JPH0525900Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ink ribbon for color thermal transfer.

[Prior Art] Traditionally, in ink ribbons used in thermal transfer color printers, heat-melting dyes of three primary colors, yellow, magenta, and cyan, are formed on a film base in a striped pattern in the running direction. Some were constructed by coating.

FIG. 6 shows the structure of a conventional ink ribbon, in which 20 is a film base material, 21 is a yellow ribbon, and 22 is a film base material.
2 is a magenta ink coating portion, and 23 is a cyan ink coating portion. There is a black color identification mark 11 at the boundary of each ink application area,
Colors are identified by changing the length L in the running direction. 30 is an uncoated area located at the boundary between the ink coated areas. Conventionally, common color inks have sufficient light transmittance when used as a single color, and can be easily distinguished from the non-light transmitting portion of the color identification mark by the optical sensor 3. A printer that prints using such an ink ribbon will be described below.

FIG. 3 shows a conventional thermal transfer printer that has been commonly used.

1 is a thermal head, 2 is an ink ribbon, 3a
is a light emitting diode, 3b is a phototransistor,
These two are paired to form an optical sensor 3. 4 is a platen, 5 is printing paper, 6 is a guide shaft, 7 is a carriage for transporting the thermal head 1, ink ribbon 2, etc. in the direction of arrow A during printing operation;
Reference numeral 8 indicates a ribbon spool on the supply side, and reference numeral 9 indicates a ribbon spool on the winding side.

Next, the winding operation of the ink ribbon will be explained below. The ink ribbon 2 is wound up in synchronization with the movement of the thermal head 1 in the direction of arrow A with respect to the printing paper 5 via the ink ribbon 2. That is, as the thermal head 1 moves, the ink ribbon 2 is pulled out from the supply ribbon spool 8. The printed ink ribbon 2 whose ink has been transferred to the printing paper 5 by the thermal head 1 tries to stick to the printing paper at that position, but when the thermal head passes in the direction A, the ribbon on the winding side It is wound up by the rotation of the spool.

[Problems to be solved by the invention] In general, the force with which the ink ribbon is drawn when the thermal head moves is determined by the pressing force between the printing paper and the thermal head, the coefficient of friction between the ink surface of the printing paper and the ink ribbon, and the ink ribbon. This is caused by the force relationship mainly caused by the coefficient of friction between the back surface of the thermal head and the thermal head.

The force relationship when the thermal head runs while pressing the printing paper through the ink ribbon will be explained with reference to FIG.

When the thermal head 1 travels while being urged by a pressing force F, a friction coefficient μ2 is generated between the ink ribbon 2 and the thermal head 1, and the ink ribbon 2
A friction coefficient μ1 occurs between the print paper 5 and the print paper 5.
At this time, in order for the ink ribbon 2 not to move together with the movement of the thermal head 1, the pull-out force P of the ink ribbon must be equal to the load C of the supply ribbon spool.
It is a necessary condition that μ1 is larger than μ2, and the following formula must hold true.

P=F(μ1-μ2)>C...Equation 1 In other words, the surface and back surfaces of the ink ribbon must be stable.

However, when the color identification mark 11 passes through the optical sensor 3 and the boundary between the ink-unapplied area 30 and the color identification mark 11 reaches the heating element of the thermal head 1, the printed paper in the ink-unapplied area 30 Since the coefficient of friction against the ink ribbon is smaller than that of the ink-applied area, the unapplied area of the ink ribbon causes slippage against the printing paper. As a result, the ink ribbon remains in a state where it is not pulled out, and no matter how long it takes, the ink of the next color to be printed does not start, and in some cases, the heating element continues to heat the same spot. This can cause the ink ribbon to break or cause the ink ribbon to rub against the surface of the printing paper, resulting in smeared prints.

An object of the present invention is to improve the drawbacks of conventional ink ribbons and to provide an ink ribbon for color thermal transfer that allows accurate identification of ink colors.

[Means for Solving the Problems] The present invention applies inks of multiple colors to the film base material by dividing them in the length direction, and in order to detect each ink, color identification marks are provided at the boundaries of the multiple inks. In the formed ink ribbon for color thermal transfer, the color identification mark is made of a material that has a larger coefficient of friction with the printing paper than the film base material of the ink ribbon.
An ink ribbon for color thermal transfer, characterized in that it is formed by applying layers of ink over both adjacent inks, and that there is no uncoated area at the boundary, at least in the range of the area where the thermal head comes into contact with the printing paper when it moves. It is.

[Example] FIG. 1 is a schematic diagram of an example of the color ribbon for thermal transfer of the present invention. Components that are the same as those in FIG. 5 are designated by the same numbers.

31 indicates a color identification mark, and the long part 31
a and a short portion 31b. The uncoated area 30 at the boundary of each pigment is a color identification mark 31
Filled in by. The coating width W of the color identification mark is sufficient within the range that the thermal head comes into contact with during travel, but it may be applied to the entire width of the base material.

The color identification mark on the long portion 31a displays the color depending on its length. The short portion 31b is used to recognize the running direction of the ink ribbon.

FIG. 2 is a sectional view of an ink ribbon according to the present invention.

The ink for the color identification mark is coated over both adjacent color inks so as to cover the uncoated portion 30 of each pigment.

It is preferable that the inks for the color identification mark have the same materials other than the coloring agent such as the binder and the softener. This is because it is better to make the friction coefficient of the ink surface of the ink ribbon approximately the same as that of other pigments.

32 is a back coat which is applied for the purpose of lowering the coefficient of friction between the thermal head and the ink ribbon.

Although FIG. 2 shows a method in which the color identification mark is applied from above to the boundary, it is also possible to apply the color identification mark and then apply each coloring matter and arrange the marks.

FIG. 5 is a schematic diagram showing another embodiment of the ink ribbon according to the present invention, and the same parts as in FIGS. 1 and 2 are designated by the same numbers. Reference numeral 24 denotes a black dye color ink coating area, which is also coated between the adjacent color ink coating areas 21 and 23 in an overlapping manner with both inks.

In this way, it is possible to use the same ink for the black ink for color printing and the ink for the color identification mark, and it is possible to have the same coefficient of friction as other pigments.

[Effects of the Invention] As detailed above, by using the ink ribbon for color thermal transfer according to the present invention, it is possible to stabilize the movement of the thermal head, and to realize reliable detection of color identification marks.

In addition, the print quality is improved without cutting the ink ribbon or staining the paper surface during printing, which conventionally occur due to poor running.

Furthermore, the structure covers the boundaries between color inks with color identification marks, eliminating unnecessary boundaries between color inks that occur at the boundaries between color inks, and enabling accurate color identification using a light transmission type sensor. There is.

Furthermore, since the color identification marks are applied overlappingly over adjacent inks, dimensional control in the manufacturing process for applying color inks is easy and manufacturing costs can be eliminated.

The present invention has various features and advantages as described above, and is extremely useful.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of a thermal transfer ink ribbon according to the present invention. FIG. 2 is a sectional view of the ink ribbon according to the present invention. FIG. 3 is a schematic diagram of a serial type thermal transfer printer. FIG. 4 is a diagram showing the force relationship when the thermal head runs. FIG. 5 is a schematic diagram of another embodiment according to the invention. FIG. 6 is a schematic diagram of a conventional embodiment. 31...Color identification mark, 20...Polyester film, 21, 22, 23...Color ink coating portion, 31a, 31b...Color identification mark, 32...Back coat.

Claims (1)

[Claims for Utility Model Registration] A color thermal transfer ink in which inks of multiple colors are divided in the length direction and applied to a film base material, and color identification marks are formed at the boundaries of the multiple inks to detect each ink. In the ribbon, the color identification mark is made of a material that has a larger coefficient of friction with printing paper than the film base material of the ink ribbon, and is formed by overcoating both sides of the ink that are adjacent to each other, and at least the thermal head. An ink ribbon for color thermal transfer, characterized in that there is no uncoated area at the boundary in the area where the ink ribbon contacts during movement.