JP3033657B2 - Platen gap adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a platen gap adjusting device for a dot impact type line printer.
In particular, the present invention relates to a platen gap adjusting device for maintaining a constant distance between the surface of the printing paper and the hammer unit according to the thickness of the printing paper.

[0002]

2. Description of the Related Art FIG. 5 is a side view showing an example of a conventional platen gap adjusting device.

A conventional platen gap adjusting device of a dot impact type line printer for maintaining a constant distance between the surface of the printing paper and the hammer unit in accordance with the thickness of the printing paper, as shown in FIG. A paper feed unit 23 with an integrated paper feed system, a guide pin 24 for guiding the mounting position of the paper feed unit 23, and a gap between a platen 25 and a hammer unit 26 of the paper feed unit 23 (this is called a platen gap). And a fixing lever 22 for fixing the position of the paper feed unit 23 at a desired position on the positioning plate 21, and guides the guide pins 24 according to the thickness of the printing paper to be used. The paper feed unit 23 is moved left and right by hand and the fixing lever 22 is fixed to the positioning plate 21 by hand. It is doing the adjustment of Ngyappu.

[0004]

As described above, the conventional platen gap adjusting device of the dot impact type line printer performs the adjustment by manually moving the platen. It has the disadvantage that you may forget to do it. Failure to adjust the platen gap can cause print paper jams, damage the hammer unit, and degrade print quality.

[0005]

According to the present invention, there is provided a platen gap adjusting device which is mounted on a shaft of a platen and driven by a stepping motor to separate the platen from a hammer unit, and a retract cam of a shaft of the hammer unit. A bearing mounted at a position corresponding to a cam, a first spring for urging the platen toward the hammer unit, and a print paper inserted between the platen and the hammer unit at one end thereof a cell Nsureba having a plurality of slits in the middle section is attached at the other end to said platen has a roller, and a second spring for urging said roller toward said printing paper, said slit of said sense lever A sensor for detecting the position of the sense lever by sensing, and attached to the retract cam Is it is intended that the rollers of the sense lever and a pin detaching from the printing paper.

[0006]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.
(A) is a front view, (b) is a side view, FIG. 2 is a side view showing an operation state of the embodiment of FIG. 1, FIG. 3 is a plan view showing a retract cam of the embodiment of FIG. 1, and FIG. FIG. 3 is a front view showing details of the sense lever of the first embodiment.

In FIG. 1, a retract cam 1 is mounted on a shaft end of a platen 5, and a bearing 2 is mounted on a shaft end of a hammer unit 6 at a position facing the retract cam 1. The platen 5 and the hammer unit 6 are disposed in parallel, and a spring 3
And biases the platen 5 toward the hammer unit 6. The retract cam 1 is driven by a stepping motor 4 and performs an action of temporarily separating the platen 5 from the hammer unit 6 when sucking the printing paper.

As shown in FIG. 2, the axis of the platen 5
One end of the sense lever 8 is attached, and the other end of the sense lever 8 is attached with a roller 11a. A spring 12 is mounted on an intermediate portion of the sense lever 8, and the spring 12 urges the roller 11a against a roller 11b provided to face the roller 11a.
1a is brought into contact with the paper 7 inserted between the platen 5 and the hammer unit 6. A sensor 9 is provided near the spring 12 to detect the position of the sense lever 8 (details will be described later).

The retract cam 1 is, as shown in FIG.
It has a symmetrical shape with respect to the Y axis 20 which is a line connecting the centers of the axes of the platen 5 and the hammer unit 6,
The lower half has a semicircular shape, and the upper half has a triangular shape with an arc-shaped tip.

[0011]

The triangular tip of the retract cam 1 is
When the state in contact with the receiving 2 rotates the retraction cam 1 in the counterclockwise direction, as shown in FIG. 2 (a), the platen 5
Approaches the hammer unit 6 while lifting the paper 7,
The roller 11a contacts the roller 11b via the sheet 7.

When the retract cam 1 is further rotated counterclockwise from this state, the platen 5 is further raised, so that the sense lever 8 rotates counterclockwise around the roller 11a as a fulcrum, and the sensor 9 operates. Let it.

As shown in FIG. 4, the sense lever 8
A plurality of slits 13 are provided.
The sensor 9 operates when passes through the sensing part of the sensor 9.

The platen gap is set to an appropriate value when the stepping motor 4 is operated several steps after the sensor 9 operates.

When the retract cam 1 is rotated clockwise from this state, as shown in FIG. 2B , the pins 10 provided around the lower half semicircular portion of the retract cam 1 sense. To lift the lever 8, the roller 11a
Is separated from the sheet 7.

By performing the feeding operation of the paper 7 in the state shown in FIG. 2 ( a ), the thickness of the paper 7 can be always detected, whereby the feeding operation of the paper 7 can be controlled. It is.

For example, since the dimension from the position of the roller 11a to the hammer unit 6 is constant, the dimension is managed by firmware, and the perforated portion provided for folding the sheet 7 is positioned at the position of the roller 11a. Come and Roller 1
When the sensor 9 is operated by lifting the sensor 1a, it is identified that the operation of the sensor 9 is caused by the perforated portion, and the platen 5 is temporarily moved immediately before the perforated portion is sent to the hammer unit 6. By lowering the load, the load on the paper transport system can be reduced.

[0019]

As described above, the platen gap adjusting device according to the present invention includes a retract cam driven by a stepping motor to separate the platen from the hammer unit, and a spring for biasing the platen toward the hammer unit. A sense lever having a roller in contact with the printing paper at one end and the other end attached to the platen, a sensor for detecting the position of the sense lever, and a pin attached to the retract cam for separating the roller of the sense lever from the printing paper; Has the effect that the platen gap can be automatically adjusted to an appropriate value according to the thickness of the printing paper, thus preventing forgetting to adjust the platen gap. This prevents paper jams, damage to the hammer unit and deterioration of printing quality. That.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of the present invention, wherein (a) is a front view and (b) is a side view.

FIG. 2 is a side view showing an operation state of the embodiment of FIG. 1;

FIG. 3 is a plan view showing the retract cam of the embodiment of FIG. 1;

FIG. 4 is a front view showing details of a sense lever of the embodiment of FIG. 1;

FIG. 5 is a side view showing an example of a conventional platen gap adjusting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Retract cam 2 Bearing 3.12 Spring 4 Stepping motor 5.25 Platen 6.26 Hammer unit 7 Paper 8 Sense lever 9 Sensor 10 Pin 11a / 11b Roller 13 Slit 20 Y axis 21 Positioning plate 22 Fixed lever 23 Paper feed unit 24 guide pin

Claims (2)

(57) [Claims] A retracting cam mounted on a shaft of the platen and driven by a stepping motor to separate the platen from the hammer unit; a first spring for biasing the platen toward the hammer unit; a cell Nsureba having a plurality of slits and the other end has a roller in contact with the inserted print sheet to an intermediate portion mounted to the platen between the platen and the hammer unit, towards the roller of the printing paper A spring that biases the sensor, a sensor that detects the position of the sense lever by sensing the slit of the sense lever, and the roller of the sense lever that is attached to the retract cam from the printing paper. A dot impact type line printer characterized by having a separating pin. Ten gap adjustment device. 2. A retract cam mounted on a shaft of a platen and driven by a stepping motor to separate the platen from the hammer unit; a bearing mounted on a position of the shaft of the hammer unit corresponding to the retract cam; A first spring for urging the platen toward the hammer unit, a roller at one end for contacting a printing paper inserted between the platen and the hammer unit, the other end attached to the platen, a sensor for detecting a cell Nsureba having a plurality of slits in section, a second spring for urging said roller toward said printing paper, the position of the sensing lever by sensing the slit of the sense lever And the roller of the sense lever attached to the retract cam from the printing paper. A platen gap adjusting device for a dot impact type line printer, comprising a separating pin.