Incremental printing of symbolic information – Thermal marking apparatus or processes
Reexamination Certificate
1999-09-17
2001-01-09
Tran, Huan (Department: 2861)
Incremental printing of symbolic information
Thermal marking apparatus or processes
C347S194000, C358S439000, C358S468000
Reexamination Certificate
active
06172699
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a thermal printing system (or thermal printer) using a thermal head for changing, according to input printing data, a color of proper parts of a recording sheet by causing the thermal head to come in contact with the recording sheet appropriately so as to print an image corresponding to the input printing data on the recording sheet. Such a recording sheet comprises a paper which is normally specially coated so that the special coating discolors when it is heated. One example of such a thermal printing system comprises a facsimile apparatus. The present invention in particular relates to a thermal printing system having a function for preventing the thermal head from being overly heated and having a function for preventing partial loss of printed information. Such partial loss of printed information may occur because the above-mentioned thermal-head over heating prevention function prevents the thermal head from further heated due to excessive rising of the temperature of the thermal head being detected.
In one example of such a facsimile apparatus according to related art, temperature detecting means such as a thermistor is provided for detecting a temperature of the thermal head. If the detected temperature of the thermal head reaches a predetermined value, operation of a printing strobe is terminated so as to stop heating of the thermal head. As a result of the heating stoppage, overly heating of the thermal head is prevented.
However, termination of the operation of the printing strobe such as mentioned above may result in a partial loss of printed information if the printing strobe operation termination occurs in the middle of the printing work. On the other hand, it may be possible, in order to prevent the termination of the operation of the printing strobe, to provide measures for reducing heat load applied to the thermal head while the printing strobe is operated. Such measures may comprise, for example, changing the resistance value and/or electric current associated with the thermal head, and/or adding a heat radiation plate into the thermal head. These measures are used for preventing heat from accumulating in the thermal head and thus for preventing the thermal head from being overheated. In this method, partial loss of printed information can be prevented but the thus printed information may become degraded due to insufficient heating of the recording (or printing) paper by means of the thermal head. Such insufficient heating may result from the above-mentioned reduction of the energy supplied to the thermal head.
Further, in the facsimile apparatus according to the related art, a printing strobe-width or strobe time-width (hereinafter used to refer to, a time period for which energy is applied to the thermal head) is determined in response to the magnitude of the detected temperature of the thermal head. Thus, a uniformity in the printing density can be realized even though the temperature of the thermal head tends to vary due to certain reasons, such as variation in ambient temperature and variation of current and/or voltage of the power source used for heating the thermal head.
In this method, however, a problem may occur in a case where a portable power source is utilized for heating the thermal head in the facsimile apparatus. The problem may occur due to a variation in the current and voltage of the portable power source, which variation occurs significantly in particular in a power source such as a portable power source. It is difficult to maintain a proper printing density only by altering the printing strobe time-width to correct the variation in the thermal head temperature due to the existence of such a significant variation in the current and voltage of the power source for heating the thermal head.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a thermal printing system in which the problems mentioned hereinbefore are eliminated. As a result, proper protection of the thermal head from over-heating and prevention of partial loss of printed information is simultaneously ensured.
To achieve the object of the present invention, a thermal printing system according to the present invention comprises:
input means for inputting printing data;
detecting means for detecting a current temperature of a thermal head which is used to print information associated with said printing data;
memory means for storing, instead of printing, a data packet of said printing data if it is determined that said current temperature of said thermal head provided by said detecting means results in controlling said thermal head so it is not used to print out said data packet of the printing data.
The printing data once stored in the memory means is then used to print the information associated therewith, the printing being started after the current temperature of the thermal head becomes lowered sufficiently. As a result, partial loss of printed information can be prevented and better printing can be realized.
Another thermal printing system according to the present invention comprises:
detecting means for detecting a current temperature of a thermal head which is used to print information associated with printing data; and
transfer controlling means for reducing a data transfer rate, at which said printing data is transferred from outside to said thermal printing system, if the current temperature of said thermal head is in a predetermined range.
The increasing of the thermal head temperature may be controlled due to the data-transfer-rate reduction. As a result, partial loss of printed information can be prevented and better printing can be realized.
Another thermal printing system according to the present invention comprises:
detecting means for detecting a current temperature of a thermal head which is used to print information associated with printing data; and
transfer repeating means which, instead of causing other printing data to be transferred to said thermal printing system from outside, causes at least a last part of once transferred printing data to be transferred again, after the current temperature of said thermal head is in a predetermined range.
During the time that the transfer of the other printing data is halted and the part of the once transferred data is being transferred again, the printing work may be halted. Thus, the increasing of the thermal head temperature may be controlled. As a result, by using an appropriate printing strobe time-width, better printing is obtained.
Another thermal printing system according to the present invention comprises:
detecting means for detecting a current temperature of a thermal head which is used to print information associated with printing data; and
strobe controlling means for controlling a strobe time width during which said thermal head is heated so as to print the information associated with the printing data, the controlling of the strobe time-width being not only responsive to the current temperature of said thermal head but also responsive to magnitudes of voltage and current of a power source used for heating said thermal head.
The controlling of the printing-strobe time-width responsive to the current temperature of said thermal head and responsive to the magnitudes of voltage and current of a power source results in the strobe-time controlling being carried out properly using information concerning the variation in the energy supplied to the thermal head. As a result, it is possible to prevent the printing data from being unnecessarily thinned out due to the increase in the thermal head temperature.
Other objects and further features of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.
REFERENCES:
patent: 4540295 (1985-09-01), Okunishi et al.
patent: 5220350 (1993-06-01), Fujii
patent: 5353044 (1994-10-01), Nakano et al.
patent: 5361090 (1994-11-01), Suzuki et al.
patent: 59-187876 (1984-10-01), None
patent: 63-40814 (1988-02-01),
Cooper & Dunham LLP
Ricoh & Company, Ltd.
Tran Huan
LandOfFree
Thermal printing system having function for preventing over... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thermal printing system having function for preventing over..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermal printing system having function for preventing over... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2471318