JP7496791B2 - Electrical Equipment - Google Patents

Description

The present invention relates to an electric device , and more particularly to an electric device suitable for being incorporated in , for example, an electric vacuum cleaner having an electric motor , and having a circuit board with a static electricity protection pattern.

Background art in this technical field can include Patent Documents 1 , 2, and 3. Patent Documents 1 and 2 describe a circuit board in which a circuit is surrounded by a static electricity protection pattern, and Patent Documents 2 and 3 describe a circuit board provided with an acute-angled conductor portion for discharging static electricity.

Japanese Patent No. 3690519 JP 2001-308586 A Japanese Patent Application Laid-Open No. 10-321398

In FIG. 1 and paragraph 0011 of Patent Document 1, which is a prior art document, it is stated that "A static electricity protection pattern 3A for discharging static electricity is formed around the internal circuit 2 on which electronic components (not shown) are arranged on the substrate 1 and near the edge of the substrate 1 in order to protect the electronic components of the internal circuit 2 from static electricity from the outside." As such, one method for protecting a circuit substrate from static electricity is to add insulating components such as resin, sheet, or tape between the gap of the housing and the circuit substrate to ensure an insulating distance. However, this method requires the provision of additional resin, sheet, or tape, which increases costs and makes it difficult to miniaturize the product. In addition, as another method for protecting a circuit substrate from static electricity, it is known that a static electricity protection pattern can be provided on the circuit substrate to provide a low-cost protection measure. However, if such a static electricity protection pattern is formed only for discharging static electricity, there is a problem that the area on the circuit substrate where components can be arranged and pattern wiring can be performed is reduced, making it difficult to miniaturize the circuit substrate and electronic device.

Furthermore, in paragraph 0018 of Patent Document 2, it is stated that "round dot-shaped land parts may be arranged closely together in this region 212 and solder may be applied there to induce more electrostatic discharge," and in paragraph 0014 of Patent Document 3, it is stated that "static electricity that has entered from outside the housing is actively discharged to the acute angle part of the end face through hole, preventing the destruction of electrical components and malfunction of circuits due to the intrusion of static electricity into other electrical circuits," so for example, since it is difficult to discharge static electricity protection patterns covered with resist, which is an insulating material of the circuit board, there are measures to make it easier to discharge static electricity by providing lands to expose copper foil, or by providing solder fillets and acute angles of through holes. However, adding such measures further increases the area used for the static electricity protection pattern just for discharging static electricity, and reduces the area on the circuit board where components can be arranged and pattern wiring is possible, which makes it difficult to miniaturize the circuit board and electronic devices.
The present invention has been made in consideration of the above-mentioned points, and an object of the present invention is to provide an electrical device that can protect a circuit board from static electricity without reducing the area on the circuit board where components can be arranged and pattern wiring can be performed, and that allows the board and electronic device to be miniaturized.

In order to achieve the above-mentioned object, the electrical device of the present invention is an electrical device comprising a housing, an electric motor incorporated in the housing, and a circuit board incorporated within the housing , wherein the housing has an opening, the circuit board is arranged in the vicinity of the opening , the circuit board comprises a drive element for driving the electric motor, and a control circuit for operating the drive element, and the insulation distance from a pattern on the circuit board that passes current through the drive element to the opening is shorter than the insulation distance from the control circuit to the opening .

The present invention makes it possible to protect a circuit board from static electricity without reducing the area available for component placement and pattern wiring on the circuit board, thereby enabling the miniaturization of boards and electronic devices.

FIG. 1 is a perspective view showing an example of an electrical device of the present invention, which is a vacuum cleaner incorporating a circuit board. FIG. 2 is a side view of the vicinity of an external housing of the vacuum cleaner shown in FIG. 1 . 3 is a cross-sectional view taken along line AA' in FIG . 2. FIG. 13 is a partially enlarged cross-sectional view of a vacuum cleaner incorporating a circuit board to which the present invention is not applied, illustrating the path of electrostatic discharge. FIG. 2 is an explanatory diagram of a circuit board used in a vacuum cleaner, which is an example of the electrical appliance of the present invention. FIG. 2 is a partially enlarged cross-sectional view of a vacuum cleaner incorporating a circuit board used in the vacuum cleaner, which is an example of the electrical appliance of the present invention, and is an explanatory diagram of a static electricity discharge path. FIG. 2 is an explanatory diagram of a land provided in a static electricity protection pattern of a circuit board used in an electric vacuum cleaner, which is an example of the electric device of the present invention. 1 is an explanatory diagram of a through-hole provided in a static electricity protection pattern of a circuit board used in a vacuum cleaner, which is an example of the electrical device of the present invention. FIG.

The following describes in detail the form for carrying out the present invention (hereinafter referred to as "embodiment") with reference to the drawings as appropriate.

FIG. 1 is a perspective view of a vacuum cleaner 1 powered by a battery 2. The vacuum cleaner 1 includes a fan motor 5, which is an electric motor, inside an external housing 10 made of resin, and a suction port motor 6, which is also an electric motor, inside an electric suction port 4. The fan motor 5 is , for example, a three-phase brushless motor, and the suction port motor 6 is , for example, a DC motor. The battery 2 is , for example, a lithium ion battery, so that it can be charged and used repeatedly, and does not require a power cord, making it easy to carry. Note that , although the present embodiment is directed to a vacuum cleaner 1 powered by a battery 2, the present invention can also be implemented in a vacuum cleaner powered by a commercial power source.

Fig. 2 is a side view of the vicinity of the external housing 10 of the vacuum cleaner 1 shown in Fig. 1. As shown in Fig. 2, the circuit board 20 is incorporated inside the external housing 10 and can drive the fan motor 5 and the suction motor 6. The external housing 10 also has an opening 12 as an exhaust port, and after dust is collected in the dust case 3 by the wind sucked in by the fan motor 5, the air is exhausted from the opening 12, which is the exhaust port, via a filter. The circuit board 20 is disposed in an air passage, and the wind after collecting the dust cools the circuit board 20 and the driving element 23 (see Fig. 5) on the circuit board 20.

FIG. 3 is a cross-sectional view of the vacuum cleaner taken along line A-A' in FIG. 2. As shown in FIG. 3, the internal housing 11 supports the circuit board 20. A gap 13 is formed at the butt surface of the external housing 10 and the internal housing 11. This gap 13 is a passageway for static electricity no matter how precisely the housings are butted against each other. Therefore, in order to prevent malfunctions or breakdowns caused by static electricity jumping to the circuit board 20, it is usually necessary to take various measures such as not providing the opening 12 , adding insulating parts, or providing a wall in the internal housing 11 to ensure an insulation distance. However, since the vacuum cleaner 1 uses the opening 12 as an exhaust port for the motor, the opening 12 cannot be removed. In addition, when making the product smaller and lighter, it is difficult to ensure an insulation distance by adding insulating parts or providing a wall in the internal housing 11. Therefore, in this embodiment , various measures are taken on the circuit board 20 .

Figure 4 is a partially enlarged cross-section of a vacuum cleaner incorporating a circuit board 20 that does not embody the present invention. The insulation distance at which electrostatic discharge occurs when an object charged in the atmosphere is brought close to another object can be set to 1 mm per 1 kV of potential difference between the objects as a guideline. If the total of the creepage distance and spatial distance from the opening 12 to the circuit board 20 is approximately 10 mm, then when an object charged to 10 kV or more is brought close to the opening 12 of a vacuum cleaner incorporating a circuit board 20 charged to 0 kV, static electricity will be discharged along the electrostatic discharge path 50, which may cause the control circuit 21 on the circuit board 20 to malfunction or fail.

FIG. 5 is an explanatory diagram of a circuit board 20 used in a vacuum cleaner, which is an example of an electrical device of the present invention. As shown in FIG. 5, the circuit board 20 is connected to a battery 2, which is a power source, and includes a control circuit 21 and a driving element 23. The driving element 23 can drive a fan motor 5 and a suction motor 6, which are electric motors. The control circuit 21 is wired and connected to a microcomputer, a transistor, a resistor, a capacitor, an inductor, and the like by patterns, and can pass a current to the driving element 23 and control the operation of the driving element 23. Note that the designer can freely design the driving element 23 within an area 22 in which the control circuit 21 can be placed. The driving element 23 is composed of a MOSFET, a transistor, and the like, and is wired and connected to a pattern ( first pattern) 24 that is connected to the positive pole of the battery 2 and passes a current to the driving element 23 , and a pattern ( second pattern) 25 that is connected to the negative pole of the battery 2 and passes a current to the driving element 23. Here, the control circuit 21 is placed in an area surrounded by the first pattern 24 and the second pattern 25. The first pattern 24 or the second pattern 25 that passes a current to the driving element 23 has a wide pattern width to pass a large current , and has low impedance. As described in FIG. 4, the abutting surface between the external housing 10 and the internal housing 11 forms a gap 13 , so there is a risk of static electricity being discharged to the circuit board 20. Therefore, the first pattern 24 or the second pattern 25 that passes a current to the driving element 23 is wired between the gap 13 and the control circuit 20 to also serve as the static electricity protection pattern 26. Then, the static electricity discharge path 50 takes a path from the opening 12 to the first pattern 24 or the second pattern 25 that passes a current to the driving element 23 , rather than from the opening 12 to the control circuit 21, so that the current due to static electricity discharge flows to the battery 2 or the fan motor 5 , which has a large earth capacitance 32 with respect to the earth ground 31 , and the control circuit 21 can be protected from malfunction or destruction. Although there is a possibility that a current due to electrostatic discharge will flow through the driving element 23, components that can withstand large currents are selected for the driving element 23, and therefore the driving element 23 has the resistance to the current due to electrostatic discharge and is unlikely to break down.

Fig. 6 is a partially enlarged cross-sectional view of a vacuum cleaner incorporating a circuit board 20 used in the vacuum cleaner , which is an example of the electrical device of the present invention. As shown in Fig. 6, the first pattern 24 or the second pattern 25 that passes a current to the driving element 23 is wired so that the insulation distance from the opening 12 to the first pattern 24 or the second pattern 25 that passes a current to the driving element 23 is shorter than the insulation distance from the opening 12 to the control circuit 21, so that the electrostatic discharge path 50 is not from the opening 12 to the control circuit 21, but from the opening 12 to the first pattern 24 or the second pattern 25 that passes a current to the driving element 23. This makes it possible to protect the control circuit 21 from malfunction or failure.

7 is an explanatory diagram of a circuit board 20 used in a vacuum cleaner , which is an example of an electrical device of the present invention , in which a first land 40a and a second land 40b are provided. Here, the first land 40a is a land related to the circuit of the control circuit 21, and is located within the area 22 in which the control circuit 21 can be arranged. The first land 40a is provided for mounting components and for contacting a test pin for inspection. Next, the second land 40b is a land provided on the first pattern 24 and the second pattern 25 that pass a current to the driving element 23 , and when the insulation distance from the gap 13 to the first land 40a is d2, the second land 40b is arranged at a position where the insulation distance from the gap 13 is d1 so that d2>d1. The first land 40a and the second land 40b are not covered with a resist, which is an insulating material, and the copper foil is exposed, so that static electricity is easily discharged, but by arranging them in such a positional relationship, static electricity is discharged to the second land 40b close to the gap 13, and the control circuit 21 can be protected. In addition, the first pattern 24 and the second pattern 25 that pass a current to the driving element 23 are originally designed to be wide as patterns that pass a large current, and there is no need to increase the width in order to add the land 40. It is also possible to make it easier to discharge by applying solder to the second land 40b.

8 is an explanatory diagram of a circuit board 20 used in a vacuum cleaner, which is an example of an electric device of the present invention , in which a first through hole 41a and a second through hole 41b are provided. Here, the first through hole 41a is a through hole related to the circuit of the control circuit 21 , and is located within the area 22 in which the control circuit 21 can be arranged, and is provided for the purpose of connecting patterns between layers by drilling holes in the circuit board 20 and plating when designing a double-sided board or a multi-layer board. Next, the second through hole 41b is a through hole provided on the first pattern 24 and the second pattern 25 that pass a current to the driving element 23 , and is connected to the first pattern 24 and the second pattern 25 that pass a current to the driving element 23 on the back side of the board, and when the insulation distance from the gap 13 to the first through hole 41a is d4, the second through hole 41b is arranged at a position where the insulation distance from the gap 13 is d3, so that d4>d3. The first through-hole 41a and the second through-hole 41b are not covered with resist , which is an insulating material, and the copper foil is exposed, and the holes have acute angles, which makes it easy for static electricity to be discharged. However, by arranging them in this positional relationship, the static electricity is discharged to the second through-hole 41b, which is closer to the gap 13, and the control circuit 21 can be protected. In addition, the first pattern 24 and the second pattern 25, which pass a current to the drive element 23 , are originally designed to be wide as patterns that pass a large current, and there is no need to increase the width to add the second through-hole 41b. By pouring solder into the second through-hole 41b, the reduction in the pattern width due to the hole can be compensated for and the heat dissipation performance of the pattern can be improved.

Although not described, it is also possible to provide static electricity protection by providing a second through hole 41b for the first land 40a, or by providing a second land 40b for the first through hole 41a.

7 and 8, the difference from the prior art is that the second land 40b or the second through hole 41b is not provided on a pattern dedicated to electrostatic protection, but on a pattern that is originally required and has a wide pattern width for passing current to the drive element 23 , thereby making it possible to improve the electrostatic protection effect without reducing the mounting area of the board.

REFERENCE SIGNS LIST 1 Vacuum cleaner 2 Battery 3 Dust case 4 Electric suction nozzle 5 Fan motor 6 Suction nozzle motor 10 External housing 11 Internal housing 12 Exhaust port 13 Gap 20 Circuit board 21 Control circuit 22 Area in which control circuit can be arranged 23 Drive element 24 First pattern for passing current to drive element 25 Second pattern for passing current to drive element 26 Static electricity protection pattern 30 Circuit ground 31 Earth 32 Capacitance to ground 40a First land 40b Second land 41a First through hole 41b Second through hole 50 Electrostatic discharge path

Claims (7)

An electric device comprising a housing, an electric motor incorporated in the housing, and a circuit board incorporated in the housing ,
The housing has an opening,
The circuit board is disposed near the opening,
the circuit board includes a drive element for driving the electric motor and a control circuit for operating the drive element;
The electrical device according to claim 1, wherein an insulation distance from a pattern for passing a current to the drive element on the circuit board to the opening is shorter than an insulation distance from the control circuit to the opening. 2. The electrical device according to claim 1 ,
the circuit board is connected to a battery;
The electrical device is characterized in that the pattern for passing current through the driving element includes a first pattern connected to the positive terminal of the battery for passing current through the driving element , and a second pattern connected to the negative terminal of the battery for passing current through the driving element. 3. The electrical device according to claim 2,
The electrical device, wherein the control circuit is disposed within an area surrounded by the first pattern and the second pattern. 4. An electrical device according to claim 1,
the circuit board includes a first land associated with the control circuit and a second land arranged on a pattern for passing a current to the drive element;
an insulation distance from the second land on the circuit board to the opening is shorter than an insulation distance from the first land to the opening . 4. An electrical device according to claim 1,
the circuit board includes a first through hole associated with the control circuit and a second through hole arranged on a pattern for passing a current to the drive element;
An electrical device, wherein an insulation distance from the second through hole on the circuit board to the opening is shorter than an insulation distance from the first through hole to the opening. The electrical device according to any one of claims 1 to 5,
The electrical appliance is characterized in that it is an electric vacuum cleaner. 7. The electrical device according to claim 6 ,
The vacuum cleaner is an electric appliance characterized in that the opening is used as an exhaust port for the electric motor .

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