JPS6229263Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a head gap adjustment device for a printer that maintains an appropriate amount of head gap between the printing surface of the platen and the tip of the printing head depending on the thickness of the printing paper, whether or not copying paper is used, etc.

Conventional devices of this kind have a structure in which a carrier and a guide shaft that guides the movement of the carrier are connected via an eccentric member that can rotate with respect to the two, or a structure in which a carrier and a guide shaft that guides the movement of the carrier are connected via an eccentric member that is rotatable with respect to the two. The left and right frames supporting the frame are connected via a rotatable eccentric member. In each of the conventional devices, the gap between the printing surface of the platen and the tip of the printing head is adjusted by rotating an eccentric member.

However, in conventional devices, no consideration has been given to measures to restrict the vertical movement of the carrier or guide shaft, and therefore the carrier or guide shaft, which is directly moved by the rotation of the eccentric member, cannot be moved directly by the rotation of the eccentric member. It is moved up and down as the head gap is adjusted. As a result, the center positions of the printing surface of the platen and the printing head are vertically misaligned, resulting in a problem of deterioration of printing conditions.

The present invention was proposed under the above circumstances, and its purpose is to eliminate vertical deviation in the center position between the printing head and the printing surface of the platen.
An object of the present invention is to provide a head gap adjustment device for a printer that allows the head gap to be adjusted in any state.

That is, in the present invention, the adjustment cams rotatably attached to the left and right frames press both ends of the guide shaft that is horizontally suspended on the left and right frames, so that the guide shaft can be moved in the direction toward and away from the platen. and a head gear for a printer characterized by a configuration in which the movement of the guide shaft is limited only in the direction of moving toward and away from the platen back and forth using adjustment holes drilled in the left and right frames, thereby achieving the above object. It is a regulating device.

An embodiment of the present invention will be described below with reference to the drawings.

In the figure, 1 is a frame body including left and right frames 1a, 1b, and the left and right frames 1a, 1b include:
A platen 2 is horizontally suspended on the rear side, and a shaft 3 and a pair of guide shafts 4 and 5 are horizontally suspended on the front side of the platen 2.
A carrier 6 that extends over both of the guide shafts 4 and 5 is fitted and movably supported, and this carrier 6 includes a motor 7, pulleys 8, 9, and
1 and 12, a spring 13, and the like, the guide shafts 4 and 5 are movable along the axial direction thereof. In addition, 6a, 6
b indicates a guide shaft fitting portion, while 6b is U-shaped and is also used to allow movement of the carrier 6 relative to the guide shaft 5 during head gap adjustment. The carrier 6 is equipped with, for example, a wire dot type printing head 14.
The tip thereof and the printing surface of the platen 2 are opposed to each other, forming a proper head gap G.

The left and right frames 1a and 1b are respectively provided with adjusting long holes 15 along the front and rear (horizontal) directions of approaching and separating from the platen 2.
Both left and right ends of the guide shaft 4 are engaged with the guide shafts 5 and 15, respectively. Therefore, the guide shaft 4 is prohibited from vertical movement by the adjustment slots 15, 15, and is horizontally mounted on the left and right frames 1a, 1b so as to be horizontally movable in the direction toward and away from the platen 2. Both ends of the shaft 3 are used as a camshaft 3a in this embodiment, and are disposed near the adjustment slots 15, 15, respectively. Adjusting cams 16, each of which has the guide shaft 4 as a cam follower, are fixedly attached to the cam shafts 3a (connected so that they cannot rotate about the shafts). The adjustment cam 16 has a rotating operation part 16a and a notch groove 1.
6b. The adjustment cam 16 and the ends of the guide shaft 4 are, for example, the left and right frames 1a, 1
cams 16 for adjusting the guide shaft 4, respectively attached to b.
The engaged state is always maintained by a leaf spring 17 (only one of which is shown) that presses it to the side. Furthermore, the rotation angle of the adjusting cam 16 is regulated within a certain range by contact between stoppers 18 protruding from the left and right frames 1a and 1b, respectively, and the notch groove 16b.
Moreover, the rotation of the adjustment cam 16 within the above-mentioned regulation range is selectively positioned at a plurality of positions by a positioning mechanism. In the case of this embodiment, this mechanism has a rotating operation portion 16a on the adjustment cam 16.
It is formed with an elastically deformable arm 19 extending in the opposite direction and having an engaging protrusion 19a at its tip, and a plurality of engaging grooves 20 provided in the left and right frames 1a and 1b, respectively.

In the figure, 21 indicates a retaining ring, 22 a ribbon cassette, 23 a platen drive mechanism, and A a printing paper.

According to the configuration of this embodiment, the engaging position between the cam surface of the adjusting cam 16 and the guide shaft 4 is changed by rotating the adjusting cam 16 using its rotation operating portion 16a. Guide shaft 4 according to
is moved horizontally back and forth. Note that the maximum movement amount is shown at l in FIG. This guide shaft 4
When the carrier 6 is moved, the carrier 6 supported by the carrier 6 is also moved in the front and rear direction at the same time.
The head gap G between the tip of the print head 14 mounted on the print head 14 and the printing surface of the platen 2 is adjusted, and a head gap G corresponding to the thickness or number of print sheets A can be obtained. This adjustment position is selected by a positioning mechanism, and this positioning mechanism prevents the printing head 14 from moving unduly in the front-back direction due to vibration or the like. and,
When adjusting the head gap G, both ends of the guide shaft 4 can be moved in the vertical direction by adjustment slots 15, 15 provided in the left and right frames 1a, 1b along the direction of approaching and separating from the platen 2. Because the printing surface of the platen 2 and the center of the tip of the printing head 14 are not displaced vertically, these centers are always at a predetermined height position (second (on line O-O' in the figure). In other words, the printing conditions are not deteriorated by adjusting the head gap G, and high quality printing can therefore be obtained.

In this embodiment, both ends of one shaft 3 are used as the cam shafts 3a and 3b, which helps to reduce the number of parts, and since the adjusting cam 16 is fixed to this shaft 3, either end of the shaft 3 is used. One adjustment cam 16
The pair of left and right head gap adjustment devices can be linked by simply operating the . Therefore, the guide shaft 4 can be moved relative to the platen 2 with a single operation, and the operation is simple.

Furthermore, since the adjustment work can be performed on the left and right frames 1a and 1b, the adjustment work can be performed not only when the carrier 6 is stopped, but also when it is moving along the guide shafts 4 and 5. .

Note that the present invention is not limited to the above embodiment.

For example, the left and right camshafts may be provided independently, or the camshaft may be fixed and an adjustment camshaft may be rotatably attached to the camshaft. In these cases, in order to move the guide shaft toward and away from the platen, it is necessary to rotate the left and right adjustment cams, but it is possible to make the amount of movement of the guide shaft by the left and right adjustment cams different. As a result, if the parallelism between the platen printing surface and the tip of the printing head is not uniform within the range of movement of the carrier due to component precision during assembly, the above-mentioned parallelism can be made uniform. Adjustments can also be made.

Further, the spring is not limited to a leaf spring, but may also be a coil spring stretched between the camshaft or frame and the guide shaft.Furthermore, the adjustment cam, spring, positioning mechanism, etc. may be arranged inside the frame. No problem.

In addition, when implementing the present invention, unless it is contrary to the gist of the invention, the platen, left and right frames, adjustment slots, guide shafts, carriers, printing heads, adjustment cams, rotation operation parts, springs, positioning mechanisms, etc. It goes without saying that the specific structure, shape, position, material, etc. are not limited to the one embodiment described above, and can be configured and implemented in various ways.

As explained above, the present invention adjusts the head gear by moving the guide shaft of the carrier. Since the head gap is configured to be rotated, the head gap can be adjusted by simply rotating the adjustment cam even when the carrier is stopped or moving. Then, both ends of the guide shaft are engaged with adjustment slots provided in the left and right frames to which the adjustment cam is attached via the cam shaft, allowing the guide shaft to move only in the direction of forward and backward movement toward and away from the platen. Because it has a configuration that prohibits vertical movement,
This has great practical effects, such as being able to adjust the head gap without vertically shifting the center position between the tip of the print head and the printing surface of the platen.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a perspective view of a serial printer, and FIG. 2 is a perspective view of a serial printer.
3 is an enlarged front view of the middle part of FIG. 1, FIG. 4 is a sectional view taken along the line - in FIG. 3, and FIG. 5 is an exploded perspective view. 1a, 1b...Frame, 2...Platen, 3
...Shaft, 3a...Cam shaft, 4...Guide shaft, 6...
...Carrier, 14...Print head, 15...Adjustment slot, 16...Adjustment cam, 16a...Rotation operation section, 17...Spring (plate spring), 19...Arm,
19a...Engagement protrusion, 20...Engagement groove, G...Head gap.

Claims (1)

[Claims for Utility Model Registration] (1) In the left and right frames that support the platen, adjusting long holes are respectively drilled along the directions of moving forward and backward toward and away from the platen, and a cam shaft is installed in the vicinity of these adjusting long holes. The left and right ends of the guide shaft are engaged with the left and right adjustment slots, and the guide shaft is horizontally mounted on the left and right frames so that it can move in the direction toward and away from the platen. A fixed guide body parallel to the platen is horizontally suspended, and a carrier carrying a printing head is mounted on the guide shaft so as to be movable in the axial direction, and on the fixed guide body so as to be movable in the direction of moving forward and backward toward and away from the platen; Each of the camshafts is equipped with an adjustment cam having a rotating operation part and the guideshaft as a cam follower, and a spring biases the guideshaft to maintain the engagement state between the adjustment cam and the end of the guideshaft. 1. A head gap adjustment device for a printer, comprising a positioning mechanism for selectively positioning the adjusting cam at a plurality of positions. (2) The left and right camshafts are formed by both ends of a shaft that is parallel to the platen and horizontally suspended between the left and right frames, and the adjustment cam is fixedly attached to these camshafts. A head gap adjustment device for a printer as claimed in claim 1.