Abstract:
A closing apparatus for a thermal printer having a fixed chassis portion and a closable cover supporting on the inside thereof a paper drive roll fixed inside of the cover for positioning itself, when the printer is closed, in a seat associated with the chassis portion and having a bottom with a level wall for locking the paper drive roll and the seat together for locking the chassis and cover together in their closed condition for preventing the paper drive roll from getting out in case of accidental pushes and consequently prevents the cover from opening, and the paper drive roll and a thermal printing head cooperate to hold the paper between the paper drive roll and the thermal printing head while the cover is closed.

Description:
BACKGROUND OF THE INVENTION 
     The invention is concerned with a closing apparatus for a thermal printer. More particularly, this invention is concerned with the prevention of damage to the thermal printer due to an accidental opening of a cover, a falling of the printer or movements due to random vibrations. 
     Thermal printers generally include a fixed chassis portion and a cover associated with the chassis so that the cover and chassis together can enclose the printer. The fixed chassis portion is provided with all the printing devices, and fixed in its inside is a paper drive roll. A cover is provided to cover the various parts and with the chassis together provide for a complete closure. 
     In the printing art, these are known as apparatuses in connection with the closing method of the cover but up to the present there is no known solution to the problem of avoiding damage when the cover is opened and damage is caused. 
     BRIEF SUMMARY OF THE INVENTION 
     The closing apparatus according to the invention permits a paper drive roll to be fixed inside the cover to position itself, when the printer is closed, the roll moves in a suitable roll housing seat that locks the paper drive roll so as to prevent the paper drive roll from getting out of the printer apparatus in case of accidental pushes. 
     The seat has a bottom wall which is positioned in the same direction of the closing apparatus both when the printer cover of the printer is opened and access to the printer is provided or when the printer cover is closed and when the printer cover is opened and is moved during operation in the roll rotation direction. This permits the cover to maintain the roll in a fixed position on the seat bottom due to the force exerted by the roll, during its rotation in a clockwise direction, which causes the creation of a downwards push which helps to block the paper drive roll in the roll housing seat. As the cover is closed or moved from its open position to its closed condition, the roll is moved from one end of the roll housing seat to the other end of the seat, so that when the cover is open, the roll may be rotated, and when the cover is closed the roll is locked in the seat. 
     When the cover is finally closed and in its closed condition, the printer is in standby condition and blockage of the printer is created, produced by the shape of the roll housing seat, that absolutely prevents the roll from exiting or going out from the seat and consequently, the roll housing seat and paper drive roll cooperate together to lock the printer cover to the chassis and prevent the printer cover from opening and exposing the printer. 
     The direction of movement of the paper drive roll in response to the direction of the moving force of the paper drive roll, which is parallel with the seat bottom, helps to generate a push that keeps the paper drive roll on the bottom and blocking it. 
     When the printing phase begins, the paper drive roll brings itself or moves itself into the printing position. In the printing position, a possible outside force (for example a printer falling, vibrations, pushes or other cause) can actuate the paper drive roll and, according to the invention, the paper drive roll and the bottom wall of the seat together oppose such outside force. 
     In the direction of opening or closing of the printer cover, the same seat wall for the paper roll. The moving force of the paper drive roll is parallel to the seat bottom wall, and the moving force of the paper drive roll generates a push that keeps the roll on the bottom wall of the seat and blocks the movement of the paper drive roll to prevent the cover from opening. 
     The last force to be generated by the rotation of the paper drive roll on itself keeps the cover locked. 
     Thermal rings are provided on a thermal print head. The paper on which printing is to take place is kept pressed between the thermal print head and the paper drive roll by the push actuated by the thermal rings of the thermal head on the paper. 
     The closing apparatus, is suitable for any kind of thermal printer with a fixed chassis portion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic showing of a thermal printer and a closing apparatus therefor, and shows a cover in an opening phase or position; 
     FIG. 2 is a schematic view or showing of the thermal printer showing the beginning of the closing phase with the printer head on its fulcrum and with the cover open and at the beginning of the closing phase; 
     FIG. 3 is a schematic view or showing of the printer in its closed phase with the cover in its completely closed condition on the printer chassis or closed phase and showing the paper drive roll into the seat and moving or going with the thermal rotating head on its fulcrum; 
     FIG. 4 is a schematic view or showing of the closed position of the cover on the thermal printer with the paper drive roll penetrating into the housing seat  4  and with the paper drive roll locked to the seat and the cover closed and the beginning of the printing phase of the thermal printing apparatus for the commencement of the printing phase and showing when the shaft of the printing roll moves from the position M in FIG. 6 a  to the position E in FIG. 6 b  with safety closing; 
     FIG. 5 is a partial schematic showing of the thermal head and the printing line shown in dashed horizontal line designated  6   a , and with the printer and the cover in their closed condition. 
     FIGS. 6 a  and  6   b  show the steel shaft  3   b  on which the paper drive roll is carried and placed proximate to the housing seat  4  at the bottom shown at the left of level of horizontal wall  4   a  thereof and the cover  2  closed during the printing phase, when shaft  3   b  moves from position M at the left in FIG. 6 a  at the left side of the drawing to the position E at the right side in FIG. 6 b  to show a safety closing; 
     FIG. 7 is a schematic view of the different forces which act in the novel safety closing apparatus, and in particular show the steel shaft  3   b which carries the paper drive roll  3  and extends through the drive roll  3  and extends outwardly from the paper drive roll  3  in the position M; 
     FIG. 8 is a view of a conventional thermal printer shown in an enclosure with cover  2  shown in full outline in its closed condition on chassis  1  and with the cover  2  open and shown in dashed outline; and 
     FIG. 9 shows the steel shaft  3   b  in three different positions as it moves during cover closing with respect to seat  4  and downwardly to the level wall  4   a  which forms the bottom or base of the housing seat for controlling the cover closing and prevent accidental pushes and vibrations, as well as an accidental opening of the cover which can damage the printer. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made more particularly to the accompanying drawings which show the presently preferred mode for carrying out the invention. 
     The invention is a closure apparatus for a thermal printer to avoid damage to the printer due to an outside cause which may impart unwanted movement to the thermal printer. 
     The thermal printer includes a fixed chassis portion  1  and a cover  2  operatively associated with and coupled to chassis  1  for closure of the internal printing apparatus, as shown in the closed condition in full outline in FIG.  8  and with the cover  1  in its open condition shown in dashed outline. Cover  2  is hinged at one end by means of a hinged connection  20  to fixed chassis portion  1  which provides support for the printing apparatus as shown schematically. 
     Cover  2  includes a support mechanism  24  for supporting in a backlash way, a paper drive roll  3  for movement of a roll of paper  5  supported on a paper core member  22 . Paper drive roll  3  comprises an outer rubber surface  3   a  and an inner steel shaft having a pair of opposite alternating outwardly from opposite ends  3   b . Outside rubber  3   a  is molded onto the shaft  3   b , and shaft has its opposite ends  3   b  which protrude from the outside rubber surface on both sides of the rubber surface. 
     Chassis  1  includes seat mechanism  4  associated with or forming part thereof, and cover  3  includes a support mechanism  24  coupled to or associated with cover  2  for carrying and supporting paper drive roll  3 . Seat mechanism  4  and paper drive roll  3  cooperate together to form a locking mechanism to lock chassis  1  and cover  2  in their closed conditions. 
     Chassis  1  is provided with housing seat  4  which has a bottom level wall  4   a  to receive the opposite ends  3   b  of the shaft, associated with cover  1 , when shaft ends  3   b  move into housing seat  4  through opening  26  from its open cover position in FIG. 1 (and FIG. 9 dashed outline, to a beginning of closed cover position when the ends  3   b  of the shaft starts to enter a U-shaped opening  4 U to move towards a bottom level wall  4   a . As best seen in FIG. 7, the seat  4 , including the U-shaped opening  4 U with one end  3   b of the steel shaft towards the right side of seat  4  resting on level wall  4   a . The end  3   b  enters into the U-shaped opening  4 U when cover  2  is substantially closed and moves downwardly towards the left side and is seated onto level wall  4   a  of seat  4  in a fully closed condition and moves from the left side towards the right side to a fully closed and locked condition. Level wall  4   a  is parallel to the arrow N, and end  3   b  moves from position M in FIG. 6 a  to position E in FIG. 6 b.    
     As shown in FIG. 5, printing head  6  with a printing line  6   a  forms part of the thermal printing apparatus and paper roll  5 , carried on core member  22  which is to be printed does not adhere to the printing line  6   a . Paper  5  as shown in FIGS. 1 to  4 , is shown as a complete paper roll, rolled upon itself carried by the core member  22  or shaft which forms a central axle so as to be easily unrolled into sheet form for printing. 
     As noted heretofore, the closing phase begins in FIG.  2  and then continues in FIG.  3 . In FIG. 2, as noted, the ends  3   b  of the steel shaft start to enter the housing seat through  4 U in FIG. 2, and then on the left side at the bottom  4   a  in FIG.  3  and then to the right side in FIG.  4 . 
     Thermal head  6  is provided for printing and is provided with a printing line  6   a . Thermal head  6  is carried or supported for rotation on fulcrum  7 . Springs  8  are provided to move the thermal head  6  about fulcrum  7  from the position in FIG. 1 towards paper drive roll  3  to the position shown in FIG. 2 with paper  5 , held between thermal head  6  and seat  4 . 
     DESCRIPTION OF OPERATION 
     During the opening of the cover  2  (FIG. 1) the paper drive roll ends  3   b  is not in, but is outside of the housing seat  4  and is not in contact with bottom with level wall  4   a . The paper  5  to be printed does not adhere to the printing line  6   a  of the thermal head  6 . At the beginning the closing phase (FIG.  2  and FIG.  3 ), cover  2  and the end  3   b  of the steel shaft of the paper drive roll  3  enters through opening  4 U and goes into the seat  4  and also causing the thermal head  6  to rotate on its fulcrum  7 . With the cover definitively closed (FIG. 4) and with the thermal printer  1  in stand-by, ends  3   b  of paper drive roll  3  penetrates into the housing seat  4  and reaches the bottom on level wall  4   a , thermal head  6  rotates from the lowering of the roll  3  on its fulcrum  7  and is pushed by the springs  8 , to press the paper  5  between the paper drive roll  3  and the thermal head  6  as seen in FIG. 6 a  and then the ends  3   b  move from the left side to the right side of seat  4  as thermal head  6  moves about fulcrum  7  and rotates in a clockwise direction towards the right as shown in FIG. 6 b.    
     Beginning with the printing phase (FIG. 4) the paper drive roll  3  begins to rotate keeping itself in the printing position E, (FIG. 6 b ) with the seat  4  and placed into operation by the rotation of the paper drive roll  3 . In this printing position E a possible outside force FE (see FIG. 7) to be made on the paper drive roll  3  by an eventual falling or by possible vibrations or pushes is opposed. In the direction A of opening/closing of the cover  2 , to the wall D (see FIG. 7) the seat  4  and the cooperation of and the paper drive roll  3  in the direction N parallel to the bottom  4   a  of the seat  4 , in response to the force F (FIG.  7 ), the moving force of the paper drive roll  3  parallel to the bottom  4   a  of the roll housing  4 . With the cover  2  locked to chassis  1  and the thermal head  6  and paper drive roll  3 , the paper  5  is held between them for printing. 
     The moving force F of the paper drive roll is generated by the rotation of the paper drive roll  3  on itself. The paper  5  is kept compressed between the thermal head  6  and the paper drive roll  3 , when this last one is in the printing position E, by the push actuated by the springs  8  on the same thermal head  6 . 
     The various steps of the closing apparatus and working phases are illustrated in FIGS. 1 to  4 , and show the various phases of opening and closing of the cover and the printing phase. 
     FIGS. 5 to  7  illustrate the housing seat  4  with its bottom  4   a . FIG. 1 shows the cover  2  in its opening phase. 
     FIG. 2 shows the cover  2  at the beginning of the closing phase. FIG. 3 shows the cover definitively, closed. 
     FIG. 4 shows the closed cover with the beginning of the printing phase. 
     FIG. 6 shows the steel shaft  3   b  placed at the bottom  4   a  of the housing seat  4  with the cover definitively closed and during the printing phase when the shaft moves from the position M to the position E with safety closing. 
     The schematic view of the different forces which act in the invented safety closing apparatus are shown in FIG.  7 . 
     FIG. 8 is a view of any suitable openable thermal printer  1  with its cover  2  closed/opened. 
     FIG. 9 is an essential scheme to point out the position of the steel shaft  3   b  on the bottom  4   a  of the housing seat so to disclose a cover closing against accidental pushes and vibrations and to show the cover in its open and closed conditions. 
     While there has been shown and described, what is considered to be the presently preferred mode for carrying out the present invention, various changes and modifications may be made without departing from the scope of the invention.