GB2324830A

GB2324830A - Friction hinge for wordprocessor or similar

Info

Publication number: GB2324830A
Application number: GB9708657A
Authority: GB
Inventors: David Joseph Cowap
Original assignee: Sharp Electronics UK Ltd
Current assignee: Sharp Electronics UK Ltd
Priority date: 1997-04-30
Filing date: 1997-04-30
Publication date: 1998-11-04
Also published as: GB9708657D0

Abstract

A friction hinge comprises a member 6 of compressible material having a cavity into which a shaft 4 is inserted. The external diameter of the shaft 4 is greater than the internal diameter of the cavity so that upon insertion of the shaft 4 the internal surface of the cavity is compressed and provides frictional resistance to rotation of the shaft. A housing may surround the periphery of the member 6 and may have internal dimensions smaller than the external dimensions of member 6 so as to compress member 6 and further increase the resistance to rotation. Alternatively the resistance to rotation may be increased by applying an external force to one side of member 6, for instance by applying a screw-tightened plate. The member 6 may also be formed with a slot running between the cavity and the exterior of the member to enable the member to fit around shafts of varying diameters.

Description

Title : Improvements relating to hinges DESCRIPTION The present invention relates to an improved type of hinge, particularly but not exclusively for use with typewriters, wordprocessors, personal computers and the like.

A wide variety of hinges exist in the marketplace for providing a moveable joint between two or more elements. Different types of hinge have been developed to provide particular characteristics depending upon the intended use to which the hinge is to be put, for example ophthalmic mountings or door hinges. One area in which the development of hinges has been extremely important is that of electronic office equipment, such as wordprocessors, personal computers and typewriters.

The use of portable wordprocessors and the like has escalated in recent years, there being a great demand for wordprocessors which may used anytime and anywhere. In order for this to be achieved it is has become customary to provide the keyboard of the wordprocessor or personal computer within a cabinet which is provided with a lid for placing over the keyboard. The lid may contain the liquid crystal display screen on the internal surface thereof which is viewed by opening up the lid. Alternatively, a separate display unit may be provided which is collapsible over the keyboard of the unit having a lid which may be placed thereover to encase the wordprocessor when not in use.

The provision of a tiltable display screen in the wordprocessor requires the screen to be hingedly mounted with respect to the cabinet and/or keyboard. It is preferable that the hinge provides resistance to the movement of the screen relative to the cabinet and/or keyboard to enable the display screen to be held at various positions thereby accounting for differences in height of the user, lighting conditions and the like.

The general name given to a hinge which provides resistance to an element throughout its entire range of motion is a torque hinge. Various types of torque hinge have been utilised in electronic office equipment to date to enable the display screen to be held at various angles. One common type of hinge uses a spring wound around a shaft which is connected to the lid and/or cabinet of the equipment. The spring is compressed such that its internal diameter is smaller than the external diameter of the shaft and is held in its compressed state by fixing the two ends of the spring to a clasp. Friction is set up between the shaft and the spring to impart continued resistance to the rotation of the shaft through its entire range of movement, thereby enabling the shaft and lid to maintain the rotational position in which they are manually placed. For example, US-A-5,173,857 (Blackwell et al.,) describes the use of a clutch spring to control the torque for opening and closing of a cover unit of a laptop personal computer.

Alternatively, a tilt spring mechanism using a tilt spring and friction plate has been employed to provide a tiltable display unit, as illustrated in Figures A and B of the accompanying drawings. This does provide an efficient tilting mechanism but involves a large number of components. Firstly, tilt springs 101 are located on left and right hand tilt arms which are secured to the display cabinet of the wordprocessor. A tilt cover is fitted to the underside of the upper cabinet and secured in place. A tilt support 102 is located to the left side of the cabinet and a LCD cable 104 is slotted therein. A friction plate 105 is greased and located in the upper cabinet and a friction arm 106 is placed in the tilt arm and positioned over the friction plate.

A greased friction spring 107 is then located over the friction arm 106 to enable the display cabinet to be tilted.

Further types of hinge have been described in relation to electronic office equipment. For example, US-A-4, 639,147 (Schwarz) uses a friction pivot assembly in which a space is provided between the shaft and its bearing in which a pliable tubular bushing is axially compressed to create rotational friction. US-A-5, 008,976 (Busch) describes a hinge assembly having a plurality of rollers pressed against an elastic washer surrounding a shaft.

US-A-5,509,176 (Karl) relates to another type of torque hinge to provide constant resistance throughout a computer lid's complete range of motion. The shaft is coated with a compressive material, such as microcellular urethane, and a housing is provided for receiving the coated shaft. The coated shaft fits into a cavity provided in the housing, the inside diameter of the cavity being smaller than the outside diameter of the annular coating. The coating must be compressed to fit into the cavity to form an interference fit between the cavity, coating and the shaft.

The hinges described above all have there drawbacks. The spring mechanism hinges have a short lifespan due to the spring stretching over time until it assumes the diameter of the shaft and hence, results in insufficient torque being provided by the hinge. The tilted spring and other mechanisms use a large number of component parts and the number of steps in the assembly of the hinge increases the cost of the resultant product. Additionally, there is a possibility that the springs may break. The provision of a compressible coating around the shaft or inside the housing also increases the number of stages and cost in producing a hinge.

It is an aim of the present invention to provide a new torque hinge for a wordprocessor, laptop personal computer or the like which has an increased life, a reduced number of component parts and is therefore easier and cheaper to install.

Accordingly, the present invention provides a torque hinge for a wordprocessor or the like comprising a member having a cavity and a shaft for insertion into the cavity, wherein the member is made of a compressible material and is arranged or adapted to resist rotation of itself relative to a mounting therefor, the external diameter of the shaft being greater than the internal diameter of the member in its relaxed state such that upon insertion of the shaft into the cavity the member compresses around the shaft to cause frictional contact therebetween thereby creating constant resistance to the entire range of movement of the shaft.

Preferably, the member is in the form of a rectangular block having a cylindrical cavity for insertion of the shaft, especially being a square block.

Preferably, the cavity is in the centre of the member. However, the member may be any suitable shape and size depending upon the application of a particular hinge and the size and shape of the shaft to be inserted therein.

The member is preferably made of a polyurethane material such that the shaft can be pushed into the cavity to provide frictional contact between the cavity of the member and the shaft. Alternatively, the member may be of any other elastic material which compresses when stress is applied thereto but returns to its original shape upon removal of the stress, such as rubber, a rubber alloy or other elastomer.

The diameter and breadth of the cavity of the member may be varied depending upon the size of the shaft to be inserted therein and on the amount of friction required.

For example, increasing the breadth of the cavity will increase the frictional surface area between the cavity and the shaft. Alternatively or additionally, decreasing the diameter of the cavity will increase the amount of friction between the member and the shaft. Likewise, the diameter of the shaft may be increased to increase the friction therebetween. The external dimensions of the member may also be increased relative to the shaft to create more resistance between the member and the shaft.

The member may be provided with a housing to prevent any axial movement thereof such that movement in the hinge of the present invention is limited to the rotation of the shaft. Preferably, the housing is dimensioned to surround the member but, alternatively the external dimensions of the member may be slightly greater than the internal dimensions of the housing such that the whole member is compressed further by the housing to increase the friction between the shaft and the cavity of the member.

The housing may be any suitable size and shape, for example, square in cross section, semi-circular in cross section or otherwise. The housing may enclose the member or may be upwardly open.

A load may also be provided to at least one surface of the housing to increase the friction of the hinge. For example, a plate may be placed across a surface of the housing. Alternatively, the housing may be upwardly open having the plate clamped over the top of the compressible member. Preferably, the plate is secured to retain the load on the housing, for example by means of screws.

The housing and the load may be made of any suitable non-compressible material, such as a plastics material or a metal.

The member may be provided with a slot between the external surface thereof and the internal cavity. This enables the member to fit around shafts of various diameters.

The hinge of the present invention may be incorporated into a wordprocessor, laptop computer or the like to provide a lid and/or display screen which may be orientated at any angle.

For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings in which: Figure 1 is a perspective view of a member of the hinge according to a preferred embodiment of the present invention; Figure 2 is a perspective view of a shaft of the hinge according to a preferred embodiment of the present invention; Figure 3 is a perspective view of the member and shaft of Figures 1 and 2 respectively fitted together to form a torque hinge; Figure 4 is a front view of the display unit of a wordprocessor fitted with a pair of hinges according to the present invention; Figure 5 is a cross sectional view of the member of Figure 1 clamped within a housing according to another embodiment of the present invention; Figure 6 is a cross sectional view of the member of Figure 1 clamped within a housing according to a different embodiment of the present invention; and Figure 7 is a perspective view of an alternative embodiment of a member according to the present invention.

Referring to Figures 1 to 3 of the accompanying drawings, a preferred embodiment of a torque hinge according to the present invention is illustrated. The torque hinge 2 comprises a cylindrical shaft 4 and a square member 6 made of a compressible material, preferably polyurethane, having a central cylindrical cavity 8.

The straight sides of the member assist in preventing rotation of the member about a mounting therefor, such as a wordprocessor cabinet (not shown). The external diameter of the shaft is greater than the internal diameter of the cavity such that compression of the member is required in inserting the shaft into the cavity. This creates friction between the surface of the shaft and the surface of the cavity to provide constant resistance to the shaft through its entire range of movement.

It is to be appreciated that the size and shape of the member and the shaft may be altered as preferred. The dimensions of the member 6 may be increased to create additional friction and similarly, the breadth of the cavity may be increased to increase the friction between the member and the shaft. Alternatively or additionally, the diameter of the cavity may be reduced relative to the diameter of the shaft to create further friction, depending upon the degree of resistance required to the movement of the shaft.

Referring to Figure 4 of the accompanying drawings, the torque hinge 2 of the present invention is shown mounted in a wordprocessor unit 10. For the sake of simplicity, only the display unit 12 of the wordprocessor unit has been shown but it is to be understood that a keyboard contained within a cabinet would be included within the wordprocessor situated below and forward of the display unit 12. The display unit is hingedly mounted to the cabinet containing the keyboard. The lid 14 of the wordprocessor 10 contains the display unit 12 and is provided with a shaft 4 running therethrough which is fixed to the lid but protrudes from the respective ends of the lid 14.

A compressible member 6 having a central cavity of smaller diameter than the external diameter of the shaft 4 is fitted over each end of the shaft and secured in position by suitable means (not shown). The compressed member creates friction between the cavity and the surface of the shaft thereby providing constant resistance to the movement of the shaft through 360 degrees. This enables the lid 14 containing the display unit 12 to be angled as required by the user of the wordprocessor and for the display unit to maintain the rotational position in which it has been manually placed.

The display unit does not have to form part of the lid of the wordprocessor 10.

For example, the display unit may be rotatably mounted to the keyboard or casing of the wordprocessor and a separate lid may be provided to affect closing of the case.

The lid may also be be rotatably mounted using the torque hinge of the present invention and may be used, for example, to support paper if the wordprocessor is provided with printing facilities.

Figures 5 and 6 of the accompanying drawings illustrate the member 6 of the torque hinge of the present invention within a housing 20 to assist in preventing any movement of the member. The housing may consist of the casing of the wordprocessor being provided with a recess for placement of the member. This would preferably be situated at a corner of the casing to allow extension of the shaft of the hinge from the member 6. However, the housing may be a separate unit for containing the member, the housing being secured to the wordprocessor by suitable means. Preferably, a plate 22 is provided across the upper surface of the housing 20 or the member 6 and is retained in place by means of screws 25. This not only assists in retaining the member in place but increases the compressive force applied to the shaft.

The housing may totally enclose the member or be upwardly open. It is to be appreciated that dimensions of the housing may be such as to surround the member without compression thereof or alternatively, the external dimensions of the member may be slightly greater than the internal dimensions of the housing such that the whole member is compressed further against the shaft upon insertion into the housing, thereby increasing the frictional resistance between the member and the shaft. The housing may be any size or shape as illustrated by Figures 5 and 6.

Referring to Figure 7 of the accompanying drawings, a further embodiment of the present invention is illustrated. The member 6 of the hinge is provided with a slot 28 running between the external surface thereof and the internal cavity 8 to enable the member to fit around shafts of varying diameter. Preferably, a load, such as a plate is clamped over the member to cause satisfactory compression around the shaft.

The main advantage of the present application is its simplicity. The torque hinge uses far fewer components than that, for example, used in the tilted spring mechanism previously employed by the Applicant. This obviously results in the hinge being cheaper and reduces the assembly time of the hinge in a wordprocessor unit. In fact, the assembly time and total cost has been shown to be reduced by more than 509E using the present hinge. Additionally, the large area of the member absorbs any heat produced during rotation of the shaft due to the friction that exists between the shaft and the cavity. Furthermore, full life tests have been conducted using the hinge of the present invention with no noticeable loss of frictional resistance being found.

The hinge provides constant resistance throughout the full range of movement of the shaft allowing the user of a word processor full control of the display position.

Claims

1. A torque hinge for a wordprocessor or the like comprising a member having a cavity and a shaft for insertion into the cavity, wherein the member is made of a compressible material and is adapted or arranged to resist rotation of itself relative to a mounting therefor, the external diameter of the shaft being greater than the internal diameter of the rnember in its relaxed state such that upon insertion of the shaft into the cavity the member compresses around the shaft to cause frictional contact therebetween thereby creating resistance to the entire range of movement of the shaft.

2. A torque hinge as claimed in claim 1, wherein the member is in the form of a rectangular block having a cylindrical cavity therein.

3. A torque hinge as claimed in claim 2, wherein the member is a square block.

4. A torque hinge as claimed in claim 1. 2 or 3 wherein the cavity is in the centre of the member.

5. A torque hinge as claimed in any one of claims 1 to 4, wherein the member is made of an elastomer.

6. A torque hinge as claimed in claim 5, wherein the member is made of polyurethane.

7. A torque hinge as claimed in claim 5, wherein the member is made of a rubber or a rubber alloy.

8. A torque hinge as claimed in any one of claims I to 7, wherein the member is provided within a housing.

9. A torque hinge as claimed in claim 8, wherein the housing completely surrounds the periphery of the member.

10. A torque hinge as claimed in claim 8, wherein the housing is upwardly open.

11. A torque hinge as claimed in any one of claims 8 to 10, wherein the external dimensions of the member are greater than the internal dimensions of the housing.

12. A torque hinge as claimed in any one of claims 8 to 11, wherein the housing is made of a non-compressible material.

13. A torque hinge as claimed in claim 12, wherein the housing is of a plastics material.

14. A torque hinge as claimed in any one of the preceding claims, wherein a load is provided to at least one surface of the member or housing.

15. A torque hinge as claimed in claim 14, wherein the load is in the form of a plate.

16. A torque hinge as claimed in claim 14 or 15 wherein the load is made of a non-compressible material.

17. A torque hinge as claimed in claim 16, wherein the load is made of a plastics material.

18. A torque hinge as claimed in claim 16, wherein the load is made of metal.

19. A torque hinge as claimed in any one of claims 14 to 18, wherein the load is secured in place by means of screws.

20. A torque hinge as claimed in any one of the preceding claims wherein a slot is provided in the member between the external surface thereof and the internal cavity.

21. A torque hinge substantially as hereinbefore described and with reference to and as shown in Figures 1 to 4, 5, 6 and 7 of the accompanying drawings.

22. A personal computer having a keyboard within a cabinet, a display screen and a lid for placing over the keyboard and display screen, wherein the display screen is hingedly mounted with respect to the cabinet by means of a pair of torque hinges according to any one of claims 1 to 20.

23. A personal computer as claimed in claim 22, wherein the display screen is integral with the lid.