Thermal head control method and device for making a stencil master plate

A thermal head control device for controlling a thermal head, consisting of an array of heat generating elements arranged along a primary scanning direction, for making a stencil master plate by perforating a thermal stencil master plate sheet for each line and moving said stencil master plate sheet in a secondary scanning direction relative to said thermal head in the manner of a dot matrix, comprising:

• measuring means for measuring a physical quantity representing a temperature of said thermal head;
• determining means for determining if the representative temperature of said thermal head measured by said measuring means is lower than a prescribed value or not;
• and
• control means for driving said thermal head with a rated power so as to perforate said stencil master plate sheet to form each line of said stencil master plate if said representative temperature is greater than or equal to said prescribed value and for pre-heating said thermal head with a power which would not substantially affect said stencil master plate sheet before driving said thermal head if said representative temperature is lower than said prescribed value.

A thermal head control method for controlling a thermal head, consisting of an array of heat generating elements arranged along a primary scanning direction, for making a stencil master plate by perforating a thermal stencil master plate sheet for each line and moving said stencil master plate sheet in a secondary scanning direction relative to said thermal head in the manner of a dot matrix, comprising the steps of:

• (a) measuring a physical quantity representing a temperature of said thermal head;
• (b) determining if the representative temperature of said thermal head measured by said measuring step (a) is lower than a prescribed value or not;
• (c) driving said thermal head with power which would not substantially affect said stencil master plate sheet if said representative temperature is lower than said prescribed value;
• (d) perforating said stencil master plate sheet to form a line of said stencil master plate by driving said thermal head with a rated power;
• (e) driving those heat generating elements which were not heated in said previous perforating step (d) with a power which would not substantially affect said stencil master plate sheet;
• (f) moving said stencil master plate sheet relative to said thermal head in said secondary scanning direction;
• and
• (g) repeating the above steps (a)-(f) for each subsequent line of said stencil master plate.

A thermal head control method for controlling a thermal head, consisting of an array of heat generating elements arranged along a primary scanning direction, for making a stencil master plate by perforating a thermal stencil master plate sheet for each line and moving said stencil master plate sheet in a secondary scanning direction relative to said thermal head in the manner of a dot matrix, comprising the steps of:

• measuring a physical quantity representing a temperature of said thermal head;
• determining if the representative temperature of said thermal head measured by said measuring step is lower than a prescribed value or not, wherein said prescribed value is varied depending on an ambient temperature;
• driving said thermal head with power which would not substantially affect said stencil master plate sheet if said representative temperature is lower than said prescribed value;
• perforating said stencil master plate sheet to form a line of said stencil master plate by driving said thermal head with a rated power;
• moving said stencil master plate sheet relative to said thermal head in said secondary scanning direction;
• and
• repeating the above steps for each subsequent line of said stencil master plate.

A thermal head control method for controlling a thermal head, consisting of an array of heat generating elements arranged along a primary scanning direction, for making a stencil master plate by perforating a thermal stencil master plate sheet for each line and moving said stencil master plate sheet in a secondary scanning direction relative to said thermal head in the manner of a dot matrix, comprising the steps of:

• measuring a physical quantity representing a temperature of said thermal head;
• determining if the representative temperature of said thermal head measured by said measuring step is lower than a prescribed value or not, wherein said prescribed value is varied depending on the kind of said stencil master plate sheet;
• driving said thermal head with power which would not substantially affect said stencil master plate sheet if said representative temperature is lower than said prescribed value;
• perforating said stencil master plate sheet to form a line of said stencil master plate by driving said thermal head with a rated power;
• moving said stencil master plate sheet relative to said thermal head in said secondary scanning direction;
• and
• repeating the above steps for each subsequent line of said stencil master plate.