JPS6334033B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a printing head for a serial printer such as a wire dot printer, and in particular allows for fine adjustment of the printing gap, as well as adjustment of printing paper, replacement of ink ribbon, etc. Later, we will discuss improvements to printhead positioning mechanisms that do not require readjustment operations.

(b) Background of the Technology In recent years, serial printers have been developed and put into practical use as terminals for various computers and office machines such as word processors. In these printers, printing is usually performed by wrapping printing paper around a platen and setting an ink ribbon between the printing paper and a print head, but it is desirable that the printing paper and ink ribbon are easy to set. Furthermore, as the use of word processors and the like is expanding, there is an increasing need to ensure print quality.

(c) Prior Art and Problems The conventional method will be explained below with reference to FIGS. 1 to 3. FIG. 1 is a plan view showing an outline of a wire dot printer to which the present invention is applied;
This figure is a side view showing the printing section and carrier section of FIG. 1, and FIG. 3 is an explanatory view showing the printing gap adjustment of FIG. 2.

As shown in FIG. 1, the wire dot printer has a side frame 9, on which a platen 10 is rotatably supported. A printing paper 11 is wrapped around the platen 10, and the printing paper 11 is wrapped around a sprocket 12a,
12b, etc., in the direction of arrow A in the figure. On the other hand, on the front side of the platen 10, that is, at the bottom in the figure, a carrier 13 is screwed into a feed screw 15 provided parallel to the platen 10, and the carrier 13 is connected to a guide shaft 1 similarly provided parallel to the platen 10.
6 and is slidably fitted. The feed screw 15 is connected to a motor 19 via a belt 17 or the like, and therefore, the feed screw 15 can move the carrier 13 in the directions of arrows C and D in the figure by rotating the motor 19 in forward and reverse directions. . An ink ribbon cassette 20 is mounted on the carrier 13, and an endless ink ribbon 20a is built into the cassette 20 with a portion thereof exposed to the platen 10 side. Further, a printing head 21 is installed in the carrier 13 surrounded by an ink ribbon cassette 20, and a plurality of printing magnets (not shown in the figure) are installed in the printing head 21 in order to form printing by dots. It is provided.

With such a configuration, the printing head 21
When activated, the printing wire of the printing magnet collides with the printing paper 11 on the platen 10 shown in FIG.
Printing is performed on the printing paper 11 while moving in the direction. When printing for one line is completed, the printing paper 11 is moved in the direction of arrow A by a predetermined amount of tension for line feed. The print head 21 continues printing while moving in the direction of arrow C.

In such a printer, the gap between the platen 10 and the print head 21, that is, the print gap a, is the width of the print paper 11 used to ensure print quality.
It is necessary to adjust the value to the optimum value depending on the paper thickness and number of sheets, and whether it is pressure-sensitive paper or carbon paper. For example, when the printing paper 11 changes from one sheet to five sheets, the printing gap a is adjusted within the range of 0.2 to 0.6 mm, and a high accuracy of ±0.05 mm is required to obtain good printing quality. Further, when setting the printing paper 11 or replacing the ink ribbon, the printing head 21 is retracted for easy operation, but in this case, a gap of 1.0 mm or more is provided. Next, to explain how to adjust this printing gap a, as shown in FIG.
The carrier 13 is composed of a carrier front part 13a and a slider part 13b.The carrier front part 13a has a printing head 21 and the like mounted thereon, and is screwed into the feed screw 15. The slider portion 13b is fitted into the guide shaft 16. The connecting part between the carrier front part 13a and the slider part 13b is connected to the stud 1 provided on the carrier front part 13a.
3c is slidably fitted into a hole 13d provided in the slider portion 13b. As shown in FIG. 3, a lever 14 is attached to the tip of the eccentric shaft 16a, and when the lever 14 is rotated in the direction of arrow EF in the figure, the eccentric shaft 16a rotates, and the guide shaft 16 is rotated.
rotates. Fixing positions 18 ₁ to 18 ₆ and 18s are provided with springs so that the tip of the lever 14 can be fixed at divided rotation angles.

With this configuration, when adjusting the printing gap a, rotate the lever 14 in the direction of arrow E in FIG. 3, the eccentric shaft 16a will rotate, the guide shaft 16 will rotate, and the carrier 13 in FIG. Since the slider portion 13b is moved in the direction of arrow G in the figure, the carrier front portion 13a is moved around the feed screw 15.
rotates in the direction of arrow B in the figure, and the printing gap a widens. Therefore, the rotation fixed position 1 of the tip of the lever 14
The size of the printing gap a can be adjusted according to 8 ₁ to 18 ₆ . When setting the printing paper 11 or replacing the ink ribbon 20a,
It is sufficient to rotate the lever 14 to the maximum rotation angle position 18s.

In this way, the print head 21 can be evacuated for adjusting the print gap a, setting the print paper 11, and replacing the ink ribbon 20a.

However, in this method, when printing is being performed at a certain printing gap a and it is desired to set the printing paper 11 or replace the ink ribbon 20a, the lever 14 is rotated to the maximum rotation angle of 18 s and the printing head 21 is retracted. There is a drawback in that the operator must remember the original position of the lever 14 in order to return to the original printing gap a after setting and replacement. That is, the original printing gap a
In many cases, the lever 14 is operated without checking, and trial printing must be repeated several times in order to obtain the optimum printing gap a again.

(d) Purpose of the Invention The purpose of the present invention is to solve the above-mentioned drawbacks, and the purpose of the present invention is to have the device hold the printing gap during printing when the printing gap is widened by setting printing paper or replacing the ink ribbon. The purpose of the present invention is to provide a print head positioning mechanism that can be used.

(e) Structure of the Invention In the present invention, the means for adjusting the gap between the platen and the print head includes a rotating plate fixed to the eccentric shaft and biased in a direction in which the eccentric shaft rotates by a first elastic member; It is slidably attached to a groove provided in the rotating plate, has a long hole in the center in the same direction as the groove and a convex portion at the tip, and the eccentric shaft engages with the long hole so as to be slidable in the longitudinal direction. , a slide plate urged in the direction of the convex portion by a second elastic member;
A lever that rotates the eccentric shaft against the elasticity of a first elastic member via a rotation plate, a dog plate having a recessed portion that engages with the convex portion, and a first moving means that linearly moves the dog plate. a second moving means for retracting the slide plate against the elasticity of the second elastic member in a direction in which the protrusion engaged with the recess is disengaged; the dog plate is moved by the first moving means; The eccentric shaft is rotated by the rotation of the rotating plate to adjust the gap, and when the slide plate is retreated by the second moving means, the eccentric shaft is rotated by the first elastic member and the printing head is moved. This print head positioning mechanism is characterized in that the convex portion can be engaged with the concave portion when the eccentric shaft is rotated by operating a lever after the print head is retreated from the platen member. By doing so, the purpose can be achieved.

(f) Embodiment of the Invention An embodiment of the invention will be described below with reference to FIGS. 4 and 5. FIG. 4 is a side view showing an embodiment according to the present invention, and FIG. 5 is an explanatory view showing the operation of FIG. 4. FIG. 4 shows a state in which the print head positioning mechanism according to the present invention is attached to the end of the eccentric shaft 16a shown in FIG. A screw block 2 having a screw hole 2a is attached to the dog plate 1, and a gear 3a is attached to one end of the screw hole 2a.
A feed screw 3 having a diameter is screwed together. The gear 3a meshes with a gear 4a attached to a shaft 4, and a rotary knob 5 and a scale plate 5a are provided coaxially. The shank portion 3b of the feed screw 3 and the shaft 4 are supported by a frame 9a attached to a side frame 9. And the screw block 2 is the preload spring 2
It is pulled downward in the figure at a. Therefore, when the rotary knob 5 is turned, the dog plate 1 moves up and down.

On the other hand, a rotating plate 6 is attached to the end of the eccentric shaft 16a.
is fixed, and a slide plate 7 is slidably attached to a not-illustrated dovetail groove of a slide portion 6a provided on the rotating plate 6. A nipple-shaped protrusion 7a is provided at the tip of the slide plate 7, an elongated hole 7b is provided at the center, and studs 7c and 7d are attached to the other end. The convex portion 7a is slidably fitted into the U-shaped concave portion 1a of the dog plate 1, and is engaged in the vertical direction in the figure. The end of the eccentric shaft 16a is slidably fitted into the elongated hole 7b. and rotating plate 6
In the figure, the right end and the stud 7d are connected by a force spring 6c, which is a second elastic member, and the elasticity of the force spring 6c biases the slide plate 7 in the direction of arrow K in the figure.

Further, the rotary plate 6 is provided with a stud 6b, which is slidably fitted into an elongated hole 8a provided in the lever 8 with the stud 9b attached to the side frame 9 as a fulcrum. stud 6b
A recovery spring 6f, which is a first elastic member, is attached to the rotation plate 6 to bias the rotary plate 6 in the direction of arrow L in the figure about the eccentric shaft 16a. In the drawing of the rotary plate 6, a hold cam 6d and a stop portion 6e are formed in a stepped manner from the back side. Furthermore, as a second moving means, an inverted L-shaped lever 22 is provided at the upper left in the figure, with a stud 9c attached to the side frame 9 serving as a fulcrum at a corner. A U-shaped notch is formed at the lower end of the lever 22, and a cam follower 22a is formed at the end face indicated by the broken line in the figure.
A stud 7c of the slide plate 7 is engaged with the notch 22b. Further, a recovery spring 22c is provided that biases the lever 22 in the direction of arrow S in the figure, and a push portion 22d is provided in the horizontal portion of the lever 22. The horizontal end of the lever 22 is in contact with the actuation lever l of the micro switch MS attached to the frame 9a, and when the push part 22d is pushed down in the direction of arrow H in the figure, the actuation lever l moves the contact c. It is designed to be restored. Micro switch MS is connected to a control unit not shown in the diagram, and the connection is turned OFF when contact c is restored.
and shuts off all mechanical functions.

With such a structure and function, when adjusting the printing gap a, when the rotary knob 5 is rotated as shown in FIG. Part 7
a lowers and the slide plate 7 rotates the eccentric shaft 16a in the direction of arrow L, so as explained in FIGS. 2 and 3, the slider portion 13b moves in the direction of arrow G, and the print head 21 moves in the direction of arrow B. The printing gap a changes in the direction of widening.
When the rotary knob 5 is rotated once, the printing gap a is
For example, by setting the conversion ratios of the gears 3a and 4a so as to suit approximately 1 to 6 sheets of printing paper 11, respectively, it is possible to mark scales corresponding to the scale plate 5a. First, print is performed by setting the printing gap a according to the scale, and if further adjustment is required, fine adjustment can be made using the rotary knob 5.

Further, when setting the printing paper 11 or replacing the ink ribbon 20a, as shown in FIG. 5, when the push portion 22d of the lever 22 is pushed down in the direction of the arrow G, the lever 22 rotates in the direction of the arrow H in the figure.
As the micro switch MS turns OFF, the slide plate 7 moves in the direction of arrow J, and the convex portion 7a
When the recess 1a is disengaged, the rotating plate 6 is rotated together with the recovery spring 6f in the direction of the arrow L in the figure, and the eccentric shaft 16a is rotated in the same direction. At this time, the stud 7c is disengaged from the notch 22b of the lever 22, and the hold cam 6d is moved from the cam follower 22a.
The rotation is stopped at the stop portion 6e. The printing head 21 is retracted to a predetermined position by the rotation angle of the eccentric shaft 16a, so that the printing paper 1
1 or the ink ribbon 20a can be replaced.

At this time, lever 8, which is indicated by the center line of the one-dot chain line in the figure,
By moving the stud 6b in the N direction in the figure,
It moves in the direction of arrow Q in the figure and rotates to the position indicated by the center line of the dashed-dotted line. That is, the lever 8 moves to the position shown by the two-dot chain line in FIG.

Setting the printing paper 11 or ink ribbon 2
0a is completed, and when returning to the original printing gap a, rotate the lever 8 in the direction of arrow R in the figure in Fig. 5. A force is applied to return the stud 6b in the direction of arrow P in the figure, and the rotating plate 6 in the direction of arrow M, the stud 7c of the slide plate 7 again engages with the notch 22b of the lever 22, and the protrusion 7a
When returns to the position of the recess 1a of the dog plate 1,
The slide plate 7 is moved by the elasticity of the forced spring 6c.
is pulled in the direction of arrow K in the figure, and the convex portion 7a engages with the concave portion 1a, returning to the original state shown in FIG. 4. Therefore, the recess 1a of the dog plate 1 returns to the position corresponding to the original printing gap a, so that printing can be started at the proper printing gap a.

(g) Effects of the Invention As explained above, according to the present invention, the adjustment of the print gap a and the operation of retracting the print head can be performed by separate mechanisms, and moreover, the operation of retracting the print head and setting or setting the print paper can be performed using separate mechanisms. When the printer is restored after replacing the ink ribbon, the original printing gap can be obtained, so there is no need for the operator to memorize the original printing gap lever position. Since fine adjustments can be made, printing quality can be improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an outline of a wire dot printer to which the present invention is applied, FIG. 2 is a side view showing the printing section and carrier section of FIG. 1, and FIG.
FIG. 4 is a side view showing an embodiment of the present invention, and FIG. 5 is an explanatory view showing the operation of FIG. 4. In the figure, 1 is a dog plate, 1a is a recess, 2b is a preload spring, 3 and 15 are feed screws, 5 is a rotating knob, 5a is a scale plate, 6 is a rotating plate,
6a is a slide part, 6b, 7c are studs, 7 is a slide plate, 7a is a convex part, 7b, 8a are long holes, 8, 14, 22 are levers, 10 is a platen, 1
1 is a printing paper, 13 is a carrier, 13a is a carrier front part, 13b is a slider part, 16 is a guide shaft, 16a is an eccentric shaft, 20a is an ink ribbon,
21 is a printing head, and 22b is a notch.

Claims (1)

[Scope of Claims] 1. A printing unit including a printing head facing a platen member with a gap therebetween; a carrier on which the printing unit is mounted and a guide shaft parallel to the platen member is slidably fitted; means for adjusting the gap by moving the carrier in a direction perpendicular to the platen member by rotating eccentric shafts provided at both ends of the guide shaft; and a drive unit for moving the carrier parallel to the platen member. In a printer that prints on a medium set in the gap, the gap adjusting means is fixed to the eccentric shaft and biased in a direction in which the eccentric shaft rotates by a first elastic member. a rotating plate that is slidably attached to a groove provided in the rotating plate, has a long hole in the center in the same direction as the groove and a convex portion at the tip, and the eccentric shaft is inserted into the long hole. a slide plate that is slidably engaged and urged in the direction of the convex portion by a second elastic member; and a slide plate that resists the elasticity of the first elastic member through the rotating plate. a lever that rotates the dog plate; a dog plate that has a recess with which the projection engages; a first moving means that linearly moves the dog plate; and a lever that disengages the projection that has been engaged with the recess. a second moving means for retracting the slide plate in a direction against the elasticity of the second elastic member, the first moving means moves the dog plate, and the rotating plate rotates to move the dog plate. The eccentric shaft is rotated to adjust the gap, and when the slide plate is retreated by the second moving means, the eccentric shaft is rotated by the first elastic member and the printing head is moved. When retreating from the platen member and operating the lever to rotate the eccentric shaft,
A print head positioning mechanism characterized in that the convex portion is configured to be engageable with the concave portion.