JPH1054881A - Lightning observation device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To surely select and shoot lightning light in a predetermined direction generated at the time of lightning strike. A lightning direction matches a shooting direction of a still camera from a difference signal based on a change in an electromagnetic field detected by loop coils and a light intensity signal detected by a photodetector. It is determined whether or not the lightning light in the shooting direction can be shot by the still camera 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightning observation apparatus for photographing a discharge path during a lightning strike, and more particularly, to an apparatus for generating an activation signal for a photographing apparatus when a lightning generation direction coincides with a photographing direction. .

[0002]

2. Description of the Related Art Lightning (lightning) generated during a lightning strike is usually recorded using a photographing device such as a still camera or a video camera. Since the imaging device needs to be activated according to the occurrence of lightning light, the light intensity of the incident lightning light exceeds a predetermined threshold value using a photodetector having directivity in a direction coinciding with the imaging direction. In this case, a shooting start signal is generated.

[Problems to be solved by the invention]

However, in order to provide the photodetector with the same directivity and incident area as the photographing apparatus, even if the detectable area is limited by a hood, it is activated by lightning in an unintended direction due to light wraparound due to reflection or the like. There is a problem in that a signal is generated, which results in wasteful consumption of a recording medium such as a photographic film due to aerial photography and an increase in analysis time due to an increase in recording data.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a lightning observation apparatus capable of photographing only lightning within a photographable area.

[0005]

That is, in order to achieve the above object, the present invention provides an electromagnetic field detecting means in which two loop coils cross each other, and an electromagnetic field detecting means in one area divided by the loop coils. A photographing means arranged so that a direction coinciding with the plane of symmetry of the loop coil is defined as a photographing direction; a light detecting means arranged such that the photographing direction of the photographing means is an incident direction; and an electromagnetic field detecting means. Control means for generating a start signal of the photographing means when a lightning generation direction determined from the detected difference signal and the light intensity signal detected by the light detection means coincides with the photographing direction of the photographing means. I made it.

[0006]

The erroneous detection of the light detecting means due to the wraparound is corrected by the electromagnetic field detecting means, and a start signal is generated only for the lightning light within the photographable area.

[0007]

Embodiments of the present invention will be described below. FIG. 1 is a top view showing one embodiment of the present invention in terms of the positional relationship between a loop coil, a photodetector, and a photographing device. In the drawings, reference numerals 1a and 1b denote two loop coils for detecting an electromagnetic field. The planes are arranged perpendicular to the ground and cross each other, preferably perpendicular to each other, and are configured to detect a vector of an electromagnetic field when a lightning discharge occurs.

Reference numeral 2 denotes a photographing device, which in this embodiment is configured as a still camera equipped with a motor drive mechanism, and symmetrical surfaces of the two loop coils 1a and 1b, that is, an area divided by the loop coils. The direction perpendicular to the plane to be equally divided, that is, the direction I in this embodiment, is set as the photographing direction.

As shown in FIG. 2, the still camera 2 includes a lens 22 and a mechanical shutter 23 on one side of a camera case 21. A roll film 24 is disposed at the focal point of the lens 22. A motor drive mechanism 25 attached to the bottom of the camera case 21 winds up the roll film 24 by one frame after photographing.

Reference numeral 3 denotes a liquid crystal shutter disposed on the front surface of the lens 22, which receives a driving signal from a liquid crystal shutter driving circuit 19 driven by a photographing start signal generating circuit 18 to be described later, and switches to a light transmitting state capable of photographing. It is configured to adjust.

Reference numeral 4 denotes a light detector for detecting lightning, such as a photodiode, whose incident direction is limited by a hood 4a so as to coincide with the photographing range of the still camera 2, and detects the photographing direction of the photographing device 2. It is arranged to be a possible area.

FIG. 2 shows an embodiment of a lightning observation device according to the present invention. In the drawing, reference numeral 11 denotes a difference detection circuit, in which the signals of the respective loop coils 1a and 1b are supplied to a preamplifier 10a. 10b, and outputs a difference signal of each coil to the first comparison circuit 12.

The first comparison circuit 12 includes a difference detection circuit 11
Is compared with the threshold value Es set by the threshold value setting circuit 13, and the result of the comparison is output to the control device 16.

The second comparison circuit 14 compares the light intensity signal P due to the lightning light detected by the photodetector 4 with the threshold value Ps set by the threshold value setting circuit 15,
The result of the comparison is output to the control device 16.

The control device 16 comprises an azimuth determination circuit 17 and a photographing start signal generation circuit 18. The azimuth determination circuit 17 includes a signal from the first comparison circuit 12 and a signal from the second comparison circuit 14. In response to this, it is determined whether or not the lightning is within the region including the direction I, out of the four divided regions in FIG. 1, and the photographing start signal generation circuit 18 is activated when the lightning light coincides with the photographing direction. is there.

The photographing start signal generating circuit 18 outputs a start signal to the liquid crystal shutter driving circuit 19 and drives the motor drive mechanism 25 after a lapse of time required for photographing a series of lightning phenomena to drive the roll film 24. To output a hoisting signal for winding up.

The liquid crystal shutter drive circuit 19 is configured to receive a start signal and apply a drive signal for adjusting the level at which the liquid crystal shutter 3 becomes transparent so that the liquid crystal shutter 3 can take a picture to the liquid crystal shutter 3.

In this embodiment, first, in a state where the mechanical shutter 23 of the still camera 2 is opened, the shooting direction is matched with the direction I in this embodiment, and the directions of the loop coils 1a and 1b and the photodetector 4 are matched. Is adjusted so that lightning in a region including the I direction can be detected.

The electromagnetic field generated by the lightning discharge is detected by the loop coils 1a and 1b, and the difference value E is
Level E1 as shown by the solid line in FIG.
To E4 (E1 = E3 <E2 = E4). That is, when the lightning discharge occurs in the region including the direction I, the electromotive forces generated in the loop coils 1a and 1b become substantially equal, and the difference value becomes the level E1, which is lower than the threshold value Es. .

When the lightning discharge occurs in the region including the direction III, the electromotive force generated in the loop coils 1a and 1b is substantially equal because the direction is exactly opposite to the region including the direction I described above. The difference value is as low as the level E3.

On the other hand, when a lightning discharge occurs in a region including the II direction or the IV direction, the electromagnetic field mainly crosses one of the loop coils, so that an electromotive force is generated between the loop coils 1a and 1b. A large difference occurs, and the level of the difference value E
2, E4 becomes a high level exceeding the threshold value Ps.

On the other hand, the lightning light is detected by the photodetector 4 which coincides with the photographing region of the photographing device, and the light intensity value P due to the lightning discharge in each region including each direction has a level as shown by a dotted line in FIG. P1 to P4 (P1> P2 ′ = P4 ′> P2 = P4>
Take the value of P3). That is, when lightning is generated in a region including the direction I, the light detector 4 receives the lightning properly, and the light intensity value P1 indicates a high level exceeding the threshold value Ps.

On the other hand, when lightning is generated in a region including the direction III, since the lightning direction is opposite to the region including the direction I, the lightning light from behind the photodetector 4 is slightly sneak. The intensity value P3 is at the lowest level.

Further, when the lightning light is generated in a region including the II direction or the IV direction, the photodetector 4 is located sideways with respect to the lightning light. And the light intensity values P2 and P4 are at intermediate levels.

However, the boundary point between the region including the direction I and the region including the direction II, or the region including the direction I and the region
When lightning is generated at a boundary point with the region including the V direction, the light intensity value P is slightly lower than the light intensity value P1 from the region including the I direction, but higher than the light intensity values P2 and P4. This indicates the level values P2 'and P4'.

To cope with this, the threshold value setting circuit 1
3, the threshold value Es for the difference value E is set to the lowest level E in the region including the I direction and the region including the III direction.
1, set slightly higher than E3, and the threshold value setting circuit 15 sets the threshold value Ps for the light intensity value P to
The level values are set slightly lower than the level values P2 'and P4' in the region including the II direction and the region including the IV direction.

The azimuth determination circuit 17 makes a determination as shown in Table 1 based on the comparison signals from the first and second comparison circuits 12 and 14, and determines whether the lightning strike point is in an area including the I direction. Can be determined. That is, as can be seen from the determination table in Table 1, when P1 ≧ Ps and E1 ≦ Es, it is possible to determine that the lightning strike point is a region including the I direction, and in other cases, It is determined to be one of the regions including the II direction to the IV direction. In particular, I
A lightning strike occurring in a region including the direction, a lightning strike occurring in a region including the II direction and a region including the IV direction adjacent to the region including the I direction can be distinguished to prevent aerial photography.

[0028]

[Table 1]

That is, in the region including the II direction or IV
A lightning strike occurs in a region near the boundary with the region including the direction I in the region including the direction, and the light intensity values P detected by the photodetector 4 are changed to the high level values P2 ′, P4 ′ (P1 ≧ P2 ′). =
Even if P4 ′ ≧ Ps), there is a large difference in the electromotive force between the loop coils 1a and 1b, and the difference values E2 and E4 are high (E2 = E4> Es).
The relationship between the light intensity value P and the difference value E when lightning strikes in a region including the direction, P1 ≧ Ps, and E1 ≦ Es can be clearly identified.

In this way, the lightning strike point coincides with the shooting direction of the still camera 2 by the azimuth determination circuit 17.
Only when it is determined that the region includes the direction, a start signal is output from the shooting start signal generation circuit 18 to the liquid crystal shutter drive circuit 19, and a drive signal having a level of transparency enough to capture lightning light is output from the liquid crystal shutter drive circuit. 19 to the liquid crystal shutter 3 to capture lightning light.

When a preset time has elapsed from the start of photographing, the control device 16 reduces the voltage applied to the liquid crystal shutter 3 to a value at which the roll film 24 is not exposed to light, and then operates the motor drive mechanism 25. Then, the roll film 24 is wound up to prepare for the next lightning light photographing.

In the above embodiment, the photographing device and the photodetector are arranged only in one area divided by the two loop coils. However, as shown in FIG.
An imaging device and a photodetector are respectively arranged in four regions in a direction coinciding with the symmetry plane of the two loop coils, and a difference signal from the loop coil and a light intensity signal from a photodetector attached to each imaging device are arranged. By determining in combination with
It is obvious that lightning strikes in multiple directions can be taken by using a single set of loop coils to minimize aerial photography.

[0033]

As described above, according to the present invention, an electromagnetic field detecting means in which two loop coils cross each other,
A photographing means arranged within one area divided by the loop coil and defining a direction coincident with the plane of symmetry of the loop coil as a photographing direction, and a photographing direction of the photographing means arranged as an incident direction; When the lightning generation direction determined from the difference signal detected by the electromagnetic field detection means and the light intensity signal detected by the light detection means matches the shooting direction of the shooting means, Control means for generating a start signal.
Based on the light intensity signal from the photodetector and the difference signal from the loop coil, the direction of lightning generation is identified, preventing erroneous shooting of lightning generated outside the shooting range and eliminating unnecessary consumption of photographic film. be able to.

[Brief description of the drawings]

FIG. 1 is a top view showing an embodiment of a lightning observation device according to the present invention in terms of an arrangement relationship among a loop coil, a photodetector, and a photographing device.

FIG. 2 is a block diagram showing one embodiment of a lightning observation device of the present invention.

FIG. 3 is a diagram showing a relationship between a difference signal detected by a loop coil for each lightning strike point and a light intensity signal detected by a photodetector.

FIG. 4 is a diagram showing another embodiment of the present invention.

[Explanation of symbols]

 1a, 1b Loop coil 2 Steel camera 4 Photodetector 16 Controller

Claims (2)

[Claims] 1. An electromagnetic field detecting means in which two loop coils are crossed with each other, and a direction in one area divided by the loop coils and coinciding with a plane of symmetry of the loop coils is defined as an imaging direction. An arranged photographing means,
Light detection means arranged so that the shooting direction of the shooting means is the incident direction, and a determination is made from a difference signal detected by the electromagnetic field detection means and a light intensity signal detected by the light detection means. A lightning observation apparatus comprising: a control unit that generates a start signal of the photographing unit when a lightning generation direction coincides with a photographing direction of the photographing unit. 2. The light detection means and the photographing means are arranged in a plurality of areas divided by the loop coil, and the control means controls the light detection direction by each of the light detection means and the loop coil. The lightning observation device according to claim 1, wherein a determination is made and an activation signal is output to the corresponding photographing unit.