JPH0691908A - Thermal transfer type recorder - Google Patents

Abstract

PURPOSE:To prevent a change in the carrying speed of an image-receiving sheet, a color shift of a recorded image and oblique feed of the image-receiving sheet without using any special device such as sensor. CONSTITUTION:In a thermal transfer type recorder in which a thermal head is brought into pressure contact with a platen roller 4 with an ink sheet and an image-receiving sheet 3 interposed therebetween, a pinch roller 5 is brought into pressure contact with the platen roller 4 with the image-receiving sheet 3 interposed therebetween, the image-receiving sheet 3 is carried by a frictional force acting between the platen roller 4 and the image-receiving sheet 3, the ink sheet is carried at a speed different from the speed of the image-receiving sheet 3 and an image is recorded on the image-receiving sheet 3, pressure contact adjusting mechanisms 11, 12 and 13 for adjusting a force of pressure contact of the pinch roller 5 with the platen roller 4 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording device.

[0002]

2. Description of the Related Art JP-A-62-199472 discloses
Controls the conveyance speed of the recording paper based on past print data from the thermal head, especially the number of heat generation dots in the past multiple lines, that is, if the number of heat generation dots in the past multiple lines is high, the temperature of the thermal head rises. Therefore, a recording apparatus is described in which the energization time of the thermal head is shortened to increase the conveyance speed of the recording paper to reduce the energization energy per dot to obtain a desired recording density. ing.

Further, Japanese Patent Laid-Open No. 63-165169 has a first capstan that conveys an image receiving sheet and a second capstan that conveys an ink sheet, and the conveying speed of the ink sheet is the image receiving speed. 1 / n of sheet conveying speed
A thermal transfer recording apparatus (n> 1) is described.

FIG. 12 shows a schematic structure of an example of a conventional thermal transfer recording apparatus. The thermal head 1 is pressed against the platen roller 4 via the ink sheet 2 and the image receiving sheet 3, and a plurality of heat generating resistance elements arranged in the main scanning direction of the thermal head 1 generate heat in accordance with image data, whereby the ink sheet 2 Ink is transferred to the image receiving sheet 3 to record an image on the image receiving sheet 3. The pinch roller 5 is pressed against the platen roller 4 via the image receiving sheet 3 by the force of the spring 6 applied via the arm 9. The platen roller 4 is driven and rotated by the platen roller driving unit, and the image receiving sheet 3 is conveyed by the frictional force acting between the image receiving sheet 3 and the platen roller 4 as the platen roller 4 rotates.

Further, the ink sheet 2 is sent from the ink sheet supply roller 7 at a speed lower than the conveying speed of the image receiving sheet 3 as the ink sheet supply roller 7 rotates. The ink sheet 2 is conveyed to the left of the thermal head 1 by the frictional force acting between the ink sheet 2 and the image receiving sheet 3, and is wound up by the ink sheet winding roller 8.

In this thermal transfer recording apparatus, the ink sheet 2 is conveyed at a speed lower than that of the image receiving sheet 3, so that the ink sheet 2 is consumed at a constant speed. Since it requires less than the device, it is possible to reduce the running cost.

In the thermal transfer recording apparatus, an ink sheet 2 having a plurality of different color regions is used, and the pinch roller 5 and the platen roller 4 are pressed against the platen roller 4 via the image receiving sheet 3 to receive an image. By reciprocally transporting the image receiving sheet 3 by the frictional force acting between the sheet 3 and the sheet 3, heat is generated according to the image data of a plurality of colors of the thermal head 1 in different color areas on the ink sheet 2, and image recording of a plurality of colors is overlaid. There is a full-color thermal transfer recording device that is designed to perform the above.

Further, in this full-color thermal transfer recording apparatus, in order to prevent the color shift of a recorded image, there is one in which image recording is performed after the front end of the image receiving sheet 3 is detected by a sensor provided in the vicinity of the thermal head 1. .

[0009]

The above-mentioned thermal transfer recording apparatus has a problem that the image receiving sheet 3 cannot be conveyed at a constant speed, and the reason therefor will be described below.
FIG. 13 shows the platen roller 4 by pressure contact with the pinch roller 5.
Shows a variation of. 13, the thermal head 1, the ink sheet 2 and the image receiving sheet 3 are omitted, and the broken line shows the shape of the platen roller 4 before deformation.

In general, the surface layer of the platen roller 4 has a high friction coefficient such as rubber in order to make the pressure contact force of the thermal head 1 uniform and to generate the friction force necessary for conveying the image receiving sheet 3. Material is used. The rubber has a Poisson's ratio of about 0.5, and its volume hardly changes even when it is deformed. Therefore, since the platen roller 4 expands laterally by the amount compressed by the pinch roller 5, the portion having the length AB before the pressing as shown by the broken line in FIG. As shown by the solid line, the length becomes A'B ', and the amount of lateral expansion is A.
A'B 'is longer than B.

However, when the platen roller 4 rotates, the time required for the peripheral surface of the rubber surface layer to move from B to A and the time required to move from B'to A'are different. Therefore, the peripheral speed of the platen roller 4 pressed by the pinch roller 5 increases as the compressive deformation increases. The conveying speed of the image receiving sheet 3 is determined by the peripheral speed of the platen roller 4 at the pressure contact portion of the pinch roller 5,
That is, it is determined by the shape of the platen roller 4 that is compressed and deformed.

The deformed shape of the platen roller 4 also changes depending on the load acting on the pressure contact portion. As shown in FIG. 14, the conveyance speed of the image receiving sheet 3 changes depending on the load acting on the image receiving sheet 3, and becomes slower as the load acting in the opposite direction to the conveying direction of the image receiving sheet 3 increases (the load acting in the conveying direction is Produces a negative value).

The load acting on the image receiving sheet 3 changes as shown in FIG. 15 due to the thermal energy generated by the thermal head 1. Therefore, when high-density image recording is performed on the image receiving sheet 3 by the high thermal energy of the thermal head 1, a large load acts on the image receiving sheet 3 and the conveyance speed of the image receiving sheet 3 becomes slower. When low-density image recording is performed on the image receiving sheet 3 with low heat energy due to the above, a small load acts on the image receiving sheet 3 and the conveying speed of the image receiving sheet 3 increases.

As described above, in the conventional thermal transfer recording apparatus, the conveyance speed of the image receiving sheet 3 changes during image recording, and the accuracy of the recording dot position decreases. However, this point is that in a thermal transfer recording apparatus that conveys the ink sheet 2 and the image receiving sheet 3 at a constant speed, the load acting on the image receiving sheet 3 is equal to the frictional force acting between the ink sheet 2 and the thermal head 1. The friction acting between the platen roller 4 and the image receiving sheet 3, that is, the conveying force is considerably small, so that it does not become a problem. However, in a thermal transfer recording apparatus that conveys the ink sheet 2 at a speed different from that of the image receiving sheet 3, a considerably large friction load acts between the ink sheet 2 and the image receiving sheet 3, so that the accuracy of the recording dot position is significantly reduced. there were.

Further, in a full-color thermal transfer recording apparatus which reciprocally scans the image receiving sheet 3 to record images of a plurality of colors, when the conveying speed of the image receiving sheet 3 changes, the length of the recorded image of each color changes. I will end up. Therefore, even if the platen roller 4 is rotated by a predetermined rotation angle after the image recording of each color is completed, the image receiving sheet 3 cannot be accurately returned to the image recording start position of the previous color. This causes color misregistration of the recorded image, which significantly deteriorates the quality of the recorded image. This problem can be solved by the image recording after detecting the front end of the image receiving sheet 3 by the sensor provided in the vicinity of the thermal head 1, but it is necessary to use the sensor.

Further, when the left and right recording image densities are different with respect to the conveying direction of the image receiving sheet 3, for example, when the left side recording image density is low and the right side recording image density is high as shown in FIG. Is the high density part on the right side (high OD
Part) has a larger load than the low-density part on the left side and the conveyance speed becomes slower, so that the sheet is obliquely fed as shown by the broken line in FIG. This skew feeding (skew) cannot be removed,
The reciprocal movement of the image receiving sheet 3 causes a cumulative deterioration of the recorded image quality.

The present invention improves the above-mentioned drawbacks and can prevent the fluctuation of the conveying speed of the image receiving sheet, the color shift of the recorded image and the oblique feeding of the image receiving sheet without using a special device such as a sensor. It is an object to provide a recording device.

[0018]

In order to achieve the above object, the invention according to claim 1 presses a thermal head against a platen roller via an ink sheet and an image receiving sheet, and a pinch roller via the image receiving sheet. The image receiving sheet is conveyed by a frictional force acting between the platen roller and the image receiving sheet, and the ink sheet is conveyed at a speed different from that of the image receiving sheet to record an image on the image receiving sheet. In the thermal transfer recording apparatus for performing the above, a press contact adjusting mechanism for adjusting the press contact force of the pinch roller with respect to the platen roller is provided.

According to a second aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, m (m
≧ 1, m: an integer) line is provided with a pressure contact force control means for controlling the pressure contact adjusting mechanism based on the total amount of the image data of the line to control the pressure contact force of the pinch roller with respect to the platen roller.

According to a third aspect of the present invention, the thermal head is pressed against the platen roller via the ink sheet having a plurality of different color regions and the image receiving sheet, and the ink sheet is conveyed at a speed different from that of the image receiving sheet and pinched. In a different color area on the ink sheet, by reciprocally conveying the image receiving sheet by a frictional force acting between the platen roller and the image receiving sheet in a state where the roller is pressed against the platen roller via the image receiving sheet. In a thermal transfer recording apparatus for recording images of a plurality of colors, a pressure contact adjusting mechanism that adjusts a pressure contact force of the pinch roller with respect to the platen roller, and a previous color when returning the image receiving sheet to a recording start position of the next color of each color. The pinch roller of the pinch roller is controlled by controlling the pressure contact adjusting mechanism based on the total amount of image data in one screen in recording. It is obtained by a pressing force control means for controlling the pressure contact force against serial platen roller.

According to a fourth aspect of the present invention, the thermal head is pressed against the platen roller via the ink sheet and the image receiving sheet, and the pinch roller is pressed against the platen roller via the image receiving sheet, and the platen roller and the image receiving roller are pressed. In the thermal transfer recording apparatus which conveys the image receiving sheet by a frictional force acting between the image receiving sheet and the ink sheet at a speed different from that of the image receiving sheet to record an image on the image receiving sheet, A pressure contact balance adjusting mechanism for adjusting the balance of the pressure contact force with respect to the platen roller in the main scanning direction is provided.

According to a fifth aspect of the invention, in the thermal transfer recording apparatus according to the fourth aspect, m (m
≧ 1, m: an integer) line, and a pressure contact balance control means for controlling the pressure contact balance adjustment mechanism based on the image data of the line to control the balance of the pressure contact force of the pinch roller with respect to the platen roller in the main scanning direction. is there.

According to a sixth aspect of the present invention, the thermal head is pressed against a platen roller via an ink sheet having a plurality of different color regions and an image receiving sheet, and the ink sheet is conveyed at a speed different from that of the image receiving sheet and pinched. In a different color area on the ink sheet, by reciprocally conveying the image receiving sheet by a frictional force acting between the platen roller and the image receiving sheet in a state where the roller is pressed against the platen roller via the image receiving sheet. In a thermal transfer recording apparatus for recording images of a plurality of colors, a pressure contact balance adjusting mechanism for adjusting the balance of the pressure contact force of the pinch roller with respect to the platen roller in the main scanning direction, and the image receiving sheet up to the recording start position of the next color of each color. When returning, the press contact balance adjustment mechanism is controlled based on the image data in the recording of the previous color. It is obtained by a pressure balance control means for controlling the main scanning direction balance contact pressure against the platen roller of the pinch rollers.

[0024]

According to the first aspect of the present invention, the pressure contact force of the pinch roller against the platen roller is adjusted by the pressure contact adjusting mechanism to prevent the speed of conveying the image receiving sheet from varying so that the image receiving sheet is always conveyed at a constant speed. It As a result,
It is possible to obtain a high-quality recorded image without color shift.

According to a second aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, the pressure contact force control means controls the pressure contact adjustment mechanism based on the total amount of image data of m lines to be recorded in the future, and the pinch is performed. The pressing force of the roller against the platen roller is controlled. Therefore, the conveyance speed of the image receiving sheet is prevented from varying, the image receiving sheet is always conveyed at a constant speed, and a high-quality recorded image without color misregistration can be obtained.

According to the third aspect of the invention, the pressure contact force of the pinch roller with respect to the platen roller is adjusted by the pressure contact adjusting mechanism, and when the image receiving sheet is returned to the recording start position of the next color of each color, the pressure contact force control means controls the previous color. The pressure contact adjusting mechanism is controlled based on the total amount of image data in one screen during recording to control the pressure contact force of the pinch roller against the platen roller. After image recording of each color, the image receiving sheet is returned to the recording start position of the next color without using a special device such as a sensor that detects the leading edge of the image receiving sheet, and there is no color misalignment due to the misregistration of the leading edge recording position. A recorded image is obtained.

In the fourth aspect of the invention, the balance of the pressure contact force of the pinch roller with respect to the platen roller in the main scanning direction is adjusted by the pressure contact balance adjusting mechanism. As a result, skew feeding of the image receiving sheet is prevented, and a high quality recorded image without color misregistration can be obtained.

According to a fifth aspect of the invention, in the thermal transfer recording apparatus according to the fourth aspect, the pressure contact balance control means performs pressure contact based on image data of m (m ≧ 1, m: integer) lines to be recorded in the future. The balance adjusting mechanism is controlled to control the balance of the pressure contact force of the pinch roller to the platen roller in the main scanning direction. Therefore, skew feeding of the image receiving sheet is prevented, and a high quality recorded image without color misregistration can be obtained.

In the invention of claim 6, the balance of the pressure contact force of the pinch roller with respect to the platen roller in the main scanning direction is adjusted by the pressure contact balance adjusting mechanism, and the pressure contact balance is returned when the image receiving sheet is returned to the recording start position of the next color of each color. The control means controls the press contact balance adjusting mechanism based on the image data in the recording of the previous color to control the main scanning direction balance of the press contact force of the pinch roller with respect to the platen roller. Therefore, when the image receiving sheet is returned to the recording start position, skew feeding of the image receiving sheet is prevented, and a high-quality recorded image without color misregistration due to misalignment of the leading edge recording position can be obtained.

[0030]

1 and 2 show a pressure contact adjusting mechanism in a first embodiment of the present invention. This first embodiment is similar to that of FIG.
In the thermal transfer recording apparatus as shown in FIG. 2, a press contact adjusting mechanism for adjusting the press contact force of the pinch roller 5 to the platen roller 4 is provided.
It has a shaft 12 and a pinch roller pressing motor 13.

FIG. 3 shows the circuit configuration of the first embodiment. The image data to be recorded on the image receiving sheet 3 is temporarily stored in the image data memory 14 and then given to the thermal control circuit 15 and the microcomputer (CPU) 16. The thermal control circuit 15 converts the image data from the image data memory 14 into a predetermined energizing pulse signal and outputs it to the thermal head drive circuit 17, and the thermal head drive circuit 17 is arranged in the main scanning direction of the thermal head 1. Heat is generated by repeatedly driving a plurality of heating resistance elements for one line in response to the energizing pulse signal for each line from the heat control circuit 15. Then, the ink sheet 2 transfers the ink to the image receiving sheet 3 by the heat generation of the heat generating resistance element of the thermal head 1, whereby the image recording of the image receiving sheet 3 is performed.

As shown in FIG. 4, the i-th line in the main scanning direction (1≤i≤a) and the j-th line in the sub-scanning direction (1≤j≤)
When the image data of the dots in b) is Dij, the CPU 16 uses the image data from the image data memory 14 when recording the image data of the nth line (1 ≦ n ≦ b) in the sub-scanning direction. Data A, which is an appropriate integer satisfying m: 1 ≦ m ≦ b, is obtained.

The data A is data obtained by averaging the total sum of the image data for each line in the main scanning direction from the nth line to the (n + m) th line. The larger A is, the larger the thermal energy generated by the thermal head 1 during image recording of m lines and the larger the load acting on the image forming sheet 3, and therefore the image forming sheet 3 with respect to the rotation speed of the platen roller 4. The ratio of transport speed becomes small.

In this first embodiment, as shown in FIGS. 1 and 2, the pinch roller 5 is pressed against the platen roller 4 by the spring 10 via the arm 9, and the spring 6 is connected to the arms 9 and 11.
Installed between. The arm 11 is attached to a shaft 12 to which a pinch roller pressure welding motor 13 is connected,
The shaft 12 is rotationally driven by the pinch roller pressing motor 13 to rotate the arm 11 from the reference position.

The CPU 16 uses the data A to obtain its function Rc.
(A) is obtained and output to the pinch roller pressure contact control circuit 18, and the pinch roller pressure contact control circuit 18 rotates the pinch roller pressure contact motor 13 from the reference position by an angle corresponding to the function Rc (A) thereof. The force of pressing the platen roller 4 through the image receiving sheet 3 of No. 5 is changed.

By the way, between the pressure contact force of the pinch roller 5 and the conveying speed of the image receiving sheet 3, as shown in FIG. 5, the conveying speed of the image receiving sheet 3 increases as the pressure contact force of the pinch roller 5 increases. Since the pressure contact force of the pinch roller 5 changes as described above, the conveyance speed of the image receiving sheet 3 is changed by the amount that cancels the influence of the load acting on the image receiving sheet 3 and the conveyance speed of the image receiving sheet 3 is changed. Fluctuations are prevented. Therefore, the image receiving sheet 3 is always conveyed at a constant speed, and a high-quality recorded image without color misregistration can be obtained.

In the first embodiment, the calculation of the function Rc (A) from the image data is performed inside the CPU 16. However, a calculation circuit for performing a calculation such as addition is provided outside the CPU 16 to perform this calculation. The circuit calculates A, stores the table of the function Rc (A) in the ROM, etc., and refers to the table of the function Rc (A) by the function Rc (A).
May be requested.

FIG. 6 shows the circuit configuration of the second embodiment of the present invention. The second embodiment is the same as the first embodiment except that the CP
A CPU 19 is used in place of U16, and an ink sheet 2 having a plurality of different color regions is used, and the pinch roller 5 is pressed against the platen roller 4 via the image receiving sheet 3 and the image is received with the platen roller 4. A full-color thermal transfer recording apparatus in which the image receiving sheet 3 is reciprocally conveyed by a frictional force acting between the sheet 3 and the thermal head 1 so as to perform image recording of a plurality of colors in different color areas on the ink sheet 2. Is.

At the time of recording an image of each color, the platen roller 4 is driven by the platen roller driving unit to rotate in the forward direction, and the image receiving sheet 3 moves forward. Then, the heating resistance elements for one line arranged in the main scanning direction of the thermal head 1 are driven by the thermal head drive circuit 17 according to the image data of each color to generate heat, so that each color from each color area of the ink sheet 2 is heated. By transferring the above ink to the image receiving sheet 3, image recording for each color is performed in an overlapping manner. Before the image recording of the next color is performed after the image recording of each color is completed, the platen roller 4 is driven by the platen roller driving unit to rotate in the opposite direction, and the image receiving sheet 3 records the next color. It is returned to the start position. The image data of each color is temporarily stored in the image data memory 14 and then sequentially sent to the thermal head drive circuit 17 via the thermal control circuit 15.
And it is sent to the CPU 19.

When recording an image of each color, the CPU 19 totalizes the image data Dij from the image data memory 14 over the entire screen. Then, the data B is obtained. The larger this data B is, the greater the thermal energy generated by the thermal head 1 during image recording of one screen (image recording of one color on one image receiving sheet 3) and the load acting on the image receiving sheet 3 is increased. Since it is large, the image receiving sheet 3 with respect to the rotation speed of the platen roller 4
The ratio of the conveyance speeds of the image receiving sheets 3 becomes small.
Screen length is shortened.

The CPU 19 uses the data B to obtain the function Rc '.
Find (B). Before the image recording of the next color is performed after the image recording of each color is completed, the platen roller 4 is driven by the platen roller driving unit before the predetermined rotation amount R.
However, the image receiving sheet 3 is returned to the recording start position for the next color. When returning the image receiving sheet 3 to the recording start position of the next color, the CPU 19 outputs the function Rc '(B) to the pinch roller pressure contact control circuit 18, and the pinch roller pressure contact control circuit 18 controls the pinch roller pressure contact motor 13 to operate the same. By rotating the pinch roller 5 from the reference position by an angle corresponding to the function Rc ′ (B), the force of pressing the platen roller 4 through the image receiving sheet 3 of the pinch roller 5 is changed. For this reason,
The conveyance speed of the image receiving sheet 3 is changed by the amount of canceling the influence of the load acting on the image receiving sheet 3, the image receiving sheet 3 is accurately returned to the recording start position of the next color, and there is no color shift due to the leading edge recording position shift. A high quality recorded image can be obtained.

7 and 8 show a part of the third embodiment of the present invention, and FIG. 9 shows a circuit configuration of the third embodiment. In the third embodiment, in the first embodiment (or the second embodiment), the CPU 20 outputs the image data Dij from the image data memory 14 from the n line to the (n + m) line in the sub scanning direction for each main scanning position. Up to Then, the regression coefficient k of (i, Ci) is calculated and output to the pinch roller pressure contact control circuit 18.

As shown in FIG. 10, the image receiving sheet 3 has k>
When 0, it rotates clockwise (skew), when K <0 it rotates counterclockwise, and when k = 0, no skew occurs. This is because, for example, when k> 0, the energy applied from the thermal head 1 is large on the right side of the image receiving sheet 3 and the load is large, and the image receiving sheet 3 has a conveyance speed on the right side as compared to the left side. This is because it will be late.

Both ends of the pinch roller 5 are arms 9a and 9b.
Is rotatably held by the arms 9a and 9b and is rotatably supported. A spring 6a is provided between the arms 9a and 11a.
Is attached, and a spring 6b is attached between the arms 9b and 11b, and the pinch roller 5 is pressed against the platen roller 4 by the force of the springs 6a and 6b. Arms 11a, 11
The shaft b is fixed to a shaft 12, and the shaft 12 is connected to a pinch roller pressing motor 13. The arms 11a and 11b, the shaft 12 and the pinch roller pressure contact motor 13 constitute a pressure contact balance adjustment mechanism for adjusting the balance of the pressure contact force of the pinch roller 5 with respect to the platen roller 4 in the main scanning direction.

The pinch roller pressure contact control circuit 18 is the CPU 2
When k> 0 by the regression coefficient k from 0, the pinch roller pressing motor 13 is driven according to k to rotate the shaft 12 clockwise from the reference position, whereby the expansion of the spring 6a increases and the spring 6b moves. Growth is reduced. Therefore, the pressure contact force of the pinch roller 5 against the platen roller 4 is the spring 6a.
The side of the image receiving sheet 3 increases, and the conveying speed of the image receiving sheet 3 on the side of the spring 6a increases. Therefore, the delay of the conveyance speed of the image receiving sheet 3 due to the increase of the load is canceled out, and the balance of the pressure contact force of the pinch roller 5 to the platen roller 4 in the main scanning direction is adjusted. As a result, skew feeding of the image receiving sheet 3 is prevented, and a high quality recorded image without color misregistration can be obtained.

Similarly, the pinch roller pressure contact control circuit 18 outputs k
When <0, depending on k, the pinch roller pressure contact motor 1
3 is driven to rotate the shaft 12 in the counterclockwise direction from the reference position, whereby the main scanning direction balance of the pressure contact force of the pinch roller 5 to the platen roller 4 is similarly adjusted.

FIG. 11 shows the circuit configuration of the fourth embodiment of the present invention. In the fourth embodiment, in the full-color thermal transfer recording apparatus of the second embodiment, the CPU 21 performs image data Dij from the image data memory 14 when recording an image of each color.
For each main scan line Then, the data Ci ′ is obtained, and the regression coefficient k ′ of (i, Ci ′) is further obtained. Before the image recording of the next color is completed after the image recording of each color is completed, the platen roller 4 is
Is driven by the platen roller drive unit and rotated in the reverse direction by a predetermined rotation amount R, and the image receiving sheet 3 is returned to the recording start position of the next color. When returning the image receiving sheet 3 to the recording start position of the next color, the CPU 21 outputs the regression coefficient k ′ to the pinch roller pressure contact control circuit 18. The image receiving sheet 3 on which one screen has been recorded rotates (skew) clockwise when k ′> 0, rotates counterclockwise when K ′ <0, and does not generate skew when k = 0.

The pinch roller pressure contact control circuit 18 is the CPU 2
When k '> 0 by the regression coefficient k'from 0, the pinch roller pressure contact motor 13 is driven according to k'and the shaft 12
Rotate clockwise from the reference position. As a result, the pressure contact force of the pinch roller 5 against the platen roller 4 is reduced by the spring 6
The a-side increases, and the image-receiving sheet 3 increases the conveyance speed on the spring 6a side. For this reason, the feeding speed of the image receiving sheet 3 due to the increase of the load is canceled, and the balance of the pressure contact force of the pinch roller 5 to the platen roller 4 in the main scanning direction is adjusted.

Similarly, when k '<0, the pinch roller pressure contact control circuit 18 drives the pinch roller pressure contact motor 13 according to k'to rotate the shaft 12 counterclockwise from the reference position. As a result, the pressing force of the pinch roller 5 against the platen roller 4 increases on the spring 6b side, and the image receiving sheet 3
Increases the transport speed on the side of the spring 6b. For this reason, the feeding speed of the image receiving sheet 3 due to the increase of the load is canceled, and the balance of the pressure contact force of the pinch roller 5 to the platen roller 4 in the main scanning direction is adjusted.

As described above, when the image receiving sheet 3 is returned to the recording start position of the next color of each color, the balance of the pressure contact force of the pinch roller 5 to the platen roller 4 is controlled in the main scanning direction, and the image receiving sheet 3 is obliquely fed. It is possible to obtain a high-quality recorded image that is prevented and has no color misregistration due to the misregistration of the leading edge recording position.

[0051]

As described above, according to the invention of claim 1, the thermal head is pressed against the platen roller via the ink sheet and the image receiving sheet, and the pinch roller is pressed against the platen roller via the image receiving sheet. Then, the image receiving sheet is conveyed by a frictional force acting between the platen roller and the image receiving sheet, and the ink sheet is conveyed at a speed different from that of the image receiving sheet to record an image on the image receiving sheet. Since the apparatus is provided with the press contact adjusting mechanism for adjusting the press contact force of the pinch roller with respect to the platen roller, it is possible to prevent the transfer speed of the image receiving sheet from varying and to always transfer the image receiving sheet at a constant speed. Therefore, it is possible to obtain a high-quality recorded image without color misregistration.

According to a second aspect of the present invention, in the thermal transfer recording apparatus according to the first aspect, the press contact is performed based on the total amount of image data of m (m ≧ 1, m: integer) lines to be recorded in the future. Since the adjusting mechanism is provided with the press contact force control means for controlling the press contact force of the pinch roller with respect to the platen roller, it is possible to prevent the transfer speed of the image receiving sheet from varying and to always transfer the image receiving sheet at a constant speed. Therefore, it is possible to obtain a high-quality recorded image without color misregistration.

According to the third aspect of the invention, the thermal head is pressed against the platen roller via the ink sheet having a plurality of different color regions and the image receiving sheet, and the ink sheet is conveyed at a speed different from that of the image receiving sheet. , A different color on the ink sheet by reciprocally conveying the image receiving sheet by a frictional force acting between the platen roller and the image receiving sheet in a state where the pinch roller is pressed against the platen roller via the image receiving sheet. In a thermal transfer recording apparatus that records images of a plurality of colors in a region, a pressure contact adjusting mechanism that adjusts the pressure contact force of the pinch roller with respect to the platen roller, and before returning the image receiving sheet to the recording start position of the next color of each color Based on the total amount of image data in one screen in color recording, the press contact adjustment mechanism is controlled to control the pinch Since a pressure contact force control means for controlling the pressure contact force of the roller with respect to the platen roller is provided, the image receiving sheet can be recorded to the next color after image recording of each color without using a special device such as a sensor for detecting the leading edge of the image receiving sheet. It is possible to return to the recording start position, and it is possible to obtain a high-quality recorded image without color misregistration due to the misregistration of the leading edge recording position.

According to the fourth aspect of the present invention, the thermal head is brought into pressure contact with the platen roller via the ink sheet and the image receiving sheet, and the pinch roller is brought into pressure contact with the platen roller via the image receiving sheet. In the thermal transfer recording apparatus, which conveys the image receiving sheet by a frictional force acting between the image receiving sheet and the ink sheet at a speed different from that of the image receiving sheet to record an image on the image receiving sheet, the pinch roller Since the press contact balance adjusting mechanism for adjusting the balance of the press contact force with respect to the platen roller in the main scanning direction is provided, skew feeding of the image receiving sheet can be prevented, and a high quality recorded image without color misregistration can be obtained. it can.

According to the fifth aspect of the invention, in the thermal transfer recording apparatus according to the fourth aspect, the press contact balance adjustment is performed based on image data of m (m ≧ 1, m: integer) lines to be recorded in the future. Since the press contact balance control means for controlling the mechanism to control the balance of the press contact force of the pinch roller with respect to the platen roller in the main scanning direction is provided, it is possible to prevent skew feeding of the image receiving sheet, and to prevent color misregistration. A quality recorded image can be obtained.

According to the sixth aspect of the present invention, the thermal head is pressed against the platen roller via the ink sheet having a plurality of different color areas and the image receiving sheet, and the ink sheet is conveyed at a speed different from that of the image receiving sheet. , A different color on the ink sheet by reciprocally conveying the image receiving sheet by a frictional force acting between the platen roller and the image receiving sheet in a state where the pinch roller is pressed against the platen roller via the image receiving sheet. In a thermal transfer recording apparatus that records images of a plurality of colors in a region, a pressure contact balance adjustment mechanism that adjusts the balance of the pressure contact force of the pinch roller with respect to the platen roller in the main scanning direction,
When the image receiving sheet is returned to the recording start position of the next color of each color, the pressure contact balance adjusting mechanism is controlled based on the image data in the recording of the previous color to balance the pressure contact force of the pinch roller with respect to the platen roller in the main scanning direction. Since it is provided with a pressure contact balance control means for controlling the image receiving sheet, it is possible to prevent the image receiving sheet from being obliquely fed when the image receiving sheet is returned to the recording start position, and high-quality recording without color misregistration caused by the leading edge recording position deviation. An image is obtained.

[Brief description of drawings]

FIG. 1 is a front view showing a part of a first embodiment of the present invention.

FIG. 2 is a side view showing the same portion.

FIG. 3 is a block diagram showing a circuit configuration of the first embodiment.

FIG. 4 is a diagram for explaining the first embodiment.

FIG. 5 is a characteristic diagram showing the relationship between the pinch roller pressure contact force and the image receiving sheet speed of the thermal transfer recording apparatus.

FIG. 6 is a block diagram showing a circuit configuration of a second embodiment of the present invention.

FIG. 7 is a front view showing a part of the third embodiment of the present invention.

FIG. 8 is a side view showing the same portion.

FIG. 9 is a block diagram showing a circuit configuration of the third embodiment.

FIG. 10 is a diagram for explaining the third embodiment.

FIG. 11 is a front view showing a part of the fourth embodiment of the present invention.

FIG. 12 is a front view schematically showing an example of a conventional thermal transfer recording apparatus.

FIG. 13 is a diagram for explaining the thermal transfer recording apparatus.

FIG. 14 is a characteristic diagram showing the relationship between the load acting on the image receiving sheet and the speed of the image receiving sheet of the thermal transfer recording apparatus.

FIG. 15 is a characteristic diagram showing a relationship between heat generation energy of a thermal head of the thermal transfer recording apparatus and a load acting on an image receiving sheet.

FIG. 16 is a diagram for explaining the thermal transfer recording apparatus.

[Explanation of symbols]

 3 Image Receiving Sheet 4 Platen Roller 5 Pinch Roller 6, 6a, 6b Spring 9, 9a, 9b Arm 11, 11a, 11b Arm 12 Axis 13 Pinch Roller Pressure Contact Motor 16, 19, 20, 21 CPU 18 Pinch Roller Pressure Contact Control Circuit

Claims (6)

[Claims] 1. A thermal head is pressed against a platen roller via an ink sheet and an image receiving sheet, and a pinch roller is pressed against the platen roller via the image receiving sheet to act between the platen roller and the image receiving sheet. In the thermal transfer recording apparatus that conveys the image receiving sheet by a frictional force to perform the image recording on the image receiving sheet by conveying the ink sheet at a speed different from that of the image receiving sheet, a pressure contact force of the pinch roller with respect to the platen roller is applied. A thermal transfer recording apparatus comprising a pressure contact adjusting mechanism for adjusting. 2. The thermal transfer recording apparatus according to claim 1, wherein the pinch is controlled by controlling the pressure contact adjusting mechanism based on the total amount of image data of m (m ≧ 1, m: integer) lines to be recorded in the future. A thermal transfer recording apparatus comprising a pressure contact force control means for controlling a pressure contact force of the roller with respect to the platen roller. 3. A thermal head is brought into pressure contact with a platen roller via an ink sheet having a plurality of different color regions and an image receiving sheet, the ink sheet is conveyed at a speed different from that of the image receiving sheet, and a pinch roller moves the image receiving sheet. Through the reciprocating conveyance of the image receiving sheet by the frictional force acting between the platen roller and the image receiving sheet in a state of being pressed against the platen roller through the image recording of plural colors in different color regions on the ink sheet. In a thermal transfer recording apparatus for performing, a press contact adjusting mechanism for adjusting a press contact force of the pinch roller with respect to the platen roller, and a one-screen in a previous color recording when returning the image receiving sheet to a recording start position of the next color of each color Based on the total amount of image data, the pressure contact adjusting mechanism is controlled to move the pinch roller against the platen roller. Thermal transfer recording apparatus characterized by comprising a pressing force control means for controlling the contact force that. 4. A thermal head is pressed against a platen roller via an ink sheet and an image receiving sheet, and a pinch roller is pressed against the platen roller via the image receiving sheet to act between the platen roller and the image receiving sheet. In the thermal transfer recording apparatus that conveys the image receiving sheet by a frictional force to perform the image recording on the image receiving sheet by conveying the ink sheet at a speed different from that of the image receiving sheet, the contact pressure of the pinch roller against the platen roller is increased. A thermal transfer recording apparatus comprising a press contact balance adjusting mechanism for adjusting balance in the main scanning direction. 5. The thermal transfer recording apparatus according to claim 4, wherein the pinch roller is controlled by controlling the pressure contact balance adjusting mechanism based on image data of m (m ≧ 1, m: integer) lines to be recorded in the future. 2. A thermal transfer recording apparatus comprising: a press contact balance control means for controlling the balance of the press contact force to the platen roller in the main scanning direction. 6. A thermal head is pressed against a platen roller via an ink sheet having a plurality of different color regions and an image receiving sheet, the ink sheet is conveyed at a speed different from that of the image receiving sheet, and a pinch roller moves the image receiving sheet. Through the reciprocating conveyance of the image receiving sheet by the frictional force acting between the platen roller and the image receiving sheet in a state of being pressed against the platen roller through the image recording of plural colors in different color regions on the ink sheet. In the thermal transfer recording apparatus that performs, a press contact balance adjusting mechanism that adjusts the balance of the press contact force of the pinch roller with respect to the platen roller in the main scanning direction, and the previous color when returning the image receiving sheet to the recording start position of the next color of each color The pinch roller is controlled by controlling the pressure contact balance adjusting mechanism based on image data in recording. Thermal transfer recording apparatus is characterized in that a pressure balance control means for controlling the main scanning direction balance contact pressure against the platen roller.