Typewriting machines – Including adjustment for optimum printing plane – By adjustment of platen relative to carriage
Reexamination Certificate
2000-07-27
2003-01-28
Hilten, John S. (Department: 2854)
Typewriting machines
Including adjustment for optimum printing plane
By adjustment of platen relative to carriage
C400S056000
Reexamination Certificate
active
06511237
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printer assembly and a printer for printing on a thermal paper of sheet.
2. Description of the Related Art
Computers are used for many applications, and along with the development of them, various types of printer are required as a peripheral device for output. Conventionally, when the computer was large and could not be moved, printers were large for having a fast processing speed. On the contrary, as personal computers such as a desktop type or the like become popular, printers become small, and desktop size printers have become popular.
Recently, various types of computers have been developed and used. Portable type computers are also developed such as a notebook type to a portable or mobile type such as PDA, that has a size easily put in a pocket. Moreover, as the Internet becomes popular, applications of the computer are widespread in various fields such as information service and communication, and the variation of users are so wide from a specialist to a general user. It is considered that as the population of users increases in the future, computers will be used in daily life in ordinary homes. In addition, the applications of computers are advancing in the direction of handling daily works with a computer at home, such as computerized account settlement, electronic commerce.
As the applications of the computer and the population of users expand, development of a printer for the various users is desired. There is an opinion that the usefulness of prints has decreased as the information and communication are computerized, however, there is a demand at all times for outputting the information obtained by a computer, history of communication and reports of account settlement in the form of printout for confirmation and for storing it temporarily. Moreover, printers being able to connect to portable phones will be required.
As the computer or other mobile equipments increase, it is desired that a printout can be available at any time when desired. Moreover, in a case where a computer is used for daily work such as electronic commerce/transactions or the like, the quantity of information to be printed out is small, and the frequency of using a printer may be low. For such a user, it will be important that the expense for buying a printer is small, and it will be an important factor that a space for installing a printer is not necessary or very small. Demand for a small and lightweight printer is so large among the users of a portable-type computer such as PDA or the portable phone.
Therefore, it is certain that one style desired as a future printer will be thin, compact, lightweight and low-cost. A printer for printing on a thermal (thermosensitive) paper using a thermal head does not require an ink nor ribbon, hence the printing mechanism can be made compact. In particular, a line thermal printer having line thermal head that is a thermal head extending in the paper width direction (in the scanning direction or the line direction), can be made very compact, since a mechanism for moving the thermal head in the scanning direction is not necessary. Hence it is suitable for the above-described demand.
However, in order to realize a printer having a thickness of about 10 mm or less, a mechanism for pushing a printing paper against the thermal head becomes a big problem. Conventionally, a thermal paper is pressed between the thermal head and a platen roller, and the platen roller is rotated. Therefore, the thermal paper is fed while being pressed against the thermal head. To realize a thin printer, it is necessary to reduce the diameter of the platen roller, but if the diameter of the platen roller is made small, the contact area becomes insufficient. Therefore, in order to push or press the printing paper against the thermal head with a predetermined force, it is necessary to press the platen roller with a stronger force. However, if the diameter of the platen roller is made 10 mm or less, the strength of the platen roller becomes insufficient, hence if a pushing force or pressure is increased, distortion or bend is likely to occur.
Moreover, if the diameter of the platen roller becomes 5 mm or less, distortion occurs, hence the platen roller cannot push the printing paper against the thermal head with a uniform force. In particular, when the printer is a line thermal printer, if a force for pressing the thermal paper against the line thermal head differs in the paper width direction, or if a pressure is partly insufficient, the printing quality is deteriorated, and printing becomes impossible.
Such distortion or bend of the roller may be prevented if the roller is divided in the longitudinal direction to expose a shaft of roller and the exposed parts of the shaft are supported by a plurality of bearings. In the case of a platen roller, however, since it is necessary to apply a uniform pressure in the scanning direction, that is longitudinal direction of the roller, the roller cannot be divided in the longitudinal direction. Hence, the above solution cannot be adapted to the platen roller. It is also possible to support a platen roller (rotating body) by several sub rollers disposed in the longitudinal direction to prevent bending or distortion of the platen roller. However, additional thickness is required for installing the sub rollers, hence the second solution is not adaptable to a thin printer.
Under such circumstances, the present inventor has developed a technology for realizing a card-type thermal printer having a thickness of 5 mm or less. As a result, a technology that can clear the above-described problems relating to the platen roller has been developed and a very thin printer having a high printing quality becomes possible.
That is to say, it is an object of the present invention to provide a printing mechanism, that is, a printer assembly, that can reduce the thickness of a line thermal type printer about 10 mm or less, preferably, about 5 mm or less. A further object is to provide a printer having a thickness of 10 mm or less, preferably about 5 mm or less.
SUMMARY OF THE INVENTION
A printer assembly of the present invention, a stationary type platen, that is, a platen or a pressure plate-type platen that does not rotate like a roller is used for pressing a printing paper against a thermal head. In addition, a paper feed or extracting device is provided on the paper ejection side of the non-roller type platen for extracting or pulling the printing paper. The printer assembly of the present invention has a line thermal head extending in the paper width direction, a non-roller type platen disposed so as to face the line thermal head for pressing a thermal paper between the line thermal head and the platen, and a paper extracting device disposed on a paper ejection side of the line thermal head (hereinafter sometimes referred to as “thermal head”) and the platen, the paper extracting device having first and second rollers for extracting the thermal paper between the first and second rollers.
As the non-roller type, it is desired to have a section of a shape tapered toward the thermal head, not a circular shape, such as a semi-circular shape or a trapezoidal shape with the thermal head side becoming narrow. The one side of such shape of platen can be supported easily by a housing or the like, and the other side is pushed against the thermal head. Therefore, adopting an elastic body having the section of above as the platen, reliably apply a predetermined force for pressure to the printing paper. In addition, it is preferable that at least a portion facing the line thermal head is covered with a covering material having a low coefficient of friction, for example, a fluoro resin type material such as Teflon (trademark). By the platen of this invention, a force for pressing the thermal paper against the thermal head can be obtained and the frictional resistance at the time of paper feed can be made small even with the non-roller type platen.
The platen having a plate or a keep plat
Blank Rome Comisky & McCauley LLP
Chau Minh H
F&F Limited
Hilten John S.
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