Typewriting machines – Means auxiliary to typewriting function – Indicator means
Reexamination Certificate
1998-04-01
2001-02-20
Yan, Ren (Department: 2854)
Typewriting machines
Means auxiliary to typewriting function
Indicator means
C400S701000
Reexamination Certificate
active
06190071
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printer with a sensor for detecting a printing medium to be set in the printer, and more particularly to a cleaning mechanism for cleaning the sensor and a control method for the cleaning mechanism.
2. Description of the Related Art
For printing on forms, slips or the like, the printer has been widely used as the output terminal of POS systems, computer systems, personal computers and others. Some printers print each on a printing sheet, e.g., a roll paper, which is preset therein, and some printer include each a mechanism for printing on cut sheets, e.g., validation sheets, which are set one by one therein by the user.
The printer usually uses a photo sensor to check as to if a printing paper is set properly or at a correct position before the printing by the printer. The photo sensor includes the combination of a light emitting element, e.g., LED, and a light sensing element, e.g., a photo transistor. Those elements are arrayed while being spaced from each other. When a printing sheet is set in the printer, it interrupts a light beam emitted from the LED. By the interruption of the light beam, the photo sensor detects the setting of the printing paper in the printer.
The conventional printer suffers from the following problem. Various dusts such as paper dust or the like are accumulated on and around the sensor, and the accumulated dust interrupts the optical path of the light beam. As the accumulation of the dust progresses, the output signal of the photo sensor decreases. When the output level of the photo sensor goes below a predetermined signal level, the printer mistakenly recognizes this state as the setting of the printing paper, and erroneously operates.
Further, strict requirements are imposed on recent printers; high reliability, and some measures being taken for environmental issues such as long life, use of regenerated papers being acceptable and so on. Dusts generated therein are easily increased in those printers which are designed to satisfy such requirements.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a printer which periodically removes various dusts such as paper dust, for example, accumulated on the sensor, to thereby ensure stable and reliable paper sensing by the printer.
Another object of the present invention is to provide a printer which prints out a state of the dust removal to thereby inform the user of the current dust removal state.
According to one aspect of the present invention, there is provided a printer (first printer) having a print head and a platen disposed opposite to the print head, in which the platen is opened and a printing medium is inserted into a gap created by opening the platen, and the platen is closed and in this state the printer prints on the printing medium, the printer comprising a detector for detecting the printing medium inserted in the printer; and a mechanism for removing foreign matters present within a detecting range of the detector while being linked with the opening and closing motions of the platen. When the printing medium detection is required, the opening and closing operations are performed. By linking the opening/closing operation of the platen with the operation of removing foreign matters from the detector, a detection error by the detector can be reliably eliminated.
The printer may further comprise: a plunger for opening and closing the platen; and a lever being coupled with the plunger, the lever turning with a forward movement and retractive movement of the plunger, the lever being coupled with the dust removing member, when the lever is turned, the dust removing member rectilinearly moving in a reciprocative manner (the printer thus constructed will be referred to as a second printer). The second printer facilitates the linking of the opening/closing operation with the foreign matter removing operation.
The first printer may further comprise: a comparing circuit for comparing an output signal level of the detector with first and second predetermined signal levels; and a control circuit for causing the dust removing mechanism to remove foreign matters when the output signal level of the detector is between the first and second predetermined signal levels; wherein when the output signal level of the detector is smaller than the first predetermined signal level, it is judged that the printing medium is inserted, and when the output signal level is larger than the second predetermined signal level, it is judged that the printing medium is not inserted (this printer will be a third printer). The second predetermined signal level is larger than the first predetermined signal level. The third printer determines if an object to be judged is a printing medium or foreign matter, and if it is foreign matter, the printer removes the foreign matter.
The first printer may be constructed such that the detector is a photo interrupter consisting of a light emitting element and a light receiving elements, the elements being disposed in opposition to each other.
The first printer may be constructed such that the dust removing member passes the adjacent area of the detector with the opening and closing movements of the platen (this printer will be referred to as a fifth printer). The fifth printer may be constructed such that the dust removing member passes under the detecting range of the detector.
The fifth printer may also be constructed such that the dust removing member moves away from the detector when the platen is opened, and moves toward the detector when the platen is closed or such that the dust removing member moves toward the detector when the platen is opened, and moves away from the detector when the platen is closed.
The first printer further comprises a visual presenting mechanism for visually presenting an operating state of the dust removing mechanism. In this case; it is preferable that the visual presenting mechanism includes a second printing medium and a printing mechanism for printing on the second printing medium. It is therefore possible to inform the user of the state of removing foreign matters.
According to another aspect of the present invention, there is provided a method for controlling a printer having a print head, a platen disposed opposite to the print head, and a detector for detecting a printing medium inserted into between the print head and the platen, the method comprising the steps of: opening the platen in preparation for the insertion of a printing medium; detecting the printing medium inserted in the printer; closing the platen after the printing medium is detected; printing on the printing medium after the platen is closed; and removing foreign matters present within a detecting range of the detector in association with the opening and the closing of the platen.
The control method further comprises: a step of comparing an output value produced in the detecting step with first and second predetermined values; and a control step for removing foreign matters when the output value is between the first and second predetermined values; wherein when the output value is smaller than the first predetermined value, it is judged that the printing medium is inserted, and when the output value is larger than the second predetermined value, it is judged that the printing medium is not inserted. In this case, the foreign matter removing operation comprises a predetermined number of opening and closing operations of the platen to thereby remove the foreign matters more positively.
The control method further comprises; a step of transporting the printing medium in the medium discharging direction; and a step of detecting the printing medium after the medium transporting step terminates; wherein the printing medium is detected the foreign matter removing step is executed. When the printing medium is transported in the medium discharging direction and it is detected out, although the printing medium does not exist within a detecting range the detected one can be
Mochizuki Hidetake
Teradaira Mitsuaki
Yamada Masahiko
Nixon & Vanderhye P.C.
Seiko Epson Corporation
Yan Ren
LandOfFree
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