JPH08128418A - Screw fastening structure - Google Patents

Abstract

PURPOSE: To provide a screw fastening structure effective in improving workability and in protecting parts when many precision parts are fastened together in a miniature precision equipment, particularly, a wristwatch. CONSTITUTION: When a plurality of parts are superimposed on a case body 1 of an equipment main body and fastened together, a plurality of boss parts provided with through holes or internal threads also serving to position parts are erected and provided on the case body 1, a plurality of fastening holes to be inserted through the outside diameters of the boss parts with the specified fitting margin are provided on respective parts, and respective parts are fastened together by the screw through the boss parts. Each boss part is composed of a base part 25a and a main body part 25b on the upper part of it, the base part 25a is so formed as to have the fitting margin between the outside diameter and the fastening holes of respective parts, and the outside diameter of the main body part 25b is made smaller than that of the base part 25a, and the boundary between the main body part 25b and the base part 25a is made into a step part 25c formed by an inclined surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw fastening structure in which precision assembling of a wristwatch or the like is improved by assembling a plurality of parts together to improve assembly workability.

[0002]

2. Description of the Related Art In the assembly of parts in general industrial equipment, in many cases, a plurality of fastening bolts and screws are used for one part. In particular, in products such as wristwatches and other small precision equipment that need to prevent size and size increases in the thickness direction in terms of functionality and design, a wide variety of small components, including LSI boards, are stacked vertically to form a case. It is built in, and each of these parts is often fastened together with a common screw. Further, in most cases, a plurality of screws are used at a plurality of places for a component, so that the pitch dimension between the screws and the centers of the screws is required to be highly accurate.

[0003]

By the way, if there are variations in the finishing accuracy of parts or the accuracy of through holes and screw holes for fastening provided in the parts, screws common to such through holes and screw holes of each part will be used. When they are jointly tightened by insertion or screwing in, it is often difficult or impossible to screw in some of the parts, which significantly deteriorates the assembly workability. In particular, in the case of the wristwatch LSI substrate of the above-mentioned example, forcible tightening or fastening by press-fitting may not only cause work failure but also damage electronic components mounted on the substrate, so that it can be avoided as much as possible. desirable. Therefore, it is an object of the present invention to provide a screw fastening structure that is effective for improving workability and protecting components when co-fastening a large number of precision components, particularly in a small precision instrument such as a wristwatch.

[0004]

In order to achieve the above-mentioned object, the screw fastening structure according to the present invention also serves as a component positioning on the main body case when a plurality of components are superposed and fastened together on the main body case. A plurality of boss portions with through holes or female threads are provided upright, and each component is provided with a plurality of fastening holes through which the outer diameter of the boss portion is inserted with a predetermined fitting margin, and each component is screwed through the boss portion. When tightening the parts together, the boss part is composed of a base part and a body part on the base part, and the base part is formed so as to have the fitting margin between the outer diameter of the base part and the fastening hole of each part. The outer diameter of the part is smaller than that of the base part, and the step is formed. In the screw fastening structure according to the present invention, the step portion between the base portion and the main body portion can be formed by the inclined surface. Further, in the screw fastening structure according to the present invention, the device is a wristwatch, and one of a plurality of components that are positioned and co-fastened by being inserted into the boss portion provided on the main body case is an LSI substrate. You can

[0005]

The electronic component such as the LSI substrate is dropped into the case body, which is the main body case, by inserting the fastening hole into the boss portion provided on the case body side. At this time, if there is a dimensional error in the machining accuracy of each component, the fastening hole of the component may be misaligned with respect to the central axis of the boss. The fastening hole of the component is brought into contact with the stepped portion of the boss portion, guided by the inclined surface thereof, and is smoothly dropped into the base portion of the boss portion, so that the fitting margin is fitted in a state where the fitting margin is offset. If the fitting is smooth, there will be no problem even if the fitting margin is offset. It is possible to protect the parts without being overloaded by being dropped by the inclined step portion.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a screw fastening structure according to the present invention is applied to a wristwatch will be described below with reference to the drawings. 1 to 3 are a front external view showing an example of a wrist watch adopting the small screw holding and fastening structure of the embodiment, a module exploded perspective view,
It is a perspective view in the module assembly bottom view shown by this exploded perspective view. In the case body 1 which is the main body case of the device according to the present invention, the display unit 3 for displaying the time and date on the liquid crystal through the transparent glass 2, the time and date displayed on the display unit 3, as well as the temperature, atmospheric pressure, altitude Set various information such as
Various push button switches 4 and 5 for changing and resetting
And a cursor switch 6 are arranged. Further, in recent years, a data communication unit for infrared signals has been provided to enhance user's preference, and a pair of a light emitting unit 7 such as an LED and a light receiving unit 8 such as a phototransistor is provided. Further, as shown in FIG. 3, a module 10 for driving these cover parts is built in the inside of the case body 1 having such cover parts. A back cover 11 which is a cover member is provided in the rear opening of the case body 1 in which the module 10 is built.
Are fastened to close the case body 1. This case back 11
A piezoelectric element 12 that utilizes vibration as an alarm sound emission source is also disposed on the inner side surface by utilizing.

As shown in the exploded view of FIG. 2, the module 1
0 consists of the following members. A liquid crystal display device (LCD) 1 protected from the outside by a transparent glass 2 facing an opening window 3a for a display unit 3 provided on the front side of the case body 1.
3 are arranged. The LCD 13 is attached to an upper housing 14 made of synthetic resin which also serves as a spacer member,
An LSI substrate 15 is also stacked and assembled to the upper housing 14, and the LCD 13 and the LSI substrate 15 are electronically connected to each other through the interconnectors 16 and 17 to form an electronic circuit. The upper housing 14 is also provided with a contact rubber 18 for the push button switch 4 and the like made of conductive rubber. A lower housing 19 made of synthetic resin is arranged below the LSI substrate 15, and a power supply battery 20 is stored in the lower housing 19. Battery 20 is a holding plate 2
The holding plate 21 is fastened to the lower housing 19 by means of a battery holding screw 30 and a washer 31 which are held in the storage portion 19a by a flat screw.

A lower housing 1 containing a battery 20 is also provided.
From the outside of 9, the main plate 2 made of an electrically conductive material with a whole ring shape
2 by using a number of flat head screws 23
Members such as 9 are fastened together and fastened to the case body 1. A spring contact 24 is provided on an end portion of the main plate 22, and the spring contact 24 is connected to the interconnector 16 so that it can be energized. From the outside of the base plate 22, the back cover 11 is closed via the insulating sheets 32 and 33, and the module 10 as described above is built in the case body 1.

FIG. 4 is a sectional view taken along the line AA of FIG. 3, showing a sectional view of an example of the screw fastening structure of the present invention. Referring to FIG. 2 together, a screw receiving boss portion is provided on the case body 1 side in correspondence with the large number of flat machine screws 23 arranged with the interval dimensions P ₁ , P _2, ... 25 is protrudingly formed. The flat board screw 23 and the boss portion 25 are screwed together so that the LSI substrate 15, the lower housing 19 and the base plate 22 are fastened together. Fastening holes 26, 27, and 28 through which flat screws 23 are inserted are provided as through holes in the components of the LSI substrate 15, the lower housing 19, and the main plate 22, respectively.

In FIG. 4, the boss portion 25 on the case body 1 side
Comprises a base portion 25a and a main body portion 25b on the base portion 25a. The base portion 25a is formed so as to have a fitting margin c between its outer diameter D ₁ and the fastening hole 26 having the hole diameter d of the LSI substrate 15. Has been done. The outer diameter D ₂ of the body portion 25b is the base portion 25
The step is formed smaller than the outer diameter D _{1 of} a. Also,
The step portion 25c is an inclined surface with a suitable slope.

The assembly mode and operation of the screw fastening structure of the embodiment having the above-mentioned structure will be described with reference to FIGS. 4 to 6. As shown in FIG.
3 and the like are sequentially assembled, and the LSI substrate 15 has the fastening holes 2
6 is inserted into the boss portion 25 and dropped. At this time,
If each component has a dimensional error in processing accuracy, the fastening hole 26 of the LSI substrate 15 may be displaced from the central axis of the boss portion 25. In such a case, the lower end of the fastening hole 26 of the LSI substrate 15 once falls into the step portion 2 of the boss portion 25 when it is dropped.
The LSI substrate 1 is contacted with the 5c and guided by the inclined surface thereof.
The fastening hole 26 of No. 5 is smoothly dropped into the base portion 25a of the boss portion 25, and is fitted in the state of 2c in which the fitting margin c is offset as shown in FIG. If the fitting is smoothly done, there is no problem even if the fitting margin c is offset. Lower housing 19 and main plate 22
Each fastening hole 27, 28 of
Since there is a considerable play size between the boss portion 25 and the outer diameter D ₂ of the main body portion 25b, there is no problem in joint fastening of these parts. In this manner, the plurality of flat head screws 23 are used for joint tightening. This means that each component and the fastening hole can be securely fastened together with play within a certain level of processing accuracy.

In the above wristwatch to which the screw fastening structure of the embodiment is applied, when the battery 20 is replaced, the memory of various data set during use up to that time may become random. is there. In such a case, an AC (all clear) switch for clearing the data up to that point is provided before reuse. That is, FIG.
As shown in FIG. 9, an inverted U-shaped clear terminal plate 40 is mounted on the lower housing 19 so that it can be electrically connected to the memory controller. Further, as the terminal member forming a pair with the clear terminal plate 40, the base plate 22 is formed with a pressing terminal portion 41 which can be flexed in the vertical direction by utilizing elasticity. Therefore, from the steady state as shown in FIG. 8, during the all clear operation, the small diameter rod jig 42 with a sharp tip is used.
When the pressing terminal portion 41 of the main plate 22 is pushed down and bent by the rod jig 42 by using, the pressing terminal portion 41 comes into contact with the lower clear terminal plate 40, and the clear signal due to the electrical contact is stored in the memory. It is designed to be sent to the control unit.
In the lower housing 19, a pair of (+) (-) electrode plates 43, 4
4 from the battery 20 via the terminal board 45 and the LSI board 1
The voltage is supplied to the 5 side.

[0013]

As described above, the screw holding structure according to the present invention is particularly suitable for screw fastening of parts in a precision small equipment such as a wrist watch, and a plurality of kinds of devices such as an LSI substrate are provided in a body case of the equipment. When co-tightening electronic parts, such an LSI board can be dropped from the drop step part due to the inclined surface provided on the screwing boss part, so it is impossible to fit it as a precision part as in the past due to finish processing accuracy error etc. Problems such as damage are prevented, and it is effective in improving workability and protecting parts when tightening many precision parts together.

[Brief description of drawings]

FIG. 1 is a plan view of a wrist watch to which a screw holding and fastening structure according to the present invention is applied.

FIG. 2 is an exploded perspective view of a wristwatch module.

FIG. 3 is an assembled bottom view of the module.

FIG. 4 is an assembly cross-sectional view of a plurality of parts by the screw holding structure according to the embodiment.

FIG. 5 is a cross-sectional view showing a mode during assembly by the screw holding structure of the embodiment.

FIG. 6 is a cross-sectional view showing a state after assembly by the screw holding structure of the embodiment.

FIG. 7 is an exploded perspective view of a wristwatch to which the screw holding structure of the embodiment is applied and which has an all-clear terminal.

FIG. 8 is a sectional view showing an all-clear mode in a wristwatch to which the screw holding structure of the embodiment is applied.

FIG. 9 is a sectional view showing an all-clear mode in a wristwatch to which the screw holding structure of the embodiment is applied.

[Explanation of symbols]

 1 case body 3 display section 10 module 11 back cover 15 LSI substrate 19 lower housing 20 battery 22 base plate 23 flat machine screw 25 boss section 25a base section 25b main body section 25c inclined step section

Claims (3)

[Claims] 1. When a plurality of parts are stacked and fastened together on a main body case of a device, a plurality of boss portions with through holes or female threads for positioning the parts are provided upright on the main body case, and each part is attached to each part. Is a screw fastening structure in which multiple fastening holes are inserted through the outer diameter of the boss with a predetermined fitting margin, and each component is fastened together with a screw through the boss. The base portion is formed so as to have the fitting margin between the outer diameter of the base portion and the fastening hole of each component, and the outer diameter of the main body portion is smaller than that of the base portion and is stepped. And screw fastening structure. 2. The screw fastening structure according to claim 1, wherein a step portion between the base portion and the main body portion is formed by an inclined surface. 3. The device is a wristwatch, and one of a plurality of components which are positioned by inserting into a boss portion provided on the main body case and are fastened together is an LSI substrate. The screw fastening structure according to 1.