JPH0562788A - Static electricity-resistant structure for electric apparatus - Google Patents

Abstract

PURPOSE:To prevent the erroneous action of an apparatus by releasing the static electricity accumulated on a secondary side charge section to the outside. CONSTITUTION:A secondary side charge section 12 is exposed on the surface of a main body 2 of an electric apparatus constituted of a container 1 and the main body 2. The first and second input section patterns 31, 32 connected to the secondary side charge section 12 and an earth section pattern 33 connected to the earth are formed on a printed board 14 stored in the main body 2. The first and second input section patterns 31, 32 and part of the earth section pattern 33 are located nearby across a discharge gap. The first and second input section patterns 31, 32 and the earth section pattern 33 can be connected via capacitors C1, C2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a static electricity resistant structure of an electric device such as a brewer, a coffee maker, etc., in which a main body and a container are separable from each other and controlled by a microcomputer. ..

[0002]

2. Description of the Related Art Conventionally, in this kind of electric equipment, a temperature sensor for detecting the temperature of the liquid in the container is provided in the container separable from the main body. Then, in order to connect the temperature sensor on the container side to the microcomputer on the printed circuit board on the main body side, the container and the main body are respectively provided with connection terminals that conduct when the container is set in the main body.
A voltage of a DC power supply (secondary side) obtained from an AC power supply (primary side) is applied to the main body side connection terminal (hereinafter, this main body side connection terminal is referred to as a secondary side charging unit). When the container is set in the main body, the secondary side voltage is applied to the temperature sensor. When the temperature sensor detects a predetermined temperature, the temperature detection signal is input to the microcomputer on the printed board via the connection terminal.

[0003]

The secondary charging section is
It is exposed on the surface of the main body so as to conduct with the connection terminal on the container side. For this reason, static electricity is generated by the human body touching the secondary charging section or contact with peripheral members, and the static electricity enters the secondary charging section and enters the input port of the microcomputer. The computer sometimes malfunctioned. It is an object of the present invention to solve such a problem, and an object thereof is to provide an antistatic structure for an electric device, which allows the static electricity on the secondary side charging unit to escape to the outside and prevent a malfunction of the device. To do.

[0004]

In order to achieve the above object, the present invention relates to an electric device in which a secondary-side charging section is exposed on the surface of the device. The input part pattern connected to the side charging part and the ground part pattern connected to the ground are formed,
The input part pattern and a part of the ground part pattern are arranged close to each other with a discharge gap. It is also possible to connect the input pattern and the ground pattern via a capacitor.

[0005]

In the above structure, the high voltage component containing the high frequency of the static electricity on the secondary side charging section flows into the input section pattern of the printed circuit board and is discharged to the ground section pattern through the discharge gap. Escape to the ground through the pattern. Also, in the case where the input part pattern and the ground part pattern are connected by a capacitor, the high frequency component of static electricity is
The capacitor is short-circuited from the input part pattern, flows to the ground part pattern, and escapes to the ground.

[0006]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows a Chinese medicine decoctioner having an anti-static structure according to the present invention, where 1 is a container and 2 is a main body. The container 1 is made of heat-resistant glass, has a detachable lid 3 and a handle 4, and is configured to accommodate water and herbal medicine materials inside.
A steam passage 7 is formed in the lid 3 from the steam hole 5 on the inner surface to the steam port 6 on the outer surface, and a steam sensor 8 is provided in the steam passage 7. The steam sensor 8 is turned on (conducting) when the water is exposed to the steam before boiling.
When exposed to steam at the time of boiling, it turns off (non-conducting). The lead wires of both terminals of the vapor sensor 8 are connected to a pair of electrode pins 9a and 9b provided on the lower portion of the handle 4.

The main body 2 is provided with a heating plate 10 on which the container 1 is placed, and a halogen lamp heater 11 is attached to the back surface of the heating plate 10 to heat the water in the container 1 to boil it. You can do it. Further, the main body 2 is provided with a pair of electrodes 12a and 12b elastically supported by a spring (not shown), and the electrodes 12a and 12b together with the electrode pins 9a and 9b of the container 1 are provided with the vapor sensor 8
When the container 1 is placed on the heating plate 10 of the main body 2, the connection portion 13 of the output circuit is formed so that the container 1 is brought into pressure contact with the electrode pins 9a and 9b to be electrically conducted. The electrodes 12a and 12b are connected to a microcomputer 27, which will be described later, of the printed board 14 housed in the main body 2.

FIG. 2 shows an electric circuit of this decoction device. A halogen lamp heater 11 is connected to an AC power source 21 via a relay contact 22. This AC power supply circuit is provided with a 12V DC power supply circuit 24 and a 5V DC power supply circuit 25 via a transformer 23. 12V DC power supply circuit 2
A relay drive circuit 26 is connected to 4. A microcomputer 27 is connected to the 5V DC power supply circuit 25. The microcomputer 27 has an input port for receiving a temperature detection signal from the temperature detection circuit 28 having the vapor sensor 8 and an output port for outputting a drive signal to the relay drive circuit 26.

FIG. 3 shows the temperature detection circuit 28, which is described above.
The DC voltage (Vdd) from the V DC power supply circuit 25 is the resistance R
₁ and R ₂ (both are 1 KΩ) are connected to one electrode 12a of the main body 2 and the other electrode 12b is connected to resistors R ₃ and R
It is connected to the input port K ₀ of the microcomputer 27 via ₄ (both 1 KΩ) and a resistor R ₅ (10 KΩ). Electrodes 12a, 12b are connected to ground via a capacitor C _1, C _2, respectively. Also, the midpoint of the resistors R _1, R ₂ are their resistance R _1, much higher resistance than R ₂ R ₆ via (1 M.OMEGA) is connected to ground, similarly the resistors R _3, R ₄ The midpoint is connected to ground via a resistor R ₇ (1 MΩ) which is much higher than them and the resistor R ₆ . D ₁ and D ₂ are protective diodes, C ₃ is a protective capacitor, R ₈ is a voltage setting resistor for the K ₀ port, and R ₉ is an electrostatic attenuation resistor.

FIG. 4 shows a partially enlarged view of the pattern of the printed circuit board 14, 31 is a first input portion pattern having a through hole A connected to the electrode 12a, and 32 is an electrode 1
It is the 2nd input part pattern which has the through hole B connected to 2b. Further, 33 is a ground portion pattern having a through hole C connected to the ground. The corners of the first input part pattern 31 and the second input part pattern 32 that are close to each other are close to the protrusions 34 of the ground part pattern 33 with a discharge gap. The first and second input section patterns 31, 32, the ground section pattern 33, and other patterns are provided with resistors, according to the wiring diagram of FIG.
Parts such as capacitors are connected.

CPU of the microcomputer 27
Controls the halogen lamp heater 13 by outputting a drive signal to the relay drive circuit 26 in cooperation with the built-in timer according to the program stored in the ROM based on the input signal from the start key (not shown) and the temperature detection signal. It is supposed to do. That is, container 1 containing water and Chinese herbal medicine
When is placed on the heating plate 10 of the main body 2, the electrode pin 9 of the container 1 and the electrode 12 of the main body 2 are brought into contact with each other, the connecting portion 13 is conducted, and the output circuit of the vapor sensor 8 is closed. Next, when the power is turned on, the microcomputer 27 outputs a heater on signal. As a result, the relay drive circuit 26 operates and the relay contact 22 is closed. As a result, the heater 11 is energized to start boiling water. The water in the container 1 boils,
When the output circuit of the vapor sensor 8 is opened, the microcomputer 27 outputs a heater off signal. This allows
The relay drive circuit 26 is stopped, the relay contact 22 is disengaged, and the power supply to the heater 11 is stopped. After that, heater 1
After 1 is turned on and off, decoction of Chinese herbal medicine is performed for a predetermined time.

In this decoction device, the electrodes 12a and 12b, which are the secondary charging parts, are exposed on the surface of the main body.
There is a risk that static electricity may be applied to the human body by touching it. Electrode 12
The static electricity on a flows to the first input portion pattern 31 of the printed board 14. Here, of the high frequency components of the static electricity, the high voltage component including the high frequency is discharged to the protrusion 34 of the ground portion pattern 33 which is in close proximity with the discharge gap and escapes to the ground. It never flows into K ₀ . Further, the high frequency component of the high frequency component of static electricity flows to the ground pattern 33 by short-circuiting the capacitor C ₁ and escapes to the ground.
It does not flow to the input port K ₀ of the microcomputer 27.

Similarly, the static electricity on the electrode 12b flows to the second input portion pattern 32 of the printed circuit board 14, of which the high voltage component including high frequency is discharged to the ground portion pattern 33 through the discharge gap, and Since the high frequency component escapes to the ground via the capacitor C ₂ , it does not flow into the input port K ₀ of the microcomputer 27.
Therefore, the electrodes 12a, 12 exposed on the surface of the body 2 are
Even if static electricity is placed on b, the static electricity escapes to the ground and does not flow to the input port K ₀ of the microcomputer 27, so that the microcomputer 27 does not malfunction. In the present embodiment, the present inventors have confirmed that static electricity up to 8 KV can be completely released.

The first and second input part patterns 31, 3
The pattern arrangement of the 2 and the ground portion pattern 33 is not limited to that of the above-mentioned embodiment, but can be changed to various shapes as shown in FIGS. In FIG. 5, the ground portion pattern 33 is formed so as to cover the periphery of the first and second input portion patterns 31 and 32, and a discharge gap is formed at each corner of the first and second input portion patterns 31 and 32. Two protrusions 34a, 34b are formed adjacent to each other with a gap between them. Further, in FIG. 6, similarly to FIG. 5, the ground portion pattern 33 is formed so as to cover the first and second input portion patterns 31, 32, and the projection portion 34c of the ground portion pattern 33 is formed in a rectangular shape. The two corners are arranged close to the circular ends of the first and second input part patterns 31 and 32, respectively. The discharge action is the same as that of the embodiment shown in FIG. 4, and the description thereof is omitted.

[0015]

As is apparent from the above description, according to the first and second aspects of the present invention, the high voltage component containing the high frequency of the static electricity on the secondary charging portion passes through the discharge gap. Since it escapes to the ground, the electric device does not malfunction, is safe, and improves reliability. Also,
Particularly, in the invention according to claim 2, since the high frequency component of the static electricity escapes to the ground through the capacitor, the static electricity is more completely eliminated, and the reliability is further improved.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a decoctioner having an antistatic structure according to the present invention.

FIG. 2 is an electric circuit diagram of the decoction device shown in FIG.

FIG. 3 is a temperature detection circuit diagram of the decoction device shown in FIG.

FIG. 4 is a partially enlarged view of a substrate pattern of the decoction device shown in FIG.

FIG. 5 is a diagram showing another example of the substrate pattern.

FIG. 6 is a diagram showing another example of the substrate pattern.

[Explanation of symbols]

12a, 12b ... Electrodes (secondary charging section), 14 ... Printed circuit boards, 31, 32 ... First and second input section patterns, 33
… Ground pattern.

Claims (2)

[Claims] 1. In an electric device in which a secondary-side charging unit is exposed on the surface of the device, a printed circuit board accommodated in the electric device is connected to an input part pattern connected to the secondary-side charging unit and ground. Forming a ground pattern that is
A static electricity resistant structure for an electric device, wherein a part of the input part pattern and a part of the ground part pattern are close to each other with a discharge gap. 2. The antistatic structure for electric equipment according to claim 1, wherein the input part pattern and the ground part pattern are connected via a capacitor.