Device of controlling head-drum angle and method therefor

A method for controlling a head-drum angle according head-drum angle device comprising a gain detecting block, a frequency signal output block, a microcomputer, and an angle control means, said method comprising:

• a step for storing a reference gain into a first memory device in the microcomputer;
• a first angle control routine for controlling the head-drum angle according to a tape speed which is detected by said frequency signal output portion;
• a detected membership function for setting a detected membership function by means of a gain difference of a video signal controlled by head-drum angle control;
• a DTF control step for controlling a head tip position of a head when said gain difference is less than a predetermined value;
• a compound routine for setting a compound function by compounding a preset membership function up to maximum value into the detected membership function;
• a weight center detecting step for producing a weight center of the compound membership function;
• and
• a second angle control routine for controlling said head-drum angle by producing a control voltage according to the weight center.

An head dram angle control device for adjusting an angle between a video head located on a head drum and a video tape driven by a capstan motor, said head drum angle control device comprising:

• gain detection means for detecting a gain of a video signal read by the video head;
• frequency detection means for determining a revolution speed of the capstan motor to generate a frequency signal;
• angle control means for adjusting the angle between the video head by moving the head drum and the video tape in response to a control voltage;
• processing means for providing said control voltage in response to frequency signal and then providing said control voltage in response to said gain of the video signal;
• and
• head tip control means for controlling a head tip position in response to said control voltage, wherein said angle control means comprises:
• motor means for operating in response to said control voltage;
• speed reduction means connected to said motor for creating a rotation at a speed less than a speed of said motor means;
• head drum adjustment means connected to said speed reduction means for moving the head drum by a rectilinear movement in response to said rotation of said speed reduction means, and said speed reduction means comprises:
• a worm connected to said motor means and powered by said motor means;
• and
• a worm gear connected to said motor means for creating said rotation.

A method of adjusting an angle between a video head located on a head drum and a video tape driven by a capstan motor, said method comprising the steps of:

• storing a reference gain;
• performing a first adjustment of the head drum based on a frequency of rotation of the capstan motor;
• setting a detected membership function based on a gain difference of a video signal received by the video head;
• setting a composition function by compounding a preset membership function up to a maximum value into said detected membership function;
• controlling a head tip position if said gain difference is less than a first predetermined value;
• and
• detecting a weight center of said composition function;
• performing a second adjustment of the head drum based on said weight center of said composition function.