JPS6334938Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing unit in a dot printer used as an output device of an information processing device, and is intended to provide a highly accurate positional relationship between an ink ribbon and a printing head.

FIG. 1 is a plan view showing an outline of a conventional serial printer, and FIG. 2 is a front perspective view of a print head. A printing paper 2 is wound around the platen 1, and a printing unit consisting of a printing head 5 mounted on a carrier 6 is supported by a feed screw 3 and a guide shaft 4 arranged parallel to the platen 1.
As the feed screw 3 is rotationally driven by a space motor 8 via a timing belt 7, the print head 5 is transported in the space direction indicated by arrows a ₁ and a ₂ .

At the tip of the print head 5, as shown in FIG. While feeding the space at a predetermined speed, each time t ₁ , t ₂ ...
, the ink ribbon 1 is fed out from the ribbon cassette 9 by selectively driving the printing wires W with the electromagnets built into the head 5 to make them protrude.
The printing paper 2 is pressed by the printing wires W through the dots 11 and 11, and a character such as "A" is printed on the printing paper 2 by a combination of dots 11.

The print head 5 is normally fixed to a carrier 6 with screws 12, as shown in FIGS. 3 and 4, and a C.
The ribbon cassette 9, which is shaped like a letter, has a support shaft 13 projecting on both sides, and an arm 1 extending from the carrier.
4, it is rotatably supported. The rear end of the ribbon cassette 9 is pushed up by a leaf spring 15 attached to the carrier 6, and the front end of the ribbon cassette 9 is supported and positioned by the upper end of a lever 16. The lever 16 is driven by an electromagnet 17, and when the electromagnet 17 is not energized as shown in the figure, the lever 16 is pushed down via the ribbon cassette 9 by the spring pressure of the leaf spring 15, and the lower end of the lever touches the stopper 18. Stop when touching. Since the ribbon cassette 9 cannot be lowered any further, the lower limit position is defined by the lever 16. In this state, the printing wire W...
The upper half 11b of the ink ribbon 11 is located directly in front of the protruding tip of the print head. Therefore, the printing head W presses the printing paper 2 on the platen 1 via the upper half 11b of the ink ribbon 11 to print. At this time, the printing wire W... is connected to the window hole 20 of the mask 19 between the ink ribbon 11 and the printing paper 2.
By pressing the ink ribbon 11 against the printing paper 2 through the
So that it doesn't get dirty. Ink ribbon 11
The upper half 11b is a black ink ribbon, so in the state shown, it is printed with black ink. The lower half 11r of the ink ribbon 11 is a red ink ribbon, and when the electromagnet 17 is energized and the armature portion 21 at the lower end of the lever 16 is attracted, the upper end of the lever 16 rotates clockwise. The ribbon cassette 9 is raised about the support shaft 13 against the leaf spring 15. Then, the red portion of the lower half 11r of the ink ribbon 11 is positioned exactly in front of the print head, and is printed with red ink. In this type of printing unit in which the ink ribbon 11 moves in its width direction, the ink ribbon 11
a ribbon guide 22a for guiding the path of the
22b also includes the ribbon cassette 9 and the ink ribbon 1.
It is designed to move up and down with 1. The ink ribbon 11 is placed on the take-up roller 2 in the ribbon cassette 9.
3 and circulates, tension is generated at the tip of the print head 5, but this tension can cause sudden changes in the moving path of the ink ribbon, causing stress that may shorten the life of the ink ribbon or cause the ink ribbon to There is a risk that the smooth movement of the vehicle will be hindered. Furthermore, if all the tension of the ink ribbon is applied directly to the print head 5, there will be problems such as friction between the ink ribbon 11 and the tip of the print head, making it difficult to smoothly switch the ribbon, especially when switching between red and black ink ribbons 11. There is. To prevent these problems, ribbon guides 22 are installed on both sides of the print head 5.
a, 22b are arranged to gently change the moving path of the ink ribbon 11 to reduce the stress applied to the ink ribbon, and also to allow the tension of the ink ribbon to act on the ribbon guides 22a, 22b, so that the printing head This reduces the tension applied to 5. In addition, especially for equipment that requires ribbon switching,
The ribbon guides 22a and 22b are the ink ribbon 1
Ribbon guides 22a and 22b are configured to slide so that they can be moved together with ribbon guide 1 to the switching position. That is, vertical grooves 24a and 24b are formed in the ribbon guides 22a and 22b, and a support column 26 fixed to the carrier 6 with a screw 25 is inserted into the groove.
a and 26b are fitted. Ribbon guide 22
a, 22b are integrally connected by a bridge portion 22c at the bottom, and a compression spring 27 is interposed between this bridge portion 22c and the carrier 6, pushing up the ribbon guides 22a, 22b with spring pressure. Further, the front end portion of the ribbon cassette 9 is placed on wing portions 28a and 28b that protrude to both sides integrally with the ribbon guides 22a and 22b. is in the lowered position, the ribbon cassette 9
By pushing down the wing parts 28a, 28b, the ribbon guides 22a, 28b are pushed down against the compression spring 27.
22b is pushed down, and the ribbon guides 22a,
22b is also in a lowered state. Further, when the electromagnet 17 is energized to switch the ribbon and the ribbon cassette 9 is pushed up by the lever 16, the compression spring 2
At step 7, the ribbon guides 22a and 22b are also pushed up to follow the ribbon cassette 9, and are in a raised state.

However, in such a conventional structure, since the ribbon guides 22a and 22b are attached to the carrier 6 via the supports 26a and 26b, the ink ribbon 11 and the print wire W at the tip of the print head 5 are connected to each other.
It is difficult to maintain the positional relationship with high accuracy. Therefore, it is necessary to provide an adjustment mechanism to adjust the height of the ribbon guides 22a and 22b.
The configuration is complicated and the cost is high. Especially print head 5
If the ink ribbon 11 is attached to and detached from the carrier 6 with a single touch instead of a screw type, it is more difficult to accurately maintain the positional relationship between the print head tip and the ink ribbon 11.

It is an object of the present invention to eliminate such problems in conventional printing units and to make it possible to maintain the positional relationship between the ink ribbon and the tip of the printing head with high precision. To achieve this objective, the present invention includes a carrier in which a print head is mounted and prints on the print medium on the platen while moving along a guide shaft arranged parallel to the platen; a ribbon cassette that is fed out from the ribbon cassette, a ribbon guide body that defines the path of the ink ribbon as it passes between the print head and the print medium, and a ribbon cassette that moves up and down to change the ribbon. a driving means; a spring means for pushing up the ribbon disposed between the ribbon guide body and the carrier; the printing head has guide protrusions protruding from both left and right sides; and the ribbon guide body is made of an elastic material. Therefore, a pair of ribbon guides are formed to sandwich both sides of the tip of the print head, and a bridge portion is formed that connects the ribbon guides. It includes a long guide slit and a wing portion on which the tip of the ribbon cassette is mounted, and as the ribbon cassette moves up and down, the ribbon guide is guided by the projection and slides up and down.

Next, an embodiment of the printing unit according to the present invention will be described. 5 and 6 are a plan view and a side view showing an embodiment of the printing unit corresponding to FIGS. 3 and 4, respectively, and the parts corresponding to FIGS. 3 and 4 are the same. A symbol is attached. FIG. 7 is a perspective view showing the printing head and ribbon guide in a separated state. In the case of the present invention, numerals 29a and 29b are ribbon guides, and projections 30a and 30b are provided on both sides of the printing head 5i to guide the vertical movement of the ribbon guides 29a and 29b. On the other hand, the ribbon guides 29a and 29b are shaped to sandwich both sides of the tip of the printing head 5i, as in the prior art, and move up and down simultaneously with the ink ribbon 11 when switching the ribbon. However, in the case of the present invention, the ribbon guides 29a and 29b are not supported on the carrier 6i side, but are supported on the print head 5.
It is directly supported on the i side and moves up and down. For this purpose, the ribbon guides 29a, 29b are formed with vertically long slits 31a, 31b, and the ribbon guides 29a, 29b are integrally connected at a bridge portion 29c at the bottom. As shown in FIG. 6, a spring receiving protrusion 32 is provided on the lower surface of the bridge portion 29c. Furthermore, wings 28a and 28b are provided for placing and pushing down the ribbon cassette 9.

A circular hole is formed in the carrier 6i at a position corresponding to the projection 32, and a compression coil spring 33 is press-fitted into the hole by its own elasticity.

For assembly, move the ribbon guides 29a and 29b to the seventh
Spread it out in the directions of arrows a ₄ and a ₅ in the figure, and place print head 5 in between.
It is sufficient to insert the protrusions 30a, 30b of i, fit the protrusions 30a, 30b into the slits 31a, 31b, and then return the ribbon guides 29a, 29b to their original positions with their elasticity. In addition, print head 5i
The protrusions 30a, 30b are the slits 31a, 31b.
The protrusions 30a and 30b are arranged so that they can be easily inserted into the
The lower side portions 34a, 34b are formed diagonally.

The print head 5i with the ribbon guides 29a and 29b attached thereto is placed and fixed on the carrier 6i, but at this time the bridge portion of the ribbon guide 2
The protrusion 32 on the lower surface of the carrier 6i fits into and engages with the ring portion at the upper end of the coil spring 33, and the ribbon guides 29a, 29b are constantly pushed upward by the coil spring 33. Thereafter, when the ribbon cassette 9 is set so as to be rotatable about the support shaft 13, the front portion of the ribbon cassette 9 rests on the wings 28a, 28b of the ribbon guides 29a, 29b. Therefore, as in the conventional case, the wings 28a and 28b of the ribbon cassette 9 are pressed against the ribbon cassette 9 by the coil spring 33, and when the ribbon cassette 9 moves up and down in the direction of arrow _a6 for ribbon switching, the ribbon guide 29a and 29b move up and down integrally with the ribbon cassette 9, and the ink ribbon 1
1, the ribbon guides 29a and 29b also move up and down.

In the case of the present invention, the ribbon guide 29a,
29b is a printing head 5 equipped with a printing wire.
i itself has protrusions 30a, 30b and slits 31.
Since it is supported by a and 31b and moves up and down,
Compared to the conventional case where the ribbon guide is supported on a carrier side separate from the printing head with the printing wire, the positional relationship between the printing wire and the ink ribbon that actually performs printing can be maintained with high precision. can do.

In the illustrated example, the print head 5i can be attached to and detached from the carrier 6i with a single touch. That is, vertical grooves 35a and 35 are formed on the side surface of the print head 5i.
b is formed in the carrier 6i, and the groove 35 is formed in the carrier 6i.
Fitting members 36a and 36b that fit into holes a and 35b are fixed with screws 37. and print head 5
Inserting the grooves 35a and 35b of i into the member 36
a, 36b to insert the fitting members 36a, 3
6b is fitted into the grooves 35a and 35b. In such a one-touch detachable printing unit, the accuracy of the positional relationship between the printing head 5i and the carrier 6i tends to be compromised, but as in the present invention, the ribbon guides 29a and 29b are supported on the carrier 6i side. By supporting the printing head 5i on the side of the printing head 5i instead of holding the printing head 5i, there is no effect of deterioration in positional accuracy between the printing head 5i and the carrier 6i, and the present invention is therefore particularly effective in a printing unit that can be attached or removed in one-touch.

Note that the slits 3 of the ribbon guides 29a and 29b
Even if grooves are provided in place of 1a and 31b, the effect is the same. Therefore, in the present invention, the term slit includes grooves.

As described above, in the present invention, a printing unit having a carrier on which a printing head is mounted prints on a printing medium on a platen while moving along a guide shaft arranged parallel to the platen, and also unwinds the printing medium from a ribbon cassette. A ribbon guide that guides the path of the ink ribbon as it passes the tip of the print head is applied to a print unit that moves in the width direction of the ink ribbon as the ribbon is switched. Guide protrusions are provided protrudingly on both left and right sides of the print head, while a pair of ribbon guides are provided so as to sandwich both sides of the tip of the print head, and are integrally connected at a bridge portion. The ribbon guide is provided with a guide slit into which the above-mentioned protrusion fits and can be slid up and down relative to each other, so that the ribbon guide is directly supported and guided by the printing head.
Therefore, the ribbon guide moves together with the ink ribbon in the width direction of the ink ribbon, together with the printing head equipped with the wire that actually performs printing. As a result, the positional relationship between the printing wire and the ink ribbon can always be maintained constant and with high precision.
Furthermore, the number of parts is reduced compared to the conventional structure in which a support is provided on the carrier to support the ribbon guide.

[Brief explanation of the drawing]

Figure 1 is a plan view showing an outline of a normal serial printer, Figure 2 is a front perspective view of the print head, and Figure 3 is a front perspective view of the print head.
5 and 4 are plan and side views showing a conventional printing unit, and FIGS. 5 and 6 are plan views corresponding to FIGS. 3 and 4, respectively, showing an embodiment of the printing unit according to the present invention. FIG. 7 is a perspective view showing the print head and ribbon guide in a separated state. In the figure, 2 is the printing paper, 5 is the printing head,
W... is a printing wire, 30a, 30b are protrusions, 29
29a and 29b are ribbon guides, 31a and 31b are slits, 29c is a bridge portion, and 28a and 28b are wing portions.

Claims (1)

[Scope of Claim for Utility Model Registration] A carrier that is equipped with a print head and that prints on a print medium on a platen while moving along a guide shaft arranged parallel to the platen, and a ribbon cassette that is mounted on the carrier and stores an ink ribbon. , a ribbon guide body that defines the path of the ink ribbon when the ink ribbon fed out from the ribbon cassette passes between the print head and the print medium; a drive unit that moves the ribbon cassette up and down to switch the ribbon; A ribbon guide body is provided with a spring means for pushing up the ribbon, which is disposed between the ribbon guide body and the carrier, guide protrusions are provided on both left and right sides of the print head, and the ribbon guide body is made of an elastic material. a pair of ribbon guides arranged to sandwich both sides of the tip of the print head; a guide slit formed with a bridge portion connecting the ribbon guides, into which the protrusion is fitted and which is longer in the vertical direction than the protrusion; 1. A printing unit comprising a wing section on which a tip of a ribbon cassette is mounted, and the ribbon guide is guided by the protrusion and slides up and down as the ribbon cassette moves up and down.