JPS6353078A - Multicolor printer - Google Patents

Abstract

PURPOSE:To minimize color misregistration in a non-chuck system, by providing a guide along the outer periphery of a platen roller, with a substantially uniform gap therebetween, and providing the guide with a means for adjusting the gap. CONSTITUTION:A guide 1 is fixed to a chassis, with a predetermine gap between the guide and the outer periphery of a platen roller 2. The gap can be adjusted by changing the thickness of washers 5-8. An image-receiving paper 20 which has been printed in the first color is fed to a position for printing in the second color, by being guided along the outer periphery of the platen roller 2 by the guide 1 and an auxiliary pressing roller 10. Since a feeding passage for the paper has not an end chucked to the platen roller, a part of the guide 1 is so constructed that the gap between it and the platen roller can be adjusted, so that the position of the paper can be corrected during the time when the paper is fed from the position for printing in the first color to the position for printing in the second color. Accordingly, position for starting printing on the paper respectively in the first color and in the second color can be made substantially the same with each other, and color misregistration can be minimized.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a printing device that performs multicolor printing by wrapping an image receiving paper around the outer circumference of a platen roller and passing it under a print head several times. This invention relates to a multicolor printing device suitable for adjusting color misregistration using a non-chuck method in which image-receiving paper is conveyed without being chucked to a platen roller.

[Conventional technology]

As seen in Tokukai No. 56-52756, conventional equipment used a platen roller to chuck the edge of the image-receiving paper before transporting it, so when printing in multiple colors, the platen roller and the image-receiving paper were misaligned, causing color misalignment. There was nothing to do. However, if the chuck mechanism at the leading edge of the receiving paper is omitted, color misregistration becomes a problem with a mechanism that performs multicolor printing by rotating the paper multiple times around the platen roller, and no effective solution has been proposed. .

[Problem that the invention seeks to solve]

The above-mentioned conventional technology (method of chucking the image receiving paper on a platen roller) has a complicated mechanism and is expensive. There are problems such as low reliability, and in order to solve these problems, it is necessary to use a non-chuck method. Ta.

An object of the present invention is to provide a non-chuck method for minimizing browning.

[Means for solving problems]

The above object is achieved by providing a guide around the platen roller with a substantially constant gap therebetween, and by providing means for adjusting the distance between the kite and the gap.

[Effect]

Consider a case where an image-receiving paper is wound around a non-chuck type platen roller and the image-receiving paper is conveyed almost integrally with the platen roller. In the case of multicolor printing, a common method is to pass the receiver paper under the print head multiple times to overlap the colors. At this time, the condition of the receiver paper when printing the first color and when printing the second color (
It is desirable that the positions (gt) relative to the print head be the same. This is because the positional deviation of the image receiving paper with respect to the print head when printing the first color and when printing the second color immediately appears as color misregistration. In the present invention, cut paper is used as the image receiving paper, and printing is performed by rotating the platen roller and the image receiving paper in the same direction by the printing color ridges. At this time, the image receiving paper that has finished printing in the first color is guided along the outer periphery of the platen roller by a guide and an auxiliary pressure roller and advances to the second color mark stand. It does not necessarily travel in close contact with the outer periphery of the platen roller, but there is a path that partially runs along the guide wall surface of the outer periphery of the platen roller. In the present invention, a part of this guide is made so that the gap with the platen roller can be adjusted to A, or in other words, the traveling path of the image receiving paper can be partially adjusted, so that it is possible to adjust a part of the guide from the first color to the second color. The position of the image receiving paper can now be corrected to the appropriate position while printing (printing).As a result, the printing start position of the first color and the printing start position of the second color on the image receiving paper can be almost the same.
I was also able to keep the color shift to a minimum.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

Figure 1 schematically shows a cross section of the main bond part of this embodiment, and the guide 1 is actually (as shown in Figure 2, the L side chassis 3 that holds the platen roller 2, and the R side chassis 3, which holds the platen roller 2. The guide 1 is screwed to the side chassis 4 via washers 5, 6, and 7.8.The guide 1 is connected to the outer periphery of the platen roller 2 with a gap of 100 μm (plus value of 100 μm) from the outer periphery of the platen roller 2. However, this gap can be adjusted by changing the thickness of the washer 5°6.7.8. Also, the variable range of this washer is O-a1
00 μm, and can be adjusted independently at each of the four locations.

The configuration and operating principle of this multicolor printing device will be explained with reference to FIG. 41. This embodiment is a multicolor printing device using a thermal transfer method. The platen roller 2 has a cylindrical surface made of rubber material. A guide 1 is placed around the platen roller 2. Sub guide 14. and height guides 15 are respectively arranged with a gap of about 0.711111 mm from the cylindrical surface of the roller. The rollers 10, 11 and 12 are rotatably held and biased by a spring member (not shown) so as to press against the cylindrical surface of the platen roller. The height guide 15 is made up of three parts, and when the part 15b rotates, it guides the image receiving paper 20i to the platen roller side or to the ejection port, which will be described later, but these are not directly related to the present invention, so the details will be omitted. . FIG. 1 shows the state in which it is guided toward the platen roller. The print head 16 is a thermal head in which a large number of well-known heating resistors 16a are arranged in a row in a direction perpendicular to the direction of movement of the image-receiving paper 20. During the printing operation, the ink film 17 and the image-receiving paper 20 are held between them and the platen is used. It is elastically pressed against the roller 2. The ink film 17 has a sublimation dye coated on the surface facing the image receiving paper 20, and is shown in FIG.
It is wound around J-roll 18 and 1゛ reel 19, and during one printing operation, the S I
It is wound up from the J-reel 18 to the 'r reel 19. The platen roller 2 and the T-reel 19 are each rotationally driven by a motor (not shown). Next, the printing operation using the above configuration will be explained. When the image receiving surface X 120 is inserted from the insertion slot with the image receiving surface facing downward, it is held between the motor-driven platen roller 2 and the jojo roller 10, moves in the direction of the arrow t through the gap between the guide 1 and the platen roller 2, passes through the jojo roller 11, and then Sub guide 14. The Hojo roller 12 reaches below the color ink film 17.

Further, when the print head 16 and the platen roller 2 (together with the ink film 17) are sandwiched together, the print head transfers the reassuring image by a well-known method and guides it to the height guide 15. In order to do this, it moves from the height guide 15 to the high roller 10 again.This operation is repeated, and after the image receiving paper 20 has passed under the head three times, the height guide 15 moves to guide it to the above-mentioned discharge port.
The image receiving paper is discharged after a predetermined print is obtained. However, it is well known that during this time, the three colors cyan, yellow, and magenta are applied to the ink film 17 one after the other, and each color is transferred in three printings.

Next, color misregistration in multicolor printing will be explained. Figure WJ3 shows the case of two colors for straw grass. If the first color image and the second color image are printed one on top of the other without misalignment, it will look like A, but if the first and second color images are misaligned in the direction of movement of the receiver paper, it will look like B. Also, when the image receiving paper is rotated about an axis perpendicular to the paper surface for the first and second colors, it becomes like C.

In this embodiment, since the non-chucking system is used, slippage between the platen roller 2 and the image receiving device 20 is unavoidable. Therefore, the color shift A is dealt with by a reflective photosensor 21 shown in FIG.

That is, conventionally, when the image-receiving paper is chucked by a platen roller and conveyed as a unit, the position γt of the platen roller is detected, for example, by the number of steps of a suiting motor, and the print signals for the first and second colors are detected. In this embodiment, the reflective photosensor 21 detects the position of the leading edge of the receiving paper and controls the print signals for the first and second colors. This causes the platen roller 2 and the two receiving papers to Even if it slips during the transition from the first color to the second color printing, the leading edge of the image will not shift and the colors will not blur as shown in B.

However, although the reflective photo sensor method can prevent color shift like B, it cannot prevent color blur like C.
The color misregistration is caused by the shape accuracy of the platen roller 2, non-uniformity of the pressure force of the print head 16, and the hojo rollers 10, 11.
Due to the unevenness of the pressing force of 12, the image receiving paper 20 is
This is because the angle is changed on the way from color printing to second color printing. In the present invention, the gap between the guide 1 and the platen roller 2 can be adjusted using the washers 5, 6, 7.8+ shown in FIG. 2, thereby solving the problem of color shift in C. The effect will be explained below.

FIG. 4 schematically shows the travel path of the image receiving paper. For example, the locus of one point approximately in the center of the image receiving paper 20 looks like a dotted line, and this is taken as the traveling route. The image receiving paper 20 is pressed against the platen roller 2 at the following four locations. That is, (
1) From the print head 16 to the ink roller 13, (
2) Hojo Roller 10, (3) Hojo Roller 11,
(4) Hojo Cola - 12 locations.

However, in areas other than these four locations, the image receiving paper 20 is not necessarily in close contact with the platen roller 2; for example, in section D shown in FIG. . Now, the distance i for one lap of the traveling route
Considering L, if the image-receiving paper is always in close contact with the platen roller, L=2πR (R is the radius of rotation), but in reality, it is larger than this because there is a section floating from the platen roller. Letting this be L', as is clear from the figure, if the distance E is changed by adjusting the ζζ guide 1, L'
is adjustable. In other words, if E→dog, the relationship L'→ is large. This relationship can be considered separately for the left and right f in the direction of travel of the image receiving paper, and can be considered for ER+EL and L, respectively.
Let it be LL'. (Suffix R indicates left side and right side.) Let us now consider the color shift of C shown in FIG.

Color shift C occurs when the image receiving paper 20 passes under the heating resistor 16a of the print head 16.
This is due to the fact that the posture (orientation) of 0 is different. This situation is shown in FIG. The image receiving paper 20 is in the positional relationship shown in (1) when printing the first color, and (6) when printing the second color.
They are in the positional relationship shown in . Receiving paper 20 from now on
The relative positional relationship with the character head 16 is changed from after printing the first color (2) to just before printing the second color (3). There are various reasons for this, such as an imbalance in the pressure contact force of the print head and the pressure roller, the shape of the platen roller 20, etc., but the traveling distance per revolution Lt, ' T L
R' is also a factor. Receiving paper 20 is print head 1
6 or Hojo Roller 1o.

It is driven at a constant speed by the frictional force with the platen roller 2 under the pressure of 11 and 12. If the diameter of the platen roller is constant and there is no slippage in the drive section, the image receiving paper 20 will move at the same speed in all parts.

Therefore, at this time, if the distance traveled per lap is the same everywhere (
(If LR' = LL') There is no difference in the posture of the image receiving paper when printing the first color and when printing the second color. In other words, even if the image-receiving paper 20 is traveling at the same speed everywhere, the attitude of the image-receiving paper can be controlled by changing the running distance 31t of one revolution from side to side. fl] For example, suppose that the color blurring shown in FIG. 5 occurs in a certain initial setting state. This is because the image-receiving paper 20 rotates clockwise until it moves from the first color printing (2) to the second color printing (3).

Therefore, when the RII + washer 5.7 shown in Figure 2 is removed, ER on the image receiving paper R side becomes small and t. Therefore, the image receiving paper R
One round traveling distance LFc' of mil+ becomes small. Since LR' has become shorter, the R side of the receiver+p paper 20 will now be in front of the receiver than before, and while moving from (2) to (3), the receiver (
The elephant paper 20 is rotated counterclockwise, and the color shift between the two colors is corrected.

In this embodiment, only the guide 1 can be used for position t'A, but
Zab Guide 14. If the height guide 15 is also capable of A-side adjustment, finer color shift adjustment will be possible. Although the details are omitted, for color misalignment that occurs due to parallel movement in a direction perpendicular to the direction of travel, it may be necessary to adjust the guides at two or more locations.

〔Effect of the invention〕

There are various factors that cause color misalignment in printed images in non-chuck type multicolor printing equipment, and there are limits to keeping all of them in the correct state due to the dimensional accuracy of parts, etc. This does not necessarily mean that the response is adequate. According to the present invention, color misregistration can be easily adjusted simply by adjusting the position of the guide, which has a great effect on simplifying a multicolor printing device.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an embodiment of the present invention, FIG. 2 is a diagram of the guide part adjustment mechanism, and FIG. 3 is an illustration of color shift in a printed image.
FIG. 4 is a schematic diagram of the travel route, and FIG. 5 is a diagram of the mechanism of color shift occurrence. 1...Guide 2...Platen roller, agent Patent attorney Masaru Ogawa 1 Figure 4 Solid section (1)↑☆Kashifugen 3 cars 1st color 8p7 Figure (3) 1 Reception ξ 2 color self tp?

Claims (1)

[Claims] 1. A print head, a platen roller, a chassis that holds the platen roller, and one or more guides arranged with a substantially constant gap from the cylindrical surface of the platen roller, and at least one of the guides A multicolor printing device characterized in that a gap between the guide surface and the outer peripheral surface of the platen roller can be adjusted.