JPS63256473A - Head gap setting method - Google Patents

Abstract

PURPOSE:To enable a head gap to be set extremely easily with high accuracy, by setting the head gap through moving a carriage backward by a predetermined measure from the position at which the carriage is stopped when a paper guide comes to press a paper, without using a detecting means such as an encoder. CONSTITUTION:A carrier 4 is moved backward by a moving means 4 in the direction for increasing a gap quantity until it is stopped by a stopping means 22. With a paper set in position, a stepping motor 18 is rotated clockwise to move the carrier 4 forward in the direction for decreasing the gap quantity, until the carrier 4 is stopped when a printing head 12 or a paper guide 13 comes to press the paper. After the carrier is thus stopped, the motor 18 is caused to step out. With the motor 18 in the step-out position, the paper can not be moved because it is clamped between the head 12 or the paper guide 13 and a platen 2. Finally, the carrier 4 is moved backward by again rotating the motor 18 counterclockwise by the number of steps required for obtaining an optimum head gap, for example, 0.3 mm. By this method, the head gap is constantly set with high accuracy, and high-quality printing can be ensured.

Description

[Detailed Description of the Invention] [Summary] The moving means moves the carrier backward in the direction of increasing the gap amount until it is stopped by the stopping means, sets the paper between the paper guide and the platen, and then sets the paper between the paper guide and the platen. The carrier is moved forward in the direction in which the gap amount decreases until the printer presses the paper and stops, and then the carrier is moved back in the direction in which the gap amount is increased until a gap of a predetermined size is created between the print head and the paper. Optimize the gap between the paper and print head.

C. Field of Industrial Application] The present invention relates to a method for optimally setting the gap between paper and a print head, the so-called head gap.

Recently, various serial printers have been used as input/output terminals of data processing devices, word processors, and the like.

Among them, serial dot printers print characters etc. composed of dots, so there are many types of characters etc., and it is suitable for office automation (OA).
Its use as a terminal device in n+ation is increasing.

In the printing section of these printers, the printing paper is guided into the gap between the platen and the print head, and the printing paper is guided to the space between the platen and the print head. A paper guide is provided to properly set the 2-gap.

[Conventional technology]

In the printer, as shown in the horizontal view of FIG. 4, a platen 2 is rotatably supported by side frames 1 on both sides, and the inserted paper 3 is ejected in the direction of arrow A.

On the other hand, a carrier 4 is slidably engaged with an eccentric shaft 5 and a guide shaft 6 provided parallel to the platen 2 on the front surface (lower side in the figure) of the platen 2, and is arranged between pulleys 7 and 7'. The timing belt 8 is stretched across the platen 2 and is fixed by a locking metal fitting 9 to a timing belt 8 which is also provided parallel to the platen 2 .

The timing belt 8 is connected to a motor 10 via a pulley 7, and therefore, the timing belt 8 can reciprocate the carrier 4 as shown by arrow C by the forward and reverse rotation of the motor 10.

The carrier 4 includes an ink ribbon cassette 11 storing the ink ribbon, a print head 12, and a device for guiding the paper 3 into the gap between the print head 12 and the platen 2, and for setting the gap between the print head 12 and the paper appropriately. A paper guide 13 is mounted, and printing is carried out via the ink ribbon exposed on the front of the print head 12, and the carrier 4 is moved in the direction of arrow C-D.
This is done while moving back and forth in the direction.

As shown in the side view of FIG. 5, the carrier 4 has a moving means 14 for appropriately adjusting the so-called head gap between the mounted print head 12 and the paper 3, and has a moving means 14 that moves along the arrow A-- with respect to the platen 2. It is movable in the front and rear directions as shown in B.

The moving means 14 includes an eccentric shaft 5 and a stepping motor 18 for rotating the eccentric shaft 5 via first to third gears 15 to 17.

On the other hand, an encoder 19 is provided at the end of the eccentric shaft 5, and encodes and outputs the amount of rotation of the eccentric shaft 5.

The encoder 19 is a fan-shaped slit disk 2 having a large number of slits 20a arranged in a semicircle as shown in the front view of FIG.
The main part of the slit disk 20 is fixed to the eccentric shaft 5 and rotates together with the eccentric shaft 5.

In such a printer, in order to set an appropriate head gap between the print surface of the paper 3 and the print head 12 in accordance with the thickness of the paper 3, first the stepping motor 18 is rotated counterclockwise. rotate the eccentric shaft 5 in the same direction,
The carrier 4 is moved backward relative to the platen 2 in the direction of arrow B.

In conjunction with this operation, the slit disk 20 also rotates together with the eccentric shaft 5, and the optical sensor 21 reads the slit 20a and outputs a pulse.

This is detected by a pulse detection device (not shown), and the stepping motor 18 rotates until the slit disk 20 rotates to the initial position 2OjZ and pulse generation stops.

After the print head 12 has retreated to the initial position in this manner, the paper 3 is drawn between it and the platen 2.

After suction is completed, the stepping motor 18 is then rotated clockwise to rotate the eccentric shaft 5 in the same direction, thereby advancing the carrier 4 relative to the platen 2 in the six directions of the arrows.

In conjunction with this operation, the slit disk 20 also rotates together with the eccentric shaft 5, and the optical sensor 21 outputs a pulse.

Pulse generation stops at the same time as the paper guide 13 or print head 12 presses the paper 3, making it impossible for the carrier 4 to move forward and stopping the rotation of the eccentric shaft 5.

The position where the pulse generation stops is the detection position of the paper 3, and the rotation of the stepping motor 18 is stopped at the same time as the detection.

This detection position is set as the second initial position, and then the stepping motor 18 is rotated counterclockwise again by a predetermined number of steps, so that there is a gap between the print head 12 and the paper 3, for example, 0.
Set the head gap to about 3mm.

[Problem that the invention seeks to solve]

The head gap is set as described above, but since the paper guide presses the paper using an encoder method that detects the slit using an optical sensor, errors due to errors and ambient light may occur. There was a problem that detection → was likely to occur.

[Means for solving problems]

FIG. 1 is a plan view of a printer that implements the head gap setting method of the present invention.

In the present invention, the moving means 14 moves the carrier 4 backward in the direction in which the gap amount increases until it is stopped by the stopping means 22, the paper 3 is set between the print head 12 and the platen 2, and then, The carrier 4 is advanced in the direction in which the gap amount decreases until the print head 12 presses the paper 3 and stops, and then the carrier 4 is advanced in the gap amount until a gap of a predetermined size is created between the print head 12 and the paper. It is designed to move backward in the direction of increasing.

[Effect]

Since this is a method of setting the head gap by pressing the paper with a paper guide and retracting it by a predetermined distance from the stopped position, the head gap can be set with high precision, without relying on a detection means such as an encoder.

〔Example〕

1 to 3 show an embodiment of the present invention.

Identical parts are designated by the same reference numerals throughout the figures.

As shown in the plan view of the printer in FIG. 1 and the side view in FIG.
is retreated in the direction in which the gap amount increases (in the direction opposite to the platen) until it is stopped by the stopping means 22.

The stopping means 22 is composed of, for example, a protruding tongue piece 23 provided on the first gear 15 provided at the end of the eccentric shaft 5, and a stopper 24 against which the tongue piece abuts. , is set to rotate by a predetermined number of steps, and after the rotation of the first gear 15 is stopped by the stopper 24, the first gear 15 will step out.

Next, the paper 3 is sucked into the widened head gap.

After setting the paper, rotate the stepping motor 18 clockwise and move it to the printing pad 12 or paper guide 13.
The carrier 4 is advanced in the direction in which the gap amount decreases (in the platen direction) until the carrier 4 presses the paper 3 and stops, and after the carrier stops, the stepping motor 18 is caused to step out in the same manner as described above.

At this out-of-step position, the paper 3 is pinched between the print head 12 or paper guide 13 and the platen 2 and cannot run, so the number of steps required to obtain the optimum head gap of, for example, 0.3 tm is completed. stepping motor 1
8 counterclockwise again to move the carrier 4 backward.

By doing so, the head gap is always set with high precision and high quality printing is guaranteed.

The daily operation of the stepping motor is as shown in the block diagram of FIG. 3, as shown in the block diagram of FIG.
It is done depending on.

〔Effect of the invention〕

As described above, the head gap setting method of the present invention allows the head gap to be set extremely easily and with high accuracy, resulting in great economical and industrial effects.

[Brief explanation of drawings]

FIG. 1 is a plan view of a printer that implements the head gap setting method of the present invention, FIG. 2 is a side view of FIG. 1, and FIG. 3 is a block diagram that implements the head gap setting method of the present invention. 4 is a plan view of a conventional printer, FIG. 5 is a side view of FIG. 4, and FIG. 6 is a front view of an encoder. In the figure, 2 is the platen, 3 is the paper, 4 is the carrier,
5 is an eccentric shaft, 12 is a print head,
13 is a paper guide, 14 is a moving means,
15 is the first gear, 16 is the second gear, 17
is a third gear, 18 is a stepping motor, 19 is an encoder, 20 is a slit disk, 20a is a slit, 20b is an initial position, 21 is an optical sensor, 22
23 is a protruding tongue, 24 is a stopper, 25 is a stepping motor drive circuit, 26 is a stepping motor control circuit, and 27 is a control program. Enco 9”A’; hi + figure ￥41 side

Claims (1)

[Claims] A platen (2), a print head (12) facing the platen (2),
a carrier (4) on which the print head (12) is mounted;
In a printer equipped with a moving means (14) for moving the carrier (4) with respect to the platen (2) so that the gap amount increases or decreases, the moving means (14) moves the carrier (4) by changing the gap amount. The paper (3) is set between the print head (12) and the platen (2) by moving backward in the direction in which the amount increases until it is stopped by the stop means (22), and then the print head (12) The carrier (4) is moved forward in a direction where the gap amount decreases until the paper (3) is pressed and stopped, and then a predetermined dimension is created between the print head (12) and the paper (3). Said carrier (4) until a gap of
A head gap setting method characterized in that the head gap is moved backward in a direction in which the gap amount increases.