III
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3.2.6
Thermal Head Drive Circuit
Figure 3.2-10 shows the thermal head drive circuit.
The print head used in the PT-1800/1810 integrates a heat generator (consisting of 128
heating elements vertically aligned at 180 dpi) and a built-in driver IC.
Synchronizing with the clock on P02, the CPU outputs print data on P00 in the serial
form. Upon receipt of the P01 signal issued by the CPU, the thermal head drive circuit
latches the print data and drives the heating elements of the thermal head according to
the signal issued from P03. Figure 3.2-11 shows the timing scheme of the thermal head
drive.
Capacitor C12 works as a thermal head overheat protector. It cuts off the P03 signal to
shut down invalid drive current if the signal sticks to the Low level due to any
malfunctions of the programs or the CPU.
Since thermal print heads are very sensitive to heat and the head drive source is not
stabilized, the CPU determines the ON-time length of the P03 signal while monitoring the
head drive source voltage and the ambient temperature (refer to Subsection 3.2.7).
Figure 3.2-10 Thermal Head Drive Circuit
Figure 3.2-11 Timing Chart of Thermal Head Drive
Summary of Contents for PT 1800 - P-Touch 1800 Thermal Transfer Printer
Page 1: ...SERVICE MANUAL MODEL PT 1800 1810 ...
Page 2: ...SERVICE MANUAL MODEL PT 1800 1810 ...
Page 5: ...CHAPTER I SPECIFICATIONS ...
Page 10: ...I 4 n U S A Canada n U K Figure 1 1 2 Key Arrangement 1 ...
Page 11: ...I 5 n Germany n France Figure 1 1 2 Key Arrangement 2 ...
Page 12: ...I 6 n Belgium Figure 1 1 2 Key Arrangement 3 ...
Page 15: ...CHAPTER II MECHANISMS ...
Page 43: ...CHAPTER III ELECTRONICS ...
Page 47: ...III 3 Figure 3 2 1 Block Diagram of Main PCB ...
Page 49: ...III 5 Figure 3 2 3 Timing Scheme and Waveforms of Key Scanning by the CPU ...
Page 62: ...CHAPTER IV TROUBLESHOOTING ...
Page 65: ...IV 2 4 1 3 Troubleshooting Flows 1 Tape feeding failure ...
Page 66: ...IV 3 ...
Page 67: ...IV 4 ...
Page 68: ...IV 5 2 Printing failure ...
Page 69: ...IV 6 ...
Page 70: ...IV 7 ...
Page 71: ...IV 8 3 Powering failure Nothing appears on the LCD ...
Page 72: ...IV 9 ...
Page 73: ...IV 10 ...
Page 74: ...IV 11 4 No key entry possible ...
Page 75: ...IV 12 5 Abnormal LCD indication ...
Page 76: ...IV 13 6 Tape cassette type not identified ...
Page 77: ...APPENDICES Circuit Diagrams A Main PCB B Power Supply PCB ...