JPH0627237A - Laser alarm - Google Patents

Abstract

PURPOSE:To provide an outdoor laser alarm in which target detectable distance is increased as long as possible while preventing erroneous alarm due to outdoor environmental conditions. CONSTITUTION:A pulse laser beam 6 is emitted from a laser driver 2 and projected through an optical transmitting section 7 under control of a controller 1a and reflected light enters through a detector 10 and an amplifier 12 into a comparator 13a. A plurality of reference voltages are prepared for the comparator 13a by a reference voltage generator 14. In prestage for beginning laser detection, noise level due to external environmental conditions such as mist is detected and a reference voltage slightly higher than the noise level is selected. This constitution ensures maximum detectable distance while preventing erroneous alarm due to external environment.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a laser alarm device,
In particular, the present invention relates to an outdoor laser alarm device that detects the presence or absence of a target using a pulse laser and outputs an alarm.

[0002]

2. Description of the Related Art A conventional laser alarm device is constructed as shown in FIG. 2 and has a controller 1 for controlling the device.
A laser driver 2 for driving a laser by receiving a charge command 3 for a laser power source output from the controller 1 and a laser trigger signal 4, and a laser oscillator 5.
A transmission optical section 7 for transmitting the pulsed laser beam 6, a reception optical section 9 for receiving the reflected laser beam 8 reflected by a target, a detector 10, and a bias circuit 11 for the detector 10.
An amplifier 12 for amplifying the detection signal, and a comparator 13 for comparing the amplified signal with the reference voltage 15 and outputting the amplified signal exceeding the reference voltage 15 as a target detection signal 16.

Only one reference voltage 15 of the comparator 13 is set, and the detectable distance is generally determined according to the reference voltage 15.

That is, since the level of a received signal from a distant target becomes smaller, the detectable distance becomes longer when the reference voltage 15 is lowered, and the detectable distance becomes smaller when the reference voltage 15 is raised.

Therefore, normally, in the manufacturing stage of the device, the reference voltage 15 is set to a level higher than system noise, external noise, etc. and to sufficiently satisfy the required detection distance.

[0006]

In the above-mentioned conventional outdoor laser alarm device, only one reference voltage is used to determine the target by comparing it with the detection signal by the comparator, and it can be changed after the initial setting. Since there is no such device, there is a problem in that the device cannot fully exhibit its function depending on the operating environment of the device, particularly the weather conditions.

Normally, the range of detecting a target is limited, and it is required to detect a predetermined target within a certain range, but it is required to detect no more unnecessary objects other than the target. .

As an example in which a problem occurs, scattered light noise, which is not a problem when the weather is good, rises to a level close to the reflection signal from the target in the case of thick fog, and the target detection signal is generated only by the scattered light noise. May be output.

Further, if the reference voltage of the comparator is increased from the beginning in consideration of the case of heavy fog, the target detection range is narrowed even when the weather is good, resulting in a situation where sufficient performance cannot be exhibited.

The object of the present invention is to solve the above mentioned problems,
An object of the present invention is to provide a laser alarm device that can suppress the influence of weather conditions due to the operating environment of the device and can always exert a sufficient function.

[0011]

The laser alarm device of the present invention detects the reflected light of the emitted laser pulse light from the target and outputs an alarm when the detected output exceeds a predetermined reference voltage. In the laser alarm device, the detection output can be compared with a plurality of different reference voltages.

Further, the laser alarm device of the present invention is adapted to eliminate the influence of the meteorological condition in response to the noise level due to scattering or reflection from an object other than the target based on the influence of the meteorological condition of the operating environment. It has a configuration for automatically selecting the optimum one from the reference voltages of.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

The embodiment shown in FIG. 1 includes a laser driver 2, a laser oscillator 5, a transmitting optical section 7, a receiving optical section 9, a detector 10 and a bias circuit 11 which are the same as those in the conventional example shown in FIG. In addition, the controller 1a directly related to the present invention
And a comparator 13a, a reference voltage generator 14, and an AND gate 18.

Next, the operation of this embodiment will be described.

First, basic functions will be described. In the laser alarm device of the present embodiment, the controller 1a inputs the charging instruction 3 and the laser trigger signal 4 to the laser driver 2. As a result, the laser oscillator 5 operates and the pulsed laser light 6 is emitted from the transmission optical section 7.

The reflected laser light 8 reflected by the target is
The light enters the detector 10 in the receiving optical unit 9, is converted into a voltage signal by the detector 10, is further amplified by the amplifier 12, and is input to the comparator 13a.

The input of the comparator 13a is the reference voltage generator 1
4 is compared with the reference voltage 15 selected by 4, and when this level is exceeded, the target detection signal 16 is output, and finally the alarm 17 is output via the AND gate 18.

Next, the specific operation of this embodiment will be described.

This operation consists of two phases. The first phase is the preliminary operation before detecting the target,
One is the actual operation of actually detecting the target. These two phases are switched by the external signal 19 under the control of the controller 1a.

In the preliminary operation for detecting the target, the reference voltage 15 is set to the lowest level initial value.

For example, when the weather is fog, scattered laser light from the fog is detected, and the amplified signal is often used by the comparator 1.
The target detection signal 16 is output when the reference level of 3 is exceeded. However, since it is a preliminary operation here, the controller 1a is controlled not to output the alarm 17.

When the target detection signal 16 is output, the reference voltage generator 14 raises the level of the reference voltage by one step under the control of the controller 1a. By repeating this operation, the reference voltage is set so that the target detection signal is not output. By this setting, the detection signal from other than the target is suppressed so as not to be output, and the detection distance has the maximum value under the operating condition.

Thereafter, the external signal 18 is used to switch to the phase for actually detecting the target, and when the target is detected, the alarm 17 is output.

In this way, it is possible to perform a laser alarm operation that eliminates the influence of weather conditions in outdoor operation.

As a similar example, a plurality of comparators having different reference voltages may be provided and any one of the comparator outputs may be made effective by the controller, and the same function can be easily achieved. Can be secured.

[0027]

As described above, according to the present invention, a plurality of reference voltages are compared with the reflection laser, and the reference voltages are self-selected according to changes in the operating conditions, so that various weather conditions can be obtained outdoors. In addition, there is an effect that the maximum detection distance under the condition can be secured without erroneously detecting the target.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a laser alarm device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional laser alarm device.

[Explanation of symbols]

 1, 1a Controller 2 Laser driver 3 Charging command 4 Laser trigger signal 5 Laser oscillator 6 Pulse laser light 7 Transmission optical part 8 Reflected laser light 9 Reception optical part 10 Detector 11 Bias circuit 12 Amplifier 13, 13a Comparator 14 Reference voltage generation 15 Reference voltage 16 Target detection signal 17 Alarm 18 AND gate 19 External signal

Claims (2)

[Claims] 1. A laser alarm device for outdoor operation, which detects reflected light of emitted laser pulse light from a target and outputs an alarm when the detected output exceeds a predetermined reference voltage,
A laser alarm device, wherein the detection output can be compared with a plurality of different reference voltages. 2. An optimum one of the plurality of reference voltages so as to eliminate the influence of the meteorological condition in response to the noise level due to scattering or reflection from an object other than the target based on the influence of the meteorological condition of the operating environment. The laser alarm device according to claim 1, wherein the laser alarm device is automatically selected.