JP2839892B2 - Reflective object detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type object detector that reflects an optical signal on a wall or the like via a monitoring area and detects a passing object from a change in the reflected light.

[Prior Art] As a conventional reflection type object detector, there is one shown in FIG. 2, for example.

In FIG. 2, reference numeral 1 denotes a light-emitting unit formed of, for example, an LED, and emits modulated light modulated at a predetermined cycle by the pulse drive circuit 2 and the modulation circuit 3 toward the wall 200 via the monitoring area 100. Reference numeral 4 denotes a light receiving unit formed of, for example, a photodiode, which receives the modulated light from the light emitting unit 1 reflected by the wall 200 and converts the modulated light into an electric signal. The light receiving signal from the light receiving section 4 is subjected to synchronous detection by the periodic circuit 6 after the modulation frequency band is extracted by the filter circuit 5, amplified by the amplifier circuit 7, converted to a DC signal by the rectifier circuit 8, and given to the comparison circuit 10. Can be

In the comparison circuit 10, a detection signal based on the steady reflected light from the wall 200, that is, the output voltage from the rectifier circuit 8 in the steady monitoring state is set as a reference value. If a signal change due to a change in light is equal to or more than a predetermined value with respect to a reference value, a comparison output is generated to cause an alarm.

Normally, the setting of the monitoring threshold value in the comparison circuit 10 is performed, for example, by setting a reference value to an upper limit monitoring threshold value and a lower limit monitoring threshold value to upper and lower limits.

That is, the comparison circuit 10 includes the comparison units 13 and 14 and the delay circuit 15.

First, the reference value Vro for the comparators 13 and 14 is determined based on the output voltage from the rectifier circuit 8 by the voltage division of the resistors R1 and R2, and is input to the comparators 13 and 14 via the delay circuit 15.

The upper limit monitoring threshold Vr1 is set in the comparator 13 by the resistors R3 and R4, and the lower limit monitoring threshold Vr2 is set in the comparator 14 by the resistors R5 and R6.

Specifically, for example, at the time of shipment from a factory or the like, a predetermined amount of reflected light Lo is incident on the light receiving unit 4, and a reference value Vro is determined based on the output voltage of the rectifier circuit 8 obtained at that time. An upper limit monitoring threshold Vr1 and a lower limit monitoring threshold Vr2 are set so as to be substantially at the center.

In such a reflective object detector, the monitoring area 10
When a person enters at 0 and the reflected light changes abruptly, the reference value Vro for the comparators 13 and 14 does not immediately change by the delay circuit 15, while the upper limit monitoring threshold Vr follows the change of the reflected light.
1 and the lower monitoring threshold Vr2 change, and when the upper monitoring threshold Vr1 falls below the reference value Vro kept constant, the comparator 13 generates an H level output, while the reference value Vro falls below the lower monitoring threshold Vr.
When r2 exceeds, the comparator 14 generates an H level output, and a person can be detected.

[Problems to be Solved by the Invention] By the way, in such a conventional reflection-type object detector, the amplified signals input to the comparators 13 and 14 provided in the comparison circuit 10 are output from the comparators 13 and 14. It is desirable that the input signal level be adapted to the circuit characteristics.

For example, in the case where the signal is installed toward the wall 200 having good reflectance, the signal level of the amplified signal obtained from the rectifier circuit 8 after being amplified by the amplifier circuit 7 exceeds the appropriate input range of the comparators 13 and 14. Since it becomes too high, it is necessary to adjust the gain of the amplifier circuit 7 at the time of installation so as to be within an appropriate input range.

However, the reflectivity of a reflective object such as a wall at a place where the reflective object detector is installed is various, and in order to adjust the amplification gain so as to have an appropriate input range for the comparison unit at the time of installation,
There is a problem that a measuring instrument such as a level meter is required, and adjustment work becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and is a reflection-type object that can automatically obtain an adjustment state in which an amplified signal level falls within an appropriate input range for a comparison unit in accordance with an installation situation. It is an object to provide a detector.

Means for Solving the Problems First, the present invention provides a light emitting unit that outputs an optical signal toward a wall or the like via a monitoring area, a light receiving unit that receives a signal reflected from the wall or the like, The present invention is directed to a reflection type object detector including an amplification unit that amplifies a detection signal received by a unit and a comparison unit that generates an output and alarms when an amplification signal from the amplification unit changes by a predetermined amount or more.

According to the present invention for such a reflection type object detector, an output monitoring unit that monitors an amplified signal from the amplification unit, and a changeover switch that selectively switches the amplified signal of the amplification unit to the comparison unit or the output monitoring unit. A timer control unit that controls the changeover switch to the output monitoring unit for a predetermined time when the power is turned on, and a light emission control unit that is provided in the light emitting unit and controls the intensity of an optical signal output from the light emitting unit. When the changeover switch is switched to the output monitoring unit side, if the amplified signal from the amplification unit is out of a predetermined range set in advance in the output monitoring unit, the light emission control unit is controlled to fall within the predetermined range. The intensity of the optical signal is adjusted by the above control, and after the adjustment is completed, the adjustment value is fixed.

[Operation] In the reflection type object detector of the present invention having such a configuration, when the power is turned on to start the monitoring operation after installation on the site, the output of the amplifying unit for a predetermined time after the power is turned on. Switched to the output monitoring unit side, if the amplified signal corresponding to the received light signal reflected by the wall or the like at that time is out of the appropriate input range of the comparison unit set in the output monitoring unit, it falls within the appropriate input range. In this way, the intensity of the optical signal from the light emitting unit is adjusted by the light emission control unit, and the amplified signal to the comparison unit is automatically adjusted to an appropriate level according to the situation of the installation location, so that a stable monitoring operation is always performed. Can be guaranteed.

Embodiment FIG. 1 is a circuit block diagram showing an embodiment of the present invention.

In FIG. 1, first, the light emitting side is composed of a light emitting unit 1, a pulse driving circuit 2 and a modulation circuit 3, and the light emission provided on the light emitting unit 1 by a modulation signal modulated at a predetermined cycle by the pulse driving circuit 2 and the modulation circuit 3. Transistor diode 1a
Controlled by T1, the modulated light from the light emitting diode 1a is monitored
It emits light by being provided on a wall 200 via 100.

The light emitting unit 1 is provided with a light emission control unit 9 which will be described later. In this embodiment, the light emission control current flowing through the light emitting diode 1a by the transistor T1 is gradually reduced by the light emission control unit 9. I can do it.
That is, the intensity of the optical signal from the light emitting unit 1 can be reduced stepwise by the light emission control circuit 9.

The modulated light from the light emitting unit 1 reflected by the wall 200 is
The light receiving signal from the light receiving unit 4 is
After the modulation frequency band is extracted, the signal is synchronously detected by the synchronous circuit 6, amplified by the amplifier circuit 7, converted to a DC signal by the rectifier circuit 8, and supplied to the comparator circuit 10 via the newly provided switch 18-1. Given. The comparison circuit 10 has, for example, the circuit configuration shown in FIG. The comparison output of the comparison circuit 10 is supplied to an alarm circuit 16 to perform a theft alarm or the like.

On the other hand, the output of the rectifier circuit 8 is given to the output monitoring unit 25 via the changeover switch 18-2. Also, changeover switch
Another switch 18-3 is connected between the output of 18-2 and the ground.
The switch 18-3 is closed when the switch 18-2 is open, thereby preventing the output monitoring unit 25 from malfunctioning due to input opening.

A changeover switch 18-1, provided on the output side of the rectifier circuit 8,
18-2 and the changeover switch 18-3 are controlled by the timer control unit 20 for switching.

The timer control unit 20 includes a timer circuit 21, and the timer circuit 21
Generates a timer output in which the Q output is at the H level and the output is at the L level for a certain period of time after the power is turned on. Timer circuit 21
Is output from a changeover switch 18 provided at the input stage of the comparison circuit 10.
-1 while the output of the timer circuit 21 is at the L level, the changeover switch 18-1 is turned off as shown by the solid line. On the other hand, the timer circuit 21
The Q output of the switch is a changeover switch 18-2 provided on the output monitoring unit 25 side.
As a control signal, and the Q output of the
While the level is at the level, the changeover switch 18-2 is switched to the ON state as shown by the solid line.

That is, the switch 18-1 is turned off for a certain period of time after the power is turned on by the timer control unit 20, and the output of the rectifier circuit to the comparison circuit 10 is cut off.
2 is turned on to supply the output of the rectifier circuit 8 to the output monitoring unit 25.

Of course, when a certain time has passed since the power was turned on, the timer circuit
The switch 21 returns to the reset state, and the switch 18-1 is turned on and the switch 18-2 is turned off when the Q output becomes L level and the output becomes H level. Furthermore, the timer circuit 21
Is a changeover signal of the changeover switch 18-3, and the changeover switch 18-3 is turned on in reverse to the changeover switch 18-2.
The off operation is performed.

Further, in this embodiment, the timer control unit 20 includes:
During a certain period of time after the power is turned on, a control function of the indicator light 24 for indicating that there is an adjustment time is also provided.

That is, the oscillating output of the oscillating circuit 22 is supplied to the indicator light 24 composed of an LED via the AND gate 23, the diode D1, and the resistor R8, and the Q of the timer circuit 21 is supplied to the other of the AND gate 23.
Output is connected. Further, the output of the timer circuit 21 is directly connected to one end of the resistor R8 via the diode D2.

Therefore, the timer circuit 21 is provided for a certain period of time after the power is turned on.
Is in the set state, and when Q = H, = L, the AND gate 23 is enabled by the Q output, the oscillating pulse from the oscillation circuit 22 is supplied to the indicator light 24, and the indicator light 24 flashes and is adjusted. Will be notified.

When the timer circuit 21 is reset after a lapse of a predetermined time from the power-on, Q = L, = H, and the AND gate 23 is disabled, and the = H level output of the timer circuit 21 connects the diode D2 and the resistor R8. The indicator light 24 is switched to a constantly lit state by being supplied to the indicator light 24 via the control unit.

Next, the output monitoring unit 25 will be described. The output monitoring unit 25 is provided with comparators 26 and 27, and the amplified signals from the rectifier circuit 8 are input to the plus input terminals of the comparators 26 and 27 via the changeover switch 18-2. The resistors R11 and R1 are connected to the comparators 26 and 27.
2, the reference voltage Vr1 and Vr2
Is set. The reference voltages Vr1 and Vr2 are supplied to comparators provided in the comparison circuit 10, for example, the comparators 13 and 1 shown in the conventional example of FIG.
The upper limit of the appropriate input range for 4 is set. That is, there is a relationship of Vr1 <Vr2, and when the amplified signal from the rectifier circuit 8 exceeds the reference voltage Vr1, the comparator 26 generates an H level output. When the amplified signal from the rectifier circuit 8 exceeds the reference value Vr2, the comparator 26 , 27 produce an H level output. Comparator 26,
The output of 27 is connected to the gates of thyristors 28 and 29 via a noise removing integration circuit consisting of a resistor R14 and a capacitor C1, and a resistor R15 and a capacitor C2. Thyristors 28 and 29 connect relays 30 and 32 as control loads. The relay contacts 30a and 32a of the relays 30 and 32 are provided in the light emitting unit control unit 9 provided in the light emitting unit 1.

A light emission control unit 9 provided in the light emission unit 1 constitutes a base bias circuit of a control transistor T2 for controlling a drive current of a drive transistor T1 of the light emitting diode 1a, and a resistor R10 connected in parallel between a base and an emitter of the transistor T2. R20,
R30 is switched by turning on / off the relay contacts 30a and 32a so that the light emission current of the light emitting diode 1a, that is, the light emission amount can be adjusted stepwise.

That is, when both the relays 30 and 32 provided in the output monitoring unit 25 are off, the relay contacts 30a and 32a provided in the light emission control unit 9 are used.
Is closed as shown, and the connection resistance between the base and the emitter of the transistor T2 is the parallel resistance of the resistors R10, R20 and R30.

Next, when the relay 30 provided with the output monitoring unit 25 is operated, the relay contact 30a opens to disconnect the resistor R10, and the transistor T2
The resistance between the base and the emitter of the transistor T2 increases to the parallel resistance of the resistors R20 and R30.With this increase in the resistance, the voltage between the base and the emitter of the transistor T2 increases, and the collector current of the transistor T2 increases. The base current for T1 decreases, and the light emission amount of the light emitting diode 1a decreases by one step.

Further, when both the relays 30 and 32 of the output monitoring unit 25 are operated, the relay contacts 30a and 32a are turned off, so that the resistors R10 and R20 are disconnected, and the resistance value between the base and the emitter of the transistor T2 becomes the resistor R30. When the resistance value further increases, the driving current of the light emitting diode 1a by the transistor T1 further decreases by one step, and the light emission amount decreases.

 Next, the operation of the embodiment shown in FIG. 1 will be described.

As shown in the figure, when the power is turned on with the reflection type object detector of the present invention installed, the timer circuit 21 provided in the timer control unit 20 is set to Q = H, = L, and the changeover switch 18-1 is turned on. The switch 18-2 is turned on at the same time as the switch is turned off, and the switch 18-3 is also turned off.
Accordingly, when the power is turned on, the light receiving signal from the light receiving unit 4 reflected from the light emitting unit 1 via the monitoring area 100 via the wall 200 is transmitted to the filter circuit 5, the synchronizing circuit 6, the amplifying circuit 7, and the rectifying circuit 8
, And is supplied to the output monitoring unit 25 via the changeover switch 18-2.

Of course, at this time, the AND gate 23 provided in the timer control unit 20 is provided.
Is in an allowable state, the oscillation output of the oscillation circuit 22 is supplied to the indicator light 24 and blinks, and the blinking of the indicator light 24 indicates that the adjustment state is being established.

The amplified signal from the rectifier circuit 8 provided to the output monitoring unit 25 via the changeover switch 18-2 is compared with the reference values Vr1 and Vr2 in the comparators 26 and 27.

Here, the reflectance of the wall 200 at the installation location is high, and the level of the amplified signal from the rectifier circuit is the reference value set in the output monitoring unit 25.
It is assumed that the value exceeds Vr1 and is less than the reference value Vr2. in this case,
Only comparator 26 produces an H-level output, and therefore a thyristor
28 is triggered and the relay 30 is driven. The relay contact 30 provided in the light emission control unit 9 of the light emission unit 1 by driving the relay 30
a opens, the resistor R10 is disconnected, and the resistors R20 and R30 are connected in parallel between the base and the emitter of the transistor T2.The resistance value increases, and the driving current of the light emitting diode 1a by the transistor T1 decreases by one step. As a result, the amount of reflected light from the wall 200 with respect to the light receiving unit 4 decreases.

As described above, when the light emission amount is reduced by two steps under the control of the light emission control unit 9 based on the output monitoring unit 25, the signal level of the amplified signal from the rectification circuit 8 decreases, and the comparator provided in the output monitoring unit 25 When the reference value Vr1 is equal to or lower than the reference value Vr1, the output of the comparator 26 becomes L
Level. However, since the thyristor 28 has already been latched in the ON state, the relay 30 is kept in the driving state even when the output of the comparator 26 becomes L level.

On the other hand, if the signal level of the amplified signal from the rectifier circuit 8 for the output monitoring unit 25 exceeds the reference value Vr2 for the comparator 27, both outputs of the comparators 26 and 27 become H level, and the thyristors 28 and 29 are triggered. And relays 30 and 32
Is activated. Therefore, the light emission control unit 9 provided in the light emission unit 1
The relay contacts 30a and 32a are both turned off, the resistors R10 and R20 are cut off, and only the resistor R30 is connected between the base and the emitter of the transistor T2. Has a light emission of 2
As a result, the amplified signal obtained from the rectifier circuit 8 after the light emission amount has been reduced by two steps has dropped to near or more than the reference value Vr set in the comparator 26 of the output monitoring unit 25. It will be adjusted to an appropriate level.

Of course, when a certain period of time has elapsed since the power was turned on, the timer circuit 21 of the timer control unit 20 is reset, and when Q = 1, = H, the changeover switch 18-1 is turned on and the output of the rectifier circuit 8 is compared with the comparison circuit 10 At the same time, the changeover switch 18-2 is turned off to disconnect the output monitoring unit 25 from the output of the rectifier circuit 8, and the changeover switch 18-3 is turned on to fix the input level to the comparators 26 and 27 to OV. To prevent the output monitoring unit 25 from malfunctioning.

In addition, the reset of the timer circuit 21 disables the AND gate 23, and the H level output of the timer circuit 21 causes
Switches from the blinking state to the lighting state.

In the embodiment shown in FIG. 1, when the output signal from the rectifier circuit switched at power-on by the output monitoring unit 25 exceeds a predetermined reference value, the light emission unit 1 Although the light emission amount is reduced by the control unit 9, as another embodiment, the light emission amount from the light emitting unit 1 is reduced by the light emission control unit 9 when the received light amplification signal becomes equal to or less than a reference value provided in the output monitoring unit 25. Needless to say, the number may be increased.
Further, although the timer circuit 21 of the timer control unit 20 is set when the power is turned on, the timer circuit 21 may be set by another switching means.

Further, a reference value corresponding to the upper limit and the lower limit of the appropriate input range of the comparator provided in the comparator circuit 10 is set in the output monitoring unit 25, and when the upper limit is exceeded, the light emission amount of the light emitting unit 1 is reduced. The light emission amount of the light emitting unit 1 may be increased when the value falls below the lower limit reference value.

Furthermore, in the embodiment shown in FIG.
Although the timer control unit 20 is provided integrally, since the timer control unit 20 is used only for a predetermined time immediately after the power is turned on, the timer control unit 20 is an independent unit, and is connected by a connector or the like at the time of adjustment by turning on the power. An adjustment operation may be performed.

[Effects of the Invention] As described above, according to the present invention, when the power is turned on to start the monitoring operation after installation on the site, the output of the amplification unit is output to the output monitoring unit for a predetermined time after the power is turned on. If the amplified signal corresponding to the received light signal reflected by the wall or the like at that time is out of the proper input range set in the output monitoring unit, the light emission control unit emits light so as to fall within the proper input range. The intensity of the optical signal from the unit is automatically adjusted, so there is no need to adjust the amplification gain according to the installation location as in the past, and the amplification is automatically performed according to the installation location The signal can be adjusted to an appropriate level,
A stable monitoring operation can be guaranteed.

[Brief description of the drawings]

 FIG. 1 is a circuit block diagram showing one embodiment of the present invention; FIG. 2 is a circuit block diagram showing a conventional example. 100: Monitoring area 200: Wall 1: Light emitting unit 1a: Light emitting diode 2: Pulse drive circuit 3: Modulation circuit 4: Light receiving unit 5: Filter circuit 6: Synchronous circuit 9: Light emission control unit 7: Amplifier circuit 8: Rectifier circuit 10 : Comparison circuit 16: Alarm circuit 18-1,18-2,18-3: Switch 20: Timer control unit 21: Timer circuit 22: Oscillation circuit 23: AND gate 24: Indicator 25: Output monitoring unit 26,27 : Comparator 28,29: Thyristor 30,32: Relay 30a, 32b: Relay contact

Claims (1)

(57) [Claims] 1. A light emitting unit for outputting an optical signal toward a wall or the like via a monitoring area, a light receiving unit for receiving an optical signal reflected from the wall or the like, and amplifying a detection signal received by the light receiving unit. Monitoring the amplified signal from the amplifying unit in a reflection type object detector including an amplifying unit that performs an output and an alarm that generates an output when the amplified signal from the amplifying unit changes by a predetermined amount or more. An output monitoring unit, a switch for selectively switching the amplified signal of the amplifying unit to the comparison unit or the output monitoring unit, and a timer control unit for switching the switch to the output monitoring unit for a predetermined time when power is turned on. A light emission control unit that is provided in the light emitting unit and controls the intensity of an optical signal output from the light emitting unit; and when the changeover switch is switched to the output monitoring unit side, the amplification unit The amplified signal from the output monitoring unit A reflection-type object that, when deviating from a predetermined range set in advance, adjusts an optical signal under the control of the light emission control unit so as to fall within the predetermined range, and after the adjustment is completed, the adjustment value is fixed. Detector.