JPH0885247A - Printer - Google Patents

Abstract

PURPOSE: To improve the reliability of printing motion and reduce manufacturing cost. CONSTITUTION: The end of a protrusion 21a provided at a bracket 21 is passed through a mounting hole 20a in a ribbon mask 20 to heat-crush the end of the protrusion 21a. In the ribbon mask 20, the traveling amount in a direction perpendicular to the printing surface of a printing medium P is limited for the bracket 21. The ribbon mask 20 receives pushing force by the expansion of the printing medium P to prevent an ink ribbon R from being put in a space to a printing head 10. Because a fitting recessed part for fitting and securing the ribbon mask 20 is eliminated, it is possible to use the ribbon mask formed out of a low-priced material thinner than the minimum forming size of the fitting recessed part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer using a ribbon mask made of a thin metal plate supported by a bracket.

[0002]

2. Description of the Related Art In a dot impact type printer, a well-known ribbon mask is used to secure an optimum gap between a print head and a print medium. A thin ribbon mask is generally used because of the mounting space. FIG. 4 is a cross-sectional view of a main part around a print head showing a mounting structure of a thin ribbon mask. On the lower surface of the print head 10, a ribbon mask 11 is supported by a bracket 12 that is a support member that moves in conjunction with the print head 10. An ink ribbon R indicated by a chain double-dashed line in the drawing is stretched on the front surface of the print head 10 by a ribbon guide mechanism (not shown), and runs in the arrow direction in conjunction with the printing operation.

The ribbon mask 11 is made of a thin metal plate and has a substantially dish-shaped cross section. The ribbon mask 11 is provided so as to slightly project from the lower surface of the bracket 12 with its central portion facing the tip of the print head 10. . The central portion of the ribbon mask 11 constitutes a print gap regulation portion 11a that optimally holds the gap between the wire pin of the print head 10 and the print medium P by abutting and pressing the upper surface of the print medium P. The print gap regulation portion 11a is exposed downward from an opening 12a provided in the center of the bracket 12. In the center of the print gap regulation section 11a,
An opening 11b is provided for hitting the ink ribbon R onto the print medium P by a wire pin protruding from the print head 10 for printing.

A reference surface 12b, which is a rectangular flat surface, is provided on the lower surface of the bracket 12 so as to sandwich the print gap regulating portion 11a of the ribbon mask 11 and slightly protrudes from the other surfaces. The reference surface 12b serves as a reference when the platen 13 is raised to detect the thickness of the print medium P, and the platen 13 is lowered to secure the optimum print gap. That is, platen 1
3, the print medium P to be printed is pressed against the reference surface 12b of the bracket 12 with a constant force to detect the thickness of the print medium P, and the platen 13 is lowered by a distance corresponding to the optimum print gap. By doing so, a certain print gap is secured. When the thickness of the print medium P is detected as described above, the ribbon mask 11
The printing gap regulating portion 11a is pressed and elastically deformed until its lower surface is at the same position as the reference surface 12b. That is, the reason why the ribbon mask 11 is made of a thin metal plate is to enable the elastic deformation as described above.

FIG. 5 is a plan view showing a method of fixing the portion A of FIG. At both ends of the ribbon mask 11, the fitting protrusions 11
c is provided, and the fitting mask 11c is fixed to the bracket 12 by inserting and fitting the fitting projection 11c into the fitting recess 12c provided in the bracket 12.

[0006]

Generally, the ribbon mask 11 is composed of a thin metal plate having a thickness of about 0.1 mm because of the necessity of elastic deformation as described above, and the bracket 12
Is usually made of a resin material which is inexpensive to manufacture, and is usually constructed by assembling both. As described above, since the bracket 12 is resin-molded, the dimensions of the fitting recess 12c vary. Therefore, as shown in FIG. 6 (enlarged cross-sectional view of the portion A in FIG. 4), a vertical play, that is, a gap g, is formed between the fitting protrusion 11c of the ribbon mask 11 and the fitting recess 12c of the bracket 12. Is often generated (note that the gap g is exaggerated in FIG. 6). If the gap g is large, the ribbon mask 11
Is pushed up by the bulge of the print medium. As a result, the print head 10 and the ribbon mask 12
In some cases, the ribbon R may be sandwiched between and, and the running of the ink ribbon R may be hindered, or excessive force may be applied to the ink ribbon R to cause the ink ribbon R to come off the ribbon guide mechanism and disable normal printing. However, there was a point that the printing operation was not reliable. Further, since the bracket 12 is made of resin, the minimum molding dimension capable of molding the interval d in the thickness direction of the fitting recess 12c is limited to about 0.1 mm. Therefore, it was not possible to use the ribbon mask 11 that is thinner than the minimum molding size, that is, inexpensive.

The present invention has been made in view of the above circumstances, and a first object thereof is to provide a printing apparatus capable of smooth running of an ink ribbon and having improved printing operation reliability. . A second object is to provide a printing apparatus that uses a cheaper ribbon mask and reduces the manufacturing cost.

[0008]

The printer of the present invention uses a ribbon mask made of a thin metal plate supported by a bracket, wherein the ribbon mask is fixed to the bracket at both ends along the running direction of the ink ribbon. Is characterized by. Further, the printer of the present invention is characterized in that the protrusion provided on the bracket is inserted into the attachment hole of the ribbon mask and the tip of the protrusion is crushed by heating to fix the ribbon mask to the bracket.

[0009]

In the ribbon mask, the amount of movement of the print medium in the direction perpendicular to the print surface of the print medium is limited. Elastically deforms until it becomes equal to the reference plane of. However, during the printing operation, even if the swelling of the print medium gives a pushing force, the ink ribbon is not deformed to the extent that it is sandwiched between the ribbon mask and the print head. When fixing the ribbon mask to the bracket by inserting the protrusion provided on the bracket into the mounting hole of the ribbon mask and crushing the tip of the protrusion by heating and crushing, it is possible to easily and reliably fix the ribbon mask to the bracket. it can.

[0010]

Next, the present invention will be described with reference to the drawings. 1 is a cross-sectional view of a main part showing a state during assembly of a ribbon mask and a ribbon bracket in an embodiment of a printing apparatus of the present invention, and FIG. 2 is a plan view of FIG.
FIG. 3 is a cross-sectional view of a main part showing a structure around a print head of the printing apparatus of the embodiment. 1 to 3, members that are the same as or correspond to those in FIG. 4 showing the conventional example are denoted by the same reference numerals, and the description thereof will be omitted.

As shown in FIGS. 1 and 2, the bracket 2
1 includes a print gap regulating portion 11a of the ribbon mask 20.
Is provided with an opening 12a for projecting
Two protrusions 21a are provided so as to sandwich the opening 12a. The ribbon mask 20 has the protrusion 21
Two mounting holes 20a through which the protrusions 21a can be inserted are provided at positions corresponding to a.

At the time of assembly, the protrusion 21a of the bracket 21 is inserted into the mounting hole 20a of the ribbon mask 20. Next, as shown in FIG. 3, the ribbon mask 20 is fixed to the bracket 21 by heating and melting the head of the protrusion 21 a and crushing it into a flat shape.

With the above-described structure, unlike the conventional printing apparatus, the fixed portion of the ribbon mask 20 and the bracket 21 does not have a gap in the vertical direction or the horizontal direction with respect to the printing surface, and both are not formed. It is fixed closely. Therefore, the ribbon mask 20 is limited to a range in which the amount of movement of the ribbon mask 20 in the direction perpendicular to the print surface of the print medium P is deformable due to its inherent elasticity. For this reason, when the bulge of the print medium P passes, the print gap regulating portion 11a of the ribbon mask 20 is elastically deformed slightly upward, but the ink ribbon R is sandwiched between the ribbon mask 20 and the print head 10. It does not reach the level. Here, when the thickness of the print medium P is detected, the gap regulation portion 11a of the ribbon mask 20 is pressed by the bulge of the print medium P and elastically deformed upward, as in the conventional case.

Further, unlike the conventional fitting and fixing, the fixing structure for the ribbon mask 20 is surely fixed so that no void is generated by the heat crushing of the resin protrusion. Therefore, it becomes possible to use the inexpensive ribbon mask 20 made of a material thinner than the minimum molding size of the conventional fitting recess.

The number of the mounting holes 20a and the projections 21a is not particularly limited, but normally, two mounting holes 20a and two projections 21a are provided so as to sandwich the print head along the running direction of the ink ribbon. If so, the fixing strength is sufficient.

When fixing the ribbon mask to the bracket, it goes without saying that a fixing means such as a screw or an adhesive may be used. However, as shown in the present embodiment, if the protrusion 21a inserted into the mounting hole 20a is fixed by heating and crushing, it can be fixed simply and surely, which is advantageous in terms of cost and has sufficient fixing strength. It is preferable because it can be obtained.

[0017]

As described above in detail, according to the printing apparatus of the present invention, the amount of movement of the ribbon mask in the direction perpendicular to the printing surface of the printing medium is limited, so that the ribbon moved by the bulge of the printing medium. The ink ribbon is not caught between the mask and the print head. Therefore, the ink ribbon can run smoothly, and the reliability of the printing operation can be improved. Further, since the fitting recess is not provided in the bracket, a ribbon mask manufactured using a low-cost material thinner than the minimum molding size of the fitting recess can be used, so that the manufacturing cost of the printing apparatus can be reduced.

When the ribbon mask is fixed to the bracket by inserting the protrusion provided on the bracket into the mounting hole of the ribbon mask and crushing the tip of the protrusion by heating and crushing, the ribbon mask has a simple structure. Also, the ribbon bracket can be easily and reliably fixed.

[Brief description of drawings]

FIG. 1 is a sectional view showing a process of assembling a ribbon mask and a bracket showing an embodiment of a printing apparatus of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a cross-sectional view of essential parts showing a structure around a print head of a printing apparatus including the ribbon mask and the bracket of the embodiment.

FIG. 4 is a cross-sectional view of a main portion around a print head showing a ribbon mask mounting structure in a conventional printing apparatus.

FIG. 5 is a plan view showing a method of fixing the portion A of FIG.

6 is an enlarged cross-sectional view of a portion A of FIG.

[Explanation of symbols]

 10 Print Head 20 Ribbon Mask 20a Mounting Hole 21 Bracket 21a Projection P Print Medium R Ink Ribbon

Claims (2)

[Claims] 1. A printing apparatus using a ribbon mask made of a thin metal plate supported by a bracket, wherein the ribbon mask is fixed to the bracket at both ends along the running direction of the ink ribbon. 2. The ribbon mask is fixed to the bracket by inserting a protrusion provided on the bracket into a mounting hole of the ribbon mask and heating and crushing the tip of the protrusion. The printing device according to 1.