.

That is, in this switching regulator 6, Q,
, Q2 are drive transistors whose collectors and emitters are connected with DC in consideration of voltage resistance issues, Q3, Q4
is a control transistor whose collector and emitter are connected in series in consideration of the withstand voltage problem, Q5 is a comparator transistor, ZD, ZD2 are Zener diodes, D is a flywheel diode, and 7a is an operating body, which will be described later. This is the excitation coil of the switching regulator 7, and these are connected together with the resistors R2 to R8 and the smoothing capacitor C2 as shown in the figure.
The DC voltage between the bus bars 4 and 5 is provided as an input. The switching regulator 6 with the new configuration operates as described below. That is, the switching regulator 6 receives DC power as an input from the buses 4 and 5, and initially the transistor Q5 is in an off state and the transistors Q and Q are turned on, and in response to this turning on, the transistor Q. , Q2 are turned on, thereby supplying power to the load via the excitation coil 7a as an inductance element and the output terminals 6a, 60 of the switching regulator 6. Then, the voltage between the output terminals 6a and 6b (in other words, the voltage across the capacitor C2 is the voltage between the Zener diode ZD2
When the Zener voltage exceeds the sum of the Zener voltage and the bias voltage sufficient to turn on the transistor Q5, the transistor Q5 turns on and the transistors Q4, Q, Q, , Q2 turn off in sequence. Thereafter, the energy stored in the excitation coil 7a is supplied to the load through the flywheel diode D, and in response, the load voltage, that is, the voltage across the capacitor C2, gradually decreases, turning off the transistor Q5. , the same operation as above will be repeated again. In this manner, the switching regulator 6 performs an operation of chopping the DC power supplied via the bridge type full-wave rectifier circuit 1 and maintaining its output voltage at a constant voltage. On the other hand, reference numeral 8 denotes an impedance changing section to which power is supplied from the switching regulator 6 through the excitation coil 7a, and between the output terminals 6a and 60 there is a transistor Q, a resistor R9, and a light emitting diode LD. are connected in series, and the above transistor Q
Therefore, when the transistor Q is turned on, the impedance of the impedance changing section 8 decreases from approximately infinity to a value determined mainly by the resistor R9.

9 is a smoothing circuit provided after the impedance changing section 8, which includes resistors R, . and smoothing capacitor C3
It acts as a low-pass filter for the constant voltage circuit 10 provided at the subsequent stage. The above constant voltage circuit 1, transistor Q7, Zener diode ZD3, resistor R, 2
This is a well-known structure in which a smoothing capacitor C4 is connected as shown in the figure. Now, 11 is a photoelectric switch element which is a detection circuit, and this is connected to a light emitting element such as a light emitting diode LD2.
and the light emitting diode LD2.
It has the same configuration as the detection circuit of a general reflective photoelectric switch, which includes a light receiving circuit 13 having a light receiving element arranged in a lotus shape, such as a photodiode PD. That is,
The light emitting circuit 12 lights up the light emitting diode LD2 at a constant cycle using an oscillator circuit consisting of a multipipelator or the like.
Further, the light receiving circuit 13 puts the timing photodiode PD in synchronization with the lighting cycle of the light emitting diode LD2 into a light receiving state, and outputs an output from the terminal A according to the light receiving state. Specifically, when a detected object is present in a predetermined light projection area by the light emitting diode LD2 and the amount of light received by the light emitting diode PD exceeds a predetermined level due to light reflected from the detected object, the terminal of the light receiving circuit 13 is activated. The configuration is such that a detection signal Sd consisting of a low level signal is output from A, and a high level signal is output from terminal A in other states, and the output from terminal A is a Z
D4 and resistance R. 3 to the base of the transistor Q6. The light emitting circuit 12 and the light receiving circuit 13 are connected to the output terminal 6 of the switching regulator 6.
Power is supplied from a and 6b through the smoothing circuit 9 and the constant voltage circuit 10. However, the relay 7
has a relay contact 7b that is activated in response to energization of the excitation coil 7a, and this relay contact 7b is connected to the normally open terminal NO and the common terminal when a current equal to or higher than a predetermined operating current lm flows through the excitation coil 7a. When the terminal COM is turned on and the current flowing through the exciting coil 7a falls below the holding current lh, which is lower than the operating current lm, the normally closed terminal NC and the common terminal C are turned on.
It has a normal configuration in which it is turned on between ON and ON. In this case, the relay 7 is configured such that when the impedance changing unit 8 causes a decrease in impedance in response to the transistor Q being turned on, a current equal to or higher than the above-mentioned operating current lm flows through the exciting coil 7a. Furthermore, the current consumption of the photoelectric switch element 11 is set to be smaller than the holding current ratio of the relay 7. Next, the operation of this embodiment having the above configuration will be explained with reference to FIG.
In FIG. 2, a is the chopper output waveform of the switching regulator 6 at point a in FIG. 1, b is the current at point b in FIG. 1, that is, the waveform of the output load current IL flowing through the exciting coil 7a, and c is The waveform corresponding to the on/off state between the normally closed terminal NO and the common terminal COM of the relay 7, d indicates the output waveform of the light receiving circuit 13 obtained at point d in FIG. 1, respectively. Now, when the light emitted from the light receiving diode LD2 does not enter the light receiving diode PD, or even if it does, it does not reach a predetermined level, in other words, when there is no detected object in the detection area by the photoelectric switch element 11, In this case, the light receiving circuit 13 outputs the /. level signal, and the transistor Q is turned off.

Therefore, the impedance changing section 8 exhibits a substantially infinite impedance, and the switching regulator 6 outputs a relatively small load current 1 corresponding to the current consumption of the photoelectric switch element 11. The chopping period of 6 is from Uto to t. in FIG. 2a. As shown, it is relatively long. In this case, since the load current 1 flowing through the exciting coil 7a is set smaller than the operating current lm and holding current lh of the relay 7, the relay 7 is turned on between the normally open terminal NO and the common terminal COM. There's nothing to do. Thereafter, when the amount of light received by the photodetector diode PD exceeds a predetermined level at time t, in other words, when a detected object exists in the detection area of the photoelectric switch element 11, a low level signal is sent from the photodetector circuit 13. Since the detection signal Sd consisting of the following is output and the transistor Q is turned on, the impedance changing section 8 causes the impedance to decrease by 4. At the same time, the light emitting diode LD lights up to indicate that the presence of the object to be detected has been detected. . Therefore, the switching regulator 6 outputs a combined current 13 of a load current 1 corresponding to the current consumption of the photoelectric switch element 11 and a load current 12 flowing through the impedance changing section 8 including the light emitting diode LD. The chopping period is at time t in Figure 1a.
,~ra' is relatively short as shown here. In this case, the load current 13 flowing through the excitation coil 7a exceeds the operating current lm of the relay 7, and the relay 7 turns on between its normally open contact NO and the common terminal CON. Accordingly, a detection output corresponding to the presence of the object to be detected can be taken out from between the terminals NO and COM.
After that, at time t2, when the amount of light received by the photodetector diode PD falls below a predetermined level, the photodetector circuit 13 again outputs a high-level signal, and the output load current of the switching regulator 6 decreases. and others'
When the load current 13 flowing through the excitation coil 7a becomes lower than the holding current m of the relay 7, the relay 7 turns on between the normally closed terminal NC and the common terminal COM, returning to the initial state. After this, the above-described operation is repeated. Incidentally, although a pulsating load current due to the chopper output waveform of the switching regulator 6 flows through the excitation coil 7a of the relay 7, the operation of the yield relay 7 can be considered based on the average value of the load current.

That is, considering that the chopping period of the switching regulator 6 is generally several KHz to several tens of KHz, but the response delay time of the relay 7 is several ms or more, the above-mentioned pulsation of the load current Therefore, the relay 7 will not malfunction. According to this embodiment, since the chopper type switching regulator 6 is used in the input part of the photoelectric switch element 11, it can be used for a wide range of power supply voltages, and it can be made into a transformerless type, so that the input part It is possible to reduce the size of the device and improve efficiency. Furthermore, since the bridge-type full-wave rectifier circuit 1 is provided before the switching regulator 6, it can be used for both AC and DC power supplies, and in particular, when used for DC power supplies, non-polar connection is possible. becomes possible. and,
The switching regulator 6 described above has a structure in which the inductance element is also used as the excitation coil 7a of the IJ relay 7 for extracting the detection output, so a choke coil as an inductance element can be eliminated and the size can be further reduced. It is possible to achieve this, and at the same time, it is possible to suppress manufacturing costs. In addition, the load current flowing through the excitation coil 7a is controlled by the impedance changing section 8, and the impedance changing section 8 is connected in series with a light emitting diode LD for indicating the operation. The output can be shared by the current flowing through the impedance changing section 8 (ie, the output for control). Furthermore, in the above embodiment,
By appropriately changing the resistance value of the resistor K9 in the impedance changing section 8, it is possible to operate relays with different ratings with desired sensitivity current values while keeping the output voltage value of the switching regulator 6 constant. become.

The photoelectric switch element 11 in the above embodiment has a so-called light-on type configuration that turns on when the amount of light received by the photodetector diode PO increases from a normal value. It may also be a so-called dark-on type configuration that turns on when the amount of received light decreases from a normal value. In addition, the present invention is not limited to the embodiments described above and shown in the drawings; for example, a transmission type photoelectric switch, a proximity switch element, an ultrasonic switch element, etc. may be applied as the detection circuit, and The present invention can be implemented with appropriate modifications without departing from the spirit of the present invention, such as applying a solenoid valve or other electromagnetic device as the body. As can be understood from the above description, the present invention can be used for a wide range of power supply voltages, can be made compact, and furthermore eliminates the need for a choke coil, which is required as a separate component. Accordingly, it is possible to provide a detection device that is effective in that the number of parts can be reduced.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram showing one embodiment of the present invention, and FIG. 2 is a time chart showing waveforms of various parts in the same embodiment. In the figure, 6 is a chopper type switching regulator, 6a
, 6b is an output terminal, 7 is a relay (operating body), 7a is an excitation coil (inductance element), 8 is an impedance change section, LD is a light emitting diode (light emitting element for display), 1
1 is a photoelectric switch element (detection circuit). Figure 2

Claims (1)

[Claims] 1. A chopper-type switching regulator having an inductance element, and a switching regulator configured to receive power from both output terminals of the switching regulator to detect the presence or absence of an object to be detected. The inductance element comprises a detection circuit, an impedance change section connected between both output terminals of the switching regulator and causing an impedance change in response to the detection of a detected object by the detection circuit. 1. A detection device comprising: an excitation coil; and an actuator that is activated only when the current flowing through the excitation coil increases in response to a decrease in impedance of the impedance changing section. 2. The detection device according to claim 1, wherein a display light emitting element is interposed in series in the impedance changing section. 3. The detection device according to claim 1, wherein the detection circuit is constituted by a photoelectric switch element. 4. The detection device according to claim 1, wherein the operating body is a relay.