JP2572838B2 - Thermal transfer color printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a thermal transfer color printer that prints on a transfer sheet wound around an outer periphery of a platen roller by a thermal head.

<Prior Art> Conventionally, as a thermal transfer color printer, for example, the one shown in FIG. 2 is known. The thermal transfer color printer includes a platen roller 1 having a transfer sheet 2 wrapped around an outer periphery and rotated by a driving unit (not shown);
Concentric guide surface 3a larger in diameter than this platen roller
And a guide means 3 having a plurality of press-contact rollers 4, 4,... For pressing the transfer sheet 2 toward the platen roller 1, and a heating element disposed linearly to transfer sheet 2 on the platen roller. A thermal head 8 is supported so as to be able to contact and separate via the ink sheet 5. On the guide surface 3a on the front side of the thermal head 8 with respect to the rotation direction indicated by the arrow A of the platen roller, a reflective first optical sensor 35 for detecting the leading end of the transfer sheet 2 is provided. A reflection type second optical sensor 9 for detecting each of the three primary color markers of the ink sheet 5 is provided on the upper part of the guide means 3 opposed to the above.

The second optical sensor 9 detects a yellow marker on the ink sheet 5 sent from the supply roll 6 to the take-up roll 7 as shown by an arrow B, and finds the first yellow ink at the contact portion 8a of the thermal head 8. . On the other hand, when the first optical sensor 35 detects the leading end of the transfer sheet 2 wrapped around the platen roller 1 and sent, the first optical sensor 35 is turned on to start energizing the thermal head 8 for printing. Then, as the platen roller 1 rotates in the direction of arrow A, line printing in the row direction is repeated in the column direction, and yellow ink is printed on the transfer sheet 2 in the first rotation. Hereinafter, the printer operates in the same manner as described above for the next magenta ink and the next cyan ink, and the color printing using the three primary colors is completed.

<Problems to be Solved by the Invention> However, in the above-described conventional thermal transfer color printer, the first optical sensor 35 is provided on the front side of the thermal head 8 with respect to the rotation direction of the platen roller 1, so that the thermal head 8 is A disadvantage is that printing is started by detecting the leading end of the transfer sheet 2 after passing through, and a margin corresponding to the length from the first optical sensor 35 to the contact portion 8a of the thermal head 8 is formed on the transfer sheet 2. There is. In other words,
There is a drawback that the entire transfer sheet 2 cannot be printed, and the transfer sheet is wasted.

Therefore, an object of the present invention is to detect the rear end of the transfer sheet in advance while the front end of the transfer sheet wound around the platen roller does not reach the thermal head, and rotate the platen roller by a predetermined angle based on this detection signal. Accordingly, it is an object of the present invention to provide a thermal transfer color printer capable of performing printing over the entire transfer sheet and disposing the detecting means at a place where there is room in a space distant from the thermal head.

<Means for Solving the Problems> In order to achieve the above object, the thermal transfer color printer of the present invention has a platen roller that is wound around a transfer sheet and rotated by a driving unit, and has a larger diameter than the platen roller. A guide means having a plurality of pressure contact rollers for pressing the transfer sheet toward the platen roller, having a concentric guide surface, and an ink sheet disposed on the transfer sheet on the platen roller by disposing a heating element linearly A thermal head provided so as to be able to come and go through the sensor, a detecting means for detecting the rear end of the transfer sheet on the platen roller whose leading end does not reach the position of the thermal head, and a detecting signal from the detecting means. Control means for outputting a print start positioning signal for rotating the platen roller by a predetermined angle. I can.

<Operation> In the thermal transfer color printer of the present invention, the transfer sheet is sent by being pressed around the outer periphery of the platen roller rotated by the driving means by a plurality of pressure contact rollers. The detecting means detects the trailing end of the transferred transfer sheet and outputs a detection signal, and the control means having received the detection signal outputs a print start positioning signal to the driving means to transfer the platen roller to, for example, the transfer roller. The sheet is rotated by a predetermined angle until the leading edge of the sheet reaches the position of the thermal head.
Then, when the rotation at the predetermined angle is completed, the power supply to the thermal head is started, and three times are transferred onto the transfer sheet via the ink sheet.
Printing of the first primary color or printing of three primary colors at the same time is started. While the platen roller makes one rotation from this position, printing using the primary colors or printing simultaneously for the three primary colors is performed over the entire transfer sheet. In the case of three primary colors simultaneously, color printing is completed by one rotation of the platen roller. In the case of each primary color, color printing is performed by three rotations of the platen roller by repeating the above-described printing start positioning and printing process twice more. Ends.

Thus, the entire surface can be printed without margins at the leading end of the transfer sheet. The predetermined angle does not need to be a value corresponding to the arc length from the detecting means to the thermal head, and it is possible to adjust the length of the margin by variously changing the angle. Further, since the trailing edge of the transfer sheet is detected, the detecting means can be arranged at a place where there is room in the space away from the thermal head, and the degree of freedom in designing the printer is increased.

<Example> Hereinafter, the present invention will be described in detail with reference to an illustrated example.

FIG. 1 is a schematic view showing an embodiment of a thermal transfer color printer according to the present invention, in which 1 is a platen roller on which a transfer sheet 2 is wound around the outer periphery and rotated in a direction indicated by an arrow A. A guide means 5 having a large diameter concentric guide surface 3a and a plurality of pressing rollers 4, 4,... For pressing the transfer sheet 2 toward the platen roller 1 is provided at an upper opening 3b of the guide means 3. An ink sheet stretched between a supply roll 6 and a take-up roll 7 and fed in a direction indicated by an arrow B. Reference numeral 8 denotes a transfer sheet on a platen roller 1 with a heating element arranged linearly. 2 is a thermal head provided so as to be able to come in contact with and separate from the ink sheet 5 via the ink sheet 5, and 9 is a reflective type head provided on the upper opening edge of the guide means 3 for detecting markers of three primary colors of the ink sheet 5. Two light It is.

The above members are the same as those in the conventional example described with reference to FIG. 2, and the same members are denoted by the same reference numerals. The thermal head 8 is attached to the lower surface on the distal end side of a rotatable holding member 10 whose base end is pivotally supported by a pin 11, and guides the ink sheet 5 to its distal end and reflects light. Board
12 is fixed. The platen roller 1 is driven to rotate by a pulse motor 14 via a timing belt 13 wound around a pulley 1a on the side and a pulley 14a on the motor side.

The rear end of the transfer sheet 2 on the platen roller whose leading end does not reach the contact portion 8a of the thermal head is provided on the guide surface 3a behind the thermal head 8 in the rotation direction of the platen roller 1 as indicated by the arrow A. A first optical sensor 25 for detection is provided. The pulse motor 14 is provided with a pulse motor drive circuit 16 for receiving a detection signal from the first optical sensor 25 and outputting a print start positioning signal consisting of a predetermined number of pulses for rotating the platen roller 1 by a predetermined angle. ing. The predetermined angle, that is, the predetermined number of pulses corresponds to, for example, the arc length from the first optical sensor 25 to the contact portion 8a of the thermal head 8, and when the rotation of the platen roller 1 at the predetermined angle is completed, the power supply circuit (not shown) starts. The energization for printing to the thermal head 8 is started. Since the first optical sensor 25 detects the rear end of the transfer sheet 2, the first optical sensor 25 is installed at a location having a space that is far away from the contact portion 8 a of the thermal head on the opposite side in the diameter direction of the platen roller 1. I have.

The thermal transfer color printer having the above configuration operates as follows.

The transfer sheet 2 inserted from the paper feed port 3c below the guide means 3 is pressed and fed around the outer periphery of the platen roller 1 rotated by the pulse motor 14 by a plurality of pressure contact rollers 4, 4,. Can be First optical sensor 25
Detects the rear end of the transferred transfer sheet 2 and outputs a detection signal. Upon receiving the detection signal, the pulse motor drive circuit 26 outputs a print start positioning signal to the pulse motor 14 and 1 is rotated by a predetermined angle until the leading end of the transfer sheet 2 reaches the contact portion 8a of the thermal head 8, for example. While the platen roller 1 rotates by a predetermined angle, the thermal head 8 is moved from the standby position (not shown) to the first position.
It rotates to the marker reading position shown by the two-dot chain line in the figure, the take-up roll 7 is rotated by the driving means (not shown), the ink sheet 5 is fed, and the second optical sensor 9 detects the yellow ink marker. Based on this detection signal, the driving means is stopped, and the first yellow ink portion is located at the contact portion 8a of the thermal head 8.

When the cueing of the ink sheet 5 and the print start positioning of the transfer sheet 2 are completed, the thermal head 8 rotates to the print position indicated by the solid line in FIG. The energization of the thermal head 8 pressing the print head 1 starts, and printing of one line is performed by yellow ink, and then the platen roller 1 is slightly rotated forward to print the next one line. By repeating this line printing, the yellow printing on the transfer sheet 2 is completed before the platen roller 1 makes one rotation. Then, the thermal head 8
Is separated from the platen roller 1 and returns to the marker reading position, and the second cue of magenta ink is performed.

The print start positioning signal output from the pulse motor drive circuit 26 has a pulse number of the first optical sensor 25.
From the contact portion 8a of the thermal head 8 and its output is always performed prior to the end of printing of the color.

Thus, printing of each primary color is performed from the leading end of the transfer sheet 2 by the above-described print start positioning signal,
By rotating the platen roller 3 three times, yellow,
The color printing using the magenta and cyan inks without any blanks over the entire transfer sheet 2 is completed. In addition,
The print start positioning signal does not necessarily have to be the number of pulses corresponding to the arc length from the first optical sensor 25 to the contact portion 8a of the thermal head, and it is possible to adjust the length of the margin by variously changing this. It is possible. In addition, if the thermal head 8 is configured such that heating elements of three primary colors are arranged linearly and the ink sheet 5 is fed in accordance with this, line printing of three primary colors can be performed in a series, and a platen roller can be used. The color printing can be completed only by one rotation.

It goes without saying that the present invention is not limited to the illustrated embodiment.

<Effects of the Invention> As is clear from the above description, the thermal transfer color printer of the present invention has a thermal head at the rear end and a thermal head at the rear end with respect to the rotation direction of the platen roller on which the transfer sheet is wound and rotated. A detecting means for detecting the trailing edge of the transfer sheet which has not reached the position of, and the platen roller is rotated by a predetermined angle by a print start positioning signal outputted by a control means receiving a detection signal from this detecting means. This allows printing on the entire surface of the transfer sheet without any margins at the leading edge or printing with the length of the margins adjusted, and the detection means can be placed in a place where there is room in the space away from the thermal head. Can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a thermal transfer color printer of the present invention, and FIG. 2 is a view showing a conventional thermal transfer color printer. 1 ... platen roller, 2 ... transfer sheet, 3 ... guide means, 3a ... guide surface, 4, 4, ... press contact roller, 5 ...
Ink sheet, 8 Thermal head, 10 Holding member, 13 Timing belt, 14 Pulse motor, 25
... First optical sensor, 26... Pulse motor drive circuit.

Claims (1)

(57) [Claims] An image forming apparatus includes a platen roller wound around a transfer sheet and rotated by a driving means, a guide surface having a diameter larger than that of the platen roller and a concentric guide surface, and pressing the transfer sheet toward the platen roller. Guide means having a plurality of pressure contact rollers, a thermal head provided in such a manner that a heating element is arranged in a line and can be brought into contact with and separated from a transfer sheet on the platen roller via an ink sheet; Detecting means for detecting the rear end of the transfer sheet on the platen roller which has not reached the position of, and receiving a detection signal from this detecting means, the driving means transmits a print start positioning signal for rotating the platen roller by a predetermined angle. A thermal transfer color printer having control means for outputting.