JP3030212B2 - Electronic thermometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic thermometer.

[0002]

2. Description of the Related Art As shown in FIG. 2, as a switch structure of a conventional electronic thermometer, a rubber elastic switch 21 coated with silicon grease or the like is provided with a resin molded body case 22.
Is fixed by being sandwiched between the rib 23 and the circuit board 24 as disclosed in JP-A-62-123532.

However, such a switch structure has the following drawbacks in terms of structure.

One of them is a main body case 22 and a circuit board 2.
4, the close contact between the main body case 22 and the rubber switch 21 is maintained. When an external force is applied to the rubber switch 21 or the main body case 22, the force is applied to the rubber switch. 21 is applied as bending stress to the circuit board 24 via the support portion 25 of the circuit board 21 and the circuit board 24 is deteriorated.

Since the circuit board 24 and the rubber switch 21 are always in contact with each other via the support 25, at least the support 25 of the rubber switch 21 needs to be formed of a non-conductive material. Yes, and rubber switch 21
The contact piece 26 needs to be formed of a conductive material, and the cost of the rubber switch 21 is high.

Further, when the rubber switch 21 receives some external pressure, the degree of adhesion between the main body case 22 and the rubber switch 21 is weakened, and the waterproof performance is also deteriorated. For this reason, a waterproof component such as an O-ring has been required.

[0007]

As described above, the above-mentioned conventional electronic thermometer has a problem that when any external force is applied to the rubber switch, the main body case, etc., the circuit board and the waterproof performance are deteriorated. .

Further, it is necessary to constitute the rubber switch with a conductive portion and a non-conductive portion, and there is a problem that it is difficult to reduce the cost.

SUMMARY OF THE INVENTION The present invention has been made in order to solve such a problem, and an electronic thermometer which does not deteriorate the circuit board and waterproof performance due to external pressure or the like and can reduce the cost of the switch portion is provided. It is intended to provide.

[0010]

According to a first aspect of the present invention, there is provided an electronic thermometer, comprising: a housing having a hole for mounting a switch; The provided tapered rib and the U-groove provided on the outer peripheral portion are fitted into the rib to support the entire switch, and the conductive contact piece that strokes inward by a pressing force from outside the housing is formed by the conductive contact piece. An electronic circuit having a resilient switch protruding into the housing and a contact portion at a position corresponding to the conductive contact and disposed at a distance within a stroke range of the conductive contact in the housing. And a substrate.

According to a second aspect of the present invention, there is provided the electronic thermometer according to the first aspect, wherein the elastic switch comprises:
It is a conductive elastic switch provided with a U-shaped groove mainly made of silicon rubber.

According to a third aspect of the present invention, there is provided an electronic thermometer according to the first aspect, wherein the elastic switch has a U-shaped switch.
A high-viscosity lubricant such as silicone grease is filled in a fitting portion between the groove and the rib.

According to a fourth aspect of the present invention, there is provided the electronic thermometer according to the first aspect, wherein the rib protruding from the perimeter of the perforation of the housing has a width such that a base thereof is pressed against the opening of the U groove. Besides, when the switch is pressed, the base to the tip are formed in a tapered shape so that the tip draws a locus along the inner periphery of the bottom of the U-groove with the press contact portion as a fulcrum. I have.

According to a fifth aspect of the present invention, there is provided the electronic thermometer according to the first aspect, wherein a distance between the conductive contact piece of the elastic switch and the contact portion of the electronic circuit board is:
It is characterized in that the distance is such that the conductive contact piece can maintain the non-contact state when the center of the elastic switch is not pressed, and is within the stroke range of the conductive contact piece.

[0015]

According to the first aspect of the present invention, the rib of the housing is fitted in the U groove of the elastic switch to support the elastic switch.
When the elastic switch is not turned on, the conductive contact of the elastic switch is separated from the electronic circuit board within its stroke range.

Therefore, even if an external force is applied to the elastic switch or the housing, the force is not transmitted to the electronic circuit board.

As a result, the circuit board and the waterproof performance do not deteriorate due to the external pressure applied to the elastic switch.

According to the second aspect of the present invention, since the elastic switch is a conductive elastic switch provided with a U-shaped groove mainly made of silicon rubber, the switch itself can be integrally molded, and the cost can be reduced. .

Further, since the high-viscosity lubricant such as silicon grease is filled in the fitting portion between the U-shaped groove and the rib of the elastic switch, the waterproofness can be maintained.

According to the fourth aspect of the present invention, the base of the rib protruding from the perimeter of the perforation of the housing has a width which is pressed against the opening of the U-groove, and when the switch is pressed, the U-groove is formed with the pressed portion as a fulcrum. The tapered rib and the U-shaped groove 7 reduce the mutual pressing force to three places because the base to the tip are formed in a tapered shape so that the tip draws a locus along the bottom inner circumference. Even if the contact surface is uneven due to a shape error or the like, the sealing effect is maintained and the waterproofness can be improved.

According to the fifth aspect of the present invention, the separation distance between the conductive contact piece of the elastic switch and the contact portion of the electronic circuit board is such that the conductive contact piece is in a non-contact state in a state where the center portion of the elastic switch is not pressed. Therefore, stress is not applied to the electronic circuit board due to external pressure or the like.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an electronic thermometer according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a main body case. The main body case 1 is formed of a resin material or the like. The body case 1 is provided with a perforation 3 for attaching an elastic switch 2. The perforations 3 are provided with ribs 4 from the peripheral edge toward the inside. This rib 4
As shown in the enlarged view of the fitting portion (in the dotted circle), the base 5
Is formed in a tapered shape so as to become thinner toward the distal end portion 6.

The elastic switch 2 is a U-shaped grooved elastic switch with conductive rubber mainly made of silicon rubber or the like. That is, the elastic switch 2 is provided with a U-shaped groove 7 for press-fitting the rib 4 on the outer peripheral portion thereof, and a conductive contact piece 8 is formed at the center thereof toward the inside of the main body case 1.
Are protruding. The contact piece 8 is connected to the elastic switch 2.
It is integrally formed by using a conductive material for itself. If only the contact piece portion 8 is conductive, it may be bonded to the elastic switch 2 having no conductivity.

The U-shaped groove 7 of the elastic switch 2 and the rib 4 of the main body case 1 are fitted after applying a high-viscosity lubricant such as silicon grease. As a result, the entire elastic switch 2 is supported by the ribs 4 of the main body case 1.

The base 5 of the rib 4 is provided with an opening 7a of the U-shaped groove 7.
Is formed in such a width as to be pressed against. Also, the tip 6 of the rib 4
Is formed in a semicircular shape so as to draw a locus along the inner periphery of the bottom 7b of the U-shaped groove 7 with the pressure contact portion between the base 5 and the U-shaped groove 7 as a fulcrum when the switch is pressed.

At the fitting portion between the rib 4 of the main body case 1 and the U-shaped groove 7, a press-contact force is generated particularly at the opening 7a of the U-shaped groove 7, and the close contact state is maintained. The high-viscosity lubricant applied to the ribs 4 remains in the minute gap 9 in the fitting portion, and the gap is filled, so that the main body case 1 and the elastic switch 2 have a completely waterproof structure against the outside. ing.

An electronic circuit board 10 is mounted in the main body case 1. The electronic circuit board 10 is provided with a contact portion 11 at a position corresponding to the contact piece 8 of the elastic switch 2 and separated by a predetermined distance, a temperature measurement calculation circuit, a display control circuit, and a power supply control circuit. Etc. have been implemented. Distance (predetermined distance) between contact portion 11 of electronic circuit board 10 and contact piece 8 of elastic switch 2
Is a distance that allows the contact piece 8 and the contact 11 to maintain a non-contact state when the central portion of the conductor switch 2 is not pressed for switch-on (normal state), and The center portion of the second member 2 is within the stroke range of the contact piece portion 8 that is elastically deformed.

In the case of this electronic thermometer, a high-viscosity lubricant such as silicon grease is applied to the ribs 4 of the main body case 1 and then the elastic switch 2 is pressed into the perforations 3 of the main body case 1 so that the U-shaped groove is formed. 7 is elastically deformed and fitted to the rib 4. Thus, the elastic switch 2 is supported by the ribs 4 of the main body case 1 while being separated from the electronic circuit board 10 by a predetermined distance.

Therefore, even if an external force is applied to the elastic switch 2, the force is not transmitted to the electronic circuit board 10. Further, within the stroke range of the elastic switch 2, the waterproof performance is maintained by the U-shaped groove 7 filled with silicon grease or the like and the tapered rib 4 which moves while being press-fitted therein.

As described above, according to the electronic thermometer of this embodiment, the entire elastic switch 2 is normally in a non-contact state with the electronic circuit board 10 in the main body case 1.
No bending stress or the like is generated on the electronic circuit board 10.

Further, the taper-shaped rib 4 and the U-shaped groove 7 make the mutual pressing force of the opening 7a and the bottom 7
Since the structure is applied to each of the parts b in a dispersed manner, the sealing effect is maintained even when the contact surface is non-uniform due to a shape error or the like.

Furthermore, since the sealing effect is maintained for loads in both directions of external pressure and internal pressure, there is no deterioration in waterproof performance.

By applying a high-viscosity lubricant such as silicon grease to the rib 4 and fitting the U-shaped groove 7, silicon grease remains in the minute gap 9 between the U-shaped groove 7 and the rib 4,
Since it is in a filled state, it can maintain a stable waterproof ability for a long time.

Furthermore, in the normal state where the switch is not turned on (the state where the power is not turned on), the elastic switch 2 does not come into contact with the electronic circuit board 10, so that the entire switch can be formed as a single molded conductor, thereby reducing the cost. Can be achieved.

Further, since the main body case 1 and the elastic switch 2 do not come into contact with portions other than the contact portion 11 of the electronic circuit board 10 and the board fixing portion, there is no restriction on the electronic component mounting surface of the electronic circuit board 10. Therefore, the degree of freedom in the layout of the substrate mounting is increased.

Further, since the U-shaped groove 7 and the tapered rib 4 can completely waterproof, no waterproof parts such as an O-ring are required.

Although the present invention relates to the switch portion of the electronic thermometer, the present invention can also be applied to other electronic devices requiring waterproofing, for example, a switch portion of an underwater camera or a waterproof radio.

[0040]

As described above, according to the first aspect of the present invention, since the U-groove of the elastic switch is fitted into the rib of the housing and the elastic switch is supported separately from the electronic circuit board. Even if an external force is applied to the elastic switch or the housing, the bending stress is not transmitted to the electronic circuit board, and the deterioration of the electronic circuit board can be prevented.

According to the second aspect of the present invention, since the elastic switch is a conductive elastic switch provided with a U-shaped groove mainly made of silicon rubber, the switch itself is integrally formed of a conductive elastic body. And cost reduction can be achieved.

According to the third aspect of the present invention, since the high-viscosity lubricant such as silicon grease is filled in the fitting portion between the U groove and the rib of the elastic switch, it is possible to improve waterproofness. it can. Therefore, an O-ring or the like is unnecessary.

According to the fourth aspect of the present invention, the base of the rib has a width to be pressed against the opening of the U-groove, and when the switch is pressed, the rib contacts the fulcrum along the inner periphery of the bottom of the U-groove. The tapered rib and the U-shaped groove 7 form a structure in which the mutual pressing force is distributed to three places because the tapered rib and the U-shaped groove 7 form a tapered shape so that the leading end traces a locus. Even when the contact surface is non-uniform due to an error or the like, the sealing effect is maintained, and the waterproofness can be improved.

According to the fifth aspect of the present invention, the distance between the conductive contact piece of the elastic switch and the contact portion of the electronic circuit board is set such that the conductive contact piece is not pressed while the center portion of the elastic switch is not pressed. Since the distance is such that the contact state can be maintained, no stress is applied to the electronic circuit board due to external pressure or the like.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a switch structure portion of an electronic thermometer according to an embodiment of the present invention.

FIG. 2 is a diagram showing a switch structure of a conventional electronic thermometer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Body case, 2 ... Elastic switch, 3 ... Perforation, 4 ...
Ribs, 5: rib base, 6: rib tip, 7: U-shaped groove, 8: contact piece, 9: minute gap. 10. Electronic circuit board,
11 ... Contact part.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01H 13/06

Claims (5)

(57) [Claims] 1. A housing having a hole for mounting a switch, a tapered rib protruding inward from a peripheral edge of the hole of the housing, and a U-groove provided on an outer peripheral portion is fitted to the rib. An elastic switch in which the entire switch is supported, and a conductive contact piece that strokes inward by a pressing force from outside the housing projects toward the housing; and a stroke of the conductive contact piece in the housing. An electronic clinical thermometer, comprising: an electronic circuit board which is disposed at a distance in a range and has a contact portion at a position corresponding to the conductive contact piece. 2. The electronic thermometer according to claim 1, wherein the elastic switch is a conductive elastic switch provided with a U-shaped groove mainly made of silicon rubber. 3. The electronic thermometer according to claim 1, wherein a high-viscosity lubricant such as silicon grease is filled in a fitting portion between the U-shaped groove and the rib of the elastic switch. . 4. The electronic thermometer according to claim 1, wherein the rib protruding from the perimeter of the perforation of the housing has a width whose base is pressed against the opening of the U-groove and is pressed when the switch is pressed. An electronic thermometer, wherein a portion from the base to the tip is tapered so that the tip traces along the inner circumference of the bottom of the U-groove with the portion as a fulcrum. 5. The electronic thermometer according to claim 1, wherein a distance between a conductive contact piece of the elastic switch and a contact portion of the electronic circuit board is such that the conductive part is in a state where a central part of the elastic switch is not pressed. An electronic thermometer, wherein the contact piece has a distance capable of maintaining a non-contact state, and is within a stroke range of the conductive contact piece.