WO1987006191A1

WO1987006191A1 - Print head carrier

Info

Publication number: WO1987006191A1
Application number: PCT/US1987/000684
Authority: WO
Inventors: Michael O. Grey
Original assignee: Ncr Corporation
Priority date: 1986-04-07
Filing date: 1987-03-30
Publication date: 1987-10-22
Also published as: EP0263869B1; EP0263869A1; JPS63503051A

Abstract

A resilient ball (60) of urethane or rubber is used in each of a plurality of conical depressions (64, 66) formed in the drive plate (40) for a thermal print head carriage (16) and also formed in the printer frame (62). Adhesive (68) is applied to the surfaces of the conical depressions (64, 66) and the resilient balls (60) are then placed into the depressions (64, 66), such resilient balls (60) being sized to provide a space between the drive plate (40) and the frame (62). The resilient balls (60) provide suspension means for the print head carriage (16) and isolate said carriage from the printer frame to substantially eliminate vibration problems.

Description

Print head carrier.

Technical Field

The present invention relates to a printer. More particularly, the invention is directed to a suspension mechanism for a print head carriage that travels back and forth across the printer and supports a thermal print head for printing on thermal paper which is directed in a path past a platen.

Background Art

In the area of thermal printers, it is well- known that the use of such printers is increasing for certain operations that require a reduction in noise levels and at a reasonable cost. While development work is continually progressing to increase the speed of operation with minimum maintenance j~r care of the equipment, it is seen that improvements are being made to provide a higher quality print with a reduced number of thermal elements.

In the case of thermal printers, it is necessary to minimize the complexity of the thermal print head and the associated electronic controls. In certain prior art printers, it has been common practice to provide a thermal print head having a plurality of thermal printing elements on the surface of the head and wherein selected elements are energized to provide printing on thermal paper or like record media with the print head operating in a stationary or fixed position relative to the printer frame. The thermal print elements on the print head may take the form of pads or contact surfaces in the shape of characters and connected by conducting runs to side or edge connectors. A flexible flat ribbon¬ like cable is normally used to connect the power and/or control circuitry with the pads or contact surfaces on the print head and the individual leads or - 2 -

wires of^" the cable may include end connectors or terminals for contact with the print head pads.

More recently, development work in thermal printers has included a shuttling-type print head having approximately 20% of the number of print elements as compared to the number of elements on a fixed or stationary head.

A problem encountered with the shuttling print head is that of smudging the thermal paper on which the printed image is formed by reason of pressure or contact between the print head and the paper or between the print head and the platen during travel of the print head across the printer. Since it is common practice to print in one direction of travel of the print head, this problem can be alleviated by reducing the pressure of the print head against the thermal paper and against the platen during the return cycle of the print head and its carriage.

Another problem encountered with a shuttling or traveling print head is that of generating vibrations through the printer by reason of the moving parts. While it is generally known that the thermal printer operates at reduced noise levels, there is a certain amount of movement transmitted by the print head carriage to the frame of the printer. It is, therefore, desirable to reduce any vibratory movement originating from the operation of the print head by isolating the print head carriage from the frame of the printer.

An arrangement which alleviates vibration problems in a typewriter is disclosed in US-A-2317821. This patent describes an apparatus in which elastic means are provided between a base plate and a bottom plate of a typewriter. These elastic means may consist of rubber balls embedded in rounded recesses provided in the opposite sides of the base plate and the bottom plate. The radii of the recesses are greater than those of the balls allowing the balls to roll to a certain extent so that the plates can be laterally displaced slightly relative to each other. The two plates are held together at the edges by bolts by means of which the tension of the elastic means may be controlled. While this arrangement reduces vibration to some degree, some vibration will be transmitted from the base plate to the bottom plate through the rigid bolts mechanically linking the two plates.

Disclosure of the Invention

It is an object of the present invention to provide improved isolation between certain parts of a printer thereby to alleviate vibration problems.

Thus, according to the invention, there is provided a printer including a movable printer mechanism, a support member for carrying said printing mechanism and having a plurality of recesses therein, a frame portion adjacent said support member and having a plurality of recesses therein at locations in opposed relationship to the recesses in said support member, and a plurality of balls of resilient material each of which is positioned in a respective pair of recesses for providing a space between said support member and said frame portion, characterized in that each recess has a conically shaped surface, and each ball is secured to the respective conically shaped surfaces by means of an adhesive.

Brief Description of Drawings

One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a side elevational view of a portion of a thermal printer of the present invention in a preferred arrangement thereof; Fig. 2 is an enlarged perspective view of a portion of the frame and of the drive plate and showing the locations of the suspension members; and

Fig. 3, on the sheet with Fig. 1, is an enlarged sectional view of the frame and plate with the suspension member therebetween.

Best Mode for Carrying Out the Invention

Referring now to the drawing. Fig. 1 shows a portion of a thermal printer 10 that includes a platen 12 suitably supported from the printer frame. A thermal print head 14 of well-known design and structure is supported from and carried by a print head carriage 16 that is caused to be shuttled or moved in reciprocating manner by appropriate mechanism in the direction of viewing by the observer in Fig. 1. The carriage 16 is pivotally supported on a shaft 18 journalled in the frame of the printer and such carriage includes an upstanding plate portion 20 and a generally horizontal plate portion 22 with gusset means 24 bridging the two portions at appropriate locations.

A plate-like cam 30 of circular configuration is positioned to be rotatably driven by drive means 32 coupled to the shaft 34 of a motor 36. The plate cam 30 having a groove of varying depth is suitably supported by bearing means 38 which, in turn, is supported by a carriage drive plate 40.

The horizontal plate portion 22 of the print head carriage 16 includes cam follower mechanism 42 having a portion riding on the bottom surface of the groove and operative to pivot the carriage 16 about the shaft 18 thereby to move the print head 14 towards and away from the platen 12.

In the case of a thermal printer utilizing a thermal transfer ribbon for transferring material therefrom and onto record media, a ribbon cassette 50 is provided and is supported on the frame 52 of the printer. A ribbon 54 is provided in coiled form within the cassette and is trained in a path between the print head 14 and record media, such as paper 56, such paper being caused to be transported by suitable drive means including a drive roller 58. The ribbon 54 and the paper 56 are driven in well-known incremental manner past the print station in the printing cycle of operation.

Fig. 2 shows the carriage drive plate 40 and Fig. 3 is an enlarged view of the mechanism supporting such drive plate in suspended manner. The means for suspending and supporting the plate 40 is accomplished by a plurality of resilient members 60, specifically shown as being four balls made of soft urethane or rubber. The four balls 60 are placed at appropriate points, as illustrated-at 70 (Fig. 2), between a frame portion 62 and the carriage drive plate 40 for providing an evenly spaced suspension system for the print head carriage 16 and its associated mechanism and for isolating the print head carriage from the printer frame. The carriage drive plate 40 is provided with four cone-shaped cutouts, as at 64, and the frame portion 62 is provided with like cutouts 66 corresponding with and opposed to the cutouts 64. Adhesive 68 is applied to the surface of each of the cutouts 64 and 66, and/or the surface of the balls 60, in order to contain and secure the parts together.

Claims

1. A printer including a movable printing mechanism, a support member (40) for carrying said printing mechanism (16) and having a plurality of recesses (64) therein, a frame portion (62) adjacent said support member (40) and having a plurality of recesses (66) therein at locations in opposed relationship to the recesses (64) in said support member (40), and a plurality of balls (60) of resilient material each of which is positioned in a respective pair of recesses (64,66) for providing a space between said support member (40) and said frame portion (62), characterized in that each recess (64,66) has a conically shaped surface, and each ball (60) is secured to the respective conically shaped surfaces by means of an adhesive (68).

2. A printer according to claim 1, characterized in that said support member (40) and said frame portion (62) are plates held substantially parallel to each other.

3. A printer according to claim 2, characterized in that said plurality of balls (60) consist of four balls each of which is substantially equally spaced from the two balls closest thereto.

4. A printer according to claim 1, characterized in that said balls (60) are of urethane material.