Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – For fault location
Reexamination Certificate
2001-10-26
2003-11-11
Patidar, Jay (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
For fault location
C324S691000, C324S713000
Reexamination Certificate
active
06646445
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and a method for determining a property of a thermal head including a plurality of heating devices.
2. Description of the Related Art
A thermal line printer (hereinafter referred to as a “thermal printer”) that is conventionally known uses, for example, a thermal head having a plurality of heating resistors linearly arranged to thermally record pictures, characters and the like on thermal paper of predetermined size. The thermal printer is composed of such main components as a printer engine PE including a thermal head and a paper feeder and a printer controller PC
2
for controlling a printing process.
As shown in
FIG. 4
, for example, the printer engine PE is comprised of a thermal head
1
, a motor
2
of a paper feed mechanism, and a sensor
3
for detecting the position of the thermal head. There are various model types of printer engines PE, and respective model types (or models) have different properties such as the rated voltage of the thermal head, the resistance of each heating resistor, the number of dots, and the number of driver ICs (that is, the number of blocks) for controlling current-carrying through the heating resistor or the like. Accordingly, the printer controller for controlling each of the different printer engines is provided with a control table which stores control information used for controlling each model optimally. Based on the control information depending on the printer engine to be controlled, the printer controller performs the control, thereby being capable of making the printer controller be commonly used.
The printer controller PC
2
is provided with a CPU
10
for controlling the entire printer engine PE, a RAM
11
for storing various control constants, a ROM
12
for storing the control tables dedicated to each of the various models of printer engines PE, and a model setting switch
13
typically composed of a DIP switch and the like for setting a specific model of printer engine PE. By selecting the setting of the model setting switch
13
, the printer controller PC
2
can be adapted to a plurality of models of printer engines.
Furthermore, the printer controller PC
2
includes a voltage measuring circuit
14
for carrying out a measurement of a power supply voltage which is supplied to the printer controller PC
2
and the printer engine PE by an external power supply device
20
, and a head configuration measuring circuit
15
for carrying out a measurement of the configuration of the thermal head
1
of the printer engine PE. The head configuration measuring circuit
15
measures specifically the resistance of each heating resistor, the number of dots, the number of blocks or the like of the thermal head
1
.
Note that, the printer engine PE is detachably connected with the printer controller PC
2
via a predetermined connector.
Incidentally, when the conventional printer controller PC
2
is connected to the printer engine PE, the above-described model setting switch
13
has to be manually operated to make the setting suitable for the printer engine PE to be connected. Therefore, there is a problem that it is inconvenient in an assembly process in a plant or in a user's replacement of the thermal head.
Furthermore, there is another problem that the inaccurate setting of the model setting switch
13
induces a breakage of the printer engine PE or a mis-action (error) of the printer engine PE, resulting in a failure in normal printing. In particular, when the printer controller PC
2
performs an initial diagnostic process of the thermal head immediately after power-up, in the case where the model setting switch
13
is not set normally, the printer engine PE includes a fear that some errors occur to result in a failure of printing. The reason will be described below.
In the procedure shown in the flowchart of
FIG. 5
, the conventional printer controller PC
2
performs an initial diagnostic process. First, the printer controller PC
2
reads the setting of model setting switch
13
on power-up at step S
100
and the process advances to step S
101
. The printer controller PC
2
reads the control table for the set model from the ROM
12
at step S
101
, and it stores the control table into the RAM
11
as a memory for control at step S
102
, and thereafter the process advances to step S
103
. In the case where the model setting switch
13
is not accurately set, the printer controller PC
2
reads a control table which does not match the thermal head connected at step S
101
, and it stores an inaccurate control table into the RAM
11
at step S
102
.
The voltage measuring circuit
14
carries out a measurement of the voltage applied to the printer engine PE at step S
103
, and thereafter the process advances to step S
104
. At step S
104
, the printer controller PC
2
compares the difference between the measured voltage and the content of setting in the model setting switch
13
. When the voltage matches the content of setting, the process advances to step S
106
, and when the voltage does not match the content of setting, the printer controller PC
2
performs an error process to display an error, output a notifying beep and the like at step S
105
.
However, as described above, in the case where the model setting switch
13
is inaccurately set, there arises a difference between the content of setting itself in the model setting switch
13
to be compared with the measured voltage and the property of the printer engine PE connected. Accordingly, the printer controller PC
2
has a problem in that it is impossible to perform an accurate determination at step S
104
. That is, the printer controller PC
2
includes such troubles that it performs the error process even in a state where the voltage primarily matches the setting, or in contrast, it keeps performing the process in spite of a state where the voltage does not match the setting.
Further, the head configuration measuring circuit
15
carries out a measurement of the configuration of the thermal head
1
(the number of dots or the number of blocks) at step S
106
, and the process advances to step S
107
. At step S
107
, the printer controller PC
2
compares the difference between the measured configuration of the thermal head and the content of setting in the model setting switch
13
. When the voltage does not match the content of setting, the printer controller PC
2
performs an error process at step S
108
, and when it is determined that the voltage matches the content of setting, it completes the processing. However, as in the case of the previous step S
104
, when the model setting switch
13
is inaccurately set, similarly the printer controller PC
2
has a problem in that it is impossible to perform an accurate determination at this step S
107
.
Therefore, when the model setting switch
13
is inaccurately set, the printer controller PC
2
has a probability in that it cannot accurately perform the initial diagnostic process of the thermal head. In the worst case, there are such probabilities in that the printer engine is not entirely actuated due to the applied voltage which does not match the specification of the printer engine PE, or in that the printer engine inaccurately works because of the setting of the control table for the other models.
A DIP switch or the like composing the model setting switch
13
has a problem in the structure where the above-described mis-setting easily occurs. Furthermore, from the viewpoint of a reduction in the cost of the thermal printer, there is a request for reducing the number of components as many as possible by removing the model setting switch itself if possible.
SUMMARY OF THE INVENTION
The present invention has been devised for solving the above-described problems. An object of the present invention is to provide a determining apparatus and determining method for determining the model type of a thermal head in a thermal printer capable of automatically performing a determination of a thermal head model type without a model type se
Adams & Wilks
Nguyen Vincent Q.
Patidar Jay
Seiko Instruments Inc.
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