JP2776788B2 - Platen gap adjustment mechanism for printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism for adjusting a printing distance which is a gap between a printing head of a printing apparatus and a platen, and more particularly to a mechanism for simply adjusting a gap between a platen and a hammer bank of a line printer. The present invention relates to a platen gap adjusting mechanism.

[0002]

2. Description of the Related Art FIG. 2 is a schematic plan view showing a platen gap adjusting mechanism of a conventional printing apparatus.

[0003] Shuttle unit 7 fixed to base 6
The hammer bank 2 is attached to a and 7b. The tractor frame 5 is mounted on the base 6 so that the position thereof can be adjusted in the front-rear direction. The platen 1 is mounted on the frame 5 via platen bushes 3a and 3b. The hammer bank 2 is provided with a plurality of print pins (not shown) arranged at predetermined intervals in the horizontal direction toward the platen 1. The printing paper mounted in the gap between the hammerbank 2 and the platen 1 is caused to travel by a tractor (see the tractor 10 in FIG.
The printing pins are appropriately moved while the hammer bank 2 is reciprocated within a predetermined distance in the horizontal direction by the a and 7b, and printing is performed by striking printing paper via an ink ribbon (not shown) provided on the hammer bank 2. I do.

A cam 4 having a circular outer shape is provided on both side plates of the base 6.
The frame 5 engages with the eccentric cams 4a and 4b and moves back and forth according to the rotation of the eccentric cams. Both the eccentric cams 4a and 4b are connected by a shaft 4c and rotate integrally. A control lever 9 is attached to the eccentric cam 4a, and a scale portion 11 indicating a rotation angle of the control lever 9, that is, a position of the frame 5, is provided. Platen bush 3a, 3
b is rotatably attached to the frame 5, and the platen 1 is attached to the platen bushes 3a and 3b so as to rotate eccentrically from the center of rotation.

To adjust the platen gap, a control lever 9 is positioned so that the platen 1 is properly positioned with respect to the thickness of the printing paper to be used, and then a thickness gage 8 corresponding to an optimum platen gap is used. The platen 1 is moved by rotating the platen bushes 3a and 3b to adjust the platen gap. It should be noted that the platen 1 does not come into contact with the hammerbank 2 even if the platen 1 is moved toward the hammerbank 2 as much as possible using the control lever 9 and the platen bushes 3a, 3b.

[0006]

In the above-described platen gap adjusting mechanism of the printing apparatus, the position where the thickness gauge is sandwiched by the ink ribbon unit or the like is limited to the positions at both ends of the hammer bank, and the state of the platen gap at the center is changed. Further, there is a disadvantage that the feeling when the thickness gauge is sandwiched between the platen and the hammer bank varies from person to person, and it takes time to adjust.

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to simply adjust the platen gap of a printing apparatus.

[0008]

SUMMARY OF THE INVENTION A platen gap adjusting mechanism of a printing apparatus according to the present invention includes a base, a print head mounted on the base, and a movable head in a direction approaching and separating from the print head. A frame attached to the base, an eccentric cam attached to the frame and rotated to move the frame on the base, and a platen attached to the frame and facing the print head is eccentrically attached and rotates. A platen bush that moves the platen toward and away from the print head, and an adjustment that positions the frame so that the platen can be brought into contact with or separated from the print head by rotation of the platen bush. Set the rotation angle of the eccentric cam Setting the rotation angle of the eccentric cam to a print position in which the platen is moved in a direction away from the print head by a platen gap suitable for printing paper from a position when the rotation angle of the eccentric cam is set to the adjustment position. Setting means for rotating the platen bush to sufficiently separate the front platen from the print head, and then set the rotation angle of the eccentric cam to the adjustment position and rotate the platen bush to rotate the platen. The platen gap is adjusted by bringing the print head into contact with the print head and then setting the rotation angle of the eccentric cam to the print position.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings.

FIGS. 1 and 2 are a plan view and a side view schematically showing a platen gap adjusting mechanism of a line printer according to an embodiment of the present invention.

The shuttle units 7a and 7b and the hammerbank 2 are the same as the conventional one shown in FIG. The frame 5 provided with the tractor 10 moves back and forth by rotation of the eccentric cams 4a and 4b. The scale section 11 is provided with a scale of an adjustment position and a scale of a print position corresponding to a plurality of printing papers. The platen 1 moves back and forth by rotation of the platen bushes 3a, 3b. Eccentric cam 4
a the control lever 9 attached to the
When the frame 5 is adjusted to the scale of the adjustment position, the frame 5 is moved toward the hammer bank 2 and the platen 1 can be brought into contact with the hammer bank 2 by rotating the platen bushes 3a and 3b. It has a dimensional relationship that can be moved.

When the control lever 9 is moved from the graduation position of the adjustment position to the printing position, the platen is located on the opposite side of the hammer bank 2 by a platen gap optimal for the thickness of the printing paper corresponding to the printing position. The scale section 11 is provided with scales for the adjustment position and the print position so as to move to the position. The printing paper 12 passes between the hammer bank 2 and the platen 1 and is run by the tractor 10.

As shown in FIGS. 2 and 4, a vertical notch 13 provided in the frame 5 is engaged with the circular outer shape of the cam 4a which rotates eccentrically with respect to the base 6. The eccentric cam 3a rotates with respect to the frame 5 concentrically with the outer shape, and eccentrically supports the rotary shaft 14 of the platen 14 with respect to the outer shape, and is rotated by the knob 15. Eccentric cam 4
b and 3b have the same structure.

In order to adjust the platen gap, first, the eccentric cams 3a and 3b are turned to sufficiently separate the platen 1 from the hammer bank 2. Next, the control lever 9 is set at the adjustment position, and the platen bushes 3a and 3b are rotated to bring the platen 1 into contact with the hammer bank 2 (the state shown in FIGS. 1 and 2). At this time, it is confirmed that the center of the hammer bank 2 is also in contact with the platen 1. Thereafter, the control lever 9 is moved to a printing position corresponding to the printing paper using the control lever 9 (the state shown in FIGS. 3 and 4), and the adjustment of the platen gap is completed.

Therefore, there is no need for the thickness gauge 8 used in the conventional platen gap adjustment method, and the gap adjustment can be confirmed not only at both ends but also at the center.

Further, by eliminating the thickness gauge 8, the influence of individual differences when the thickness gauge is sandwiched between the platen 1 and the hammer bank 2 can be eliminated, and an accurate platen gap can be obtained.

The setting of the eccentric cam at the adjustment position and the printing position is not limited to the scale, but other structures such as determining the position of the control lever with a stopper and locking the eccentric cam with a detent are also conceivable. If a sufficiently large knob is provided on the eccentric cam, a control lever is not required. Further, the present invention can be applied not only to a line printer but also to a serial printer, and also to an ink jet printer and the like.

[0018]

As described above, according to the present invention, an appropriate platen gap is set by setting the eccentric cam to the adjustment position by contacting the pre-ten with the print head by rotating the platen bush with the eccentric cam set to the printing position. As a result, there is no need to use a thickness gauge, which was necessary for adjusting the conventional platen gap.Therefore, there is no individual difference in feel when sandwiching the thickness gauge, and the platen gap is checked not only at both ends but also at the center. Also has the effect that it has become possible.

[Brief description of the drawings]

FIG. 1 shows a state in which an eccentric cam 4a, 4b of a platen gap adjustment mechanism of a printing apparatus according to an embodiment of the present invention is set to an adjustment position, and a platen 1 is brought into contact with a hammer bank 2 by rotation of platen bushes 3a, 3b. FIG. 2 is a plan view schematically showing a tractor.

FIG. 2 is a side view of FIG.

FIG. 3 is a view schematically showing a state in which eccentric cams 4a and 4b of a platen gap adjusting mechanism of the printing apparatus shown in FIG.

FIG. 4 is a side view of FIG. 3;

FIG. 5 is a plan view showing a platen gap adjusting mechanism of a conventional printing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Platen 2 Hammerbank 3a, 3b Platen bush 4a, 4b Eccentric cam 5 Frame 6 Base 7a, 7b Shuttle unit 8 Thickness gauge 9 Control lever 10 Tractor 11 Scale 12 Printing paper

Claims (2)

(57) [Claims] 1. A base, a print head attached to the base, a frame attached to the base so as to be movable in a direction approaching and separating from the print head, and a pivot attached to the frame. An eccentric cam that moves the frame on the base, and a platen attached to the frame and facing the print head is eccentrically mounted and rotated to move the platen closer to and away from the print head. A platen bush to be moved, and a rotation angle of the eccentric cam is set to an adjustment position for positioning the frame so that the platen can be brought into contact with or separated from the print head by rotation of the platen bush. Adjust the cam rotation angle to the adjustment position Setting means for setting the rotation angle of the eccentric cam to a print position to be moved in a direction away from the print head by a platen gap suitable for a print sheet from a position set in the printing apparatus. Platen gap adjustment mechanism. 2. Rotating the platen bush to sufficiently separate the platen from the print head, then setting the rotation angle of the eccentric cam to an adjustment position, rotating the platen bush, and bringing the platen into contact with the print head. 2. The method according to claim 1, wherein the rotation angle of the eccentric cam is set to a print position.