JPS598872B2 - proximity warning device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a proximity warning device that uses an electric field.

Conventionally, collisions have often occurred between moving objects such as cranes or between moving objects and other buildings due to operator carelessness, and countermeasures have been taken to prevent this. If there is another object within a certain distance of the moving object or building, it is equipped with a device that detects it and issues an alarm, and the alarm alerts the operator. By doing this, methods are being taken to prevent the above-mentioned collisions from occurring.

However, since the above-mentioned type of alarm device uses light, ultrasonic waves, high frequency waves, etc., the following disadvantages occur.

In other words, devices that use light or ultrasonic waves tend to malfunction due to external conditions such as dust or wind. It can only be used to detect the distance to an existing object, and is unsuitable as a collision prevention device in a free space.

Furthermore, although devices that use high frequencies do not have the above drawbacks, due to their wavelength, the nodes and antinodes intersect in various ways, which may cause large errors in distance detection depending on the location, and the antenna tension may vary depending on the location. However, it is not suitable for practical use because of its limitations.

The present invention aims to eliminate the above-mentioned drawbacks.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a state in which an approach warning device according to the present invention is installed on each of two crane booms moving in a free nitrogen space.

In the figure, an antenna 2 is attached to a crane boom 1, and the antenna 2 is schematically shown as a rectangle in the figure, but is actually an approach warning device placed at an appropriate position within the crane having the crane boom 1. It is electrically connected to 3.

Similarly to the crane boom 1, the other crane boom 11 is provided with an antenna 12 that electrically communicates with an approach warning device 13 disposed at an appropriate position within the crane having the crane boom 11.

In the figure, a broken line 4 indicates an electric field generated by the antenna 2, and a dashed line 14 indicates an electric field generated by the antenna 12.

FIG. 2 is a diagram schematically showing the circuit configuration of the proximity warning devices 3, 13.

In the figure, the low frequency generated by the oscillation circuit 21 is divided into appropriate time intervals by the timing adjustment circuit 22.
The signal is sent to the amplifier 23 intermittently.

The low frequency amplified here is transmitted from the antenna 25 via the matching circuit 24.

The electric field obtained in this way is as shown in the graph shown in FIG.

In the graph, a waveform 26 shows the transmitted electric field, and the transmission time t1 and cutoff time t2 shown therein.
is set by the timing adjustment circuit 22.

Note that in this graph, the vertical axis represents the electric field strength E, and the horizontal axis represents the time t.

On the other hand, the electric field waves received by the antenna 25 are sent to the amplifier 27 via the matching circuit 24, where they are amplified.

The amplified received wave is then sent to a bandpass filter 28, where only its low frequency components are passed.

The low frequency thus obtained is then divided at appropriate time intervals in the timing adjustment circuit 29, and is intermittently applied to the DC converter 3.
Sent to 0.

At this time, the time t3 for the timing circuit 29 to pass the received wave and the time t4 for blocking the received wave are determined by the timing control circuit 29.
1, and the control is based on the transmission time t1 of the transmission wave set by the timing adjustment circuit 22.
and cutoff time t2.

That is, control is performed such that the receiving time t3 of the received wave occurs during the cutoff time t2 of the transmitted wave.

Therefore, the received wave 32 is as shown in the graph shown in FIG.
The signal passes through the timing adjustment circuit 29 intermittently.

However, here, in order to make the explanation easier to understand, the transmitted waves shown in FIG. 3 are drawn temporally superimposed.

Note that the vertical axis represents the electric field strength E1, and the horizontal axis represents the time t.

The thus obtained intermittent reception wave is then converted into DC by a DC exchanger 30, and then sent to a compensation circuit 33 having a peak hold function and the like.

The received wave that has passed through the compensation circuit 33 is branched, and one side is sent to the indicator 34 and the other side is sent to the alarm 36 via the amplifier 35.
sent to.

Crane booms 1 and 11 move in free space while emitting electric fields 4 and 14 from attached antennas 2 and 12, as described above.

Then, when both crane booms 1 and 11 approach and, for example, the antenna 2 enters the electric field 14, the received waves obtained thereby pass through each of the above-mentioned processes in the alarm device 3,
Finally, the indicator device 34 and alarm device 36 in the alarm device 3?
This action activates them.

Therefore, the operator of the crane boom 1 is alerted by the alarm issued by the alarm device 36, and the operator of the crane boom 1 is alerted by the alarm issued by the alarm device 36.
Crane boom 1 and crane boom 1 according to the indicated value of 4.
You can specifically know the distance between 1 and 1.

The same applies to the crane boom 11, and when the antenna 12 enters the electric field 4 emitted from the antenna 2, the indicator device 34 in the alarm device 13 and the alarm 3
6 allows the operator to detect or confirm the presence of the crane boom 1.

As mentioned above, since the alarm device according to the present invention detects the distance between objects using an electric field, it is not affected by external conditions such as dust or wind.

In addition, since the electric field has no blind spots or directivity, this alarm device can be used not only between objects moving on the same straight line, or between an object moving on a certain straight line and an object on that straight line. , it can also be applied between objects moving within a free space between each other.

Furthermore, in this case, there is no need to strictly consider impedance matching between the antenna and the transmitter/receiver as in the case of using high frequencies, so the length and number of antennas,
The installation location etc. can be set very freely.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing the electrical system of the embodiment shown in FIG. 1, FIG. 3 is a graph showing the intermittent state of transmitted waves versus time, and FIG. The figure is a diagram showing the intermittent state of received waves over time in comparison with transmitted waves. 4, 14... Electric field, 21... Oscillation circuit, 2, 12, 25... Antenna, 22, 29...
. . . Timing adjustment circuit, 31 . . . Transmission/reception timing control circuit, 3, 13 . . . Approach warning device.

Claims (1)

[Claims] 1. A low frequency oscillation circuit for generating an electric field, an antenna for transmitting and receiving an electric field, a timing adjustment circuit for allowing the transmitted wave to pass for a specified time, a timing adjustment circuit for allowing the received wave to pass for a specified time, and both of the above timings. A proximity warning device comprising a transmission/reception timing control circuit for controlling an adjustment circuit, and appropriately switching between a transmission time of an electric field emitted by the device itself and a reception time of reception of an electric field emitted from another electric field source.