Thermal printer

Abstract

Abstract A thermal printer provides first and second sub-frames pivotally supported on a main frame to provide access to a dot resistance heater for cleaning and easy removal of the respective structures. Each structure is releasably fixed in operating position in which a resilient drive roller on the second sub-frame presses the thermally sensitive paper against the printer head. The same roller is driven by a motor on the second sub-frame and moves the paper along the paper path by friction drive. The paper moves between a fixed and rotatable knife on the second sub-frame actuated by crank and linkage connection to the core of a solenoid whose winding is fixed on the main frame. A curved guide plate directs the paper toward an opening and into a surface which imposes an S curve on the paper. The S curve allows enlargement of a storage loop in the paper in case the opening is blocked. su The present invention relates to a thermal printer for the rapid production of tickets, or the like. It particularly has relation to an advantageous configuration of the printer which facilitates cleaning, efficient drive and feed of continuous stock through the printer, efficient cut-off of the continuous paper tape and prevention of jamming of the cut-off mechanism. There has been a need for devices to quickly and accurately produce tickets or receipts in situations where the printer output needs to be rapidly generated but also must be arranged and formated so that the printed product cannot be easily counterfeited. One application of such printers is in the printing of tickets where the print-out is not sequential or otherwise predetermined but some original data input is required. Such an application is the printing of betting tickets, either at a race track or in an off-track situation. Another application is lottery tickets. The printer finds considerable advantage where the ticket contains variable data, preferably in fixed format, but which must be adjusted in some respect in a custom fashion, as when it must contain variables selected on the spot by a bettor, and the ticket must be rapidly generated. Thermal printers have been designed in the past for printing such tickets on thermally sensitive paper. Such printers include line printers and matrix printers which provide dot resistance elements in at least a row across the path of the tape which can be selectively heated to generate numbers, letters, or other characters or marks incrementally. The present invention relates to a thermal printer having mechanical features or associated structural improvements making such a printer more useful and more acceptable in the environment in which it is commonly used. A common problem with thermal printers, because the papers employed are chemically coated to accept heat induced marking, is that the printer head or surface of the resistance elements over which the coated paper moves becomes covered with paper particles and chemical debris which interfere with its efficient operation. Various techniques have been suggested for enabling cleaning of the printer head or element. The present invention provides a very simple means whereby the printer head is supported on a sub-frame structure which is able to be pivoted out of its operational position to a cleaning position in which the thermal print elements are exposed and can be easily wiped or otherwise cleaned by techniques prescribed by the particular manufacturer in each given case. In particular, the present invention relates to providing such a printer head on a support platform which extends beyond the region of the printing element or head. The platform is supported on a sub-frame which, in turn, is rotatably supported to rotate about pivot means on the frame. Such rotation enables the printer head to be rotated away from its operational position to an alternative cleaning position when releasable means holding it to the frame in operational position are removed. Preferably, the pivot means is an axle or aligned pins on the frame. The support platform is removable from the sub-frame. The support frame has a support member which snugly engages but does not surround the pin or other coaxial member. Because the support member is provided only on the side of the pin toward the work surface, the support platform which rests on another structure of the sub-frame at its opposite end may be removed from the sub-frame, or the like, if desirable or necessary for repair or replacement of the printing elements, for example. Another aspect of such printers which has caused a problem in printers of the prior art has been the drive. The present invention provides an extremely simply drive in the form of a driven resilient roller which, in effect, urges the continuous coated tape into good printing contact against the print elements by direct pressure. This resilient roller is also a friction element which drives the tape, which advantageously has a lower coefficient of friction on the coated or treated surface and a higher coefficient of friction on the opposed surface against which the resilient roller bears. Since the drive is so simple, it allows the roller itself to be driven by a very lightweight motor directly or through simple gearing. Preferably, the driven roller and its driving motor are supported on a second common sub-frame, separate from the sub-frame of the printer elements. In accordance with the present invention, it is preferred to provide a second sub-frame for supporting the roller and the motor, as well as cut-off means to cut the tape to form a ticket of desired length. Also, in accordance with the present invention, this second sub-frame is preferably pivotally supported on the main frame in a manner similar to the support of the printer supporter sub-frame by means which permits pivoting out of the operational position to an alternative position from which easy removal for work on or replacement of the parts of the sub-frame is faciliated. A further aspect of the present invention has to do with the cut-off means which is also advantageously included on the second sub-frame. In accordance with preferred embodiments of the present invention, the cut-off device is a rotary knife which operates in combination with a fixed knife. The rotary knife has an axis of rotation parallel to the friction drive roll and preferably permits the paper tape to pass between the rotatable cut-off knife and the fixed knife, both of which are preferably provided on the sub-frame. The present invention also provides guide means on the sub-frame for guiding the tape up toward an access slot or opening in a printer housing or cover through which tickets which have been printed and cut off may be removed. This opening ordinarily constitutes a slot through which the ticket may pass, and it is a common problem that the person taking the ticket, whether he be the customer or a machine operator, may sometimes block the opening. When this is done, the tendency is for tickets to pile up and jam the cutter so that the machine will fail to function properly. In accordance with the present invention, however, the frame is located in its operating position such that paper tape is guided toward an opening along a curved path. This curved paper path strikes a deflection surface adjacent the opening. The paper path is changed by the deflection surface into an S-shaped path such that pressure against the paper end will cause its S form to flex and resiliently yield, enlarging at least one loop of the S as a storage loop as it continues to be fed through the printer until it is cut off. Therefore, an individual tickeet which is held within the printer by closing the opening will be retained and accommodated by assuming the S shape. Then, due to its inherent resiliency, when the opening is released, the ticket will release the energy stored in the enlarged loop and cause the end of the ticket to pop out of the opening and be readily removable. The configuration also permits a pile or conforming stacking of the tickets so that even if the hold up is prolonged, within reasonable limitation, several tickets can be printed out and cut off and assume a conforming S curvature in the stack without jamming the machine.

Inventors

• 👤 Robert Lees

Bibliographic Details