JPS6345954B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to stamp type serial printers used in data processing equipment, and more particularly to apparatus for preventing noise produced during printing in such printers.

It is known that one of the main drawbacks of stamp printers is the considerable noise generated during their operation. This is a non-imprint printer (inkjet type,
This is one of the reasons why we focused our efforts on research and development of electrostatic methods, etc.

However, the need to have different print copies in different fields of activity still makes the need for stamp printers mandatory. In addition, the printing speed of matrix type stamp printers currently satisfies the needs of a wide range of users, and the need for stamp printers continues to be great.

The solution adopted in the past to reduce noise in such printers has been to provide the printer with a cover and connect the frame with soundproofing material, thus enclosing the noise source in the best possible way.

Therefore, the objective was not to eliminate the cause of the noise, but to reduce its effect. The reason for this is that it was considered impossible to eliminate or reduce the causes of noise.

It is an object of the invention to provide a device which is capable of limiting noise by acting on the noise source itself, rather than by reducing the effect of the generated noise.

As is known, the stamp type serial printer is
Generally, it has a rigid frame with mutually parallel guides arranged in the direction of the print rows, and a platen against which a print support member rests. These guides and platens are rigidly fixed to the frame and are part of the frame. Optionally, the platen is rotatable. A printing carriage fitted with a printing head (in the form of a needle in the case of mosaic printing, or in the form of a bearing-type element in other cases) slides over these guides.

Experiments have shown that the main sources of noise are provided by the impact on the platen caused by the print head, and the vibrations of the head and carriage as they slide over the guides. However, the generated vibrations induce vibrations on the entire frame via the mechanical restraints, and this frame thus acts as a sound source.

According to the invention, noise reduction is achieved with respect to vibration diffusion by decoupling the mechanical elements constituting the primary noise source from each other and from the secondary elements or frames.

In achieving such decoupling it is necessary to maintain the necessary connections between the elements. This is because they are essential for the relative and constant arrangement of the elements forming the printer.

According to the invention, such a decoupling is obtained via an intermediate elastic element and an elastic element made of a rigid material. The resilient element made of a rigid material described above is used to reciprocally restrain the platen and carriage guide in a defined position, and the resilient element described above is used to restrain the carriage guide to the frame. used.

These and other features of the invention will become apparent from the following description taken with reference to the drawings.

With reference to FIGS. 1 and 2, the mechanical structure of the device according to the invention has a metal frame formed by a bottom part 5 and at least two side plates 2,3. The bottom part 5 and the side plates 2, 3 are both made of metal plates of appropriate thickness in order to make the device sturdy. Alternatively, a cast structure may be used. Both side plates 2, 3 are provided with grooves in which the front metal bar 6 and the rear metal bar 7 are to be engaged.

FIG. 2 shows such grooves 24, 2 provided in the side plate 2.
The details of 5 are shown more clearly. It is clear that side plate 3 is similar to side plate 2.

Bars 6 and 7 have a supporting and guiding function for the carriage supporting the print head.

Figure 1 shows the carriage 21 and print head 2.
2 is shown. The carriage 21 is mounted on the guide by a bush or an axial bearing. Bars 6 and 7 are preferably
It is made cylindrical and provided with cylindrical ends of smaller diameter. In FIG. 2, these smaller diameter ends are designated 26,4 and 27,1, respectively.

4 rubber bushings 8 provided with shoulders;
9, 10, 11 are engaged with the two small diameter cylindrical ends of bars 6 and 7, respectively. These rubber bushings are inserted into grooves in the side plate of the printer.

Referring to FIG. 1, the front bar 6 is engaged with two grooves in the side plates 3 and 2 via bushes 9 and 10, respectively, and the rear bar 7 is engaged with two grooves in the side plates 3 and 2 via bushes 12 and 11, respectively. 3 and two grooves in the side plate 2.

The various bushes 10, 11 and 8, 9 are clamped to the side plates 2 and 3 via clamp plates 13, 12, respectively.

In this way bars 6 and 7 are restrained to the frame via the intermediate rubber bushing, and the mutual position of these bars to ensure correct sliding of the carriage is determined within acceptable tolerances. .

The clamp plates 12 and 13 are secured to the side plates 3 and 2 by a pair of screws. Figure 2 shows the clamp plate 1.
3 and two clamping screws 17, 18 are shown.

The platen 16 is formed by a prismatic elongated rigid element, which is not fixed to the frame but is provided with two fixing holes 19, 20 at each end thereof, and which has two arms 14, 15.
are fixed to bars 6 and 7 in some cases. One of these arms is clearly shown in FIG. Each arm has two holes 28, 29 designed to receive the small diameter ends of bars 6 and 7.
and a third hole corresponding to one of the two holes 19, 20 at the end of the platen 16 and designed to receive a platen screw or fixing element.
hole 30.

As shown in FIG.
5 is engaged with the small diameter ends of bars 6 and 7;
and are placed between the unreduced ends of these bars and the walls of the pairs 8, 9 and 10, 11 of rubber bushings. The platen 16 is secured to the ends of the two arms 14 and 15 via clamping screws 23,24.

The two arms 14 and 15 are made of plastic material. Their function is to support platen 16 while allowing the parallelism between platen and bars 6 and 7 to be maintained within acceptable tolerances during printing operations. What is noteworthy is that parallel side plates 2 and 3 between the axes of bars 6 and 7 are defined within acceptable tolerances.

Parallelism between bars 6 and 7 is essential for correct advancement of the print head carriage. Parallelism between platen 16 and bar 7 is essential for uniform printing.

It is noteworthy that the ends of the platen 16 are not constrained to the side plates 2 and 3 of the metal frame (the solution adopted in the prior art);
Due to the presence of arms 14 and 15, platen 16 together with bars 6 and 7 forms a unitary member connected to the metal frame only via bushes 8, 9, 10, 11. That's true.

In this way, the vibrations caused in the platen 16 by the needles of the printing head are strongly damped by the bar 6 due to the provision of the plastic arms 14 and 15.
and 7, and is further damped by the damping effect of the rubber bushing and propagates to the metal frame. Without departing from the spirit of the invention, it is also contemplated that two structural members, namely the bar 6, may be coupled together to form a vibration damping structure.
It will be clear that other configurations may be used to form the parts 7 and one part associated with the platen and the other part associated with the metal frame of the printer.

[Brief explanation of drawings]

FIG. 1 is a simplified perspective view of a printer device with a noise prevention device designed in accordance with the present invention, and FIG. 2 is a perspective view showing details of some of the components of the device of FIG. 2, 3: Frame side plate, 5: Frame bottom wall,
6: Front guide bar, 7: Rear guide bar,
8, 9, 10, 11: Rubber bushing, 12, 1
3: Clamp plate, 14, 15: Arm, 16: Platen, 21: Carriage, 22: Print head.

Claims (1)

Claims: 1. In a noise prevention device for a stamp-type printer having a frame, a platen, at least one pair of guide bars, a carriage moved along these guide bars, and a print head attached to the carriage. , wherein the platen is restrained to the guide bar via an elastic member made of a relatively hard material, and the guide bar is fixed to the frame via an intermediate elastic member. Noise prevention device for type printers. 2. In the noise prevention device as set forth in claim 1, the resilient member made of a relatively hard material extends from two arms made of plastic material that are engaged with the ends of a pair of guide bars. A noise prevention device for a stamp type printer, characterized in that: 3. The noise prevention device according to claim 1, wherein the elastic member comprises a rubber bushing inserted into a housing formed in the frame and engaged with an end of the guide bar. A noise prevention device for stamping type printers.