Coherer iRadio Conductorj@
New Coherer@ipatent 4295698j
The coherer was used as a detector about 100 years ago. Coherer is a device that detects electromagnetic wave. It consists of a very small quantity of nickel fillings lying loosely between a couple of metal electrodes. The electric resistance of a couple of electrodes is usually high (The coherer is almost insulated state.) however once it receives the shock electromagnetic wave generated from the aerial spark discharge, the coherer responds sensitively, and the electric resistance decreases rapidly. (The coherer becomes almost conduction state.)
The coherer was used as a detector about 100 years ago. Coherer is a device that detects electromagnetic wave. It consists of a very small quantity of nickel fillings lying loosely between a couple of metal electrodes. The electric resistance of a couple of electrodes is usually high (The coherer is almost insulated state.) however once it receives the shock electromagnetic wave generated from the aerial spark discharge, the coherer responds sensitively, and the electric resistance decreases rapidly. (The coherer becomes almost conduction state.)
After Herts (Ger.) discovered the electromagnetic wave through experiment in 1888. Branly (Fr.) found that the electric resistance decreases when some pieces of metal powder received the electromagnetic wave in 1890. He supposed that the reason is because the metal powder "coherer"  Branly has named the coherer "Radio Conductor" It is the origin of "coherer" It is said that "radio" means the electric wave in the beginning. Lodge (U.K) presented that the coherer is a wave detector in 1894. In those days there were not a convenient detector except the coherers, so they had been produced as detectors for practical use , and used in many countries.
The coherer has some fatal faults as a device which detects electromagnetic wave of communication.
Z The sensitivity varies every time.
Z The characteristic will change in a short term There are a lot of secular changes.
Z It is necessary to give the vibration to the coherer in order to return it to its former
    state, so we can not raise the transmission rate.
Z The malfunction by the lightning is awful. (We can not decode Morse. ) 
Z It is not possible to use it for a wireless telephone.  
Fleming (U.K.) a@had a hard time in the improvement of the coherer, and he invented the diode vacuum tube as the fundamental solution in 1904.Picard(U.S.)invented the crystal detector in 1906. It is said that the coherer completed his roles as a practical detector just dozens of years after it launched.
In comparison with breakthrough of the crystal detector or the diode vacuum tube, coherer has not be researched or made improvements as a practical device, so it has been appeared in one corner of school textbooks. The coherer is unusable as a device for the communications now, but Hirakawa Institute of Technology paid attention to an excellent character as the device for detecting the lightning.
Z There is sensitivity to static electricity.  It can detect the lightning before it strikes.
Z It has high sensitivity of the shock electromagnetic wave (impulse voltage)         
    such as the lightning. It has low sensitivity of the broadcast communication wave.
Z The device itself is highly selective for the lightning. It can detect the lightning even  
    under  strong electromagnetic field.
Z The turning on operation is extremely fast and the turning on current is  extremely 
    large.
Z Impulse withstand voltage is high. It is hard to break down when close lightning strikes. 
    The device itself works a surge absorber.
We solved a fault of old coherer and wanted to make a thunder detector with the high durability. And we put a study on an experiment about coherer more than six years. 
When the result was never given and was beginning to give up it, we succeeded in producing good Schottky barrier diode of the comparatively stable sensitivity in materials of old coherer and suddenly developed the situation. 
And we completed one movement model about coherer, and the result of the experiment supported it.
As for the coherer, the electrode and metal powder are exposed to air at the time of production. 
On an electrode of the coherer and the surface of the metal powder, a thin oxidation film and hydration film are made naturally by the oxygen and water of this air. 
This thin oxidation film and hydration film are semiconductors, and the movement of the coherer is caused by the destruction of this semiconductor film.
Even if the thickness of the film was heterogeneous, and it put an electrode and metal powder during a vacuum because it just used a semiconductor film formed naturally in the air in the old coherer, it was the unstable thing which occurred of the big individual difference.

A figure is an electric equivalent figure of the coherer. 

When we increase the voltage above a certain level between electrodes of the coherer, it becomes equal that a diode and resistance were connected to series like a figure by an electric field. 

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An electrode of the coherer and metal powder or contact between the metal powder are point contact. The semiconductor film of the part which a point came in contact with causes a breakdown phenomenon by the voltage and an electric current is concentrated here and drifts. 
The semiconductor film of the part which a point came in contact with is destroyed at last by an increasing electric current, and the metal which there is under a semiconductor film becomes a joining state, and, in the electrode interval, it is it with a conductive state. The movement of so called coherer is fixed after a breakdown phenomenon was caused not the voltage how much electric current flows through the point contact part.
In other words the main electric characteristic of the coherer flows between breakdown voltage (=Vb) and electrodes, and it is defined in electric flow quantity to do namely electric energy (=W dt) between electrodes by a conductive state.
The lower figure showed an example of the reaction of the coherer for the impulse. 
The movement of the coherer is divided into three so that a figure shows it.
The upper photograph possess a certain new coherer which we developed in a resistor to limit an electric current, 1.2/50(sec) 40(kV peak) It is a voltage reply characteristic when it added an examination surge wave pattern. 
The lower photograph is in condition not to install a resistor to confine an electric current to the same coherer, and it is a voltage reply characteristic when it added the same examination surge wave pattern. 
The voltage that coherer works lowers than the upper thing and, with the voltage that this coherer causes a breakdown phenomenon, agrees almost.
Hirakawa Institute of Technology pursed the principle of operation of coherer by a mordern semiconductor theory, and we successfully have made it to revive as a practical electronic device in our time by using new materials instead of nickel and aluminum.
New small coherer CS-1FF
@CS-1FF Specifications @iMicrosoft Word) 
Thunder detector@iCoherer Lightning Detectorj
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