Speed control of a label printing apparatus

A label printing apparatus for printing image data onto an elongated recording medium comprising:

• memory means for storing image data to be printed onto said recording medium;
• recording means for recording the image data dot wise onto said recording medium in subsequent printing cycles;
• conveying means for conveying the recording medium relative to said recording means;
• means for determining the number of dots to be activated in each printing cycle;
• and
• speed adjustment means for controlling the speed of said conveying means based on the volume of image data stored in the memory means or the number of dots to be activated and available for printing in the present printing cycle, wherein said speed adjustment means drives said conveying means at a minimum print speed when the memory means is provided with printing data at a rate which is lower than that at which data is sent to said recording means when printing at the minimum print speed, the speed adjustment means switching the power of said conveying means off before the volume of data in the memory means and available for printing becomes zero, the recording means being controlled to print the data stored in said memory means onto said recording medium when the conveying means stops entirely, wherein the recording means is controlled by a recording medium movement sensing means for sensing the movement of the recording medium, and wherein the speed adjustment means controls the conveying means to resume conveying and the recording means to resume recording once the volume of data stored in said storing means and available for printing exceeds a predetermined threshold level.

A label printing apparatus for printing image data onto an elongated recording medium comprising:

• a memory for storing image data to be printed onto said recording medium;
• a print head for recording the image data dot wise onto said recording medium in subsequent printing cycles;
• a motor for conveying the recording medium relative to said print head;
• a print buffer for determining the number of dots to be activated in each printing cycle;
• and
• a speed adjuster for controlling the speed of said motor based on the number of image data stored in the memory or the number of dots to be activated in the present printing cycle, wherein the speed adjustment means calculates a first predetermined speed dependent on the volume of image data dots stored in the memory means and available for printing and a second predetermined speed dependent on the number of dots to be activated in the present printing cycle and the number of dots activated in a previous printing cycle, the speed adjustment means reducing the second predetermined speed linearly with respect to a maximum speed depending on a value V when the value V exceeds a predetermined threshold level, wherein the value V is determined according to the equation
• V=A.times.B+C,
• wherein C is the number of dots to be activated in the present printing cycle and B is the value V of the previous printing cycle and A is between 0 and 1.