JPS60127177A - Wire dot printer - Google Patents

Abstract

PURPOSE:To enable vibration to be reduced, by a method wherein a platen is provided with a constructional damping effect, and vibration is damped while maitainning printing performance. CONSTITUTION:A main body 1 of the platen is pressed into a pipe 2, and both end parts thereof are fixed by threaded collars 3, 4. When a small gap is present at the contact surface of the pipe 2 and the main body 1 of the platen and the main body 1 is minutely displaced due to vibration, relative slipping occurs between the inside surface of the pipe 2 and the surface of the main body 1 of the platen, thereby producing a damping effect. In addition, the threaded collars 3, 4 are provided at joint parts for bearings, in consideration of strength. Accordingly, the level of transmission of vibration from the vicinity of a printing head can be attenuated by the gaps present at the threaded parts. Accordingly, the resonance response level of each constructional part constituting the part surrounding the head can be lowered, whereby the shock response at the head part is lowered, so that vibration level (namely, noise level) can be lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a wire dot printer, and particularly to a wire dot printer characterized by a platen structure for reducing noise generated from the platen (printing device).

[Background of the invention]

In a conventional wire dot printer, which includes a head assembly, a platen (print bar), and a side plate for fixing the platen, printing paper is fed along the platen, and the dot wire of the head impacts the platen to perform printing. When the dot wire hits the platen, the platen is vibrated, and the vibrations are also transmitted to the side plates, and these vibrations are the cause of noise generation. For this reason, in conventional wire dot printers, the platen is coated with an elastic material such as rubber to absorb noise, such as by coating the outer circumferential surface of the platen with an elastic material such as rubber. but,
This method has the disadvantage that the impact of the head causes deformation of the surface of the elastic member, which distorts the wire stroke of the head and reduces printing performance. For this reason, high-speed printers with printing speeds of approximately 100 characters/second or more are forced to use metal platens, resulting in higher noise levels than conventional printers.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a platen (print bar) with a vibration damping function in a wire dot printer to reduce vibration.

[Summary of the invention]

In wire dot printers, the impact sound generated when the head hits the platen (print bar) during actual operation, and the vibrations generated at that time, are transmitted from the platen to the side plate and the printer body, causing a large amount of noise to be generated outside. .

The present invention relates to this problem and is characterized by providing a platen with a structural damping effect to damp vibration without impairing printing performance.

[Embodiments of the invention]

Hereinafter, an example of the platen structure of the present invention will be explained with reference to FIGS. 1 to 3.

In FIG. 1, a platen main body 1 has four parts 1a formed on its outer periphery. The four parts 1a are formed by, for example, machining the outer peripheral part of the platen 1 using a lathe or the like and cutting the surface part into a spiral shape. This platen body 1
is press-fitted into the vibrator 2 and fixed by threaded collars 3 and 4 at both ends of the platen body 1.

The threaded collars 3, 4 come into contact with bearings (not shown) when the platen is supported on the side plate of the printer. With this structure, there is a slight gap between the contact surface between the vibrator 2 and the platen body 1, and when a small displacement occurs in the platen body 1 due to vibration, the vibrator 2
A burr occurs between the inner surface and one surface of the platen body, resulting in a damping effect. In addition, threaded collars 3 and 4 are provided at the joint position with a bearing (not shown) in consideration of strength. As a result, the level of vibration transmitted from the vicinity of the print head can be attenuated by the gap in the threaded portion. The vibration model of the platen system in this embodiment is shown in FIG. That is, the space between the surface of the platen body and the inner surface of the cylindrical shaft to be pressed can be represented by a spring and a damper, and damping due to the threaded portion and the gap can also be expected in the portion of the platen that is joined to the bearing surface. Figure 3 shows the vibration response characteristics of the platen system of the prior art and the invention, where the horizontal axis represents the frequency and the vertical axis represents the vibration level in terms of mechanical impedance, and this level is said to rise upwards. This indicates that it is difficult to vibrate.

In the figure, the resonance response level of the present invention, indicated by a solid line a, was clearly higher than the resonance response level of the conventional structure (section 0 in the figure), and vibration reduction could be achieved. In other words, the attenuation ability at the peak was significantly improved, and it now exhibited a large attenuation ability. As a result, the vibration of the platen itself during actual operation has become considerably lower.

〔Effect of the invention〕

According to the present invention, it is possible to reduce the resonance response level of each structural part constituting the print head periphery, and this reduction in the resonance response level causes a decrease in the impact response in the head, thereby reducing the vibration level, that is, the noise level. reduction can be implemented.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of the platen structure of the present invention;
Fig. 2 is a diagram showing the vibration model in Fig. 1, and Fig. 3 is a diagram showing the vibration response characteristics of the present invention6.

Claims (1)

[Scope of Claims] 1. A wire dot printer comprising a head assembly, a platen (printer), and a side plate for fixing the platen, characterized in that the platen has a vibration damping function through solid contact. . 2. The wire dot printer according to claim 1, wherein the platen comprises a platen body having a recessed portion on the outer periphery and a pipe that presses the platen body inside.