JPH05185621A - Thermal transfer printer - Google Patents

Abstract

PURPOSE:To make use of the same ink film for both kinds of sheets and enable high- quality and high-density printing even in the case of an OHP sheet, by providing a control part which performs overlapping printing by repeating thermal transfer actions of an ordinary paper case a plurality of times in the case where recording paper is an OHP sheet by a decision of a discrimination device. CONSTITUTION:A kind of recording paper which is conveyed from recording paper 2 by being placed between a platen roller 3 and belt 10 and fed by an output signal through a sensor 6 is decided by a control device. Then as a result of a decision, in the case where the recording paper is ordinary paper, printing enters a standard STD mode and in the case where the recording paper is an OHP sheet, the printing enters an OHP mode. Hereupon, in the case where the recording paper is the OHP sheet, a printing sequence of the ordinary paper is established at an OHP sequence for repeating the same a plurality of times. Then a matrix deciding a pattern of impression information to a thermal head 4 and impression voltage to the thermal head may be the same as the ordinary paper. After establishment of the sequence by corresponding to the printing modes each like this, printing action is performed at each and every mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer printer, and more particularly to a thermal transfer printer which enables high density and high quality printing even on an OHP (overhead projector) sheet.

[0002]

2. Description of the Related Art Recent thermal transfer printers can print on both plain paper (standard paper) and OHP sheets made of transparent plastic film. However, in the case of an OHP sheet, since the light is transmitted by an OHP projector and projected on a screen for viewing, the density of the projected image is considerably lower than the density of characters printed on the OHP sheet itself. Therefore,
When printing on an OHP sheet, it is necessary to print clearly with a higher contrast than on plain paper.

Conventionally, in order to perform printing on such an OHP sheet, a high-sensitivity and high-density type ink film dedicated to the OHP sheet is used, or the same ink film as plain paper is used. When printing on a sheet, a technique of increasing the energy applied to the thermal head for printing to increase the density has been used.

[0004]

In the prior art as described above, in order to make the ink film exclusively for the high sensitivity (high density) type OHP sheet into the high sensitivity type,
The components of the dye itself are different from those for plain paper, and the dye itself has a poor storability and is not suitable for long-term storage. Also, an ink film for plain paper and O
Since it is necessary to prepare two types of ink films for the HP sheet and select a dedicated ink film for each type of recording paper (plain paper and OHP sheet), it is necessary to identify the two ink films and control them. There is also a disadvantage that the device becomes complicated and the cost of the device is increased by providing an identification sensor in the printer. In addition, since the types of ink films increase, the management of them becomes complicated.

Further, in the case of printing on an OHP sheet by using the same ink film as that for plain paper, in the method of increasing the energy applied to the thermal head to increase the density, the temperature of the printing portion rises violently. , OH
The curl amount of the P sheet becomes large, the surface of the OHP sheet is roughened by heat and diffused, and when projected by an OHP projector, light is scattered and the color saturation is reduced and the color becomes dark and turbid. There was a problem that it would become.

In view of the above problems in the conventional method, an object of the present invention is to use the same ink film for both plain paper and OHP sheet in a thermal transfer printer, and also in the case of OHP sheet, high quality and high quality. It is to be able to print density.

[0007]

In order to achieve the above object, a thermal transfer printer according to the present invention has a platen roller for winding and conveying recording paper and a recording paper wound around the platen roller. An ink film which is guided and run, a thermal head which is arranged to face the recording paper wound around the platen roller via the ink film, and which heats the ink film in accordance with print information during thermal transfer, and the recording paper is an OHP sheet. In some cases, a control unit for repeating the thermal transfer operation in the case of plain paper a plurality of times to perform overprinting is provided.

Further, there is provided a discriminating means for clarifying whether or not the recording paper is an OHP sheet, and in response to the discriminating means judging that the recording paper is an OHP sheet, the control section is It is convenient to automatically perform overprinting.

[0009]

In the above construction, the desired print information is given to the thermal head disposed opposite to the recording paper wound around the platen roller, and the thermal head heats the ink film according to the print information to print on the recording paper. Do. In this case, the control unit controls the number of times such a thermal transfer operation is performed depending on whether the recording paper is an OHP sheet or plain paper. That is, in the case of plain paper, one thermal transfer operation is normally performed in the case of monochrome printing, and in the case of color printing, for example, one for each of yellow (Y), magenta (M), and cyan (C).
Perform thermal transfer operation one by one. On the other hand, the recording paper is OH
In the case of a P sheet, even in monochrome printing, the thermal transfer operation is repeated at least twice to perform overprinting. In the case of color printing, the thermal transfer operation is performed twice or more for each color of Y, M, and C, for example. In this case, the control unit may be configured to automatically perform such overprinting according to the determination result from the determination unit that determines whether the recording paper is an OHP sheet.

In such a printing operation, even when printing is performed on an OHP sheet, the same ink film as that for plain paper is used, and overlapping printing is performed a plurality of times with the same applied energy as for plain paper. Therefore, the problem of the storability of the printing ink is also solved, and the curl of the OHP sheet does not become large and the surface is not roughened, and high quality and high density print can be obtained.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the structure of a mechanical portion of a thermal transfer printer according to an embodiment of the present invention. The thermal transfer printer shown in the figure has a paper feed tray 1 for storing recording paper.
3, a paper feed roller 14, a platen roller 3 that winds and conveys recording paper, an ink film 1 that guides and runs opposite to the recording paper that is wound around the platen roller 3, and a platen roller 3 through the ink film 1. A thermal head 4 for printing on the wound recording paper, a paper discharge lever 8 for discharging the recording paper after printing is completed, and the like.

The thermal transfer printer of FIG. 1 further includes a recording paper identification sensor 6 for determining the type of the recording paper 2 discharged from the paper feed tray 13, and belts 10 and 11 for winding and guiding the recording paper around the platen roller 3. And each guide roller 12
Have. Further, another guide roller 5 is provided to guide the ink film 1 from the supply unit 1a to the winding unit 1b along the platen roller 3. Further, a sensor 7 is provided for detecting a predetermined boundary mark on the ink film 1 in order to find the head of the ink film 1.

For example, as shown in FIG. 3, the ink film 1 is provided with print ink areas Y, M, and C for three colors in an area sandwiched by predetermined boundary marks 1c. In FIG. 3, the ink areas Y, M, and C are shown as areas surrounded by dotted lines, for example, and this area corresponds to the printing range. Further, the pitch of the boundary mark 1c is equal to the length 3L which is three times the outer peripheral length of the platen roller 3, and each color has a region having a length equal to the outer peripheral length L of the platen roller 3. Furthermore, the ink area Y for each color,
Separation regions S each having a predetermined width are provided between M and C.

FIG. 4 shows a recording paper 2 used in the apparatus of FIG.
Shows the configuration of. The recording paper 2 shown in FIG. 4 is provided with recording paper identification marks 2a and 2b for each type of recording paper. For example, in the case of an OHP sheet, the identification marks 2a are provided at the upper left corner and the lower right corner, and in the case of plain paper, the identification marks 2b are provided at the upper right corner and the lower left corner. These recording paper identification marks 2a and 2b are identified by the recording paper identification sensor 6 shown in FIG. Note that the recording paper identification mark is not limited to such a mark, and any mark can be used. Also,
It is also possible to distinguish it from other sheets by utilizing the fact that the OHP sheet is transparent. Alternatively, the type of recording paper can be manually set by a recording paper type setting switch or the like. Further, some kind of identification mark or identification symbol may be provided on the paper feed tray for storing the recording paper.

Next, the operation of the thermal transfer printer having the above construction will be described with reference to FIG. For example, if a print switch (not shown) is pressed, the platen roller 3
Starts rotating in the direction of the arrow, and the belts 10 and 11 also move due to friction with the platen roller 3 without slipping. At the same time, the recording paper 2 is fed to the paper feed tray 1 by the paper feed roller 14.
The sheet is discharged from the sheet 3 and sandwiched between the platen roller 3 and the belt 10 and conveyed.

In this case, the control unit 15 determines the type of recording paper fed by the output signal from the sensor 6. Then, as a result of this determination, if the recording paper is plain paper, the standard (STD) mode is entered, and if it is an OHP sheet, O is set.
Enter HP mode. In the standard mode, a normal print sequence for plain paper is executed. In this case, a standard plain paper is used as a matrix for determining the pattern of print information on the thermal head. The applied voltage to the thermal head 4 is also set to an applied voltage suitable for plain paper. When the recording paper is an OHP sheet, it is set to an OHP sequence for repeating the print sequence of plain paper a plurality of times, as described in detail later. The matrix that determines the pattern of information applied to the thermal head 4 and the voltage applied to the thermal head 4 may be the same as those for plain paper. However, the voltages applied to the matrix and the thermal head 4 can be different from those for plain paper.
In this way, after the sequence or the like is set according to each print mode, the printing operation is performed for each mode as described in detail later.

First, in the so-called standard mode in which plain paper is used as the recording paper, the recording paper 2 transported as described above is transferred to the roller portion 12 of the belt 10.
Then, it is pressed by the ink film 1 guided by the guide roller 5 and is fed to the portion facing the thermal head 4 while closely contacting the outer periphery of the platen roller 3. When the recording paper 2 passes through the thermal head 4, a sensor (not shown) detects the leading end of the recording paper 2 and starts printing the first color.

At this time, the paper discharge lever 8 is at the position indicated by the solid line, the recording paper 2 passes inside the paper discharge lever 8, and the belt 11
Sent to. The recording paper 2 further passes between the belt 11 and the platen roller 3, is fed from the guide member 9 and then guided to the belt 10 again, and advances between the ink film 1 and the platen roller 3.

In this way, after the printing of the first color is completed, the recording paper 2 is sent to the position facing the thermal head 4 again. At this time, the ink film 1 has the second color printing area (M) facing the recording paper, and the thermal head 4 prints the second color in the same manner as described above. When Y, M, and C three-color printing is completed by repeating such a process, the paper discharge lever 8 rotates counterclockwise to the position indicated by the broken line, and the platen roller 3 and the tip of the paper discharge lever 8 come into contact with each other. The recording paper 2 is discharged in the direction of the dashed arrow. When the sensor 7 detects the boundary mark 1c of the ink film 1 after the discharge of paper and the cueing of the ink film 1 is completed, the thermal head 4 rises, the rotation of the platen roller 3 stops, and the discharge lever 8 also moves. Return to the solid line position again. As a result, the printing sequence in the standard mode ends. The ink film 1 is wound up by sharing the motor that drives the platen roller 3, is fed at the same speed as the recording paper 2, and is wound up by the winding portion 1b.

Next, the recording paper fed by the control unit 15 becomes O
When it is determined that the sheet is the HP sheet, the OHP mode is entered. In this mode, by pressing a print switch (not shown) in advance, the platen roller 3
Starts to rotate in the direction of the arrow, and the belts 10 and 11 also move due to friction with the platen roller 3 without slipping. At the same time, the recording paper 2 is fed by the paper feed roller 14. At this time, the sensor 6 determines that the recording paper 2 is an OHP sheet, and the control unit 15 sets the OHP mode as described above. When the recording paper 2 comes out of the roller 12 of the belt 10, it is then pressed by the ink film 1 and sent to the thermal head 4 while closely contacting the outer periphery of the platen roller 3. When the recording paper 2 passes through the thermal head 4, a sensor (not shown) is shown. Detects the leading edge of the recording paper 2 and
Start printing the color.

At this time, the paper discharge lever 8 is at the position indicated by the solid line, and the recording paper 2 which has completed the first printing passes through the inside of the paper discharge lever 8 and is fed again between the belt 11 and the platen roller 3. .. Further, the recording paper 2 passes through the belt 11, passes through the guide member 9, and is guided to the belt 10 again.

By repeating such an operation, the first printing of each color of YMC is completed, but in the OHP mode, such a printing sequence of YMC is repeated again to print twice. When the printing of the final color C for the second time is completed, the paper discharge lever 8 rotates counterclockwise to the broken line position, the platen roller 3 and the tip of the paper discharge lever 8 come into contact, and the recording paper 2 is broken line. The paper is ejected in the direction of the arrow. Thereafter, as in the case of the standard mode, when the sensor 7 detects the boundary mark 1c of the ink film 1 and the cueing of the ink film 1 is completed, the thermal head 4 is raised, the platen roller 3 is stopped, and the sheet is ejected. The lever 8 also returns to the solid line position, and the OHP print sequence ends.

In such an OHP sequence,
The recording paper 2 is wound around the platen roller 3 and is rotating in the same direction, and the format of the ink film 1 is repeatedly formed in the same length as the outer peripheral length L of the platen roller 3 for each color as described above. The first Y, M,
Even when the printing of each color of C is completed and the second printing of the first color Y is started, the printing of the next color is started after the separation area, that is, the non-printing range S is sent, and the color misregistration does not occur. The second overprinting is performed.

Therefore, the same ink film can be used in both the standard mode and the OHP mode, and high density printing can be performed on the OHP sheet only by changing the printing sequence. Note that the number of times of overprinting on the OHP sheet is not limited to twice, but may be any desired number of times. Further, in each of the above embodiments, the recording paper 2 is conveyed by the belts 10 and 11, but it is clear that the recording paper conveyance system is not limited to this. Further, in the above embodiment, the case of color printing has been described,
The present invention can also be applied to a thermal transfer printer that performs monochrome printing, in which case the thermal transfer operation in the standard mode is repeated a plurality of times in the OHP mode.

[0025]

As described above, according to the present invention, the common ink film is used for both the plain paper and the OHP sheet, and in the case of the OHP sheet, the overlapping printing is performed plural times. Change only OH
It is possible to perform high-quality and high-density printing on P sheets as well. Further, in the case of an OHP sheet, it is not necessary to particularly increase the energy applied to the thermal head, so that there is little curl of the OHP sheet after printing and there is no inconvenience that the surface is roughened by heat and diffused. Also,
Only one type of ink film is required, and it is not necessary to provide a sensor for identifying the ink film, which simplifies the device configuration and is advantageous in management of the ink film and the like.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing a structure of a mechanical portion of a thermal transfer printer according to an embodiment of the present invention.

FIG. 2 is a schematic flowchart for explaining the operation of the thermal transfer printer according to the present invention.

FIG. 3 is an explanatory diagram showing a format of an ink film used in the thermal transfer printer of FIG.

FIG. 4 is an explanatory diagram showing identification marks of a recording paper used in the thermal transfer printer of FIG.

[Explanation of symbols]

 1 Ink Film 1a Ink Film Supply Section 1b Ink Film Winding Section 2 Recording Paper 2a, 2b Recording Paper Identification Mark 3 Platen Roller 4 Thermal Head 5 Guide Roller 6 Recording Paper Identification Sensor 7 Ink Film Detection Sensor 8 Ejection Lever 9 Guide Member 10, 11 Belt 12 roller 13 paper feed tray 14 paper feed roller 15 control unit

Claims (2)

[Claims] 1. A platen roller for winding and conveying recording paper, an ink film which is guided to run against the recording paper wound on the platen roller, and wound around the platen roller via the ink film. A thermal head, which is arranged to face the recorded paper and heats the ink film according to print information during thermal transfer, and a thermal transfer operation when the recording paper is an OHP sheet and plain paper is repeated a plurality of times. A thermal transfer printer, comprising: a control unit for performing printing. 2. The recording paper is at least OHP.
It is characterized in that it is provided with a discriminating means for clarifying whether or not it is a sheet, and in response to the discriminating means discriminating that the recording paper is an OHP sheet, the control section automatically carries out the overlay printing. The thermal transfer printer according to claim 1.