JPH0446350Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a highly reliable reed switch that is small in size and has high operating speed.

(Prior Art) Conventionally, in this field, for example, a normally closed reed switch has a structure in which a magnet is attached to the outside of a glass tube of the reed switch. This magnet normally closes the contact, but when an external magnetic field is applied that cancels out the magnetic field of this magnet, the contact opens. Next, the reed switch which has a normally closed contact and a normally open contact and has a transfer (switching) function is disclosed in JP-A-56-106314, JP-A-106315 and Oki R&D VoL.44 [No.1] P99. -100, the contact point of the movable reed piece is brought into contact with a non-magnetized normally closed contact with a mechanical bias applied, and this mechanical bias and the spring of the movable reed piece are applied from the outside. When a magnetic field strong enough to overcome the strength is applied, the contact of the movable reed piece is attracted to the normally open contact.

(Problem to be solved by the invention) However, among the reed switches with the above configuration, in the case of , it is necessary to fix the magnet to the outside of the glass tube of the reed switch, so there is an extra process of assembling the reed switch and the magnet. This has the disadvantage of increasing cost due to the materials required for assembly, and is considerably larger than a normally open reed switch. In addition, when sealing, mechanical bias (2 to 3
In order to apply g), the mechanism of the assembly machine is complicated in terms of manufacturing technology, and furthermore, it is difficult to adjust the mechanism, and it is difficult to obtain a stable contact force at a normally closed contact. That is, in this adjustment, the bias is greatly affected by an adjustment deviation of about 50 to 150 μ. Therefore, this is an operation that requires great care and takes a lot of man-hours in the manufacturing process.

(Means for solving the problem) This invention is based on this type of reed switch.
An ultra-small magnet is fixed to at least one contact of the fixed lead piece, and the magnetic field of this magnet constantly attracts the movable lead piece to bring the contact points into contact.

(Function) In such a configuration, when an external magnetic field that cancels the magnetic field of the magnet is applied, the movable lead piece either stops contacting or comes into contact with the other contact.

(Embodiment) FIG. 1 is a configuration diagram showing an embodiment of the reed switch of the present invention. Thickness 0.2~0.5mm as shown in the picture
An ultra-small magnet 1 with a width of about 0.5 to 2 mm and a length of about 1 to 10 mm is welded to the contact point 2a of a fixed lead piece 2, and a movable lead piece 3 facing it is enclosed in a glass tube 4. The movable reed piece 3 is attracted to the fixed contact 2a by the magnetic field of the magnet 1, so that the contact is always closed. Second
The figure shows a case where the magnet 1 is demagnetized in FIG. 1, and the fixed contact 2a enclosed in the glass tube 4 is
A magnet 1 fixed to the magnet 1 and a movable lead piece 3 face each other with a contact gap 5.

In this way, when the magnet 1 is magnetized, the magnetic field of the magnet 1 exceeds the spring force of the movable lead piece 3, and the movable lead piece 3 is bent.
The contact gap 5 disappears and the contact is closed, forming a normally closed reed switch. However, when a magnetic field is applied from outside that cancels the magnetic field of the magnet 1, the spring force of the movable reed piece 3 returns to the state shown in FIG. 2, and the contact is opened. The material of the magnet is, for example, an alloy of iron, cobalt, and chromium.
The ALNICO5 series is used, and its manufacturing method is to fix the last magnetized magnet 1 to the contact 2a of the lead piece 2.
The fixed lead piece 2 and the movable lead piece 3 thus fixed are housed in a glass tube 4, and both ends are sealed. In this case, the movable lead piece 3
Gap 5 is generated without applying any mechanical bias. After sealing, the magnet 1 is magnetized by placing it under a magnetic field of several thousand Gauss.

In this way, there is no need to fix the magnet to the outside of the reed switch, and it is possible to avoid the extra step of assembling the reed switch and magnet and the increase in cost due to the materials required for assembly. It has the advantage of being about the same size as .

FIG. 3 is a configuration diagram showing another embodiment of the present invention,
In particular, the case of a transfer reed switch is shown. In the figure, a fixed lead piece (normally closed lead piece) 2 has a fixed contact (normally closed contact) 2a to which a magnet 1 is welded, and a fixed lead piece (normally open lead piece) has another fixed contact (normally open contact) 6a. 6 and a movable lead piece 3 are sealed in a glass tube 4 with a contact gap 7 (approximately 20 to 40μ) between the movable lead piece 3 and the normally open contact 6a.

In this state, if an external magnetic field that cancels the magnetic field of the magnet 1, for example a reverse magnetic field of 20 to 40 AT, is applied, the movable reed piece 3 will no longer be attracted to the normally closed contact 2a, and this external magnetic field will cause the movable reed piece 3 to
When a magnetic circuit is formed between the movable reed piece 3 and the normally open reed piece 6, the strength of which exceeds the strength of the spring, the movable reed piece 3 closes the contact between it and the normally open contact 6a, as shown in FIG. A contact gap 8 is formed between the normally closed contact 2a and the normally closed contact 2a. Furthermore, when the external magnetism is extinguished, the movable reed piece 3 is attracted to the normally closed contact 2a and the third
The movable reed piece 3 and the normally closed contact 2a return to the closed state as shown in the figure.

In this way, the contact force can be increased by the magnetic attraction force between the movable reed piece 3 and the normally closed contact 2a, which eliminates the complexity of the mechanism, the difficulty of adjustment, and the contact force caused by the conventional mechanical bias application method. Instability can be resolved.

FIG. 5 is a configuration diagram showing yet another embodiment,
An example of a bistable transfer reed switch is shown below, which is a transfer reed switch with a memory function. 3rd as shown in the figure
A magnet 9 is also welded to the fixed contact 6a of the fixed lead piece 6 in the figure. That is, the fixed contact 2a to which the magnet 1 is fixed and the movable lead piece 3
closes the contact, and a contact gap 10 exists between the magnet 9 and the movable lead piece 3.
Note that the magnets 1 and 9 have the same strength and dimensions and have opposite polarities, and as a manufacturing condition, the movable lead piece 3 is inserted so as to be located approximately in the center of the magnets 1 and 9. The moment it is inserted, it will be attracted to the magnet 1 that is even somewhat close to it, and the contact will be closed with the fixed lead piece 2 having the fixed contact 2a to which the magnet 1 is fixed. However, when a magnetic field in the opposite direction to the magnet 1, that is, an external magnetic field in the same direction as the magnet 9 cancels the magnetic field of the magnet 1 and is applied in such a manner that it exceeds the spring strength of the movable lead piece 3, the movable lead piece 3 is a fixed member that is attracted to the magnet 9 and holds the magnet 9 firmly in place until an external magnetic field is applied in the opposite direction to the magnet 9, canceling the magnetic field of the magnet 9 and exceeding the strength of the spring of the movable reed piece 3. The contact continues to be closed with the fixed lead piece 6 having the contact 6a.

In this way, since the magnets 1 and 9 are fixed to the two fixed contacts 2a and 6a, respectively, the magnets 1 and 9 are attached to the two fixed contacts 2a and 6a.
A large contact force can be obtained due to the magnetic attraction force caused by the mechanical bias application method in the case of normal transfer reed switches with normally closed and normally open contacts. This is the same as the previous embodiment in that instability can be eliminated, and in addition, this is the first time that a bistable transfer reed switch having a memory function at the two fixed contacts has been realized.

(Effects of the invention) As explained in detail above, the invention is a normally closed type reed switch in which a magnet is fixed to the contact point of at least one fixed reed piece of the reed switch, and the magnet is attached to the outside of the reed switch. There is no need for fixation, and the cost increase due to the extra process of assembling the reed switch and magnet and the materials required for assembly can be avoided, and it is also about the same size as the conventional normally open reed switch. It has the effect of saving time. Therefore, it can also be used as a reed relay proximity switch.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing one embodiment of the reed switch of the present invention, Fig. 2 is an explanatory diagram of its operation, and Fig. 3 is a block diagram showing another embodiment of the reed switch of the present invention.
FIG. 4 is an explanatory diagram of its operation, and FIG. 5 is a configuration diagram showing another embodiment of the present invention. 1, 9... Magnet, 2... Fixed lead piece (normally closed lead piece), 2a... Fixed contact (normally closed contact),
3...Movable lead piece, 4...Glass tube, 6...Fixed lead piece (normally open lead piece), 6a...Fixed contact (normally open contact), 5, 7, 8, 10... Gap.

Claims (1)

[Claims for Utility Model Registration] A fixed lead piece that is not affected by magnetic force, a permanent magnet fixed to the contact side of this fixed lead piece, and a permanent magnet that is brought into contact with the contact side by the magnetic force of this permanent magnet, and the magnetic force A reed consisting of a movable reed piece having a spring force that releases from contact with the permanent magnet when an external magnetic force is applied to cancel the reed, and a container enclosing the contact side of the fixed reed piece and the movable reed piece. Switch.