JPH02172777A - Thermal transfer printer - Google Patents

Abstract

PURPOSE:To eliminate folds or slacks when recording paper is wound back by controlling the rotating speed of a motor for roll paper based on the speed data of a storage device which detects and stores the feed displacement speed of recording paper during its wind-back operation. CONSTITUTION:A control section 23 drives transport motors 6, 7 to transport recording paper 3 from a paper feeder roll 11 to an area between a platen roller 1 and a thermal head 2 with the help of transport rollers 4, 5. Then the control section 23 allows thermal transfer of data through an ink film 8. This feed speed is detected by a sensor 26 and stored in a storage section 27. When the recording paper 3 is transported back, the control section 23 controls the rotating speed of a motor 22 for roll paper based on speed data stored in a storage section 27. Thus it is possible to wind back the recording paper of a length fed out for transfer operation without generation of folds or slacks.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thermal transfer printer, and in particular to a thermal transfer printer that performs drip printing on recording paper using an ink film coated with inks of multiple colors to form a color image. This article relates to a thermal transfer printer.

FIG. 5 shows the basic structure of a thermal transfer printer used to form a color image on recording paper based on conventional image data.

As shown in the figure, the thermal transfer printer includes a platen roller 1
and a thermal head 2 that can be pressed into contact with and released from pressure contact therewith. In order to convey the recording paper 3 between these, a conveying roller 4 consisting of a driving roller 4a and a driven roller 4b is located upstream of the platen 1, and a driving roller 4 is located downstream of the platen 1. A conveyance roller 5 consisting of a roller 5a and a driven roller 5b is located. One conveyance roller 4 is driven by a motor 6, and the other conveyance roller 5 is driven by a motor 7. Between the thermal printer 2 and the recording paper 3, an ink film 8 coated with yellow, magenta, and cyan heat-melting or heat-sublimation inks is guided and conveyed by guide rollers 9 and 10. I have to.

The recording paper 3 is unwound from a recording paper roll wound into a roll, that is, a paper roll 11, and after a color image is formed thereon, the recording paper 3 is cut into a predetermined length by a cutter 12.

Note that reference numeral 13 is a sensor for detecting the leading edge of the recording paper 3.

In order to form a color image on the recording paper 3 using such a thermal transfer printer, in the case of the feed printing method described later,
The yellow part of the ink film 8 is transferred to the thermal head 2.
and the platen 1, and the recording paper 3 is positioned at a predetermined position.

After the thermal head is pressed in this state, the ink film 8 and the recording paper 3 are conveyed to transfer a yellow image onto the surface of the recording paper 3, and then the thermal head 2 is released from the pressure contact. Further, the ink film 6 is conveyed to position the next magenta portion to the thermal print position 2, and the recording paper 3 is returned to the printing start position. In this state, magenta is superimposed and transferred onto the recording paper 3, and cyan is further superimposed and transferred in the same manner, thereby completing one sheet of transfer work with three transfer operations. However, an ink film coated with ink of a total of six colors or an ink film coated with black may be used, in which inks of intermediate colors are coated to match the inks of these colors. A thermal transfer printer that forms a color image using a strip-shaped ink film in which a plurality of colors of ink each having a certain length is applied in a certain order is called a field-sequential printer.

Problems to be Solved by the Invention In the thermal transfer printer of the above-mentioned type, the process of rewinding the recording paper 3 multiple times is unavoidable. As shown, not only is it necessary to provide a space for slack, but doing so may cause the image to bend or be scratched. Especially when forming images on long recording paper such as A3,
Such inconveniences are likely to occur. If you rewind the recording paper onto the paper roll 11, you must ensure that only the amount of conveyance required for feeding is returned, otherwise the recording paper may become wrinkled or scratched, resulting in color misalignment during transfer. Therefore, there is a problem that a good and high quality transfer operation cannot be performed.

To this end, attempts have been made to develop a thermal transfer printer as shown in FIG. 6(A). In this case, in order to rewind the recording paper 3, a rewind roller 16 driven by a motor 15 is brought into pressure contact with the outer peripheral surface of the paper roll 11. Therefore, during the printing operation, the recording paper 3 is transferred to the paper roll 1 by the conveyance roller 4.5.
1, and during the rewinding operation, the unwinding roller 16
As a result, the recording paper 3 is returned to the paper roll 11.

In such a technique, as the diameter of the paper roll 11 decreases as the image forming operation progresses, it is necessary to always press the rewind roller 16 against the surface of the paper roll 11. When recording paper 3 runs out,
Since it is necessary to separate the rewind roller 16 from the roll shaft portion of the paper roll 11, the rewind roller 1
A mechanism that allows the paper roll 6 to move freely in the radial direction of the paper roll 11 is required. Furthermore, since the rewind roller 16 is pressed against the paper roll 11 before recording, the recording paper 3 before recording
The surface has the disadvantage of being scratched and dirty.

FIG. 6(B) is a diagram showing another example of a thermal transfer printer that has been developed so far, and in this case, the paper roll 1
Torque limiter 1 connected to motor 15 for rewinding 1
This is done through 7.

This motor 15 has the driving force necessary to rewind the recording paper 3, and when rewinding the recording paper 3, the length returned by the conveyance roller 4 is rewound onto the paper roll 11 by the motor 15. However, if the load exceeds the fixed value, paper roll 1
1, the torque limiter 17 slips and prevents the rotation of the motor 15 from being transmitted to the paper roll 11.

However, this method has the disadvantage that it is not only expensive, but also increases mechanical loss due to slippage caused by extra torque. Moreover, in this case, even if the torque of the motor 15 is constant, the paper roll 11
Since the winding diameter of the paper roll 11 changes, the tension applied to the recording paper 3 changes in inverse proportion to the winding diameter of the paper roll 11, and it is quite difficult to control this tension or set the torque value of the torque limiter.

Therefore, in a thermal transfer printer that uses a paper roll and performs overlapping printing in a field-sequential manner, when rewinding the recording paper, the length of the recording paper that is fed out during the transfer operation is removed so that it does not wrinkle or sag. The purpose is to make it possible to rewind reliably without causing any problems.

Means for Solving the Problems To achieve the above objects, the present invention includes a platen roller and a thermal head that is movable to press against and release from the platen roller, and to transfer a strip of recording paper from a paper roll to the thermal head. In a thermal transfer printer, an ink film is conveyed between a platen roller and the thermal head, and an ink film is conveyed between the recording paper and the thermal head to perform overlapping printing on the recording paper. a conveyance motor connected to a conveyance roller that performs and returns; a paper roll motor that rotates the paper roll in the return direction; a feed speed detection means that detects the feed movement speed of the recording paper; a storage means for storing data;
The thermal transfer printer further includes a control means for controlling the rotational speed of the paper roll motor based on the speed data when returning the recording paper.

Function: Regardless of whether printing is performed on the recording paper as it is fed out of the paper roll or when printing is performed while the recording paper is returned to the paper roll, the color To form an image, it is necessary to return and transport the recording paper multiple times. During this return conveyance, the feed speed of the recording paper during the previous feed conveyance is detected by the feed speed detection means, and since this speed is stored in the storage means, this stored feed speed can also be used. Then, the recording paper is returned to the paper roll. As a result, the recording paper is returned without sagging or bending between the paper roll and the transport roll. Therefore, wrinkles and the like do not occur on the recording paper during image formation, making it possible to form high-quality images.

EXAMPLES Hereinafter, the present invention will be explained in detail based on the illustrated examples of the present invention.

The thermal transfer printer of the present invention has a platen roller 1 and a thermal head 2 that can be brought into and out of pressure contact with the platen roller. A conveying roller 4 consisting of a roller 4a and a driven roller 4b is located upstream with respect to the platen 1, and a driving roller 5a and a driven roller 5b are located downstream.
A conveyance roller 5 consisting of the following is located. One conveyance roller 4 is driven by a conveyance motor 6, and the other conveyance roller 5 is driven by a conveyance motor 7. Between the thermal printer 2 and the recording paper 3,
An ink film 8 on which yellow, magenta, and cyan heat-melting or heat-sublimation inks are applied in this order.
is guided and conveyed by guide rollers 9 and 10.

The above-mentioned structure is almost the same as the basic structure of the thermal transfer printer shown in FIG. 5, and image forming methods using such a thermal transfer printer include a return printing method and a forward printing method.

The return printing method is a method in which the recording paper 3 is fed out by the length to be recorded, and then the image is recorded while being returned. This method will be explained with reference to the drawings. First, the conveyance motor 6.7 is driven and the recording paper 3 is fed out from the paper roll 11 by the conveyance roller 4.5 by a predetermined length. For example, A3 size (210X
If an image is to be formed on the recording paper 3 of 420flIII), the recording paper 3 is first fed out by a length corresponding to 420flIII11. At the same time, a predetermined color necessary for printing is positioned on the ink film 8 at the position of the thermal head 2.

Next, the thermal head 2 moves into pressure contact with the platen roller 1, and the recording paper 3 is returned to the paper roll 11 side by the drive of the conveyance roller 4.5 by the motor 6.7.
Image transfer is performed.

When printing for one color is completed in this manner, the next color is printed in a similar manner, and a color image is obtained by printing operations for three colors.

This return printing method prints after sending out the -degree recording paper 3, so it takes time to print, but it has the advantage of being able to widen the printing area. The reason why the width can be increased is that printing can be started from the very edge of the recording paper 3 while returning the recording paper 3 with high precision using the conveyance roller 4 on the side connected to the paper roll 11 side.

When a printing operation is performed using the feed printing method, which allows printing to be performed relatively quickly, the following procedure is performed. First, the recording paper 3 is sent by the transport roller 4.5,
When the tip of the thermal head 2 is detected by the sensor 13, the thermal head 2 is pressed against the platen roller 1. As a result, when printing starts, the recording paper 3 is transferred to the transport roller 4.5.
While being unwound from the paper roll 11 by the ink film 8, the ink film advances together with the ink film 8.

When one color is printed in this manner, the thermal head 2 separates from the platen roller 1, and the ink film 8 is wound up until the next color portion is located at the thermal head 2. Then, the recording paper 3 is returned by the conveyance roller 4.5 until the leading edge is detected by the sensor 13, and then
Printing of the next color is done in the same way. By bringing the conveyance roller 5 as close to the thermal head 2 as possible, the recording area can be expanded.

As mentioned above, the two pairs of transport rollers 4.5 are used to feed and return the recording paper 3, and both rollers 4.5 operate at the same speed during these transports. It is desirable that both rollers 4. and 4. rotate in the same direction.
It is practically desirable to set the rotational speed as follows in consideration of the occurrence of the rotational error in No. 5. In other words, in the return printing method in which printing is performed when the recording paper 3 is conveyed back, the return speed of the recording paper 3 is set by the conveyance roller 4 on the upstream side of the recording paper at the time of return; The rotational speed of the roller 5 is set higher than that of the roller 4. This prevents tension from being applied to the recording paper 3 during conveyance due to a rotational error between the two. On the other hand, when printing is not performed, that is, when the recording paper 3 is fed and conveyed, a slight tension is applied by the conveyance roller 4 so that the recording paper 3 does not slacken.

When performing the above-mentioned feed printing, printing is done when the recording paper 3 is sent out, so when printing is done,
That is, when the recording paper 3 is fed to the right in FIG. 1, the feeding speed is set by the conveyance roller 5, and the conveyance speed of the conveyance roller 4 is made slightly faster. Even if you do not print, that is, when you return recording paper 3,
As described above, the recording paper 3 is prevented from sagging.

In the thermal transfer printer of the present invention shown in FIG. 1, either the above-mentioned reverse printing method or forward printing method can be used, but the case where the forward printing method is used will be explained below.

As shown in the figure, a roll shaft 2 on which a paper roll 11 is mounted
0 is connected to a paper roll motor 22 by a transmission means 21 such as a belt in order to return and rotate the paper roll. In order to control the rotation of this motor 22, this motor 2
2 is connected to a control section 23 having a built-in microcomputer.

A control signal is also sent from the control section 23 to a motor 6.7 for driving the conveyance roller 4.5.

A disk-shaped detection plate 24 is attached to the roll shaft 20, and this detection plate 24 rotates together with the paper roll 11. In addition, this detection plate 24 has a notch 2.
5 is formed, and a detection sensor 26 is provided adjacent to the detection plate 24 to detect passage of this notch 25. The signal from this detection sensor 26 is sent to the control unit 23, and the rotational speed of the detection plate 24, that is, the rotation speed of the paper roll 11, is calculated from the time from when the -degree sensor 26 detects the notch 25 until the next detection. The rotational speed is calculated and the feeding speed of the recording paper 3 is detected. A storage section 27 is provided in the control section 23 to store data on this feed rate. In other words, this detection sensor 26 constitutes a feed rate detection means.

Therefore, when the recording paper 3 is fed out from the roll 11, the transport motor 6.7 is driven to rotate the transport roller 4.5, but at this time, the paper roll motor 22 is not driven. sensor 26
The feed speed of the recording paper 3 is calculated by the control section 23 based on the signal from the control section 23, and the speed value is stored in the storage section 27. In the feed printing method, printing operations are performed during this feeding process, so the recording paper 3 is returned to the roll 11 for printing in the next color. In this return process, the conveyance rollers 4.5 rotate in the opposite direction at the same speed as the respective feed speeds, and in order to prevent the recording paper 3 from becoming loose between the paper roll 11 and the conveyance roller 4, motor 2
2 is driven by a signal from the control section 23, and the roll section 11 is rotated in the return direction. This rotational speed is calculated based on the signal from the sensor 26 when feeding the recording paper 3, and is set to the same speed as the feeding speed stored in the storage section 27. As a result, the returned recording paper 3
A high quality image is formed on the recording paper 3 without wrinkles or creases. Note that by increasing the number of notches 25, it is possible to further improve the detection accuracy of the feed rate.

The printing process in the thermal transfer printer of the present invention shown in FIG. 1 will be explained with reference to the flowchart shown in FIG.

When the recording paper 3 is fed to a predetermined position and the yellow position of the ink film 8 is set to the position of the thermal head 2, when a print start command signal is input manually, in step 1 in FIG. 2 is pressed against the platen roller 1. At the same time, the conveyance roller 4.5 is driven in step 2 to feed the recording paper 3, and this feed amount is determined by adjusting the number of pulses sent to the motor 7 in step 3 to the set size of the recording paper 3. It is set by being counted to the corresponding value.

Furthermore, in step 4, the rotation speed of the paper roll 11 is calculated by the control unit 23 based on the signal from the sensor 26.

In step 5, it is determined from the number of pulses applied to the motor 7 whether or not the recording paper 11 has been sent out by a predetermined length. For example, if an image is to be formed on A3 recording paper 11, it is determined whether or not the number of pulses equivalent to 420 m has been sent, and if it is determined that a predetermined length has been sent,
In step 6, the rotation of the motor 6.7 is stopped. As a result, the conveying rollers 4.5 stop, the feeding of the recording paper 3 stops, and then, in step 7, the thermal head 2 separates from the platen roller 1.

In this way, when the yellow recording is completed, the recording paper 3 is transferred to the paper roll 1 in order to perform the next magenta recording.
Since it is necessary to return toward 1, a reverse rotation data processing subroutine for return is executed in step 8. In this subroutine, the motor 7 when feeding the recording paper 3
The feed length calculated from the number of steps and the sensor 26
The rotational speed of the paper roll 11 during feeding is calculated based on the time from when the notch 25 is detected once to when it is further detected.
The rotation speed is set.

In order to return the recording paper 3, in step 9,
The conveyance roller 4.5 will rotate in the reverse direction, and at the same time, in step 10, the paper roll motor 22 is rotated to rotate the paper roll 11 in the reverse direction at the rotation speed determined by the calculation result described above. In step 11, the pulses of the reverse rotation speed of the motor 6 for returning the recording paper 3 are counted, and in step 12 it is determined whether the recording paper 3 has been returned by a predetermined length. If you return it by the specified length, this step 1
If it is determined in step 2, the next magenta recording and cyan recording are performed in the same manner as described above.

If it is determined in step 13 that printing for three colors has been completed, the recording paper 3 is cut to a predetermined length by the cutter 12 in step 14, and the recording paper 3 is discharged outside the printer.

In the above case, the motor 2 for returning the paper roll 11
As a method of calculating the rotation speed of 2, the detection sensor 26
This shows a case in which a general encoder method using the Speed can be calculated.

In other words, if the diameter of the paper roll 11 is found, then the length of its outer circumference can be found, so by dividing the length of the recording paper 3 that has already been sent out by the outer diameter, the rotational speed of the paper roll 11 to be returned can be found. As a result, the rotational speed, that is, the rotational speed of the motor 22 is determined.

As described above, FIG. 3(A) is a diagram showing a feed speed detecting device that determines the rotational speed of the paper roll 11 during feeding by determining the outer circumferential diameter of the paper roll 11. A detection roller 32 is rotatably attached to one end of a lever 31 that is swingable about a bin 30 attached to the main body side. This detection roller 32 is adapted to come into contact with the outer peripheral surface of the paper roll 11. Further, the other end of the lever 31 is connected to a resistor 33.
It is designed to slide. Therefore, the lever 31
By determining the resistance value between the other end and the output terminal of the resistor 33, this resistance value and the outer diameter of the paper roll 11 can be set in a linear relationship, so the diameter can be determined. becomes.

FIG. 3(B) is a diagram showing another method for determining the outer circumferential diameter of the paper roll 11. In this case, a large number of CCD elements or photo array elements 40 arranged in a straight line are used.
The detection member 41 having
It is placed on the side of 1. In this case, the outer diameter of the paper roll 11 is determined from the position where the element detects light. Similarly, a light-emitting element may be provided in the light-emitting element 41, and a light-receiving member having a light-receiving element (not shown) may be placed on the other side of the paper roll 11 at a position facing this member. . In this case, the diameter of the paper roll 11 can be determined from the position where the paper roll 11 blocks light. The calculated value of the diameter in these cases is determined as a stepped value corresponding to the number of elements 40, but if the arrangement density of the elements 40 is increased, the accuracy of the determined diameter value can be increased to a practical level. can be sufficiently increased.

The diameter of the paper roll 11 can also be calculated by calculating the electromotive force of the motor, as shown in FIG. 3(C).

As shown in FIG. 3(C), a motor 45 for measuring electromotive force is connected to the roll shaft of the paper roll 11. When the recording paper 3 is sent out at a constant speed by the conveyance roller 4, the rotational speed of the paper roll 11 changes depending on the diameter of the paper roll 11.
The electromotive force changes linearly. In other words, as the rotational speed increases, the electromotive force of the motor 45 increases. Therefore, by measuring the electromotive force of this motor 45, it is possible to calculate the diameter of the paper roll 11.

As shown in FIGS. 3(A) to 3(C), when the diameter of the paper roll 11 is determined, the length of the outer circumference of the paper roll 11 can be determined from the diameter at that time. In step 8 shown in the figure, the number of rotations required to return the paper roll 11, that is, the rotation speed, is calculated by dividing the length of the fed recording paper by the length of the outer circumference. As a result, the rotational speed of the motor 22 for returning the recording paper 3 is calculated.

Next, still another embodiment of the present invention will be described.

In the above embodiment, the case where the feeding speed and return speed of the recording paper 3 were set to the same speed was explained, but in the case of the feed printing method, when returning the recording paper 3, the print operation is required. Therefore, in order to shorten the final printing time, the return speed may be set faster than the feed speed.

Even when fast reversing is performed in this way, the basic structure of the printer is the same as the structure shown in FIG.

To explain the operating procedure of the printer in this case, the recording paper 3 is fed out from left to right in Figure 1, printing of one color is completed, and the recording paper 3 is returned to prepare for the next overlapping print. It becomes a process. At this time, in step 8 shown in FIG. 2, the number of revolutions of the motor 6 that rotates the conveyance roller 4 has been calculated, so a value obtained by multiplying this by n is calculated. Based on the speed as a result of this calculation, the conveyance motor 4.5 is reversed in step 9, and the motor 22 for reversing the paper roll 11 is rotated in step 11. In this case, the recording paper 3 can be returned quickly without wrinkles or folds, and the time required for printing can be shortened.

The thickness of normal recording paper used in thermal transfer printers is not so large, and even if one sheet of recording paper is fed out, the change in the diameter of the paper roll 11 can be practically ignored. Therefore, as shown in FIG. 1, the rotational speed of the paper roll 11 when feeding the recording paper is determined by the detection sensor 26, and
If the recording paper is returned at that speed or at a speed n times higher than that, it is possible to reliably return the recording paper without causing folding or the like.

However, considering the case where the heat of the recording paper 3 becomes thicker, especially when the remaining amount of the recording paper 3 on the paper roll 11 becomes small, the process of feeding out one sheet of recording paper will be performed at a constant speed. Even if the paper roll 11 is fed out, the rotational speed of the paper roll 11 will gradually change.

Therefore, an example will be described below in which the return speed is also gradually changed in consideration of the fact that the rotational speed of the paper roll 11 changes during the feeding process due to the thickness of the recording paper. do.

FIG. 4(A) is a diagram showing a main part of this embodiment, and this diagram corresponds to a part of the thermal transfer printer shown in FIG. 1. If the radius of the conveyance roller 4 is R2 and the rotational angular velocity is ω2, then the conveyance speed V when sending out the recording paper 3 is
is expressed as the product of R2 and ω2. This conveyance speed V is constant, but if the radius of the paper roll 11 is R1 and the angular velocity is ω1, then R1 and ω1 will change during the conveyance process. The relationship between R1 and ω1 is shown in Figure 4 (
As shown in B).

In this embodiment, the detection plate 24 has a large number of notches 25.
By forming , it is possible to determine the change in the rotational speed of the paper roll 11 within a relatively short period of time. 1
The angular velocity ω1 of the paper roll 11, which changes moment by moment while feeding out sheets of recording paper, is stored in a storage section 2 provided in the control section 21.
It will be stored in the microcomputer in 7.

Therefore, when returning the recording paper 3, reverse data processing is performed in step 8 in FIG. The rotation of the motor 22 is controlled to reverse the paper roll 11.

This eliminates the occurrence of wrinkles or folds in the recording paper 3 during the return process even when thick recording paper 3 is used.

Also in this embodiment, the recording paper 3 can be quickly reversed. In that case, the conveyance roller 4 will be reversed at a speed n times faster than the feeding speed, and the paper roller 11 will also be returned at a speed n times the feeding speed, but the broken line in FIG. 4(B) As shown, the rotational speed of the motor 22 is controlled based on a stored table corresponding to a relationship diagram between ω1 and R1 multiplied by n.

Furthermore, embodiments that combine the embodiments described above are also possible.

For example, when the outer diameter of the paper roll 11 is large, the change in outer diameter required for printing one sheet is small;
If the outer diameter of the roll shaft of the paper roll 11 is small and the remaining amount of recording paper is small, the change in the diameter of the paper roll 11 will be large even when one sheet is fed out. Therefore, paper roll 11
When the outer diameter of the tube is large, the embodiment shown in Fig. 1 is used, and when the outer diameter is small, the embodiment shown in Fig. 3 is used, so these methods are used in combination. It's okay.

Note that, as described above, the present invention can be practiced even when the ink film is coated with ink of other colors than yellow, magenta, and cyan.

Furthermore, various types of recording paper, such as cut paper and continuous paper, can be used.

Effects of the Invention As described above, the present invention is effective regardless of whether a printing operation is performed on the recording paper while it is fed out from the paper roll or when the printing operation is performed while the recording paper is returned to the paper roll. In order to perform overlapping printing on recording paper, the recording paper is returned and conveyed multiple times. During this return conveyance, the feed speed of the recording paper during the previous feed conveyance is detected by the feed speed detection means, and this speed is stored in the storage means, so that at this stored feed speed, The recording paper will be returned to the paper roll. As a result, the recording paper is returned to the paper roll without sagging or bending between the paper roll and the transport roll. Therefore, wrinkles and the like do not occur on the recording paper during image formation, making it possible to form high-quality images.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a thermal transfer printer according to an embodiment of the present invention, FIG. 2 is a flowchart showing the operating state of the thermal transfer printer shown in FIG. 1, and FIGS.
FIG. 4(C) is a schematic diagram showing a device for detecting the feed speed of a paper roll, FIG. figure(
B) is a characteristic curve showing the relationship between the radius of the paper roll and the rotational angular velocity, Figure 5 is a schematic diagram showing a conventional thermal transfer printer, and Figures 6 (A) and 6 (B) are related technology thermal transfer printers. FIG. 1 is a schematic diagram showing a printer. 1...Platen roller, 2...Thermal head, 3
...Recording paper, 4.5...Conveyance roller, 6.7...
Conveyance motor, 8... Ink film, 11... Paper roll, 22... Paper roll motor, 23... Control unit (1; j control means), 24... Detection plate, 25...・
Notch, 26... detection sensor (speed detection means), 3
2... Detection roller, 33... Resistor (speed detection means), 41... Light emitting member (speed detection means).

Claims (1)

[Claims] It has a platen roller and a thermal head that can be brought into and out of pressure contact with the platen roller, and conveys a strip of recording paper from a paper roll between the platen roller and the thermal head, and also transports the recording paper and the thermal head between the platen roller and the thermal head. A thermal transfer printer that conveys an ink film between a thermal head and performs overlapping printing on the recording paper, includes a conveyance motor connected to a conveyance roller that feeds and returns the recording paper, and a conveyance motor connected to a conveyance roller that feeds and returns the recording paper; a paper roll motor that rotates the paper roll in the return direction; a feed speed detection means that detects the feed movement speed of the recording paper; a storage means that stores the feed speed data; and a paper roll motor that rotates the paper roll in the return direction; and control means for controlling the rotational speed of the paper roll motor.