JP2552346B2 - Ionized smoke detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ionization type smoke detector having a one-radiation source and two-chamber structure.

[Prior Art] Conventionally, as an electrode structure of an ionization type smoke sensor of this type, that shown in FIG. 4 is known.

In FIG. 4, reference numeral 1 denotes an internal electrode, the upper part of which is electrically connected to a printed circuit board (not shown) and a radiation source is provided on the lower side. An intermediate electrode 2 is provided outside the internal electrode 1, and the intermediate electrode 2 is provided with an opening hole 3 that allows radiation from a radiation source provided in the internal electrode 1 to pass therethrough. A chamber (internal ionization chamber) A is formed.

Further, an external electrode 4 capable of inflowing smoke from the outside is provided outside the intermediate electrode 2, and an external chamber (external ionization chamber) B is formed between the external electrode 4 and the intermediate electrode 2. The inner electrode 1, the intermediate electrode 2, and the outer electrode 4 are insulated by an insulator 5 such as plastic in order to maintain a high insulation state.

[Problems to be Solved by the Invention] However, in the conventional ionization type smoke detector provided with such an electrode structure, an insulator 5 such as plastic for keeping each electrode in a highly insulated state is used in the manufacturing process. As shown in the drawing, static electricity is charged after work or after the installation of the sensor, and the static electricity affects the ion current in the chamber, making the operation in the chamber unstable.

The present invention has been made in view of the above conventional problems, and provides an ionization type smoke sensor capable of preventing static electricity from charging the electrode insulator and ensuring stable operation in the chamber. The purpose is to

[Means for Solving the Problems] First, the present invention relates to a printed board on which an electric component is mounted,
An internal ionization chamber is formed between an internal electrode electrically connected to the printed circuit board and provided with a radiation source, and the internal electrode is disposed outside the internal electrode and has an opening hole through which radiation from the radiation source passes. An external electrode that is provided outside the intermediate electrode and that forms an external ionization chamber capable of inflowing smoke from the outside between the intermediate electrode and the intermediate electrode, and also serves as a shield case; and the internal electrode and the intermediate electrode. And an insulator that supports each of the external electrodes in an insulated state, a printed board on which the electrical component is mounted on the opposite side of the insulator that supports the external electrodes, and a shield case that surrounds the printed board, In an ionization type smoke detector that shields externally induced noise with the external electrode and the shield case, the printer is provided on the back surface side of the insulator opposite to the electrode side. A plurality of printed circuit boards, and a metal shield is provided by forming a conductor pattern on the side of the printed circuit board that is adhered to the insulator, and the metal shield is electrically connected to the ground portion of the printed circuit board. It is grounded to prevent the insulator from being charged.

[Operation] In the ionization-type smoke detector of the present invention having such a configuration, the printed circuit board is placed on the back surface side of the insulator that keeps the internal electrode, the intermediate electrode, and the external electrode in a highly insulated state. , A metal shield is provided by forming a conductor pattern on the mounting surface side of the printed circuit board with respect to the insulator, and the metal shield is connected to the ground portion of the printed circuit board and electrically grounded. Even if the insulator is charged with static electricity due to work in the manufacturing process, etc., when the completed sensor is connected to the power supply line and put into operation, it is charged by the ground connection of the metal shield provided on the back surface of the insulator. Static electricity is removed, as a result, the operation inside the chamber is stable, there is no variation in the operating characteristics of each sensor, and stable sensor characteristics are obtained even after the sensor is installed.
The reliability of the sensor can be improved.

[Embodiment] FIG. 1 is a configuration diagram of an embodiment showing one embodiment of the present invention.

In FIG. 1, reference numeral 1 is an internal electrode, which is provided with a radiation source in the lower part, and is made of an insulating material 5 made of plastic or the like as shown in the drawing.
Be attached to. An intermediate electrode 2 is mounted on the outside of the internal electrode 1 while supporting it with respect to an insulator 5. The intermediate electrode 2 is provided with an opening hole 3 for passing radiation from a radiation source provided in the internal electrode 1. Further, an outer electrode 4 which covers the outer side of the intermediate electrode 2 and allows smoke to flow from the outside is attached to an insulator 5, and with the interposition of the insulator 5, the inner electrode 1, the intermediate electrode 2, and the outer electrode 4 are mutually connected. Highly insulated.

Then, an internal chamber A which is ionized by irradiation with radiation from a radiation source is formed between the internal electrode 1 and the intermediate electrode 2, and the opening hole 3 of the intermediate electrode 2 is passed between the intermediate electrode 2 and the external electrode 4. An external chamber B is formed which allows smoke from the outside to be ionized by the irradiation of radiation.

In an electrode structure in which each electrode is supported in a highly insulated state by such an insulator 5, static electricity is charged on the high insulator 5 made of plastic or the like due to work in the manufacturing process or the like, which adversely affects chamber characteristics. .

Therefore, in the present invention, since the printed board 6 on which the electric component 7 is mounted is arranged on the back surface side of the insulator 5, the conductor pattern 8 is formed on the entire mounting surface of the printed board 6 on the insulator 5. The conductor pattern 8 forms a metal shield.

Therefore, when the printed board 6 is assembled on the back surface of the insulator 5, the conductor pattern 8 formed on the entire back surface of the printed board 6 contacts the back surface of the insulator 5, and the conductor pattern 8 is attached to the printed board. When the conductor pattern 8 is connected to the ground line 6, the conductor pattern 8 is connected to the ground by receiving the connection of the power source / signal line from the outside.

Next, the operation of the embodiment shown in FIG. 1 will be described. In the assembly of the electrode structure in the manufacturing process, when an operator shakes his hand on the insulator 5 or when an appropriate frictional contact is made, the insulator 5 is charged with static electricity. Then, the inner electrode 1, the intermediate electrode 2, and the outer electrode 4 are assembled to the insulator 5 while being charged with static electricity.

However, since the conductor pattern 8 is formed on the entire contact surface of the printed circuit board 6 mounted on the back surface side of the insulator 5, static electricity charged on the back surface side of the insulator 5 is printed through the conductor pattern 8. It will be connected to the ground line of the substrate 6.

Therefore, when the completed sensor is connected to a signal line that also functions as an electric power from a receiver or the like, or when it is connected to a test device for a test operation, it is insulated by the conductor pattern 8 via the ground line of the printed circuit board 6. Since the back side of the body 5 is grounded, static electricity charged on the back side of the insulator 5 can be removed.

On the other hand, static electricity is also charged on the inner chamber A side which is the electrode side in contrast to the static electricity charged on the insulator 5 side. In the (ionization state), the static electricity charged by the ions generated in the internal chamber A is neutralized, and the charge of the insulator 5 on the internal chamber A side is removed without any special means. There is no.

FIG. 2 is a constitutional view of an embodiment showing a concrete embodiment of the ionization type smoke detector of the present invention having the electrode structure for preventing electrostatic charging shown in FIG.

In FIG. 2, the ionization type smoke detector is a detector base.
17 has a detachable sensor body 9, which is composed of a body cover 10 and an outer cover 12 having a smoke inlet 11, and an opening of a circuit housing portion 13 formed on the body cover 10 side. The insulator 5 is incorporated in the part.

Below the insulator 5, an inner electrode 1 having a radiation source, an intermediate electrode 2 having an opening 3 and an outer electrode 4 capable of inflowing smoke from the outside are mounted. On the other hand, a printed circuit board 6 is incorporated on the back surface side of the insulator 5, and a metal shield composed of a conductor pattern 8 on the entire back surface of the printed circuit board 6 is provided between the printed circuit board 6 and the insulator 5. By means of 8, the static electricity charged on the insulator 5 can be removed by grounding it via the earth line of the printed circuit board 6.

Furthermore, a shield case 14 is incorporated behind the circuit housing part in which the printed circuit board 8 is incorporated.
And the external electrode 4 located on the lower side realize a shield structure against inductive noise from the outside. That is, the metal shield formed by the conductor pattern 8 formed on the entire back surface of the printed circuit board 6 is for removing static electricity charged in the insulator 5, while the shield case 14 and the external electrode 4 are removed.
Is a shield structure for preventing malfunction of the sensor circuit due to electrical induction noise from the outside, and the functions of the two as metal shields are different.

FIG. 3 is a block diagram of an embodiment showing another embodiment of the present invention. In this embodiment, a metal shield 15 is provided on the back surface of the insulator 5 by a metal case or metal vapor deposition, while the insulator 5 is provided with a ground terminal 16 on the back surface of the printed circuit board 6 arranged on the back surface side of 5 to make electrical contact with the metal shield 15, and when the printed circuit board 6 is attached to the insulator 5, the ground terminal 16 is contacted with the metal shield 15. By electrically connecting to the ground, the static electricity charged in the insulator 5 can be removed.

Further, as another embodiment for preventing electrostatic charge, a resin member having a low degree of insulation, for example, an ABS resin or a vinyl chloride resin, is provided on the back surface of the insulator 5, and the ground terminal 16 of the printed circuit board 6 is provided.
It is also possible to perform a static electricity antistatic treatment by connecting to. Of course, the insulator 5 and the resin member having a low degree of insulation may be integrally molded.

In such an embodiment, for example, even if a resin member having a low degree of insulation is charged with static electricity, the static electricity can be removed through the ground terminal 16 provided on the printed circuit board 6.

Further, even when the back surface of the insulator 5 is subjected to static electricity anti-static treatment by using an antistatic spray or the like, by connecting the back surface of the insulator 5 to the ground terminal 16 of the printed circuit board 6, more effective static electricity can be generated. Antistatic is achieved.

The electrostatic charge preventing means is not limited to the above-mentioned embodiment, and it goes without saying that any suitable means can be used.

As described above, according to the present invention, the internal electrode,
The printed circuit board is placed on the back side of the insulator that keeps the intermediate electrode and the external electrode in a highly insulated state, and the metal shield is provided by forming a conductor pattern on the mounting surface side of the printed circuit board with respect to the insulator. Is electrically grounded by connecting it to the ground part of the printed circuit board to prevent the insulator from being charged, so even if the insulator made of plastic or the like is charged with static electricity during the manufacturing process or after installation, the Static electricity that is charged can be removed by grounding the shield, and the operation inside the chamber is stable because there is no electrostatic charge, and the sensor characteristics are stable with no variation in the operating characteristics of each sensor. Is obtained,
The reliability of the sensor itself can be greatly improved.

[Brief description of drawings]

 1 is a block diagram of an embodiment showing one embodiment of the present invention; FIG. 2 is a block diagram of an embodiment showing a concrete embodiment of the present invention; FIG. 3 is another embodiment of the present invention. FIG. 4 is an explanatory view of a conventional example. 1: Internal electrode 2: Intermediate electrode 3: Open hole 4: External electrode 5: Insulator 6: Printed circuit board 7: Electrical component 8: Conductor pattern 9: Sensor body 10: Body cover 11: Smoke inlet 12: Outer cover 13: Circuit compartment 14: Shield case 15: Metal shield 16: Ground terminal 17: Sensor base

Front Page Continuation (72) Inventor Eiji Matsushita Kamiosaki 2-10-43, Hochiki Co., Ltd., Shinagawa-ku, Tokyo (72) Inventor Tetsuya Nagashima Kamiosaki 2-10-43, Shinagawa-ku, Tokyo, Hochiki Co., Ltd. (72) Inventor Yoshihito Hirai 2-10-43 Kamiosaki, Shinagawa-ku, Tokyo Within Hochiki Co., Ltd. (56) Bibliography Sho 59-166492 (JP, U) JP 53-100295 (JP, B2)

Claims (1)

(57) [Claims] 1. An internal ionization chamber is formed between a printed circuit board on which electric parts are mounted, an internal electrode electrically connected to the printed circuit board and provided with a radiation source, and an internal ionization chamber disposed outside the internal electrode. And an external ionization chamber, which is disposed outside the intermediate electrode and has an opening through which the radiation from the radiation source passes, and through which smoke from the outside can flow, is formed between the intermediate electrode and the intermediate electrode. An external electrode that also serves as a shield case, an insulator that supports the internal electrode, the intermediate electrode, and the external electrode in an insulated state, and a print that mounts the electrical component on the opposite side of the insulator that supports the external electrode. A board and a shield case surrounding the printed board are provided, and in the ionization type smoke detector that shields inductive noise from the outside by the external electrode and the shield case, the electrode side is provided. On the other hand, the printed circuit board is arranged on the back side of the insulator on the opposite side, and a metal pattern is formed by forming a conductor pattern on the adhesive surface side of the printed circuit board to the insulator. Electrically grounded by connecting to the ground part of the printed circuit board,
An ionization type smoke detector characterized in that the insulator is prevented from being charged.