Patent Publication Number: US-4733980-A

Title: Printer

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a printer and, more particularly, to a printer of heat-sensitive transfer type, which is intended to have a thin structure. 
     2. Description of the Prior Art 
     A printer of heat-sensitive transfer type according to the prior art has heretofore used a detachable ink ribbon cassette which holds an ink ribbon. This ink ribbon cassette has its spools wound with a number of turns of tape-shaped ink ribbon, which is unwound, when used, and brought into a printing position. 
     This printing position is defined by a platen and a printing head, which are arranged in upright positions so that the ink ribbon brought into a printing zone is positioned to have an upright width. 
     Upon application of heat by the printing head, on the other hand, the ink is melted to stick to the printing paper. In order to prevent the ink ribbon and the printing paper from sticking, there is provided in the ink ribbon cassette a mechanism for peeling off the ink ribbon from the printing paper. 
     Since the printing head and the platen are arranged in the upright positions, however, it has been difficult to make the printer thin because reduction in its height is restricted. On the other hand, it has been difficult to provide the ink ribbon cassette for use with a thin printer with a suitable ink ribbon peeling mechanism 
     SUMMARY OF THE INVENTION 
     The present invention has been conceived in view of the background thus far described and has an object to provide a printer which can be made thin although it is equipped with the ink ribbon peeling mechanism. 
     In order to achieve this object, according to the present invention, there is provided a printer of heat-sensitive transfer type for use with an ink ribbon cassette to print a sheet of printing paper with the ink ribbon of said cassette, comprising: a platen for holding thereon the printing paper; a printing head made movable over said platen for bringing said ink ribbon into close contact with said printing paper held on said platen to thermally transfer the ink of said ink ribbon onto said printing paper; and a carriage made movable longitudinally of said platen, while carrying said printing head thereon, in accordance with the printing operation of said printing head, wherein the improvement comprises ink ribbon peeling means arranged around the sides of said printing head and carried together with said printing head by said carriage for sequentially peeling off that portion of said ink ribbon, which is used for said printing operation, from said printing paper. 
     According to the present invention, the ink ribbon used for the printing operation is sequentially separated from the surface of the printing paper by the ink ribbon peeling means which is arranged in the horizontal position. As a result, the ink ribbon can be peeled off without attaching the peeling means to the ink ribbon cassette. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Other objects, features and advantages of the present invention will become apparent from the following description made with reference to the accompanying drawing, in which: 
     FIG. 1 is a perspective view showing one embodiment of the present invention; and 
     FIG. 2 is an enlarged section showing the detail of the printing head and its neighborhood of the embodiment of FIG. 1. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention will be described in the following in connection with its one embodiment with reference to the accompanying drawing. 
     As shown in FIGS. 1 and 2, a printing head 1 is arranged in a horizontal position to form a thin printer (the whole structure is not shown) and is carried on a carriage (not shown) so that it can move over a platen 2. The printing head 1 is framed on its sides by the legs of an ink ribbon peeling member 3. This ink ribbon peeling member 3 is joined in the form of a letter &#34;U&#34; to the carriage. An ink ribbon 4 is guided over the legs of peeling member 3 onto the printing surface of the printing head 1. On the other hand, a sheet of printing paper 5 is held on the platen 2 which is arranged in a horizontal position. 
     An ink ribbon cassette 10 charged with the ink ribbon 4 is arranged horizontally and is equipped with guide means for orienting the ink ribbon horizontally in the printing zone so that it may be used with the thin printer body. 
     The ink ribbon cassette 10 is constructed of a case 11 having box-shaped compartments at its right and left sides. From the two side ends of the case 11, there project a pair of guide portions 12a and 12b, each of which is equipped therein with a plurality of ribbon guide rollers. In one of the box-shaped compartments, there is disposed a supply spool 13 which has a rotatable core wound with an ink ribbon. In the other of the box-shaped compartments, on the other hand, there is disposed a take-up spool 14 which has its core rotatable for taking up thereon the ink ribbon as it is used. The latter spool 14 is rotationally driven in accordance with the printing state by a drive mechanism mounted in the printer body, after the ink ribbon cassette 10 has been attached to the printer body. 
     The guide portion 12a is equipped with: a sloped guide roller 15a for guiding the upright ink ribbon 4 let off from the supply spool 13 in an upward direction; a reversing guide roller 16a for reversing the upward ink ribbon 4 coming from the sloped guide roller 15a in a downward direction; and a turning tensile guide roller 17a for turning the downward ink ribbon 4 coming from the reversing guide roller 16a  into a horizontal direction and for tensioning the same. Likewise, the guide portion 12b is equipped with a sloped guide roller 15b, a reversing guide roller 16b and a turning tensile guide roller 17b, which have respectively the same functions and are symmetrically arranged to guide the ink ribbon 4 from the printing position to a guide roller 18. 
     With the construction thus far described, in the ink ribbon cassette 10, the ink ribbon 4 let off from the supply spool 13 is turned at 90 degrees in the upward direction by the sloped guide roller 15a, reversed in the downward direction by the reversing guide roller 16a, turned in the horizontal direction by the turning tensile guide roller 17a, and tensioned by the pairing turning tensile guide rollers 17a and 17b. These guide rollers 17a and 17b define the printing zone inbetween. The ink ribbon 4 coming from the guide roller 17a is turned from its horizontal to vertical positions by the guide roller 17a. The ink ribbon 4 thus turned is reversed from its upward to downward positions by the guide roller 16b and is then guided into the upright position until it is taken up on the take-up spool 14 through the guide roller 18. 
     When the ink ribbon cassette 10 thus constructed is to be attached to the printer body, the ink ribbon 4 existing in the printing zone is pulled along the lower surface of the printing head 1 such that its portions located at the two sides of the head 1 ride on the two legs of the ribbon peeling member 3. In other words, the ink ribbon 4 runs between the printing head 1 and the ribbon peeling member 3. 
     If the main switch of the printer is turned on in this state, the carriage is moved to carry the printing head 1 to a print starting position. Following this movement, the ink ribbon peeling member 3 is also carried to the print starting position. When the heating resistor of the head 1 is then energized, the carriage is responsively driven to carry the head 1 in the direction of the lines of the printing paper 5. The ink ribbon peeling member 3 is also carried so that the used ink ribbon 4 contacting closely with the printing paper 5 is sequentially peeled off by the drive of the head 1. 
     As has been described hereinbefore, according to the present invention, the U-shaped peeling member 3 is provided to surround the printing head 1 and is carried by the carriage. As a result, it is possible to make a thin printer and to simplify the structure of the ink ribbon cassette. 
     Moreover, the ink ribbon corresponding to the horizontal arrangements of the printing head and the platen can be peeled off in accordance with the driving state of the head. As a result, the problems accompanying the horizontal arrangement of the ink ribbon in the printing zone can be solved to permit making a thin printer.