JPS62161659A - Paper feeding mechanism for hot transfer type color printer - Google Patents

Abstract

PURPOSE:To eliminate a paper slip as well as to improve accuracy in superposition of dots, by installing a device which drives a platen roller paper feeding device and sprocket wheel paper feeding device both in a synchronous manner. CONSTITUTION:Paper 2 and Y color of an ink film 15 are superposed on a platen roller 8 and then an initial location is carried out. Next, a thermal head 21 is pressed to the roller 8, a sprocket wheel 1 and the roller 8 both are rotated clockwise by a motor 6, and the Y color is printed while doing a progressive advance. If printing is over, the thermal head 21 is separated from the roller 8, rotating the motor 6 in reverse. With this operation, the paper 2 is returned to the initial position, and during this time, the ink film 15 is conveyed to a position of the next M color. The thermal head 21 is repressed to the platen roller 8, and the M color is printed. After completion of printing, the same operation is repeated, and a C color is printed, thus register printing for three colors of Y, M and C is completed.

Description

Detailed Description of the Invention [Industrial Field of Application] This invention relates to a paper feed mechanism for a thermal transfer color printer that performs color printing by thermally transferring multiple color inks coated on an ink film onto paper. Regarding.

[Prior Art] This type of thermal transfer color printer generally overlaps paper with an ink film alternately coated with ink of three colors: yellow (Y), magenta (M), and cyan (C). Printing is performed while moving between the head and platen roller. In this case, each time printing of the I vane for one color is completed, the paper is returned and the ink film is advanced by one color, three colors are overlapped and color printing is performed. In other words, the paper must be moved back and forth three times in order to print one color sheet.

The most important point in the above color printing is the matching of the three colors. That is, since each color is expressed by a dot with a diameter of about 0.1 mm, precision is required to accurately superimpose the three colors Y, M, and C on the same dot.

Especially in recent years, the number of dots per mm has increased to 8.12.16.
As a result, the demand for overlay accuracy is increasing.

[Problems to be Solved by the Invention] However, in conventional color printers, there is an inconvenience in that while the paper is moved back and forth, the paper is misaligned and three colors are rubbed off. This is because the feed holes provided on both sides of the paper and the sprocket pins fitted into the feed holes are misaligned.

This invention was made against this background, and an object of the present invention is to provide a paper feeding mechanism for a thermal transfer color printer that eliminates paper misalignment, increases dot overlay accuracy, and improves the quality of color printing. purpose.

In addition, the present applicant first filed a patent application in 1973! A similar proposal was made in J-241363. However, in this proposal, a one-way clutch was interposed on the drive shaft of the platen roller to prevent the platen roller from rotating when the paper was being fed backwards, which meant that the force applied to the paper would be too strong when the paper was being fed back. was there.

This invention attempts to solve these problems as well.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a sprocket wheel paper feeding means for feeding paper in both forward and reverse directions, and a sprocket wheel paper feeding means for feeding paper in both the forward and reverse directions in synchronization with the sprocket wheel paper feeding means. A rotating platen roller paper feeding means, and when the paper is being fed in the forward direction, the paper and the ink film are pressed against the platen roller paper feeding means, and when the paper is being fed in the reverse direction, the paper and the ink film are separated from the platen roller. The platen roller paper feeding means and the sprocket wheel paper feeding means are synchronized so that the paper feeding speed by the platen roller paper feeding means is slightly smaller than the feeding speed by the sprocket wheel paper feeding means. The gist is to include a driving means for driving.

Further, the paper feeding speed is adjusted by increasing or decreasing the diameter of the platen roller paper feeding means.

[Function] According to the above configuration, during mark II+ operation (forward rotation), the paper feed speed by the platen roller is slightly slower than the paper feed speed by the sprocket wheel, so tension is applied to the paper between the platen roller and the sprocket wheel. does not work, and the paper feed hole will not be torn. On the other hand, when the paper is returned in reverse (forward rotation), the thermal head separates from the platen roller and the paper is returned by the sprocket wheel. In this case, since the feed speed of the sprocket wheel is slightly faster than the feed speed of the platen roller, the looseness of the paper during forward rotation is eliminated, and the sprocket wheel's pin (sprocket pin) comes into contact with the trailing edge of the paper feed hole. Therefore, there is no misalignment between the sprocket pin and the paper, and the paper is always returned to a fixed position. Therefore, the three color dots can be accurately superimposed.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

In Figures 1 to 3, ■ indicates a large number of sprocket pins on the outer periphery! It is a sprocket wheel having a.... A feed hole 2a for the paper 2 is fitted into the sprocket pin Ia, and when the sprocket wheel 1 rotatably supported on the shaft 3 rotates, the paper 2 is conveyed. . This drive mechanism is as follows.

First, a timing pulley 4 for driving a sprocket wheel is fixed to the left end of the shaft 3 (FIG. 2). A gear is formed on the outer periphery of the timing pulley 4, and meshes with teeth of a timing belt 5 passing under the gear. The timing belt 5 is a loop-shaped belt with seven teeth formed on both sides, and one end meshes with a driving timing pulley 7 attached to the shaft of the stepping motor 6, and the other end is attached to the shaft 9 of the platen roller 8. The timing pulley IO for driving the platen is meshed with the timing pulley IO. That is, the timing belt 5 is stretched between the two timing pulleys 7 and 10, and approximately the center of the outer circumference meshes with the timing pulley 4. Therefore, when the stepping motor 6 rotates, the sprocket wheel 1 and the platen roller 8
Rotate in opposite directions while synchronizing.

Here, the outer circumferential speed of the platen roller 8 is made to be slightly slower than the outer circumferential speed of the sprocket wheel l. That is, assuming that the diameter of the platen roller 8 is D2 when the outer circumferential speeds of both rollers theoretically match, the actual diameter DI of the platen roller 8 is made slightly smaller than the diameter D2. Expressing this in a formula, where ΔD is a minute value, DI=D2−ΔD (1).

Now, the above sprocket wheel I and platen roller 8
A paper guide 11 is arranged above the paper guide 11 with a gap in between. Further, a paper guide I2 is provided facing the paper guide 1.1 from the inlet side (right side in FIG. 1) to the outlet side of the sprocket wheel I, and the paper guide 13.1 is provided on the outlet side of the platen roller 8.
14 are provided respectively. Then, the paper 2 passes through the gap formed by the paper guide II and 12 to I4,
It is stretched from the front of the sprocket wheel 1 to the exit side of the platen roller 8.

On the other hand, on the outer periphery of the platen roller 8, the paper 2 and the ink film I5 are overlapped. ink film 1
As shown in FIG. 3(b), 5 is a strip-shaped film coated with Y, M, and 03 colors alternately, and is pulled out from the supply bobbin 16 and wound onto the take-up bobbin I7. It has become. That is, the paper 2 is guided by the guide roller 18 in FIG.
The film is superimposed on the film and is wound onto the winding bobbin 17 via the film stripping roller 19. The winding bobbin 17 is rotationally driven by a winding motor (not shown) and winds up the ink film I5.

The paper guide 13 includes a pair of sensors 20a.

20b is provided. This is the 31st ffl(c)
As shown in FIG. 1, the ink film I5 is conveyed by detecting the fins 15Y, 15M, and 15G attached between each color of the ink film 15.

Paper 2 and ink film 1 on the outer periphery of platen roller 8
Thermal head 2 is placed opposite the position where 5 and 5 overlap.
1 is placed. The thermal head 2I rotates around an axis 21a that is parallel to the platen roller 8, so that it comes into contact with the platen roller 8 and moves away from the platen roller 8. That is, the ink film 15 and paper 2 are pressed against the platen roller 8 by the action of a solenoid (not shown), and the ink film 15 and paper 2, which are superimposed on each other, are pressed against the outer peripheral surface of the platen roller 8, while being separated from the platen roller 8 by the action of a spring (not shown). Then, this pressure contact is released.

In such a configuration, in order to perform color printing on one sheet, first, the paper 2 and the Y color of the ink film 5 are superimposed on the platen roller 8, and an initial position is set.

At this time, the paper 2 is drawn in the direction of the platen roller 8 (in the direction of arrow F in FIG. 4), so the sprocket bin 1
As shown in FIG. 4, a has a shape that abuts on the rear edge of the feed hole 2a.

Next, the thermal head 2I is pressed against the platen roller 3, and the sprocket wheel 1 and the platen roller 8 are rotated in the normal direction by the motor 6 to print Y color while feeding the paper 2 and the ink film 15. Note that the sprocket wheel 1 and the platen roller 8 always feed the paper while reversing each other, but the direction in which the paper 2 is fed forward (direction of arrows Af and Br in FIG. 1) is the normal rotation, and the direction in which the paper 2 is returned. (arrows Ar and Br directions) are reversed.

When Y color printing is completed, the thermal head 21 is separated from the platen roller 8, and the motor 6 is rotated in reverse. As a result, the platen roller 8 and the sprocket wheel 1 are reversely rotated, and the paper 2 is returned to the initial position. Note that during this time, the ink film 15 is transported to the next M color position.

When the paper 2 returns to the initial position, the thermal head 21 is again pressed against the platen roller 8 to print M color. Also,
After printing the M color, repeat the same operation as above to print the C color, and then print the 3 colors Y and M.

Overprinting of C is completed. In this way, one sheet of color printing is performed.

Next, the state of the paper 2 during forward rotation and reverse rotation will be considered in more detail.

First, during normal rotation, that is, when printing is performed, the sprocket wheel J and the platen roller 8 rotate in the normal direction and convey the paper 2 in the normal direction. In this case, the feed speed of the platen roller 8 is somewhat smaller than the feed speed of the sprocket wheel I.

Therefore, the paper 2 that is fed out from the sprocket wheel I and sent out due to the frictional force between the outer peripheral surface of the platen roller 8 and the ink film 15 becomes slightly loosened between the sprocket wheel 1 and the platen roller 8. Therefore, excessive tension is applied to the paper 2, causing the feed hole 2a to
This eliminates the inconvenience of breakage.

Next, during the reverse rotation, that is, when the paper 2 is returned, the sprocket wheel 1 and the platen roller 8 reversely feed the paper 2. In this case, thermal head 2
1 is away from the platen roller 8, so no friction is caused by the thermal head 21 against the paper 2. on the other hand,
Since the feeding speed of the paper 2 that is reversely fed by the sprocket wheel l is slightly faster than the speed of the outer peripheral surface of the platen roller 8, looseness during forward feeding of the paper is eliminated.

Furthermore, friction occurs between the platen roller 8 and the paper 2,
Appropriate braking force is applied to the paper 2, and the sprocket bin Ia is inserted into the feed hole 2 of the paper 2, as shown in FIG.
It comes into contact with the trailing edge of a. Since the paper 2 is returned to the initial position in this state, there is no deviation in the positional relationship between the sprocket wheel l and the paper 2. In other words, the paper 2 can be accurately returned to the initial position.

Note that when the thermal head 21 is separated from the platen roller 8 and the paper 2 is fed in the forward direction, as in the case of home feed, the platen roller 8 rotates but only plays an auxiliary role, and the sprocket Wheel 1 mainly performs feeding.

[Effects of the Invention] As explained above, the present invention includes a sprocket wheel paper feeding means for feeding paper in both forward and reverse directions, and a platen roller paper feeding means that rotates in both forward and reverse directions in synchronization with the sprocket wheel paper feeding means. When the paper is being fed in the forward direction, the MVJ's own paper and ink film are pressed against the platen roller paper feeding means, while when the paper is being fed in the opposite direction (this is the thermal head that separates it from the platen roller). and the platen roller paper feeding means and the sprocket wheel paper feeding means are synchronously driven so that the speed at which the paper is fed by the platen roller paper feeding means is slightly lower than the rate at which the paper is fed by the sprocket wheel paper feeding means. Since the driving means is provided, the following effects can be obtained.

(1) During printing, no tension is applied to the paper even if there are variations in the processing accuracy of each part. Therefore, the paper feed hole will not be torn.

(2) When returning the paper, the difference between the paper feeding speed by the sprocket wheel and the feeding speed by the platen roller acts on the paper as a frictional force, so that an appropriate amount of tension is generated in the paper. As a result, the sprocket pin comes into contact with the trailing edge of the feed hole, allowing accurate paper positioning at all times and preventing color misregistration.

[Brief explanation of drawings]

FIG. 1 is a side view showing the configuration of the main parts of an embodiment of the present invention, FIG. 2 is a plan view showing the structure of the main parts of the embodiment, FIG. 3 is a diagram showing the structure of the ink film 15, FIG. 4 is a plan view showing the relationship between the foot hole 2a and the sprocket pin 1a when returning the paper. 1...Sprocket wheel, la...Sprocket bin, 2...Paper, 2a...Feed hole, 4...Timing pulley for driving sprocket wheel, 5 ...Timing belt, 6...
...Stepping motor, 7...Drive timing pulley, 8...Platen roller, 10...
. . . Timing pulley for driving the platen (4 to 8 and 10 are driving means), 15 . . . Ink film, 21 . . . Thermal head. nostalgia

Claims (2)

[Claims] (1) A sprocket wheel paper feeding means for feeding the paper in both forward and reverse directions, a platen roller paper feeding means for rotating in both the forward and reverse directions in synchronization with the sprocket wheel paper feeding means, and the paper being fed in the forward direction. A thermal head presses the paper and the ink film against the platen roller paper feeding means at times, but separates the paper from the platen roller when the paper is being fed in the opposite direction; , a thermal transfer color printer comprising a driving means for synchronously driving the platen roller paper feeding means and the sprocket wheel paper feeding means so that the feeding speed is slightly lower than the feeding speed by the sprocket wheel paper feeding means. Paper feed mechanism. (2) The paper feeding mechanism for a thermal transfer color printer according to claim 1, wherein the paper feeding speed is adjusted by increasing or decreasing the diameter of the platen roller paper feeding means.