GB2235414A - Sound deadening constructions for selective printers - Google Patents

Abstract

In a selective printer of the kind in which the floorpan of the case is an integral part of the structural framework of the printing assembly, measures are taken to reduce the transmission of vibration to unbroken panel portions of the case. The housing is thereby prevented from operating as a sounding-board. As shown (in plan view in Fig 2) the printing components 2 are secured to a central area of the floorpan 3, and the whole assembly is supported (e.g. upon a desk) by resilient feet 4 located at the juncture between the floorpan and the components 2. Slits 5 in the floorpan constrain sound transmission to junctions 7, and also destroy the potential of the floorpan to act as a sounding board. Immobilisation and strengthening of the floorpan during transit may be provided by U shaped shipping-clamps which engage integral formations either side of slits 5 and/or by strips which are inserted in the slits themselves. <IMAGE>

Description

12 - 1 Imprinting machines This invention relates to imprinting machines

such as typewriters, printers or the like.

Some known machines have a machine frame integrated with bottom wall or trough of a machine housing which in turn has damping feet disposed below the bottom trough.

Integration of the machine frame with the housing assists in reducing manufacturing costs.

In the previously known designs, however, vibrations are transmitted from the machine frame into. the housing, particularly the bottom trough, which normally rests on a typing desk or the like, and the housing forms a sounding board which amplifies the vibrations of the machine housing. Accordingly, machines thus designed are comparatively noisy.

In accordance with the present invention, there is provided an imprinting machine, such as a typewriter, having a machine frame integrated with the bottom wall of a machine housing, supported on damping feet, wherein a resilient connection is formed between the machine frame and a surrounding portion of the housing to reduce the transmission of vibration from the machine frame to the housing.

The resilient connection could be formed by - 2 incorporating buffers of resilient material between the machine frame and the housing. Such an arrangement provides an improvement in comparison with the prior art but it has the disadvantage that, as a result, a true integration of-the machine frame and housing is difficult to achieve.

Preferably, the bottom wall of the housing has openings adjacent the resilient connection. The cross-section for the sound conduction into the housing from the region of introduction from the machine frame is reduced by such openings, that is to say the resistance to the conduction of sound is increased and accordingly the transmission of vibration is reduced.

Fundamentally, the openings may be formed, for example, by regions of reduced thickness in the bottom of the housing.

In the simplest case, they are formed as slits surrounding the transition region, particularly the region where the damper feet are attached.

As a result of this, the transmission of sound is completely eliminated in the slit region. Tongues are thus formed which are connected to the housing or the bottom trough only along a relatively short portion. If the tongues are arranged below the damper feet, the effect is that vibrations of the machine housing are essentially intercepted by the damper feet and only a very small proportion of the vibrations can still be introduced into the housing at all.

In order to render possible transport without problems and sufficient stability in use, despite the openings or slits provided according to the invention, it is provided that the housing and/or machine frame should have extensions and undercuts !51 respectively at both sides of an opening for the insertion of a retaining cramp. With the retaining cramp inserted, the tongue-like part of the housing produced by the openings can only swing upwards or downwards with -a limited amplitude.

The retaining cramp is preferably made Ushaped and the undercuts are formed by hooked extensions. A particularly secure retention is achieved if undercuts are provided by hooked extensions at two opposite sides of a housing opening and on the machine frame, in which case the bottom of the U of a corresponding U-shaped retaining cramp engages in the undercut on the machine frame while the U-arms of the retaining cramp engage in the undercuts in the housing. The hooked extensions which form the undercuts are orientated so that they face away from the opening in question.

The retaining cramps may comprise detents at the free ends of its arms that lock with an extension on insertion so that unintentional release is avoided during transport or in use. Because of the natural resilience of the retaining cramps produced from plastics material for example, a slight elastic deformation is possible during the locking.

The retaining cramp may alternatively be constructed in the form of a resilient O-ring.

In order to achieve an optimum reduction of the introduction of sound into the bottom trough, it may be provided that an opening in the bottom trough extends along the machine frame, in front of it or behind it.

In order to ensure that the openings formed as slits do not, in turn, allow sound to penetrate through and at the same time in order to eliminate the 4 penetration of dirt, form-fitting sealing strips of rubber like resilient material may be inserted in the openings.

In order to avoid the need of separate damper feet, it may further be provided that at least some of the sealing strips have extensions extending horizontally below the bottom trough and forming foot members. Accordingly, these sealing strips have an Lshaped section for example in which case one L-arm then extends at the underside of the bottom trough.

An embodiment of the invention is described in more detail below by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a perspective, diagrammatic view of a printer according to the invention with a bottom trough partially cut away; Figure 2 is a plan view of the bottom trough; Figure 3 is a perspective view of the arrangement of a retaining cramp; Figure 4 is a plan view corresponding to Figure 3; Figure 5 is a section corresponding to Figure 4; along the top of a retaining cramp; Figure 6 is a partial perspective view from below, showing a sealing strip inserted in an opening; and Figure 7 is a section through a region of the bottom trough with a sealing strip inserted.

The invention is explained in more detail below with reference to the example of a printer 1 which essentially comprises a bottom machine housing wall formed as trough or tray 3 surrounding a machine frame 2. The machine frame 2 is constructed in conventional manner and is therefore only illustrated r diagrammatically. The bottom trough 3 rests on damping feet 4 which are likewise known as such.

In order to reduce the transmission of sound from the machine frame 2 to the large area of the bottom trough 3, slits 5 are provided round the region of the damping feet 4, the slits defining resilient tongues 6 in the region of the damping feet 4.

The connecting portion 7, which connects the tongue 6 to the rest of the bottom trough 3 surrounding the area in which the frame is supported, ensures adequate strength with a high resistance to the conduction of vibration and sound.

In order to avoid excessively high vibration amplitudes in use and for safety during the transport of the printer, means are provided which are described in more detail below in connection with Figures 2 to 5.

In the embodiment illustrated in Figures 2 to 4, the bottom trough 3 comprises, adjacent to the slits 5, extensions 8 with hooks 9 which are formed on the extensions 8 at their upper side and extend away from the slits 5.

A substantially U-shaped retaining cramp 11 with U-arms 12 and a crosspiece 13, and having detent extensions 14 formed at the free ends of the U-arms 12, is positioned around the extensions 8, so that the retaining cramp 11 engages with its cross-piece 13 under one hook 9 and with its Uarms 12 under the other hooks 9 at both sides of the slits 5. Thus, the retaining cramp 11 limits relative vertical movement between the machine frame 2 and the surrounding region of the bottom trough 3 outside the region in which the machine frame is mounted. The cramp 11 is made of a resilient material, such as a plastics material.

The above described retaining cramp may be replaced by an O-ring of elastomeric material looped round the hook-shaped extensions 8.

Figure 6 and 7 illustrate L-shaped sealing strips 12 inserted in the openings 5. A first L-arm 13 of each strip fits closely in the openings 5 and seals them so that the penetration of sound, and on the other hand also the penetration of dirt is avoided. The other L-arm 14 extends along the under side 15 of the bottom of trough 3 and serves simultaneously as a standing foot or standing strip as a substitute for the damping feet 4. The strips 12 extend as shown, in front and behind the machine frame.

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Claims (11)

Claims:

1. An imprinting machine, such as a typewriter, having a machine frame integrated with the bottom wall of a machine housing, supported on damping feet, wherein a resilient connection is formed between the machine frame and a surrounding portion of the housing to reduce the transmission of vibration from the machine frame to the housing.

2. A machine according to claim 1, wherein the bottom wall of the housing has openings adjacent the said resilient connections.

3. A machine according to claim 2, wherein the openings are formed as slits surrounding the said connection, preferably in the region where the damping feet are attached.

4. A machine printer or the like according to claim 1, 2 or 3, wherein at both sides of an opening, the housing and/or the machine frame have extensions or undercuts in which a retaining cramp can be inserted.

5. A machine according to claim 1, wherein the retaining cramp is Ushaped and the undercuts are formed-by hooked extensions.

6. A machine according to claim 5, wherein the retaining cramp comprises detents at the free ends of its arms.

7. A machine according to claim 4, wherein the retaining cramp is formed as an elastomeric 0-ring or the like.

8 8 A machine according to claim 1, wherein an opening in the bottom wall extends along the machine frame in front of it or behind it.

1 v

9. A machine according to claim 2, wherein close fitting sealing strips of elastomeric material are inserted in the openings (5).

10. A machine according to claim 9, wherein at least some of the said sealing strips have portions extending horizontally below the bottom wall to form supporting feet.

11. An imprinting machine, substantially as herein described with reference to the accompanying drawings.

f Published 1991 atrbe Patent Office. State House.66/71 High Holborn. London WC I R4TP. Further copies may be obtained from Sales Branch. Unit 6. Nine Mile Point. Cwmfelinfach. Cross Keys, Newport. NPI 7HZ. Printed by Multiplex techniques ltd, St Mary Cray. Kent