Ricoh JP3000, Руководство по обслуживанию, Страница: 82 / 693

IMAGE-PROCESSING
2-18
C231/C237/C238 SM
2.2.7 THERMAL HEAD
Specifications
•
Length 260.2 mm
•
Number of thermal head elements 3072 dots
•
Density of thermal head elements 300 DPI
•
Applied voltage Approximately 21 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 (VHD) 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 54
°
C
Thermistor
E - 09
Under - 20
°
C (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