JPS5931758B2 - light beam warning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention includes a light projecting section 1 that sends modulated light α emitted at a predetermined period, and a light receiving section 2 that receives the light from the light projecting section 1.
In a light beam warning device that issues an alarm using the output of the light receiver 2 when the light from the light emitter 1 is blocked, the period T of the modulated light α is
1 is set to be sufficiently longer than the cycle T3 of the harmonic component β of a noise pulse light emitting source such as a fluorescent lamp, and shorter than the cycle T2 at which the harmonic component β intermittently occurs, and It relates to a light beam type warning device characterized by being provided with a light blocking time measuring circuit whose output is reversed when the non-light receiving time is longer than the period T1 of the modulated light α, and its purpose is to Malfunctions caused by harmonic components such as light are eliminated, a sufficiently practical response speed is obtained, and the period of modulated light does not become too high, reducing the number of times pulsed light is generated within a unit time. To provide a light beam type warning device which can send a correspondingly more powerful pulsed light and lengthen the warning distance accordingly.

In general, in light beam warning devices, (1) preventing malfunctions due to ambient light and (1) increasing the distance between the 11 layers are equally important.

To solve the former technical problem, as disclosed in Japanese Patent Publication No. 52-33309, the light emitting period of the light projecting element is changed to the period of the harmonic component of a noise pulse light source such as a fluorescent lamp. However, in such conventional examples, the number of times the light emitting element emits light within a unit time becomes extremely large, so the intensity of the pulsed light emitted from the light emitter is not set too high. In this case, there is a problem that the current consumption of the light emitter increases and the amount of heat generated by the light emitter increases.

That is, in FIG. 6, b shows the conventional example, and a shows the case of the present invention, but as shown in the figure, the pulse period of the light emitter is set to a period shorter than the period T3 of the harmonic component of the fluorescent lamp. In the case of X8T4, the number of times of light emission within a unit time is significantly increased, so unless pulsed light with a low peak value is used, the light emitting body will overheat.

The present invention solves these problems of the conventional example, and makes it possible to reduce the number of times that pulsed light is generated within a unit time, thereby making it possible to send a correspondingly more powerful pulsed light, thereby increasing the warning distance. The aim is to make it possible to last longer.

The configuration of the present invention will be described below with reference to illustrated embodiments.

1 and 2 show one embodiment of the present invention.

The light emitting section 1 is composed of an oscillation circuit 3 and a light emitting element 4 such as a lamp or a light emitting diode driven by the oscillation circuit 3, and the light receiving section 2 is composed of a light receiving element 5 such as a phototransistor or a solar cell. It is composed of an amplifier circuit 6 that amplifies the output of the light receiving element 5.

A charge/discharge circuit 7 is connected to the output end of the increase/fuku circuit 6 via a capacitor C4 and a transistor Tr1.
This charging/discharging circuit 7 causes the output transistor Tr2 to operate.

The charging/discharging circuit 1 includes resistors R1, R3 and capacitors C1, C2.
and a diode D, and the resistor R3 is the resistor R3.
The resistance is about 5 to 10 times that of 1.

The resistor R1 and the capacitor C1 are set so that the charging time of the capacitor C1 is longer than the period T1 of the modulated light α of the light projector 1.

Here, the charging time is R3/Rt + R2 (Vcc VD) + DCV, assuming the forward voltage of diode D is VD.
cc: power supply voltage] This is the time it takes to reach cc: power supply voltage.

Further, the resistor R3 and the capacitor C2 are arranged so that the discharge time is longer than the intermittent generation cycle T2 of the harmonic component β, which is periodic optical noise, for example, the noise of a fluorescent lamp lit at a commercial frequency. It is selected.

The resistor R2 is a protection resistor for the transistor Tr1 due to the discharge current of the capacitor C1.

2 is a time chart for explaining the operation of the same embodiment as above, A is a voltage waveform at point a in FIG. 1, an opening is a voltage waveform at point b, and C is a voltage waveform at point 0. , Figure 2 is d
This shows the output waveform at a point, where the modulated light α is
enters with period T1, the transistor Tr1 repeats on and off, and the potential at point b becomes as shown in the figure due to the capacitor C□.

At this time, the charge stored in the capacitor C2 gradually discharges as shown in Figure 2, and when it becomes below the operating level q of the transistor Tr2, the transistor Tr2 is turned off and the point d goes high as shown in Figure 2. level.

When the potential of the capacitor C2 becomes below a certain level, the capacitor C2 as well as the capacitor C1 is charged to some extent through the diode D.

Therefore, when the modulated light α is no longer input, the capacitor C1
and C2 are gradually charged, and when the potential of the capacitor C2 reaches the operating level 9 or higher, the transistor Tr2 is turned on and the point d becomes low level, and the light-blocking state is indicated by an alarm or the like.

In this state, when harmonic component β is input, capacitor C
1 is instantaneously discharged, and capacitor C2 is gradually discharged.

Here, the intermittent generation period T2 of harmonic component β is the modulated light α
Since the cycle T1 is longer than the cycle T1, the capacitor C2 does not turn off the transistor Tr2, and the alarm state continues.

Subsequently, when the modulated light α enters, the capacitor C1
is discharged, the potential of capacitor C2 becomes low, and d
The potential at the point becomes high and it becomes alert again.

The time t1 is a delay caused by the long discharge time of the capacitor C2.

FIG. 3 shows a time chart of another example of operation, and FIG. 3 shows the voltage waveform at the same point as in FIG.

Here, as long as the modulated light α is continuously input, the potential of the capacitor C2 is equal to the operating level q of the transistor Tr2.
The potential at the 6 points becomes higher after a delay tl.

4 shows a time chart of yet another operating state, and as in FIG. 3, Ill. 2 corresponds to Ill. 2 in FIG. 2.

Here, even if the alert state changes to the light shielding state (indicated by p) and the harmonic component β continues, the intermittent generation period T2 of the harmonic component β is longer than the period T1, so the capacitor C2 It is gradually charged and the alarm state continues with the potential at point d set to low level.

Next, when the modulated light α enters, after a delay t2, the potential at point d becomes high level, and the state becomes alert.

FIG. 5 shows another embodiment in which a transistor T3 is used to invert the output, which is basically the same as the embodiment shown in FIG.

As a matter of course, in each of the above embodiments, the resistance R
3 and the capacitor C2 is a general high frequency generation period T2.

It is longer than oH2 (=20mSeC), and the resistance R
The charging characteristics determined by C1 and capacitor C1 are (-'20
m5eC) is a shorter comb.

The present invention is constructed in such a way that the period of the modulated light emitted from the light projector is sufficiently longer than the period of the harmonic component of a noise pulse light source such as a fluorescent lamp, and It is set to be shorter than the period at which the component occurs intermittently, and is equipped with a light-blocking time measuring circuit that inverts the output when the non-light receiving time in the light receiving section is longer than the period of the modulated light.
The light beam detector no longer malfunctions due to harmonic components, which are disturbance light noise generated from fluorescent lights, etc.
In addition, the response speed can be made sufficiently practical.
Moreover, compared to the conventional example, the number of times pulsed light is generated within a unit time can be reduced, which has the effect of allowing stronger pulsed light to be sent and a longer warning distance. .

[Brief explanation of drawings]

1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is a time chart for explaining the operation of the same as above, and FIG.
Figure 2 is a time chart of another example same as the above, Figure 5 is a circuit diagram of another embodiment, and Figures 6a and 6b are operation explanatory diagrams comparing the present invention and a conventional example. 1 is a light emitter, 2 is a light receiver, α is modulated light, β is a harmonic component, T1 is the period of modulated light, T2 is the generation period of the harmonic component,
T3 is the harmonic period of the harmonic component.

Claims (1)

[Claims] 1 It has a light emitter that sends modulated light that is emitted at a predetermined period, and a light receiver that receives the light from the light emitter, and is configured to issue an alarm using the output of the light receiver when the light from the light emitter is blocked. In the optical alarm device, the period of the modulated light is sufficiently longer than the period of the harmonic component of a noise pulse light emitting source such as a fluorescent lamp, and shorter than the period at which the harmonic component is intermittently generated. 1. A light beam type warning device, characterized in that it is provided with a light blocking time measuring circuit which inverts the output when the non-light receiving time in the light receiving section is longer than the period of the modulated light.