JPH0352038Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of the Invention The present invention relates to a small timer having an operating axis for time adjustment.

(b) Prior art and its problems Conventionally, this type of timer (for example, Utility Model 40540
When adjusting the timer setting operation by implementing the electronic circuit (No. 1) in an electronic circuit, there was a problem in that when the timer setting operation was performed, electrostatic induced current due to static electricity from the human body entered the electronic circuit through the volume and was likely to destroy semiconductor elements. .

(c) Purpose of the invention In order to solve the above problems, the present invention has developed a small timer that can protect the electronic circuit connected to the volume by bypassing the static electricity applied to the operation shaft of the volume to the ground. The purpose is to provide a structure for

(d) Structure of the invention The small timer of the invention forms a timer circuit between two upper and lower printed circuit boards supported at a distance from each other, is housed in a dual in-line package, and is mounted on the lower printed circuit board. The operation shaft of the time limit setting volume, which has been set up, faces the through hole provided on the upper printed circuit board, and the operation insulating cap, which is attached to the upper end of the operation shaft, is exposed through the operation hole on the top surface of the package. A grounding conductive pattern is formed around the operating shaft operation hole of the printed circuit board so that human body static electricity applied through the operating driver is bypassed to the ground through the grounding conductive pattern.

(E) Description of Embodiment The figure shows an embodiment of the small timer of the present invention. In FIG. 1, 1 is a main body of a dual in-line type package, 2 is a cover, and a timer circuit formed over two upper and lower printed circuit boards 3 and 4 is housed inside the cover. Both printed circuit boards 3 and 4 are connected to two pillars 5 and the upper printed circuit board 3
They are supported at a distance from each other by output relays 6 attached to the lower surfaces of the circuit boards, and circuit components 8 are attached to conductive patterns 7 formed on each printed circuit board. Both pillars 5 are used as a power line and an earth line connecting both printed circuit boards 3 and 4, and external connection pins 9 are led out from each printed circuit board. A volume 10 is fixed on the upper surface of the lower printed circuit board 4, and its operating shaft 11 is exposed through an operating shaft through hole 12 provided in the upper printed circuit board 3, and is covered with a D-cut portion at the upper end of the operating shaft 11. A driver groove 14 is cut into the upper surface of the attached insulating cap 13. This insulation cap 13
The upper surface is located slightly inside the operating hole 15 provided in the cover 2 of the package, or the third
As shown in the figure, it is configured to slightly protrude outward from the through hole 15. A grounding conductive pattern 16 is formed on the upper surface of the upper printed circuit board 3 around the operating shaft through hole 12, and the lower edge of the insulating cap 13 comes into sliding contact with the grounding conductive pattern 16.

(f) Effects of the invention The small timer of the invention is constructed as described above, in which the lower edge of the insulating cap attached to the upper end of the operating shaft of the volume connects to the ground formed on the upper surface of the upper edge printed circuit board. Since the grounding conductive pattern is in contact with the grounding conductive pattern, the electrostatic shielding effect of the grounding conductive pattern and the static electricity accumulated in the operator's body by touching the insulating cap with a screwdriver or hand are transmitted to the operating shaft through the surface of the insulating cap. At the front, the flow flows towards the grounding conductive trace with a shorter creepage distance than the operating shaft, which is transmitted through the conductive column to the grounding conductive trace on the lower printed circuit board, and then through the earthing connection pin to the external circuit. The advantage of bypassing the ground line is that there is no risk of static electricity affecting the timer circuit or external circuits and destroying semiconductor components.

[Brief explanation of drawings]

The figures show an embodiment of the small timer of the present invention, in which Figure 1 is an exploded perspective view, Figure 2 is a sectional view of the main parts,
FIG. 3 is an overall side view. 1...Package body, 2...Package cover, 3...Upper printed circuit board, 4...Lower printed circuit board, 5...Strut, 6...Output relay, 7...
Conductive pattern, 8...Circuit component, 9...External connection pin, 10...Volume, 11...Operation axis, 1
2... Operating shaft through hole, 13... Insulating cap, 1
4...Driver groove, 15...Operation through hole, 16...
...Conductive pattern for grounding.

Claims (1)

[Scope of utility model registration request] A timer circuit is formed between two upper and lower printed circuit boards supported at a distance from each other and housed in a package, and the operating shaft of the time setting volume mounted on the lower printed circuit board is mounted on the upper printed circuit board. In a configuration in which the insulating cap for coaxial operation, which is protruded and attached to the upper end of the operating shaft, is exposed on the top surface of the package, a conductive pattern for grounding is formed around the operating shaft through hole of the upper printed circuit board,
A small timer consisting of the lower edge of the above-mentioned insulating cap that is in sliding contact with a conductive pattern for grounding.