Incremental printing of symbolic information – Thermal marking apparatus or processes – Record receiver and transfer medium feeding or driving means
Reexamination Certificate
1998-06-12
2001-12-04
Tran, Huan (Department: 2861)
Incremental printing of symbolic information
Thermal marking apparatus or processes
Record receiver and transfer medium feeding or driving means
C400S248000
Reexamination Certificate
active
06326991
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the uniform separation of an ink ribbon of a thermal transfer apparatus, and more particularly, to a thermal transfer apparatus equipped with ink ribbon uniform separation means, which prints an image on an image receiving sheet by way of an ink ribbon and through use of a thermal head, the means reliably and simultaneously separating the ink ribbon at all points in a widthwise direction thereof.
2. Description of the Related Art
FIG. 10
is a perspective view showing the principal elements of a thermal transfer apparatus to which the present invention is applied. In
FIG. 10
, reference numeral
1
designates a thermal head;
2
designates a platen disposed opposite to the thermal head
1
;
3
designates a pair of conveyor rollers for carrying an image-receiving sheet
4
;
5
designates an ink ribbon;
6
designates a separation bar;
7
designates a guide roller for the ink ribbon
5
; and
8
designates a core for taking up the ink ribbon
5
. In this thermal transfer apparatus, after ink has been thermally transferred to the image-receiving sheet
4
from the ink ribbon
5
by the application of heat to the thermal head
1
, the image-receiving sheet
4
is separated from the ink ribbon
5
. The separation bar
6
is provided for simultaneously separating the ink ribbon
5
from the image-receiving sheet
4
at all points in a widthwise direction.
Despite the aforementioned configuration, the prior art suffers from a problem that the ink ribbon
5
fails to simultaneously separate from the image-receiving sheet
4
at all points in the primary scanning direction (i.e., the widthwise direction of the ink ribbon or the image-receiving sheet) after the printing operation. This is attributable to a tendency that in the existing thermal transfer apparatus, slight tension is applied to the center of the ink ribbon and the image-receiving sheet, while strong tension is applied to the side edges of the image-receiving sheet.
Accordingly, since uneven tension is applied to the ink ribbon and the image-receiving sheet in the widthwise direction thereof, they are quickly separated at the side edges or slowly separated at their center in an upstream direction, thus resulting in irregularities in the separation of the ribbon from the sheet. In the event of such separation irregularities, ink is unevenly transferred to the image-receiving sheet, resulting in an ink transfer failure.
Japanese Patent Unexamined Publication No. Hei. 9-39349 describes the idea that a separation bar has a thickness in its center differing from that of the ends thereof, but fails to quantitatively disclose the thickness.
SUMMARY OF THE INVENTION
The present invention has been made in view of the foregoing circumstances, and an object of the present invention is to solve the foregoing problem in the prior art, and to provide an ink ribbon separation device for use with a thermal transfer apparatus, the device being capable of preventing a transfer failure due to a separation failure.
To achieve the foregoing object, according to a first aspect of the present invention, there is provided a thermal transfer apparatus having a separation bar, wherein the thickness of the separation bar in an ink ribbon travelling direction is greater at its center in the direction orthogonal to the ink ribbon travelling direction than at the ends thereof; and the center bulges in a downstream direction in a bow shape at a rate of 10 to 200 &mgr;m with respect to a toner width of 100 mm.
According to a second aspect of the present invention, there is provided a thermal transfer apparatus having a thermal head and a separation bar, wherein a spacer is interposed between the thermal head and the center of the separation bar in the direction orthogonal to an ink ribbon travelling direction; and the ends of the spacer are curved toward the thermal head at a rate of 10 to 200 &mgr;m with respect to a toner width of 100 mm.
According to a third aspect of the present invention, there is provided a thermal transfer apparatus having a separation bar, wherein a bottom portion of the separation bar in the vertical direction is lower at its center in a direction orthogonal to an ink ribbon travelling direction than that at the ends thereof, at a rate of 10 to 200 &mgr;m relative to a toner width of 100 mm.
According to a fourth aspect of the present invention, there is provided a thermal transfer apparatus having a separation bar, wherein the center of the separation bar in a direction orthogonal to an ink ribbon travelling direction is provided with Teflon coating so that a frictional coefficient of the center of an area of the separation bar which comes into contact with an ink ribbon is smaller than that at the ends thereof.
According to a sixth aspect of the present invention, there is provided a thermal transfer apparatus having a guide roller for guiding an ink ribbon, wherein the guide roller has a spindle or stepped shape and has at its center a thickness greater than that at the ends thereof in the axial direction of the roller. The guide roller having a spindle or stepped shape is curved at a rate of 10 to 200 &mgr;m with respect to a toner width of 100 mm.
According to an eighth aspect of the present invention, there is provided a thermal transfer apparatus having a core for taking up an ink ribbon, wherein the core has a spindle or stepped shape and has at its center a thickness greater than that at the ends thereof in the axial direction of the core.
According to a ninth aspect of the present invention, there is provided a thermal transfer apparatus having a thermal head and a separation bar, and an ink ribbon press member having a high frictional coefficient is interposed between the thermal head and the separation bar.
As mentioned above, the thermal transfer apparatus prevents nonuniform separation of the ink ribbon from the sheet in the widthwise direction by changing tension of the ink ribbon in the widthwise direction at a position downstream of the thermal transfer apparatus so that uniform tension is applied, which results in prevention of a transfer failure.
REFERENCES:
patent: 61-16878 (1986-01-01), None
patent: 7-178993 (1995-07-01), None
patent: 07-266649 A (1995-10-01), None
patent: 09-039349 A (1997-02-01), None
patent: 9-123494 (1997-05-01), None
Kinjyo Kazuaki
Sawano Mitsuru
Fuji Photo Film Co. , Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Tran Huan
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