JPH0825316B2 - Image printer head - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head of an image printing apparatus that performs gradation expression of a pixel, which is the minimum unit of an image, by changing a recording area in the pixel. It is a thing.

[Conventional technology]

In an image printing apparatus in which an image is composed of a set of pixels, which is the minimum unit, and each pixel is recorded and transferred based on the image information of each pixel, in order to perform gradation expression in each pixel, printing in the pixel is performed. A method of changing the area or changing the print density of pixels is adopted.

FIG. 5 is a side view showing a head portion of an image printing apparatus which performs gradation expression of each pixel by changing a printing area in the pixel. In the figure, 1 is a transfer roller (head roller), 2 is an auxiliary roller that rotates in contact with the transfer roller 1, 3 is an ink supply roller that rotates in contact with this auxiliary roller 2, and 4 is an ink supply roller 3. It is a supply ink of. As shown in FIG. 6, the transfer roller 1 has a strip-shaped convex surface 1a protruding from the outer peripheral surface thereof, and the width W of the convex surface 1a is set to correspond to the size of one pixel. Has been done. The outer peripheral surface of the auxiliary roller 2 is brought into contact with the convex surface 1a so as to rotate, and the tip end surface of the blade 5 formed wider than the width W of the convex surface 1a is the blade 5 When the actuator 6 provided on the transfer roller 1 is turned on, the entire surface in the width direction of the convex surface 1a of the transfer roller 1 is brought into contact with the structure.

That is, by turning on the actuator 6 based on the image information for each pixel, the tip end surface of the blade 5 is contacted with the entire convex portion surface 1a of the transfer roller 1 in the width direction and is supplied to the convex portion surface 1a. The attached ink 4a is scraped off to change the printing area of the pixels printed on the paper surface 7. FIG. 7 shows a state in which the supplied and adhered ink 4a is scraped off by the tip surface of the blade 5 on the convex surface 1a of the transfer roller 1, and in each pixel divided by the length L in the drawing, The white portion is the ink scraping portion (ink scraping area) generated by the scraping operation of the deposited ink by the blade 5. That is, it is possible to express the gradation for each pixel printed on the paper surface 7 by the area ratio of the ink adhered portion and the scraped portion on the convex surface 1a of the transfer roller 1. In FIG. 5, 8 is a drain receiver for the ink scraped off by the blade 5, 9 is a cleaning blade for scraping off the ink remaining on the convex surface 1a after printing on the paper surface 7, and 10 is the cleaning blade 5. It is a drain receiver for scraped ink.

[Problems to be solved by the invention]

However, according to the head of such a conventional image printing apparatus, when the ink 4a supplied and adhered to the convex surface 1a of the transfer roller 1 is scraped off by the blade 5, the ink is completely scraped off due to abrasion of the blade 5 or the like. It may not be done. That is, inadequately scraped ink may remain thin on the scraped portion of the ink, where originally all the adhered ink should be scraped. As a result, there is a problem that the ink left in the scraped portion is transferred to the paper surface 7, the pixels that should be white are stained on the paper surface 7, and the gradation is impaired.

[Means for solving problems]

The present invention has been made in view of such problems,
A second head roller is arranged on the outer peripheral surface of the head roller on which the supplied ink has been scraped off, and the outer peripheral surface is in contact with the outer peripheral surface with a predetermined gap.

[Action]

Therefore, according to the present invention, it is possible to transfer only the ink film having a predetermined film thickness or more among the adhered ink left on the outer peripheral surface of the head roller to the second head roller.

〔Example〕

Hereinafter, the head of the image printing apparatus according to the present invention will be described in detail. FIG. 2 is a side view showing an embodiment of this head. In the figure, the same reference numerals as those in FIG. 5 indicate the same components, and the description thereof will be omitted. That is, the transfer roller 1 serves as a first head roller, and the transfer roller 11 as a second head roller is arranged between the head roller 1 and the paper surface 7. FIG. 3 shows a specific example of the arrangement structure of the transfer roller 11 and the head roller 1. On the outer peripheral surface of the head roller 1, on both sides sandwiching the convex surface 1a, the convex surface 1a is provided. Large-diameter convex surface 1b and 1c are formed. On the other hand, the transfer roller 11 is formed with a strip-shaped convex portion surface 11a protruding toward the outer peripheral surface thereof, and the width W1 of the convex portion surface 11a is
And the width W of the convex surface 1a of the head roller 1 are equal to each other and are set to correspond to the size of one pixel. Then, the transfer roller 11 is arranged so that the outer peripheral surface portion 11b is in contact with the convex surface 1b and 1c of the head roller 1. At this time, adjustment is made so that the convex surface 1a of the head roller 1 and the convex surface 11a of the transfer roller 11 are exactly aligned in the width direction, and the convex surface 1a and the convex surface 11a are several in number. The outer dimensions of the convex surface 1a and the convex surface 11a are set so as to face each other with a minute gap t of about μm. In FIG. 2, reference numeral 12 is a cleaning blade for scraping off the ink remaining on the convex surface 11a after printing on the paper surface 7 using the transfer roller 11, and 13 is a drain receiver for the scraping ink of the cleaning blade 12. Is.

In the head of the image printing apparatus configured as described above, as shown in FIG. 1, the head roller 1 is moved by the movement of the blade 5 driven based on the image information for each pixel.
Ink 4a supplied on the convex surface 1a of the head roller 1 is scraped off, and the convex surface 1a of the head roller 1 on which the ink is scraped off is scraped off.
, Come into contact with the convex surface 11a of the transfer roller 11 at a minute interval t. That is, the convex surface 1a of the head roller 1
Has a portion where ink is adhered and a portion where the ink is scraped off by the scraping operation of the blade 5,
The convex surface 1a of the head roller 1 of the ink-attached portion
Only the ink film having a thickness larger than the minute gap t between the convex surface 11a of the transfer roller 11 and the convex surface 11a of the transfer roller 11 comes into contact with the convex surface 11a of the transfer roller 11 and is transferred. That is, the ink film having a film thickness smaller than the minute gap t between the head roller 1 and the transfer roller 11 does not contact the convex surface 11a of the transfer roller 11 and thus does not transfer, and the convex surface 1a of the head roller 1 is not transferred. Will be left in. That is, in the case of scraping the supplied adhered ink 4a on the convex surface 1a of the head roller 1 with the blade 5, the residual ink is removed in consideration of the fact that the ink remains thin on the scraped portion due to abrasion of the blade 5. The minute gap t is set to be wider than the film thickness and narrower than the film thickness of the originally supplied and adhered ink 4a. Therefore, the ink film thickness that remains thin in the ink scraping portion is transferred to the convex surface 1a of the transfer roller 11. There is nothing to do. In this way, the ink film selectively transferred to the convex surface 11a of the transfer roller 11 is transferred to the paper surface 7 by the rotation of the transfer roller 11, and in the pixels which should become white on the paper surface 7. A blade 5 that is prevented from becoming dirty and is driven based on image information for each pixel
It becomes possible to transfer the pixels of the ink adhering area that is faithful to the movement of the sheet onto the paper surface 7.

In the above-described embodiment, the convex roller surfaces 1b and 1c (FIG. 3) provided on both sides of the head roller 1 are provided on the transfer roller 11.
By making contact with the outer peripheral surface portion 11b of the head roller 1, the minute gap t between the convex surface 1a of the head roller 1 and the convex surface 11a of the transfer roller 11 is accurately set. As shown, roller 14 (corresponds to head roller 1)
Distance P between roller and roller 15 (corresponding to transfer roller 11)
May be simply determined, and a minute gap t may be set between the convex surfaces 14a and 15a. Also, in the case of the structure shown in FIG. 3, the convex surfaces 1b and 1c provided on both sides of the head roller 1 are formed by, for example, rubber winding, and the distance between the shaft centers of the two rollers is set. Can be finely adjusted. In this case, the distance between the shaft centers can be realized by fixing one roller shaft and fixing the bearing of the other roller shaft with an eccentric holder, or by simply adjusting the distance by an adjusting screw. . Of course, such adjustment of the distance between the axes can also be realized with the structure shown in FIG.

〔The invention's effect〕

As described above, according to the head of the image printing apparatus of the present invention, the second head is in contact with the outer peripheral surface of the head roller, which has been scraped off the supplied and adhered ink, with a predetermined gap therebetween. Since the rollers are arranged, by appropriately setting the above-mentioned predetermined gap, only the ink film having a predetermined film thickness or more of the adhered ink left on the outer peripheral surface of the head roller is transferred to the second head roller by contact. This makes it possible to prevent the transfer of the ink, which remains thinly on the scraped portion of the ink and disturbs the gradation, to the paper surface.

[Brief description of drawings]

FIG. 1 is a diagram showing a transfer operation of an ink film from a head roller to a transfer roller in an embodiment of the head of the image printing apparatus according to the present invention, and FIG. 2 shows an embodiment of the head of the image printing apparatus. A side view, FIG. 3 is a front view showing a specific arrangement structure of the transfer roller and the head roller in this head, and FIG. 4 shows another embodiment of the arrangement structure of the transfer roller and the head roller in this head. A front view, FIG. 5 is a side view showing a head of a conventional image printing apparatus, FIG. 6 is a schematic perspective view of a transfer roller portion in this head, and FIG. 7 is a convex surface of the transfer roller in this head. FIG. 7 is a diagram showing a scraped-off state of the supplied and adhered ink in FIG. 1 ... Head roller, 1a ... Convex surface, 4a ... Supply ink, 5 ... Blade, 6 ... Actuator, 11 ...
Transfer roller, 11a: convex surface.

Claims (1)

[Claims] 1. A head of an image printing apparatus comprising a blade for scraping off ink supplied and adhered to the outer peripheral surface of a head roller, wherein the ink adhered for supply is scraped off by the blade. A second roller that contacts the outer peripheral surface of the head roller at a predetermined distance from the outer peripheral surface
Head of an image printing apparatus comprising the head roller of.