GB2261258A

GB2261258A - Shaft locking mechanism

Info

Publication number: GB2261258A
Application number: GB9223240A
Authority: GB
Inventors: Tsuneo Yamada
Original assignee: Kato Spring Works Co Ltd
Current assignee: Advanex Inc
Priority date: 1991-11-05
Filing date: 1992-11-05
Publication date: 1993-05-12
Anticipated expiration: 2012-11-05
Also published as: GB9223240D0; GB2261258B

Abstract

A shaft locking mechanism comprising a shaft 2 and a supporting member 14 which freely rotates around this shaft. The supporting member 14 has a cylindrical part 16 enclosing and elastically gripping the shaft 2 and a base part 15 extending radially outward from the cylindrical part 16. Within the cylindrical part 16, a gap is formed extending in the direction of the length of the shaft 2 and this gap provides an appropriate amount of frictional resistance between the shaft 2 and the cylindrical part 16. A number of cylindrical parts 16 may be provided which are formed in opposing directions thereby providing resistance to rotation of the shaft 2 in either direction. The lengths of the cylindrical parts 16 may differ if the resistance provided in each direction is to be varied. <IMAGE>

Description

SHAFT LOCK MECHANISM This invention relates to a shaft lock mechanism and in particular a shaft lock mechanism which enables fixation of a display board at a set angle to the main body of a computer which is equipped with a keyboard and etc. and is used, for example.

on laptop personal computers or word processors.

In general, the display board for a laptop personal computer or a word processor is incorporated as a lid to the main computer body equipped with a keyboard and is opened when the computer is in use.

And when the display board is in use, depending on the condition and the location of use, the light reflected from the display screen causes difficulty in reading letters and pictures on the screen. For this reason, a method was developed to enable adjustment of the display board at any chosen angle to the main computer body.

An example of a shaft lock mechanism which enables adjustment of a display board to the main body at any chosen angle is disclosed in the first publication of Utility Model (Heisei) 1-135397; This shaft lock mechanism consists of a movable shaft, fixed shafts of an identical diameter as the movable shaft on each side of the movable shaft and a coil spring externally surrounding and in close contact with both the movable and the fixed shafts. When the movable shaft is rotated in one direction, the diameter of the part of the coil spring in contact with one of the fixed shafts decreases and the friction force acting between the fixed shaft and the coil spring called "locking torque" is generated.At the same time, the diameter of the coil spring on the other side in contact with a fixed shaft of the other side Is increased by the same rotational motion and "slipping torque" is generated therefrom. This combination of the locking torque and the slipping torque acting on the movable shaft enables adjustment of the display board at any chosen angle.

However, in a shaft lock mechanism of this structure, the degree of control for the adjustment of the display board at any chosen angle depends on the strength of the coil spring. Because the area of surface contact between the coil spring and the movable shaft is limited to the length of the coil spring, in order to increase this area of surface contact it is necessary to increase the coil diameter to a certain degree. Accordingly, there is a limit to size or weight reduction of this shaft lock mechanism. Moreover, because the coil spring must touch and encase both the movable shaft and the fixed shafts on either side of the large-diameter central section of the movable shaft, it is necessary to make sure that the diameter of the central section of the movable shaft and that of the fixed shaft on either side be identical. Therefore, there is a problem of high manufacturing cost.And since the cost increases as the diameter of the shaft becomes smaller, this fact also hinders the size and weight reduction of this particular type of shaft lock mechanism.

According to the present invention, there is provided a shaft lock mechanism comprising a shaft: and a support member rotatably mounted on said shaft and comprising i) a tubular portion which comprises one or more tubular bodies each of which has a gap extending along its length and which portion elastically grips said5shaft, and ii) a base portion which extends from said tubular portion.

The shaft lock mechanism according to one embodiment of the present invention comprises a shaft and a support member which freely rotates relative to the shaft. The support member encases the shaft and cylindrical parts elastically holds the shaft and the support member. The mechanism also contains a base part which extends radially outward from the cylindrical part and forms a gap which extends throughout the cylindrical part, parallel to the shaft.

In the shaft lock mechanism of this invention, when the shaft and the support member is made to rotate relative to each other, the cylindrical part elastically grips the shaft and an elastic force working between the surface of the shaft and that of the cylindrical part.

Because this elastic force creates an appropriate amount of friction resistance between the shaft and the cylindrical part, the mechanism maintains a constant resistance independent of the direction of rotations and enables to stop the shaft at any chosen angle.

In another aspect of the present invention, the cylindrical part is combined into one body with the base part of the supporting member for a flat plate. And this combination makes easy the construction of support member by merely bending this part into a tubular shape Also, the cylindrical part may be divided into manp parts in the direction of the shaft. This division makes possible shortening of the length of each cylindrical part and thereby easily improves the degree of circularity of each cylindrical part as well.

Moreover, by including a case in which each cylindrical part is wound around the body of the shaft with its neighboring part in the opposite direction, it is possible to suitably control the frictional resistance based on the rotational direction or, in other words, the working of the rotational torque. For example, it is possible either to equalize the torques of opposite direction or to provide minute differences.

Also, according to the present invention, of the two surfaces by which the cylindrical part and the shaft body face each other, on one surface a projection may be formed and on the other a concavity corresponding to the projection. This relationship between the projection and the concavity makes possible determination of the placement of the supporting member and the shaft body at a certain relative rotational position. - Furthermore, the shaft lock mechanism of the present invention may contain at least one lubricating channel on the surfaces of the cylindrical part and the shaft body mutually facing each other and, through this channel, supplies a lubricating oil such as grease. Because this mechanism prevents wearing of the surfaces, it is possible to maintain a smooth sliding condition for a long period.

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:- Fig. 1 is a front view of the entire structure of a shaft lock mechanism of an embodiment according to the invention: Fig. 2 is a left side view of the shaft lock mechanism of Fig. 1; Fig. 3 is a right side view of the shaft lock mechanism of Fig. 1; Fig. 4 is a plain view of the shaft lock mechanism of Fig. 1; Fig. 5 (a) is a cross-sectional view along the line a-a of Fig. 4; Fig. 5 cub) is a cross-sectional view alog the line b-b of Fig. 4; Fig. 6. is a close-up cross section of the cylindrical part.

Fig. 7. is a front view of another embodiment of the present invention.

Fig. 8 is a side view of the shaft lock mechanism shown in Fig. 6.

The shaft lock mechanism according to this invention will be explained as follows with reference to Figs. 1 to 6. Moreover, although this application is explained in terms of examples taken from the mechanisms used in laptop computers or personal computer word processors, it can also be used for various machines other than these apparatus.

In the drawings, reference numeral 1 represents a shaft lock mechanism of the present invention; reference numeral 2, the movable shaft 1; and reference numeral 3 represents a bracket which rotatably supports the movable shaft 2.

The movable shaft 2 has a cylindrical form and can be made from metals such as SUM (suipher-added free cutting steel) and SUS (stainless steel), ceramics or resins. At one end of the movable shaft 2 is disposed an attachment part 4 which adjusts the position of the display board which also functions as the lid of a laptop-model personal computer.

Bracket 3 is fixed onto a main body such as a laptop-model personal computer or a word processor and consists of the support plates 5 and 6 which face each other from both sides of the movable shaft 2, a connecting member 7 disposed between the facing sides of the support plates 5 and 6 having a channel like cross-section and a support member 8 clamped by the connecting member 7.

On the supporting plates 5 and 6 are formed holes through which the movable shafts 2 are inserted, and slip-preventing rings 9 and 10 are engaged to the movable shaft 2 at the outside of the supporting plates 5 and 6, thereby rotatably supporting the movable shaft 2 without being slipped off. One of the supporting plate 5 extends in the direction away from the shaft and is bent toward the other supporting plate 6, which is attached thereto by bolts 11. Thus, this combination constructs a "frame" structure. Installation holes 12 are provided for setting this "frame" structure to the main computer body or other various accessory parts to the "frame" structure.

The aforementioned connecting member 7 has its one end fixed to the inside surface of the supporting plate 6 and extends in the direction of the support plate 5 on the other end. In the connecting member 7 is provided a slit 13 which extends along the axis of the shaft. And the base part 15 of the supporting member 14 (to be described hereinafter) is inserted into the slit 13.

This supporting member 14 comprises two tube-shaped cylindrical parts 16 and a flat base part 15 which extends radially outward from one end of a cylindrical part 16. Each cylindrical. part 16 is installed parallel to the shaft. The supporting member 14 is made by punching and bending a sheet of metal. In other words, a slit is punched and extended in a line from the center of the sheet of metal to an edge of the sheet to yield two rectangular flaps. These rectangular flaps are bent round outward in opposite directions to form two oppositely facing cylindrical parts 16 of the supporting member 14. The inside diameter of the cylindrical parts 16 is smaller than the outside diameter of the movable shaft 2. And two gaps 17 are formed between the two ends of the circle of the cylindrical parts 16.

Thus, the cylindrical parts 16 acquire the elasticity to radially contract and expand. These gaps 17, as shown in (a) and (b) of Figure 5, exist on the opposite sides of the base part 15.

Because the nature of contact between the cylindrical parts 16 and the movable shaft 2 is on the surface, the contact area increases compared to linear contact of the prior art aforementioned.

Consequently, it is possible to shorten the length of the cylinder of the cylindrical parts 16 and improve the degree of circularity of each cylindrical part 16.

Moreover, although the supporting member 14, as described above, is fixed to the connecting member 7 by inserting its base part 15 into the slit 13, if necessary, the supporting member 14 and the connecting member 7 can be fixed together by applying adhesives or welding or by another method combining the two parts into one body.

Moreover, the cylindrical part 16 can be made of any elastic material. For example, materials such as copper.alloy or synthetic resin can be used therefore.

As described above, the shaft lock mechanism 1 is installed to a laptop personal computer by attaching the bracket 3 to the main body of the computer by means of the holes 12 of the shaft lock mechanism.

The shaft lock mechanism 1 is also attached to the display board by means of the attachment part 4 of the movable shaft 2.

When the display board Is opened or closed against the main body, the elastic cylindrical part 16 of the bracket 3 exerts a countering frictional force upon the movable shaft 2 and the movable shaft 2 rotates while in contact with this cylindrical part. The contact between the bracket 3 and the movable shaft 2 produces friction resistance and torque.

When the torque applied to the movable shaft 2 from outside becomes stronger than the torque generated by the friction resistance between the movable shaft 2 and the bracket 3, the display board opens and closes by making the movable shaft 2 rotate relative to the bracket 3.

Also, if the torque for opening and closing, which should be sufficient to adjust the display board at any chosen angle, is removed, only the torque which exerts to close the display board by its own weight is applied between the movable shaft 2 and the bracket 3.

Thus, this torque becomes weaker than the friction resistance between the movable shaft 2 and the bracket 3 and makes possible adjusting the position of the display board at any chosen angle.

Here, since the contact between the movable shaft 2 and the cylindrical part 16 is on the surface, the area of their contact is enlarged and a large friction resistance can be obtained. Therefore, it becomes possible to reduce the diameters of both the movable shaft 2 and the cylindrical part 16.

At the time of rotation, because each division of the cylindrical part 16 winds around the movable shaft 2 in a mutually opposite direction, depending on the rotational direction relationship, the frictional force becomes different. In other words, if the movable shaft 2 is made to rotate clockwise in Fig. 5, the frictional force generated between the movable shaft 2 and a cylindrical part 16 is, as shown in Fig. 5 (a), applied in the direction of opening the cylindrical part 16 and in the direction of weakenIng the pressing force of the cylindrical part 16 In Fig. 5, the same frictional force is applied in the direction of compressing the cylindrical part 16 and in the direction of strengthening the pressing force of the cylindrical part 16.

However, in this preferred embodiment, because the frictional force is exerted as a result of the sum of the friction forces generated by the two oppositely facing cylindrical parts 16 rubbing against the movable shaft 2, such friction mechanism can produce equal torques and affords easy manipulability in a rotation of any direction.

Moreover, in case such uniform torques are-not required (for example, if the weight of the panel is fairly large), a large force is necessary to open the computer lid and thus the shaft lock mechanism may be adjusted to reduce the friction. In such case of giving a direction to the frictional force, besides the method of making all coil directions of the cylindrical part 16 the same, it is possible to use an odd number of the cylindrical parts 16 such as 3 or 5 and, by rotating in the opposite directions in a proportion of 1: 2 or 2: 3, designate a suitable value to the torque difference for these opposite directions.Moreover, as will be shown in a later preferred embodiment, by changing the length of 2 cylindrical parts along the direction of the shaft, it is possible to assign a torque difference proportional to such length difference Furthermore, a groove which can be used as either a lubricant oil-supplying groove or an oil storage recess can be provided in at least either of the aforementioned movable shaft 2 or the cylindrical part 16 and therefore grease can be supplied. As a result, this feature prevents frictional scorching and oil dripping and makes smooth sliding possible.

Figs. 6 and 7 present another example of application of said invention and, except for the structures of the movable shaft 18 and the supporting member 19, this embodiment has the same features as the one aforementioned. As for the supporting member 19 of this preferred embodiment, of the two cylindrical parts 20 and 21, one is longer than the other in the direction of the shaft, and on the shorter side of the inside wall of the cylindrical part 21 is formed the projection 22. As for the movable shaft 18, at the location on the shaft corresponding to the projection 22 of the aforementioned cylindrical part 21 is provided the concavity 23 which engages with the projection 22. Also, the base part 24 of the supporting member 19 is bent around the boundary between the cylindrical parts 20 and 21.

In this preferred embodiment the two cylindrical parts 20 and 21 perform different functions. In other words, in the same manner as in the aforementioned preferred embodiment, the inside surface of the larger cylindrical part 20 touches and grips the movable shaft 18 and the frictional force created therefrom supports the weight of the display board. The smaller cylindrical part 21, in the neighborhood of the projection 22, is separated from the surface of the movable shaft 18 and only the leading part of the projection 22 is in contact with the shaft 18. Therefore, when the movable shaft 18 is rotated, the projection 22 slides past the surface of the movable shaft 18 and when it reaches the concavity 23, the projection 22 is engaged with the concavity.Thus, the smaller cylindrical part 21 functions as a positioning mechanism which holds suspended the supporting member 19 and the movable shaft 18 at a rotational position. Thus, when the display board is closed or opened, for example, the location of this positioning mechanism is preset at a standard location. Also, although in this particular preferred embodiment there is only one concavity, it is possible to install a multiple number of concavities around the movable shaft 18 and to set the height of the projection 22 and the depth of the concavity 23 at any desired value. When these numbers are appropriately set, at any given location of rotation the projection 22 and the concavity 23 elastically fit together and generate a so-called "click sensation." Thus, it is possible to create a feeling of user-friendliness.

As explained in detail above, the shaft lock mechanism of said invention causes an appropriate amount of frictional resistance exist between the shaft body and the cylindrical parts and makes possible, through a simple structure, to maintain a state of suspension Involving the mutual rotation of the shaft body and the cylindrical part and the suitable location thereof.

Because the shaft body and the cylindrical parts are in surface contact with each other, in comparison to the contact between a spring and a shaft body of prior art, said invention can acquire the same level of frictional force with smaller diameters. As a result, it is possible to achieve size and weight reduction of the shaft lock mechanism and because the number of parts is few and the structure simple, It is also possible to produce the product at a low cost.

The supporting member which includes the cylindrical part can easily be made, for example, by bending one part of one supporting member at a time. Also, by dividing the cylindrical part into many divisions in line with the direction of the shaft. it is possible to shorten the length of each division of the cylindrical part and thereby easily improve the degree of roundness in each division. The improved degree of roundness helps to provide stable torques necessary for the rotation. Moreover, because divided cylindrical parts coil around the shaft body in mutually opposite directions, it is possible to control the frictional resistance based on rotational directions or, in another word, rotational torques. Thus, it is also possible to control the workings of the torque corresponding to the particular circumstance of said invention's application.

Moreover, by providing a projection on the surface of one side of the cylindrical part facing the shaft body and a concavity, which fits in with the projection, on the facing surface of the shaft body, or vice versa, this invention makes possible to position the mutual locations of the supporting member and the shaft body.

Also, by forming an oil-supply groove on at least one of the contacting surfaces of the cylindrical parts and the shaft body and supplying a grease-like lubricant thereto, said invention prevents frictional wearing between these two surfaces and maintains a good sliding condition for a long time.

Claims

CLAIMS:

1. A shaft lock mechanism comprising: a shaft; and a support member rotatably mounted on said shaft and comprising i) a tubular portion which comprises one or more tubular bodies each of which has a gap extending along its length and which portion elastically grips said shaft, and ii) a base portion which extends from said tubular portion.

2. A shaft lock mechanism according to claim 1, wherein said base portion extends from the part of the or each tubular body adjacent said gap.

3. A shaft lock mechanism according to claim 1 or 2, wherein said tubular portion comprises a plurality of tubular bodies.

4. A shaft lock mechanism according to in claim 2 or 3, wherein said tubular portion comprises two tubular bodies, the gaps of which bodies are located on opposite sides of said base portion.

5. A shaft lock mechanism according to claim 3 or 4, wherein said tubular bodies include tubular bodies having different lengths.

6. A shaft lock mechanism according to any preceding claim, wherein one of the inner surface of said tubular portion and the outer surface of said shaft is provided with a projection, and the other of the inner surface of said tubular portion and the outer surface of said shaft is provided with a recess, the arrangement being such that said projection can fit into said recess.

7. A shaft lock mechanism according to any preceding claim) wherein said support member is formed from an elastically deformable plate, part of which has been plastically deformed.

8. A shaft lock mechanism according to any preceding claim, wherein a groove is formed in at least one of said shaft and said tubular portion for supplying lubricant therethrough.

9. A shaft lock mechanism as claimed in any preceding claim, wherein said shaft and said base portion are connected to respective members which are foldable relative to one another about the longitudinal axis of said shaft.

10. A shaft lock mechanism substantially as hereinbefore described with reference to Figures 1-6 and Figures 7 and 8 of the accompanying drawings.