Service manual

28 March 2006 IMAGE PROCESSING
6-9
Detailed
Descriptions
6.5.2 THERMAL HEAD
Specifications
• Length 256 +- 0.2 mm
• Number of thermal head elements 3024 dots
• Density of thermal head elements 300 dpi
• Applied voltage Approximately 15 volts
Thermal Head Control
The thermal head has heating elements at a density of 300 dpi. The thermal
heating elements melt the over-coating and polyester film layers of the master,
according to the image signal for each pixel.
The power supply unit applies power to the thermal heating elements. The power
source varies from one head to another since the average resistance of each
element varies. Therefore, when the thermal head or power supply unit is replaced,
it is necessary to readjust the applied voltage with particular values for each
thermal head.
Thermal Head Protection
The thermistor on the thermal head provides thermal head protection, preventing
the thermal head from overheating when processing a solid image. The CPU
detects any abnormal condition when the Start key is pressed, and displays an SC
code on the operation panel as follows:
SC Code Conditions
Detecting
Component
E - 04
Over 65°C
Thermistor
E - 09 More than 4.432V - (Normally, this indicates
that the thermistor has become open, or a
related connector is disconnected.)
Thermistor
E - 10 When the pulse width that controls the thermal
head energy becomes abnormal, master
making stops and this SC lights.
MPU
E-40 The CPU detects an abnormal ID signal from
the thermal head.
MPU