Abstract:
The present invention relates a sublimation type color printer for printing a paper  11  pulled out from a roll of the paper, cutting the paper to a predetermined length, and outputting the printed paper; wherein the roll is installed into a cassette  22 . The printer comprises a paper transfer means composed of a pair of transfer rollers  23  and the like which can transfer a leading edge of the paper along the front and rear directions between a print stand-by position at the outside of the cassette and a stand-by position in the cassette at the inside of the cassette. Because of this sublimation type color printer, a high-quality picture can be provided at low running cost.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sublimation type color printer used for an output device for a digital photograph. This application is based on Japanese Patent Application No. Hei 11-273456, the contents of which are incorporated herein by reference. 
     2. Description of the Related Art 
     Recently, an output device which can prints a high-quality picture at low-cost is required due to the popularization of the digital camera. In response to this requirement, there is a sublimation type (heat transcription type) color printer which prints a picture on a paper pulled out from a roll of the paper. The adoption of the rolled paper is moreadvantageous than a pre-cut paper in terms of costs. 
     FIG. 6 shows a structure of a conventional sublimation type color printer. In this figure, reference number  1  denotes a paper, reference number  2  denotes a roll of the paper  1 , reference number  3  denotes a platen, reference number  4  denotes a pair of first transfer rollers, reference number  5  denotes a pair of second transfer rollers, reference number  6  denotes a cutter, reference number  7  denotes a paper guide, reference number  8  denotes a thermal head, reference number  9  denotes an ink ribbon, and reference number  10  denotes a paper outlet. 
     In this sublimation type color printer, an operator sets the roll  2  at the predetermined position, and pulls the leading edge of the paper  1  from the roll  2  and manually inserts the tip between the first transfer rollers  4 , in preparation for the operation. Next, the operator gives a paper induction command by operating a switch button (omitted in the Figure) for example, then, an initial operations such as cutting the leading edge of the paper  1  are done, and the tip is finally guided to a print stand-by position PS in FIG.  7 . At this print stand-by position PS, the leading edge of the paper  1  projects slightly from the first transfer rollers  4  in the direction of the second transfer rollers  5 . 
     Further, as a result of giving a print command at the print stand-by position PS shown in FIG. 7, a print operation is carried out and the paper  1  reciprocates within a predetermined printing area. In the normal color print, the printed colors are expressed by stacking the layers of three colors: yellow (Y), magenta (M), and cyan (C), on the paper  1 , and an overcoat layer covers these layers for preventing the fading of the colors. Therefore, in the case of the conventional printer as shown in the Figure, the paper  1  reciprocates four times within the printing area, and the printing by the each ink ribbon which corresponds to the each color of Y, M, and C, and the coating of the overcoat layer are successively carried out. 
     The print operation for a piece of paper is finished in the above-described manner, and then, the paper  1  is cut by the cutter  6  to the predetermined length and ejected from the outlet  10 . In addition, when a series of the above-described work for printing is finished, the leading edge of the paper  1  is returned to the print stand-by position PS in FIG.  7 . 
     In the sublimation type color printer, when dust and the like lie on the paper, or the paper is folded, inks are not transferred on this part and an insufficient transfer occurs. Such an insufficient transfer reduces the commercial value of the output device for the digital camera in which a high-quality picture is required. 
     Furthermore, in addition to the quality requirements of the picture, the reduction of the running cost is also required for the widespread adoption of the pictures by the sublimation type color printer instead of photographs using silver-salt. 
     However, in the conventional sublimation type color printer as described above, the paper  1  at the print stand-by position PS is prepared away from the roll  2 , and therefore, dust can easily accumulate on the paper  1 . Furthermore, the paper  1  at the print stand-by position PS is prepared in a holding manner by the guides  7  and the first transfer rollers  4  which locate the upper and lower sides of the paper  1 , and therefore, the paper  1  can easily become folded. 
     In addition, the dust which attaches to the paper  1  at the production of the paper  1 , the dust which exist in the printer and lies on the surface of the paper  1 , and cellulose which exist in the paper  1  and lies on the surface of the paper  1 , are thought to be the source of the dust which causes the insufficient transfer However, it is difficult to remove this dust completely. 
     The present invention is provided in consideration of the above circumstances, and purposes of the present invention are to provide a sublimation type color printer which can provide a high-quality picture with low running cost. 
     SUMMARY OF THE INVENTION 
     In the present invention, to solve the above-described problems, the following measures are adopted. 
     The present invention relates a sublimation type color printer for printing a paper pulled out from a roll of the paper, cutting the paper to a predetermined length, and outputting the printed paper; wherein the roll is installed into a cassette. The printer comprises a paper transfer means which can transfer a leading edge of the paper along the front and rear directions between a print stand-by position at the outside of the cassette and a stand-by position inside the cassette. 
     In this case, it is preferable that the tip reverts to the stand-by position in the cassette for stand-by when no print command is received during a predetermined time. 
     It is further preferable that the tip is transferred to the print stand-by position when the tip is located in the stand-by position in the cassette and some operation is done by a host of the printer. 
     In this sublimation type color printer, the paper is covered in the cassette when no print command is received because the paper transfer means is provided, and therefore, the adhesion of dust and the like to the surface of the paper decreases, and the folding of the paper in the cassette is prevented. Therefore, the cause of the insufficient ink transfer is solved and a high-quality a picture can be provided with low running cost using the rolled paper which is advantageous in cost. Furthermore, the total time for the print operation is not increased because the tip is transferred to the print stand-by position by some operation of the host. 
     The present invention also relates a sublimation type color printer for printing a paper pulled out from a roll of the paper which is installed in a cassette by reciprocating the paper within a predetermined print area, cutting the paper to a predetermined length by a cutter, and outputting the printed paper. The printer comprising a plurality of dust collection rollers which have adhesive surfaces and provided for attachment to the transference course of the paper between the cassette and the cutter, and respectively provided to a position adjacent to the paper outlet of the cassette and to a position adjacent to the front of the cutter. 
     In this case, it is preferable that the dust collection rollers are provided at the outlet of the print area. 
     It is further preferable that at least one of the dust collection rollers has a means for detecting the transference situation of the paper. 
     In this sublimation type color printer, dust on the paper is removed by the dust collection rollers before the print. Furthermore, the desirable material for the dust collection can be employed for the dust collection rollers without consideration for the reverse transcription toward the dust collection rollers because the dust collection rollers are provided at the outlet of the printing area. In addition, the abnormal transference of the paper is detected and the appropriate measure can be carried out because the means for detecting a transference situation of the paper is provided on the dust collection rollers. 
    
    
     BRIEF EXPLANATION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram of the first embodiment of the sublimation type color printer of the present invention. 
     FIG. 2 shows the sublimation type color printer in FIG. 1 at the stage that the leading edge of the paper is located at the print stand-by position. 
     FIG. 3 shows the sublimation type color printer in FIG. 1 at the stage that the leading edge of the paper is located at the stand-by position in the cassette. 
     FIG. 4 is a schematic diagram of the second embodiment of the sublimation type color printer of the present invention. 
     FIG. 5A is a side view of the embodiment of the detecting means for detecting the moving state of the paper. 
     FIG. 5B is a front view of the disc of the detecting means. 
     FIG. 6 is a schematic diagram of the conventional sublimation type color printer. 
     FIG. 7 shows the sublimation type color printer in FIG. 6 at the stage that the leading edge of the paper is located at the print stand-by position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the sublimation type color printer of the present invention will be explained below with reference to Figures. 
     In the first embodiment of the present invention shown in FIG. 1, reference number  11  denotes a paper, reference number  12  denotes a roll of the paper  11 , reference number  13  denotes a platen, reference number  14  denotes a pair of first transfer rollers, reference number  15  denotes a pair of second transfer rollers, reference number  16  denotes a pair of third transfer rollers, reference number  17  denotes a cutter, reference number  18  denotes a paper guide, reference number  19  denotes a thermal head, reference number  20  denotes a ink ribbon, and reference number  21  denotes a paper outlet. 
     In the first embodiment, the roll  12  is composed by the wound paper  11  and inserted into the cassette  22 , which is set into a printer main body PR. This cassette  22  is detachable from the printer main body PR, and is installed in the predetermined position of the printer main body PR after the installation of the roll  12  in the predetermined position of the cassette  22 . 
     Furthermore, in the inside of the cassette  22 , a pair of paper supply rollers  23  are provided adjacent to a paper outlet  22   a . The paper supply rollers  23  have a supply roller axial gear  23   a , which has a same axis as that of one of the paper supply rollers  23 . This supply roller axial gear  23   a  engages with a paper supply gear  2 , 4  which is provided at the side of the printer main body PR, when the cassette  22  is installed in the predetermined position of the printer main body PR. The paper supply gear  24  has a stepping motor which is omitted in the Figure. In addition, the paper outlet  22   a  of the cassette  22  is connected to a paper inlet  25 , which is provided at the printer main body PR for guidance of the paper  11  to the paper guide  18 . 
     Meanwhile, in the Figure, reference number  26  denotes a roll gear that is fixed on the axis for supporting the roll  12 , and reference number  27  denotes a rewind gear that engages with the roll gear  26 . The paper  11  can be transferred in the forward direction in accordance with the transference of the paper  11  to the printer main body PR side by rotating the paper supply rollers  23 , which have the same axis as the supply roller axial gear  23   a  that is driven by the paper supply gear  24 , and also can be transferred in the backward direction in accordance with the rewind of the paper  11  by rotating the roll  12  simultaneously with the rotation of the roll gear  26 , which is driven by the rewind gear  27 . As a result, a paper transfer means which can transfer the leading edge of the paper  11  between the “print stand-by position PS” at the outside of the cassette  22  (refer to FIG. 2) and the “stand-by position in the cassette CS” at the inside of the cassette  22  (refer to FIG. 3) as described below is composed. Furthermore, the rewind gear  27  is provided at the printer main body PR side and has a driving source, which is omitted in the Figure. The rewind gear  27  is engaged with the roll gear  26  when the cassette  22  is installed. 
     The operation of the sublimation type color printer having the above-described structure is explained below. 
     First, the operator installs the cassette  22  in which the roll  12  is installed and the leading edge of the paper  11  is inserted between the paper supply rollers  23 , in the predetermined position of the printer main body PR. Next, the operator pushes a paper sending switch (not shown in Figure), and thereupon, the stepping motor is operated and the paper supply rollers  23  are driven, and the leading edge of the paper  11  is sent to the printer main body PR. The leading edge of the paper  11  is introduced into the paper inlet  25  from the paper outlet  22   a , and guided to a cutting position which is predetermined at the paper outlet  21  side by the cutter  17 , through the paper guide  18 , the first transfer rollers  14 , the second transfer rollers  15 , and the third transfer rollers  16 . The leading edge of the paper  11  which is sent to the cutting position is cut by the operation of the cutter  17 . 
     After that, the paper  11  reverts to the print stand-by position PS, which is located between the second transfer rollers  15  and the third transfer rollers  16  in case of the embodiment of FIG.  2 . In this embodiment, the stand-by position PS is determined the above position because the print is preformed by transferring the paper  11  from the stand-by position PS along a printing direction shown in arrow P, and therefore, the print stand-by position PS can be changed in compliance with the printing direction of the printer and the like. In addition, the sagging of the paper  11  is prevented by the paper guide  18 , which is omitted in FIG.  2 . Normally, the print operation is started from the print stand-by position PS and paper  11  reciprocates four times within a predetermined print area, and the print of the layers of Y, M, and C and the overcoat layer are successively carried out. The printed paper  11  is sent to the paper outlet  21  and cut to the predetermined length by the cutter  17 , and is output as a sheet of printed paper. When the cutting by the cutter  17  is finished, the leading edge of the paper  11  reverts to the print stand-by position PS again, and the same motions are repeated in case of the print operation is continued. Furthermore, the print operation for the predetermined number of paper is finished, the leading edge of the paper  11  is reversed to the print stand-by position PS and is on stand-by during the predetermined time. 
     When the above-described waiting time at the print stand-by position PS exceeds a predetermined time, that is, there is no further print command during a predetermined time, the leading edge of the paper  11  reverts to the stand-by position in the cassette CS in FIG.  3 . At this time, the roll gear  26 , which is driven by the rewind gear  27 , rotates to rewind the paper  11  around the roll  12  until the leading edge of the paper  11  is located adjacent to the paper supply rollers  23  in the cassette  22 , and the paper  11  is on stand-by at this position. As a result, the waiting time of the paper  11  at the printing area (transference course), which is located outside of the cassette  22 , does not exceed the predetermined time, and therefore, the capability of adhesion of dust on the surface of the paper  11  is decreases greatly in comparison to the conventional printer. 
     Furthermore, the paper  11  in the stand-by position in the cassette CS has no folding part such as the part which is attached the platen  13  at the print stand-by position PS, and therefore, there is no worry that the paper  11  will be folded at the stand-by position in the cassette CS. 
     Next, the operation in the case that the printer receives the print command when the leading edge of the paper  11  is located on the stand-by position in the cassette CS is explained below. This print command is normally is outputted by a host (a personal computer and the like) in which the sublimation type color printer is connected. Therefore, in this case, by starting the operation that transfers the leading edge of the paper  11  in the stand-by position in the cassette CS to the print stand-by position PS simultaneously to the starting of the operation of the key or touch-panel of the host, the operation for transference is finished before the processing of the host is finished. 
     According to this procedure, the paper  11  is already on stand-by in the print stand-by position PS when the print command has been received, and the print operation can be started immediately. Hence, even the leading edge of the paper  11  is hidden in the stand-by position in the cassette CS for preventing the attachment of dust, the time for transference of the tip to the print stand-by position PS is saved, and the total time for the print operation is not increased. 
     Next, a second embodiment of the present invention will be explained with FIG.  4 . 
     In this embodiment, dust collection rollers  30 ,  31  have adhesive surfaces that are provided so as to attach the surface of the paper  11  which is subjected to print, at the transference course between the cassette  22  and the cutter  17 . This dust collection rollers  30 ,  31  are driven by the transferred paper  11  which is attached to the adhesive surfaces of the dust collection rollers  30 ,  31 , and adhesive rubber rollers are preferably used as the dust collection rollers  30 ,  31 . 
     However, when the dust collection rollers  30 ,  31  are provided in the printing area in which the paper  11  is reciprocally transferred during the print operation, the sublimation dyestuffs that are printed on the paper  11  are transcribed in reverse with respect to the dust collection rollers  30 ,  31 . Normally, a material that does not react to the sublimation dyestuffs, such as a fluoro plastic, is used for the material of rollers located in the print area for preventing this reverse transcription. However, it is difficult to employ the material for the dust collection rollers in which the adhesiveness is required. 
     Accordingly, in the present invention, the dust collection rollers  30 ,  31  are provided at the outlet of the printing area. That is, the one dust collection roller  30  is provided adjacent to the paper outlet  22   a  of the cassette  22  so as to mainly remove the dust on the surface of the paper  11  which is sent out from the cassette  22 , and the other dust collection roller  31  is provided adjacent to the front of the cutter  17  so as to mainly remove the dust produced by the cutting of the paper  11 . 
     As described above, a suitable material for the dust collection can be employed for the dust collection rollers  30 ,  31  without consideration of the measure to the reverse transcription toward the dust collection rollers  30 ,  31  because the dust collection rollers  30 ,  31  are provided at the outlet of the printing area. In addition, the other dust collection roller  31 , which is provided at the front side of the cutter  17 , is attached to the printed surface of the paper  11 , however, the reverse transcription does not occur because the overcoat layer covers the printed surface. 
     Meanwhile, as described above, the roll of the dust collection rollers  30 ,  31  is driven by the friction between the dust collection rollers  30 ,  31  and the paper  11 . However, the paper  11  has no end edge because the paper  11  is continuously supplied, and therefore, the inconvenience that the position of the paper  11  in the printer main body PR cannot be accurately grasped may occur. The inconvenience occurs by the error of the stepping motor and the like for transference or the slack of the paper  11 , for example. 
     This inconvenience can be solved by detecting the abnormal transference of the transference paper  11  by measuring the rotation speed of the dust collection rollers  30 ,  31 . That is, a disc  32  which is installed on the dust collection rollers  30 ,  31  so as to have a same axis as shown in FIGS. 5A,  5 B, and measuring the rotation speed of the dust collection rollers  30 ,  3  from that of the disc  32 . The rotation speed of the disc  32  is measured by detecting a plurality of slits  33  which are formed on the disc  32  with the same pitch along the circumference of the disc  32 , by using a photo sensor  34  and calculating the rotation speed from the detected pulse signals. The rotation speed can also be measured by detecting the reflection mark which is printed in black and white and attached the surface of disc  32  instead of the slits, by the photo sensor  34 . 
     According to the measurement of the rotation speed of the dust collection rollers  30 ,  31  by the method as disclosed above, when the abnormal rotation of the dust collection rollers  30 ,  31  corresponding to the abnormal transference of the paper  11  occurs, the presence of the abnormal transference can easily be detected, and therefore, the measure such as an emergency stop can be done as required by necessity. 
     In addition, the dust collection rollers  30 ,  31  may be detachably installed on the printer. In this case, the dust collection rollers  30 ,  31  can easily be cleaned in order to remove the dust and the like which adheres on the dust collection rollers  30 ,  31 , by removing the dust collection rollers  30 ,  31 .