GB2114370A

GB2114370A - Electrical leaf switch mounting construction

Info

Publication number: GB2114370A
Application number: GB08234042A
Authority: GB
Inventors: Muneyoshi Miyata; Shigeru Omori
Original assignee: Mik Electronic Corp
Current assignee: Mik Electronic Corp
Priority date: 1982-01-30
Filing date: 1982-11-30
Publication date: 1983-08-17
Also published as: GB2114370B; FR2520925A1; JPS58115021U; DE3243290C2; KR860002922Y1; KR840002442U; HK90786A; DE3243290A1; FR2520925B1

Abstract

A construction for mounting a leaf switch A on to a chassis 2 of an electrical device comprises an insulating base 1 which has at one end a resilient pawl element B and at the other end a L-shaped resilient locating element C. These two elements B, C are adapted to be engaged securely in at least one opening 11a, 11b in the chassis 2. <IMAGE>

Description

SPECIFICATION Leaf switch construction The present invention relates to a leaf switch construction, as might be used for example in an electrical or electronic device such as a computer.

Various kinds of leaf switches have been proposed for use in electronic and electrical devices such as electronic computers, acoustic units and the like. In such cases, the leaf switches are typically mounted on the devices by fixing the insulating base of the leaf switch onto a chassis of the device by means of screws which are inserted through holes in base into threaded holes in the chassis.

However, such conventional mounting techniques tend to be unsatisfactory in that they require screws of various kinds to meet the various requirements, resulting in the necessity to select the correct screws. This tends to be troublesome and so the manufacturing and mounting costs tend to be significantly increased. Furthermore, it also renders it necessary to form screw holes in the base.

In addition, these conventional leaf switch mounting techniques require the troublesome operations of inserting the screws one by one through the holes of in the base into the threaded holes in the chassis, and then fixing the screws with respect to the chassis using a tool such as a screw driver or the like.

The foregoing disadvantages of the known constructions have not been particularly serious in the past. However, recently, the number of leaf switches used in electrical or electronic devices has increased significantly. Also, the leaf switches themselves and the devices on which they are to be mounted have become highly miniaturised, so that the mounting of a leaf switch with respect to the device can be extremely awkward. In addition, since the number of leaf switches used has increased substantially, the increase in the number of screws required has resulted in a considerable rise in the assembly cost.

Accordingly, it is an object ofthe present invention to provide a leaf switch construction capable of being easily mounted on the chassis of a device by means of a simple, single operation which does not require the use of any screws.

In accordance with the present invention, there is provided a leaf switch construction for mounting on a chassis, including an insulating base and a plurality of electrical contacts embedded in the base, the base having a surface adapted to abut against the chassis, a resilient pawl element and a resilient locating element, the pawl element having a stem portion projecting beyond the abutting surface a distance equivalent to the thickness of the chassis and a pawl portion at the end of the base portion, the locating element being substantially L-shaped with a base portion projecting a distance equivalent to the thickness of the chassis from the abutting surface and a resilient portion extending outwardly from the base portion in a direction substantially parallel to the abutting surface.

Preferably, the locating element has at its outer end a projection arranged to abut against the chassis.

The leaf switch may include a groove formed between the stem portion of the pawl element and the abutting surface of the base, thereby providing the pawl element with a degree of resilience.

Conveniently the pawl element and locating element are formed integrally with the base.

The invention may extend to such a leaf switch in combination with a chassis, the chassis having an opening arranged to receive the stem portion of the pawl element and the base portion of the locating element.

The invention may be carried into practice in various ways and some embodiments will now be described by way of example with reference to the accompanying drawings, in which: Figure lisa bottom plan of a leaf switch of the normal close type which is provided with a mounting construction according to the present invention; Figure 2 is a front view of the leaf switch shown in Figure 1; Figure 3 is a side view of the leaf switch shown in Figure 1; Figure 4 is a plan view showing an opening formed in a chassis by means of which the leaf switch is mounted on the chassis; Figure 5 is a plan view showing an alternative opening in the chassis; Figures 6 and 7 are front views showing consecutive stages in mounting the leaf switch on the chassis;; Figure 8 and 9 are front views to larger scales showing the engagement between the base of the leaf switch and the chassis; and Figure 10 and 11 are front view showing further examples of leaf switches provided with a mounting construction according to the present invention.

Figures 1 to 3 show a leaf switch A of the normal close type having an insulating base 1 formed of a plastics material and two spring-loaded contacts 2a, 2b, embedded parallel with one another in the insulating base 1. Such a leaf switch A may be formed by an insert moulding technique. The insulating base 1 has a surface 3 which in use abuts against a chassis 2 of a device, such as an electronic device, in which the leaf switch A is to be used.

The base 1 has at one end an elastic pawl element B in the form of a leaf, which is separated from the abutting surface buy a deep recess 5 in order to provide the pawl element B with an effective elasticity. The pawl element B has a stem portion 4 which projects a distance equivalent to the thickness e, of the chassis beyond the abutting surface 3 and which has at its end a pawl portion 6.

At the other end of the base 1, an L-shaped elastic element projects from the abutting surface 3. The L-shaped element C has a body portion 7 which projects a distance equivalent to the thickness e, of the chassis beyond the abutting surface 3 and an elastic portion 8 extending perpendicularly outwardly from the body portion 7. The elastic portion 8 has at its outer end a small projection 9 which faces back towards the base 1. The pawl element B and the L-shaped elastic element C may be formed integrally with the insulating base 1 in the mouldiny process.

Figure 4 shows a chassis 2 in an electronic device or the like on which the leaf switch is to be mounted.

The chassis 2 is provided at the position 10 which the leaf switch is to be mounted with an opening 11 of a shape suitable for receiving the elastic pawl element B and the L-shaped elastic element C. Alternatively, the opening 11 of the chassis 2, may be divided into an opening portion 1 1a arranged to receive the elastic pawl element B and an opening portion 1 ib arranged to receive the L-shaped elastic element C, as shown in Figure 5.

The way in which the leaf switch A is mounted on the chassis 2 is shown in Figures 6 to 9, the chassis 2 having openings 1 lea and 11b as shown in Figure 5.

Firstly, the L-shaped elastic element C is inserted in the opening 1 1b of the chassis 2 with the elastic portion 8 positioned on the far surface of the chassis, as shown in Figure 6. Then, the elastic pawl element B is forced through the opening 1 1a of the chassis 2 so that the pawl portion 6 engages snugly with the far surface of the chassis, as shown in Figure 7. This causes the body portion 7 of the L-shaped elastic element C to fit snugly in the opening 1 lib, with the elastic portion 8 positioned parallel with the far surface of the chassis 2. In this way, the elastic pawl element B and L-shaped elastic element C are properly positioned in the openings 1 1a and 11b, respectively, and the surface 3 of the insulating base abuts the near surface of the chassis 2.It will be noted that this method of mounting the leaf switch on the chassis can be carried out in a single operation.

When the elastic pawl element B and L-shaped elastic element C are properly positioned with respect to the chassis 2, the small projection 9 of the elastic portion 8 contacts the rear surface of the chassis. This causes the elastic portion 8 to be elastically deformed in that its end is displaced by a distance equivalent to the height t2 of the projection.

9 in the downward direction.

This deformation causes a reaction force P1 to act on the insulating base 1 through the projection 9.

This in turn results in forces P2 and P3 being applied to the insulating base 1 through the body portion 7 as shown in Figure 8, so that the abutting surface 3 of the insulating base 1 is forced against the chassis 2 and the pawl portion 6 of the elastic pawl element B is forced against the far surface of the chassis.

Thus, the insulating base 1 is held securely in contact with the chassis, without any looseness.

In addition, the relative portions of the elements B and C and the openings 11 a and 116 are such that the pawl element B is deformed inwards. This results as shown in Figure 8, in forces P4 being set up between the chassis 2 and the elastic pawl element B and L-shaped elastic element C. The elements B and C press outwardly so that they are forced against the side walls of the openings 1 la and 1 1b, respectively.

This also helps to locate the insulating base 1 more securely and stably. As may be seen from Figures 10 and 11, various kinds of leaf switches can be mounted on the chassis of a device using the teaching of the present invention. Thus, it will be noted that the leaf switch is not limited to specific configurations nor to a specific switching mechanism. The leaf switch may be a normal close type switch as shown in Figure 1, a normal open type switch as shown in Figure 10 (namely, a switch in which contacts are open in the normal state) or a compromise type switch as shown in Figure 11.

Also, the leaf switch may be one having at least two spring-loaded contacts, a tumbler switch and the like.

Thus, it should be noted that the present invention is not specifically concerned with the type of leaf switch but its mounting construction.

The present invention may enable the leaf switch to be mounted on the chassis securely and in a single operation by resiliently engaging the elastic pawl element B and L-shaped elastic element C in the opening or openings in the chassis. This allows the mounting operation to be carried out with high efficiency and a significant decrease in cost may be achieved.

Claims

1. A leaf switch construction for mounting on a chassis, including an insulating base and a plurality of electrical contacts embedded in the base, the base having a surface adapted to abut against the chassis, a resilient pawl element and a resilient locating element, the pawl element having a stem portion projecting beyond the abutting surface a distance equivalent to the thickness of the chassis and a pawl portion at the end of the base portion, the locating element being substantially L-shaped with a base portion projecting a distance equivalent to the thickness of the chassis from the abutting surface and a resilient portion extending outwardly from the base portion in a direction substantially paralel to the abutting surface.

2. A leaf switch construction as claimed in Claim 1 in which the locating element has at its outer end a projection arranged to abut against the chassis.

3. A leaf switch construction as claimed in Claim 1, or Claim 2 including a groove formed between the stem portion of the pawl element and the abutting surface of the base, thereby providing the pawl element with a degree of resilience.

4. A leaf switch construction as claimed in any preceding claim in which the pawl element and locating element are formed integrally with the base.

5. A leaf switch construction constructed and arranged substantially as herein specifically described with reference to and as shown in Figures 1 to 3 and 6 to 9 or Figure 10 or Figure 11 of the accompanying drawings.

6. A leaf switch construction as claimed in any preceding claim in combination with a chassis, the chassis having an opening arranged to receive the stem portion of the pawl element and the base portion of the locating element.

7. A combination as claimed in Claim 6 in which the opening in the chassis is divided into an opening portion for engagement with the pawl element and a separate opening portion for engagement engaging with the locating element