초록 ▼

In the field of blasting, it is often desirable to ignite explosives at various relative times. Such delayed ignition can have advantages in better break up of rock and reduced ground vibration. A principle problem in using the time delay technique is the accuracy rate of a local oscillator which me

In the field of blasting, it is often desirable to ignite explosives at various relative times. Such delayed ignition can have advantages in better break up of rock and reduced ground vibration. A principle problem in using the time delay technique is the accuracy rate of a local oscillator which measures the delay time for each of the delay circuits. In the described system, a calibration interval, independent of any delay time, is transmitted from a control unit concurrently to each of the delay circuits wherein each delay circuit counts the output of its local oscillator during the calibration interval. This local oscillator output is then compared to a predetermined reference count, either at the delay circuit or at the control unit, and a correction factor is established. This correction factor is then applied to a delay count for the individual delay circuit. The delay count is modified to produce a corrected delay count that is utilized individually within the delay circuits to count the output of the corresponding local oscillator for determining the delay time until ignition. This technique utilizes the precise oscillator at the control unit to substantially eliminate the delay errors due to the less precise oscillators within the delay circuits.

대표청구항 ▼

A method of operation for a blasting system having a control unit connected to a plurality of spaced apart delay ignition circuits, each having a unique address and a fuse for igniting an adjacent explosive, the method comprising the steps of: storing in said control unit a table of addresses for sa

A method of operation for a blasting system having a control unit connected to a plurality of spaced apart delay ignition circuits, each having a unique address and a fuse for igniting an adjacent explosive, the method comprising the steps of: storing in said control unit a table of addresses for said delay ignition circuits and a delay time for each delay ignition circuit, transmitting a broadcast address and a negative verify command from said control unit concurrently to all of said delay ignition circuits, monitoring by said control unit to detect a response from any one of said delay ignition circuits, and proceeding with the following steps if no response is received for said transmitted negative verify command within a preset time, transmitting a calibration interval concurrently to all of said ignition delay circuits, counting the output of a local oscillator in each of said delay ignition circuits to produce a calibration count in each said delay ignition circuit, producing a corrected delay count for each of said delay ignition circuits as a function of said local oscillator count, a pre-determined delay time for each delay ignition circuit and a reference count, transmitting a broadcast detonate command concurrently to each of said delay ignition circuits, and upon receipt of said detonate command, each of said delay ignition circuits firing its fuse after a time delay corresponding to the corrected delay count for that delay ignition circuit.