JP3003792B2 - Ink film controller for thermal transfer printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink film controller for a thermal transfer printer, which can accurately control the amount of ink film transport.

[0002]

2. Description of the Related Art For example, Y (yellow), M (magenta),
2. Description of the Related Art Thermal transfer printers that perform color printing on an image receiving body using an ink film composed of three color frames of C (cyan) or four colors of Y, M, C, and K (black) are widely used. In this type of thermal transfer printer, it is necessary to identify each color frame and perform printing while accurately controlling the transfer amount of the ink film.

FIG. 3 is a perspective view showing an example of a conventional ink film controller for a thermal transfer printer. Y, M, C,
The ink film 1 on which a color frame of four colors of K is repeatedly applied in the longitudinal direction is a thermal head 3
The ink application surface is stretched between the platen roller 4 and the platen roller 4. For example, Y, M, C,
The color frames of the first to fourth colors applied in the order of K are denoted by 1a to 1d. This ink film 1 is
The ink film 1 is supplied from a bobbin 5 on which an unused ink film 1 is wound, and is wound on a bobbin 6 on which the used ink film 1 is wound. A card 2 is conveyed between the ink film 1 and the platen roller 4 by an unillustrated conveyance mechanism as one of image receiving bodies.

The platen roller 4 is driven at a predetermined pitch by a platen motor 7 which is a step motor.
The bobbin 6 is driven by an ink film winding motor 8 which is a DC motor, and the ink film 1 is wound. A photo detector 9 is provided at the side end of the ink film 1.
This photodetector 9 is selectively made transparent or non-transparent by only one color of the color frames 1a to 1d of the ink film 1, and detects the start end and the end of the one color frame. I do. Further, the ink film 1 is provided between the photodetector 9 and the bobbin 5.
A rubber roller 12 is provided on one surface side of the device, and a backup roller 13 is provided on the other surface side. A slit disk 10 is connected to the rubber roller 12. A photodetector 11 is arranged close to the slit disk 10,
The slit disk 10 and the photodetector 11 constitute a rotary encoder that detects the transfer amount of the ink film 1. A photodetector 14 is arranged at a position corresponding to the rear end of the card 2 side end, and the origin of the card 2 is detected.

In the thermal transfer printer configured as described above, the ink film 1 is controlled as follows. When the ink film 1 is wound by the ink film winding motor 8, the ink film 1 is transported leftward in the drawing. At this time, the color frame 1 of the ink film 1
Since a to 1d pass through the photodetector 9, the start position of a predetermined color frame can be known. For example,
When the output signal of the photodetector 9 changes at the boundary between the color frames 1a and 1b, the front end of the color frame 1a is positioned directly below the thermal head 3.

At this time, when the thermal head 3 is pressed downward and the platen motor 7 is rotated at a predetermined pitch in the direction of the arrow, the ink film 1 and the card 2 are sandwiched between the thermal head 3 and the platen roller 4. The ink film 1 is driven leftward in the figure at a predetermined pitch by the driving force of the platen roller 4. When a signal current to be printed in the color of the color frame 1 a is given to the thermal head 3, an image of the color of the color frame 1 a is thermally transferred to the surface of the card 2. Further, when the boundary between the color frames 1b and 1c is located below the photodetector 9, a signal opposite to the signal obtained by passing through the boundary between the color frames 1a and 1b is generated in the photodetector 9, so that the tip of the color frame 1b is It is possible to know that the thermal head 3 has just been reached. Therefore, the color image of the color frame 1b can be thermally transferred so as to overlap the color image of the color frame 1a. When printing the second color ink, the thermal head 3 is raised after the printing of the first color is completed, and the platen roller 4 is reversed to return the card 2 to the original position.

Further, the color frames 1c and 1d are sequentially conveyed to thermally transfer the third and fourth color inks onto the card 2, but the thermal head 3 of the color frames 1c and 1d is transferred.
The control of the transfer to the hopper is performed by the rotary encoders 10 and 11. The rotation of the rubber roller 12 causes the ink film 1 to rotate.
Of the color frame 1 by controlling a predetermined transfer amount from the reference position.
The cueing of c and 1d can be performed. As described above, the transfer amount of the ink film 1 is controlled, and the color image is thermally transferred onto the card 2.

[0008]

In the thermal transfer printer constructed as described above, the thermal head 3
Performs downward pressing operation, the ink film 1 is moved from the position shown by the solid line to the position shown by the broken line as shown in FIG. 4, and as a result, the transport path of the ink film 1 becomes longer. The ink film 1 corresponding to the length of the longer conveyance path is drawn out from the supply-side bobbin 5. This operation is performed at the time of cueing of each color. At this time, the slit disk 10 is rapidly rotated. Then, the slit disk 10 slips and is rotated more than necessary, and the count of the feeding amount of the ink film 1 becomes inaccurate, and there is a problem that an image with a shifted color is printed. Was.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and an object of the present invention is to provide an ink film control device for a thermal transfer printer that can control the amount of ink film transport very accurately.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention provides an ink film in which a plurality of color inks are repeatedly applied in a longitudinal direction as one set.
Winding a bobbin rotatable supply side turning, ball of the supply-side
To wind the ink film wound in a bottle,
And ink film take-up motor that drive the can up side of the bobbin, a thermal head disposed on one side of the ink film, a platen roller arranged on the other side of the ink film, the platen roller by the platen drive pulse And a platen motor for driving the ink film. The ink film control of the thermal transfer printer, which superimposes the ink film and the image receiving body, sandwiches them between the thermal head and the platen roller, and transfers the ink of the ink film onto the image receiving body. An apparatus for detecting a boundary of at least one ink serving as a reference in a plurality of color inks of the ink film, thereby detecting a first color ink of the ink film; and a bobbin on the supply side or the winding side. Rotating bobbin on take-off side A platen drive pulse and the bobbin rotation amount detection unit when printing while transporting the ink film at a constant speed by driving the platen roller by the platen motor. The winding radius of the bobbin is calculated and obtained based on the calculated rotation amount of the bobbin, and the ink film winding motor is operated during printing.
Is controlled in accordance with the winding radius of the bobbin, and after the printing with the first color ink is completed, the ink film is transferred to locate the next color ink after the second color. At this time, the ink film so that the rotation amount of the bobbin detected by the bobbin rotation amount detection means becomes the rotation amount calculated by the winding radius of the bobbin and the distance to transfer the ink film. And a control means for driving the bobbin on the take-up side by a take-up motor to transfer the ink film.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a thermal transfer printer according to the present invention.
FIG. 1 is a perspective view showing an example of an ink film control device of the thermal transfer printer of the present invention, and FIG. 2 is a timing chart for explaining the ink film control device of the thermal transfer printer of the present invention. In FIG. 1, the same parts as those in FIG. 3 are denoted by the same reference numerals.

In FIG. 1, four colors of Y, M, C, and K are represented by 1
The ink film 1 on which the set color frames are repeatedly applied in the longitudinal direction is stretched between the thermal head 3 and the platen roller 4 with the ink application surface facing the platen roller 4. For example, the color frames of the first to fourth colors applied in the order of Y, M, C, and K are 1a.
To 1d. The ink film 1 is supplied from a bobbin 5 around which the unused ink film 1 is wound, and is wound around a bobbin 6 around which the used ink film 1 is wound. A card 2 is conveyed between the ink film 1 and the platen roller 4 by an unillustrated conveyance mechanism as one of image receiving bodies.

The platen roller 4 is driven at a predetermined pitch by a platen motor 7 which is a step motor.
The bobbin 6 is driven by an ink film winding motor 8 which is a DC motor, and the ink film 1 is wound. A photo detector 9 is provided at the side end of the ink film 1.
This photodetector 9 is selectively made transparent or non-transparent by only one color of the color frames 1a to 1d of the ink film 1, and detects the start end and the end of the one color frame. I do. Further, in the present invention, the slit disk 10 is connected to the axis of the bobbin 5. A photodetector 11 is arranged close to the slit disk 10, and the slit disk 10 and the photodetector 11 constitute a rotary encoder (bobbin rotation amount detecting means) for detecting the transfer amount of the ink film 1. . A photodetector 14 is arranged at a position corresponding to the rear end of the card 2 side end, and the origin of the card 2 is detected.

When the ink film 1 is wound by the ink film winding motor 8, the ink film 1 is transported leftward in the drawing. At this time, since the color frames 1a to 1d of the ink film 1 pass through the photodetector 9, the start position of a predetermined color frame can be known. For example, when the output signal of the photodetector 9 changes at the boundary between the color frames 1a and 1b, the leading end of the color frame 1a is located immediately below the thermal head 3. Therefore, the photodetector 9 is a boundary detecting means for detecting the boundary of at least one ink serving as a reference in the inks of the plurality of colors of the ink film 1 and locating the first color ink.

At this time, when the thermal head 3 is pressed downward and the platen motor 7 is rotated at a predetermined pitch in the direction of the arrow, the ink film 1 and the card 2 are sandwiched between the thermal head 3 and the platen roller 4. The ink film 1 is driven leftward in the figure at a predetermined pitch by the driving force of the platen roller 4. When a signal current to be printed in the color of the color frame 1 a is given to the thermal head 3, an image of the color of the color frame 1 a is thermally transferred to the surface of the card 2. After printing of the color frame 1a, the thermal head 3 is raised and the platen roller 4
In the further separated state, the ink film 1 is conveyed based on the principle described later so that the leading end of the next color frame 1b is located immediately below the thermal head 3, and the second color ink is printed. Further, the color frames 1 c and 1 d are sequentially conveyed, and the third and fourth color inks are thermally transferred onto the card 2.

Here, the principle of the operation of transporting the ink film 1 and cueing the color frame by the ink film control device of the thermal transfer printer of the present invention will be described.
Photodetectors 9, 11, 14 arranged as described above
Is input to the control circuit 15. The control circuit 15 controls the platen motor 7 and the ink film winding motor 8 based on the input signals from the photodetectors 9, 11, and 14, as described later. The control circuit 15 also controls the pressing / separation of the thermal head 3 from / to the platen roller 4 and also controls the transport of the card 2.

As described above, when the ink film 1 is wound by the ink film winding motor 8, the ink film 1 is transported to the left in the drawing. At this time, the supply-side bobbin 5 also rotates counterclockwise. Rotary encoder 1
From 0 and 11, a rotation pulse N of the bobbin 5 is output.
As the ink film 1 is consumed, that is, the winding radius R of the bobbin 5 becomes smaller as the ink film 1 is wound around the bobbin 6 on the winding side, the transfer amount S of the ink film 1 and the rotation pulse N of the bobbin 5 Is represented by the winding radius R as follows.

S = 2πR · N / No (1) In the equation (1), No is the number of slits of the slit disk 10.

Further, since the ink film 1 during printing is transferred by the platen roller 4 at a predetermined pitch (print line pitch) P together with the card 2, it can be expressed as S = n · P (2). In the equation (2), n is a platen drive pulse (number of print lines / second) supplied to the platen motor 7. Further, in this embodiment, one printing line corresponds to one printing line.
Since the pulse is a pulse, the platen driving pulse n may be pulse / sec. During printing, since the above equations (1) and (2) are equal, S = 2πR · N / No = n · P (3) From this, the winding radius R of the bobbin 5 at that time is
R = nPNo / (2πN) (4) From the equation (4), the control circuit 15 can know the winding radius R of the bobbin 5.

For example, n = 100 lines / sec, P = 8
Assuming that 4.5 μm and No = 360 are designed,
When N = 32 pulses / sec is detected by the rotary encoders 10 and 11, R = 15.1 mm. in this way,
By detecting the output pulse N of the rotary encoders 10 and 11 during printing (that is, the rotation amount of the bobbin 5), the control circuit 15 can know the winding radius R of the bobbin 5.

After the printing of the color frame 1a is completed, with the thermal head 3 raised and separated from the platen roller 4, the ink film winding motor is moved so that the leading end of the next color frame 1b is located immediately below the thermal head 3. The distance by which the ink film 1 is to be transferred by 8 is a value S1 obtained by subtracting the printing length from the length of the color frame 1a. Since this value S1 can be known in advance, the ink film winding motor 8 is connected to the rotary encoder 10, It is sufficient to drive the control circuit 15 so that the output pulse N of 11 becomes the following N1. From 2πR · N1 / No = S1 (5), N1 = S1 · No / (2πR) (6)

The control circuit 15 outputs a predetermined platen drive pulse n to the platen motor 7 to drive the platen motor 7 and supplies a voltage V1 for giving a predetermined winding torque to the ink film winding motor 8 at the time of printing. At this time, the control circuit 15 detects the current winding radius R of the bobbin 5 by the calculation of the above equation (4) based on the rotation pulse N output from the photodetector 11. After the printing operation of the color frame is completed, the control circuit 15 determines that the leading end of the next color frame is the thermal head 3.
Is supplied to the ink film winding motor 8 for a time t until the number of rotation pulses N output from the photodetector 11 becomes N1 according to the above equation (6). .

Thus, after the printing of the color frame 1a is completed, the control circuit 15 sends the second and subsequent color frames 1a.
The cue of b to 1d can be accurately performed. When the thermal head 3 is pressed against the platen roller 4 after the cue of the color frames 1b to 1d, the ink film 1 is slightly pulled out from the bobbin 5, but in the present invention, the rotary encoders 10 and 11 are connected to the bobbin 5 , The slit disk 10 does not slip and slide more than necessary. Moreover, since the control circuit 15 detects the rotation of the bobbin 5, the ink film take-up motor 8 can be controlled in consideration of the rotation amount of the rotation when the thermal head 3 is pressed against the platen roller 4. Therefore, it is possible to control the transfer amount of the ink film 1 extremely accurately as compared with the related art. Therefore, according to the present invention, it is possible to satisfactorily solve the conventional problem of printing an image with a shifted color.

The operation control by the ink film control device (control circuit 15) of the thermal transfer printer of the present invention as described above is shown as timing in FIG. In FIG. 2, (A)
Is the output pulse of the photodetector 9, (B) is the output pulse N of the photodetector 11, (C) is the operation of the thermal head 3, (D) is the platen drive pulse of the platen motor 7, and (E) is (F) shows the drive control of the ink film winding motor 8, and (G) shows the output pulse of the photodetector 14.

As can be seen from FIG. 2, when the control circuit 15 detects the start end of the color frame 1a by the photodetector 9, it presses the thermal head 3 against the platen roller 4 and drives the platen motor 7 at n pulses / sec. The ink film 1 is transferred by driving the ink film winding motor 8 at the voltage V1 while driving the ink film 1 in the direction of the arrow in the middle. During this period, printing of the first color is performed. After printing is completed, the thermal head 3 is separated from the platen roller 4, and the ink film winding motor 8 is driven at the voltage V2 to transfer the ink film 1 to the next color frame. At this time, the platen motor 7 is driven in the direction opposite to the direction of the arrow in FIG. 1 to convey the card 2 in the direction opposite to the printing direction until the photodetector 14 detects the rear end of the card 2. In FIG. 2, the operation of returning the card 2 to the origin while the ink film 1 is being transported is performed. However, actually, the transport of the ink film 1 and the operation of returning the card 2 to the origin are performed sequentially. That is, after the ink film 1 is transferred, the operation of returning the card 2 to the origin is performed.

The accuracy of the cueing operation of the ink film 1 of the thermal transfer printer of the present invention described above will be examined. The thickness T of the ink film 1 is 0.006 mm, and the color frame length Lc is 100 m.
m, print length Lp is 90 mm, bobbin radius r of bobbin 5
Is 12 mm and the maximum winding radius Ro of the bobbin 5 is 30 mm, the change (maximum value) ΔR of the winding radius R of the bobbin 5 in the color frame is approximately ΔR = (Lc / 2πR) · T (7) 0.008 mm. Therefore, ΔR / R is approximately 0.0007, which is 0.07%. Therefore, even if the winding radius R of the bobbin 5 is calculated at any position within one color frame, the error can be ignored.

In practice, the bobbin 5 is used once during four-color printing.
If the winding radius R is calculated, sufficient accuracy can be obtained. Since the calculation of the winding radius R of the bobbin 5 according to the above equation (4) is performed by the print pulse which is the platen drive pulse n, the measurement accuracy is ± Pm from the print line pitch P.
m.

The number of slits No. of the slit disk 10
Is 360, the transfer amount (maximum value) of the ink film 1 for one pulse output is 0.52 mm from ΔS = 2πRo / No (8). Since the pulse control accuracy during the transfer of the ink film 1 is within ± 1 pulse, the feed accuracy of the ink film 1 is ± 0.52 mm. This value is ± 0.52% with respect to the color frame length Lc. The margin M before and after determined by the color frame length Lc and the printing length Lp is obtained by M = (Lc−Lp) / 2 (9), and the margin M is 5 mm from the equation (9).
Becomes Therefore, the feeding accuracy of the ink film 1 ± 0.5
It can be said that 2 mm is a sufficient margin for 5 mm of the margin M.

The accuracy of one rotation pulse N output from the photodetector 11 with respect to one pulse is P = 84.5.
When calculated as 0.085 mm from μm, ± P / ΔS = 0.085 mm / 0.52 mm = ± 0.16, but the photodetector 1 during one color frame printing
The accuracy with respect to the rotation pulse N output from 1 is ± P / Lp = 0.085 mm / 90 mm = ± 0.00094, and there is no problem in the calculation of the winding radius R of the bobbin 5.

In the above-described embodiment, the rotary encoders 10 and 11 are provided on the bobbin 5 on the supply side. However, even if they are provided on the bobbin 6 on the winding side, there is no change in principle. However, for the following reason, the rotary encoder 1
More preferably, 0 and 11 are provided on the bobbin 5 on the supply side. That is, since the bobbin 5 on the supply side is strictly wound in the production factory of the ink film 1, the relationship between the amount S with which the ink film 1 is pulled out and the rotation angle of the bobbin 5 is accurate. Further, since the used ink film 1 shrinks due to heat and the winding torque of the bobbin 6 on the winding side is not so large, the winding of the ink film 1 by the bobbin 6 is loose, and the winding amount of the ink film 1 and the ink film 1 The relationship with the rotation angle of the winding motor 8 is not accurate. For these reasons, it is better to control the transfer amount of the ink film 1 based on the rotation of the bobbin 5.

The ink film controller for a thermal transfer printer according to the present invention based on the above principle can be used for controlling the tension of the ink film 1. That is, since the total amount of the ink film 1 is determined in advance, the winding radius of the bobbin 6 on the winding side can be detected every moment by detecting the winding radius R of the bobbin 5 on the supply side. Therefore, in order to set the tension of the ink film 1 to a predetermined value, the output voltage V1 may be determined by the control circuit 15 so as to obtain the output torque of the ink film winding motor 8 according to the winding radius of the bobbin 6. In this embodiment, the ink film take-up motor 8 is controlled by controlling the magnitude of the output voltage V1.
The output power of the control circuit 15 may be a constant voltage, and the supply power may be controlled by controlling the ink film winding motor 8 at a high speed pulse width.

Further, in this embodiment, the color frame 1
Although the control of the ink film 1 having a to 1d has been described, the present invention can also be applied to a thermal transfer printer that performs printing of a predetermined size using a long monochrome ink film.

[0033]

As described in detail above, the ink film control device of the thermal transfer printer according to the present invention is capable of controlling at least one of the inks of a plurality of colors of the ink film.
Boundary detecting means (photodetector) for detecting the ink of the first color of the ink film by detecting the boundary between the two inks, and bobbin rotation amount detecting means for detecting the rotation amount of the supply-side bobbin or the winding-side bobbin. (Rotary encoder) and, based on the platen driving pulse and the amount of rotation of the bobbin detected by the bobbin rotation amount detecting means, when printing while transporting the ink film at a constant speed by driving the platen roller by the platen motor. the winding radius of the bobbin determined by calculation, during the printing
The output torque of the ink film take-up motor is
The control is performed in accordance with the winding radius, and after the printing with the first color ink is completed, when the ink film is transported to locate the next color ink after the second color, it is detected by the bobbin rotation amount detecting means. A control for driving the bobbin on the winding side by the ink film winding motor to transfer the ink film so that the amount of rotation of the bobbin is the amount of rotation calculated by the winding radius of the bobbin and the distance to transfer the ink film. Since the apparatus is provided with the means, it is possible to control the transfer amount of the ink film very accurately, and therefore, it is possible to print a good image without color shift.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of the present invention.

FIG. 2 is a timing chart for explaining the present invention.

FIG. 3 is a perspective view showing a conventional example.

FIG. 4 is a side view for explaining a problem of the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink film 1a-1d Color frame 2 Image receiving body (card) 3 Thermal head 4 Platen roller 5 Supply side bobbin 6 Winding side bobbin 7 Platen motor 8 Ink film winding motor 9 Photodetector (boundary detection means) 10 Slit disk (Bobbin rotation amount detecting means) 11 Photodetector (Bobbin rotation amount detecting means) 15 Control circuit (Control means)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 35/16 B41J 17/07 B41J 17/36

Claims (1)

(57) [Claims] 1. A method in which a plurality of color inks are repeated in the longitudinal direction as one set.
Roll the ink film that has been applied repeatedly and rotate freely
A supply-side bobbin, and the ink film wound around the supply-side bobbin.
And ink film take-up motor that drive the take-up side of the bobbin to take come, a thermal head disposed on one side of the ink film, a platen roller arranged on the other side of the ink film, the platen drive pulse And a platen motor for driving the platen roller. The thermal transfer that overlaps the ink film and the image receiving member, and sandwiches the ink film with the thermal head and the platen roller to transfer the ink of the ink film onto the image receiving member. In the ink film control device of the printer, a boundary detecting means for finding the first color ink of the ink film by detecting a boundary of at least one ink serving as a reference in the plurality of color inks of the ink film; Bobbin or the above winding Bobbin rotation amount detecting means for detecting the rotation amount of the bobbin on the print side, and the platen drive pulse and the bobbin when printing while transferring the ink film at a constant speed by driving the platen roller by the platen motor. The winding radius of the bobbin is calculated and calculated based on the rotation amount of the bobbin detected by the rotation amount detecting means.
Output of the ink film take-up motor during printing.
The torque is controlled according to the winding radius of the bobbin, and after the printing with the first color ink is completed, the ink film is transferred to find the next color ink of the second color and thereafter. At this time, the ink film so that the rotation amount of the bobbin detected by the bobbin rotation amount detection means becomes the rotation amount calculated by the winding radius of the bobbin and the distance to transfer the ink film. And a control means for driving the bobbin on the winding side by a winding motor to transfer the ink film.