JPH0440931Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a dot impact type printing head.

(Prior Art) In the prior art, a dot impact type printing head is constructed by fixing a wire assembly to a wire drive section that drives a printing wire. In this wire assembly, the support frame of the wire guide is fixed to the wire drive part by a fixing screw.

(Problem to be solved by the invention) In such a print head, the print head generates heat during printing operation.Especially as the printing speed increases in recent years, the print head generates a tremendous amount of heat, which causes the support frame to thermally expand. Then, the nose portion protrudes in a direction approaching the platen. Because the nose of the dot-impact printing head faces the platen with a small gap, the gap between the support frame nose and the platen becomes increasingly narrow, and this causes the ink ribbon that passes through the gap to get caught, and the recording paper to pass through. Contact with the ink ribbon sometimes caused stains on the recording paper. When the gap between the fixing screws of the support frame was 30 mm, the protrusion of the nose due to thermal expansion was 0.06 mm. Normally, the gap between the nose of the print head and the platen is set to about 0.2 mm, and the recording paper (0.1 mm thick) and ink ribbon (0.05 mm thick) are inserted into this small gap.
The recording paper and the ink ribbon come into contact with each other due to the protrusion of the nose portion.

The purpose of the present invention is to prevent the north portion from protruding due to thermal expansion of the support frame even if the print head generates heat, thereby preventing the ink ribbon from being caught and the recording paper from becoming stained.

(Means for Solving the Problems) The present invention is characterized by being composed of a wire assembly and a wire drive section, and the wire assembly is held by a support frame having a nose section and a support frame having a nose section. It consists of a wire guide, a wire guide slidably held by the wire guide, and a printing wire slidably supported by the wire guide. The wire assembly is fixed to the wire drive part by a pair of fixing screws on both sides of the nose part, and the support frame has a structure between the nose part and the fixing screws to absorb elongation due to thermal expansion of the support frame. There is a slit formed there.

(Function) Even if the print head generates heat due to the printing operation and the support frame expands thermally, the presence of the slit absorbs the expansion and prevents the nose of the wire guide from protruding forward. Ru.

(Example) An example of the present invention will be described below based on the drawings.

As shown in FIGS. 1-3, the print head of the present invention is comprised of a wire assembly 1 and a wire drive section 2. As shown in FIGS. A heat dissipation fin 3 is attached to surround the outer periphery and back surface of the wire drive section 2. The wire assembly 1 includes a support frame 11 having a nose portion 11a.
And the wire guide 3 held in this nose part
and a printing wire 5 slidably supported by this wire guide. The support frame 11 is made of synthetic resin, aluminum die-casting, or the like. The wire guide 4 is made of ceramic, and a plurality of wire guides 4 are held in parallel at a predetermined interval on the nose portion 11a. The printing wire 5 can freely slide through guide holes arranged in a diamond shape in the center of the wire guide 4. The wire assembly 1 is fixed to the front surface of the wire drive section 2 by a pair of fixing screws 6, 6 on both sides of the nose section 11a. The fixing screws 6, 6 pass through holes 11b, 11b provided in the support frame 11, and the nose portion 11a
There are through holes 11b, 1 between the and each fixing screw 6, 6.
Arc-shaped slits 11c, 11c are formed concentrically with 1b. 7 is a screw for fixing the wire drive section 2.

When the printing head generates heat during the printing operation and the support frame 11 thermally expands and extends in the left-right direction in FIG. 1, the expansion is absorbed by the slits 11c and 11d. In other words, if there are no slits, the support frame is curved so that the nose portion 11a protrudes forward because it is fixed by the fixing screws 6, 6 and cannot extend further in the left and right direction. The purpose is to reduce the gap between the tip of the nose portion 11a and the platen, but in the case of the present invention, as described above, the slits 11c absorb the horizontal expansion of the support frame, and the gap between the tip of the nose portion 11a and the platen is reduced. is prevented from protruding forward.

Note that the slit 11c is not limited to an arcuate shape, but may be linear or any other shape as long as it absorbs the expansion of the support frame in the left-right direction.

(Effects of the invention) With the present invention having the above configuration, even if the printing head generates heat due to printing operation, the elongation due to thermal expansion of the support frame is absorbed by the slit, so that the nose protrudes forward. There is no need to narrow the gap between the ink ribbon and the platen, and the practical effects are truly significant, such as preventing the ink ribbon from getting caught and the recording paper from getting smudged.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a front view, FIG. 2 is a right side view, and FIG. 3 is a plan view. 1... Wire assembly, 11... Support frame,
11a...nose part, 11c...slit, 2...
...Wire drive unit, 4...Wire guide, 5...Printing wire, 6...Fixing screw.

Claims (1)

[Claims for Utility Model Registration] The wire assembly is composed of a wire assembly and a wire drive section, and the wire assembly includes a support frame having a nose section, a wire guide held by the nose section, and a wire drive section. a printing wire slidably supported by a guide, the wire assembly being secured to the wire drive part by integral fixing screws on both sides of the nose part, and the support frame A printing head characterized in that a slit is formed between the nose portion and the fixing screw to absorb elongation due to thermal expansion of the support frame.