JPH0259070B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multicolor thermal printer that performs color printing using a transfer ribbon coated with a plurality of heat-melting color inks.

FIG. 1 is a diagram showing an example of the configuration of a printing section of a conventional multicolor thermal printer, and in the figure, 1 is a platen roller. A sheet of paper 2 is brought into contact with the outer peripheral surface of the platen roller 1 and is conveyed to the left in the figure. On the other hand, 3 is the transfer ribbon 4
The transfer ribbon 4 is overlapped with the paper 2 on the outer peripheral surface of the platen roller 1, passes through the gap formed by the thermal head 5 and the platen roller 1, and then is separated from the paper 1. It is adapted to be wound onto a take-up reel 6 provided on the left side of the thermal head 5. On the left side of the thermal head 5, ribbon position sensors 10, 10 shown in FIGS. 1 and 2 are provided. This ribbon position sensor 10 includes U-shaped mounting members 7, 7, and protruding portions 7a, 7b of the mounting member 7.
The transfer ribbon 4 is composed of a light emitting element 8 and a light receiving element 9 which are provided facing each other, and both sides of the transfer ribbon 4 pass between the protrusions 7a and 7b. The black mark attached to the transfer ribbon 4 is detected by the ribbon position sensors 10, 10, and the transfer ribbon 4 is controlled to stop at that position.

By the way, as is clear from FIG. 2, in the multicolor thermal printer described above, the transfer ribbon 4 is placed between the protrusions 7a and 7a of the ribbon position sensors 10, 10.
7b, and at this time, the transfer ribbon 4 was sometimes damaged. Also, if the transfer ribbon 4 is not wound properly and becomes slack,
The transfer ribbon 4 is caught on the protrusions 7a and 7b,
There were some unfavorable points in terms of operation, such as the transfer ribbon 4 breaking.

In view of the above-mentioned circumstances, the present invention provides a multicolor thermal printer that does not cause damage to the transfer ribbon, and includes a reflective optical sensor provided at a position where the transfer ribbon and printing paper are conveyed in an overlapping manner. The light emitted from the light emitting element of the optical sensor passes through the transfer ribbon and is reflected by the printing paper, and this reflected light passes through the transfer ribbon again and reaches the light receiving element of the optical sensor. , the color of the transfer ribbon is detected based on the output signal of the light receiving element.

Embodiments of the present invention will be described below based on the drawings.

FIG. 3 is a diagram showing the structure of a transfer ribbon used in a multicolor thermal printer according to the present invention.
The transfer ribbon 11 shown in this figure is a color area 11 formed by applying cyan, magenta, and yellow color ink alternately in a band shape on a capacitor paper.
C, 11M, 11Y, and an area 11S provided between the color areas. Each color area 11C, 11M, 11Y is formed by the transfer ribbon 11.
The length of the paper is slightly longer than one page, taking into account the transport deviation of the paper. Note that the black mark for position detection, which has been conventionally provided in the area 11S, is not used in the present invention, so it is not provided.

Next, FIG. 4 is a schematic diagram showing the configuration of the printing section of this embodiment. In the figure, parts corresponding to each part in FIG. . In this figure, reference numeral 11 is the above-mentioned transfer ribbon, which is stretched in the same manner as the transfer ribbon 4 in FIG. 1. Further, reference numeral 12 denotes a reflective optical sensor, which is attached near the top of the thermal head 5. This optical sensor 12 consists of a light emitting element 12a and a light receiving element 12b, and the light emitted from the light emitting element 12a is transmitted through the transfer ribbon 11 and the paper 2
reflected at. Then, this reflected light is configured to pass through the transfer ribbon 11 again and reach the light receiving element 12b. The important point here is that
In order to use the paper 2 as a reflection source, it is necessary to place the optical sensor 12 at a location where the light emitted from the light emitting element 12a is irradiated onto the position where the transfer ribbon 11 and the paper 2 overlap. must be placed.

In such a configuration, the light receiving element 12b is
Depending on the intensity and wavelength of the arriving light,
Outputs the output voltage shown in E. That is, FIG. 5A shows the output voltage of the light-receiving element 12b when the paper 2 is removed; FIG. This is the voltage output from the light receiving element 12b for each color. Photodetector 1 thus obtained
The output voltage of the transfer ribbon 2b is supplied via an analog-to-digital converter to a control unit consisting of a microcomputer or the like, where the color of the transfer ribbon 11 is recognized. Based on this result, the take-up reel 6 can set the transfer ribbon 11 at the correct position.

In addition, in the embodiment described above, the optical sensor 12 is connected to the color area 11C (or 11M or 11Y).
When the head of the transfer ribbon 11 is detected, it is determined that the transfer ribbon 11 is set correctly.
The closer the distance to the color areas 11C, 11M,
It is possible to shorten the length of 11Y, and the optical sensor 12 according to the present invention is also advantageous over the conventional ribbon position sensor 10 in this respect. This is because the color detection point can be moved very close to the thermal head 5 by adjusting the elements 12a and 12b.

Further, in the above embodiment, the optical sensor 12
was installed above the thermal head 5, but as shown by the two-dot chain line in FIG.
It is also possible to provide it below. However, in this case, after color detection, the transfer ribbon 11 is conveyed by a certain amount (that is, from the color detection point to the point of the thermal head 5), and the transfer ribbon 11 is transferred to the color area 11C (or 11M or 11Y).
You must also bring the head of the head to the position of the thermal head 5.

As explained above, in this invention, the light emitted from the light emitting element is reflected by the paper, this reflected light is received by the light receiving element, and the color of the transfer ribbon is detected thereby. It can be easily attached and detached without damaging the transfer ribbon. Furthermore, since the color detection point of the transfer ribbon can be set very close to the thermal head, the length of the transfer ribbon can be set to the minimum necessary length.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the configuration of the printing section of a conventional multicolor thermal printer, and FIG.
3 is a diagram showing an example of the configuration of a transfer ribbon used in a multicolor thermal printer according to the present invention; FIG. 4 is a schematic diagram showing the configuration of a printing section of a multicolor thermal printer according to the present invention; FIG. 5 is a diagram showing the output voltage of the light receiving element 12b of the optical sensor 12 provided in the same thermal printer. 2... paper, 11... transfer ribbon, 12... optical sensor, 12a... light emitting element, 12b... light receiving element.

Claims (1)

[Claims] 1. A reflective optical sensor is provided along a path in which the transfer ribbon and paper are conveyed in an overlapping manner, and light emitted from a light emitting element of the optical sensor is transmitted through the transfer ribbon and reflected by the paper, The multicolor thermal printing system is characterized in that the reflected light is configured so that it passes through the transfer ribbon again and reaches the light receiving element of the optical sensor, and the color of the transfer ribbon is detected based on the output signal of the light receiving element. printer.