JPS635133Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a printed circuit board for an input switch that switches and extracts a temperature measurement input signal from a thermocouple or the like.

[Prior Art] For example, the input switching circuit shown in FIG. 1 can be considered. In the same figure, thermocouples and the like are connected to input terminals 11 and 12, and the input signals supplied to these input terminals 11 and 12 are switched by an input switch 2 consisting of switching switches 21 and 22 such as reed relays into one signal. is selected, a compensation voltage is superimposed by a reference junction compensator 3 which forms a reference junction and electrically compensates for temperature, and an output signal is taken out from an output terminal 4. In addition, changeover switch 2
Thermocouples or compensation conductors are connected between the input terminals 11 and 12 and the reference junction compensator 3, except for terminals 1 and 22. Each of the changeover switches 21 and 22 has contacts s ₁₁ , s ₁₂ , s ₂₁ , and s ₂₂ , and the contact s ₁₁ has a terminal.
t ₁ , t ₂ , contact s ₁₂ have terminals t ₃ , t ₄ , contact s ₂₁ has terminal
Terminals t ₇ and t ₈ are provided at t ₅ , t ₆ , and contact s _{22 ,} respectively.

[Problems to be solved by this invention] When such changeover switches 21 and 22 are used, the terminals t ₁ , t ₂ , t _{3 , t 4} , t ₅ , t ⁶ , t ₇ , _{t 8 ,} The temperatures are respectively T ₁ , T ₂ , T ₃ , T ₄ , T ₅ , T ₆ , T ₇ , T ₈
Then, T ₁ = T ₂ , T ₃ = T ₄ , T ₅ = T ₆ , T ₇ = T ₈
It is desirable that In other words, if there is a temperature difference between each terminal, a thermoelectromotive force is generated at each terminal, which is a major cause of error when switching minute input signals. In particular, switching devices such as reed relays are mounted on a printed circuit board and housed inside the instrument, so internal heat generation can cause uneven temperature distribution and increase errors. It was.

In view of the above points, the purpose of this invention is to provide a printed circuit board for an input switch that achieves uniform heat distribution by providing a heat equalizing material and a heat insulating material to the terminals of the changeover switch mounted on the printed circuit board. It is to provide.

[Embodiment] FIG. 2 is a configuration explanatory diagram showing an embodiment of this invention. In the same figure, 5 is a printed circuit board,
On the parts mounting surface of this printed circuit board 5, there are changeover switches 21, 22 such as reed relays, and a reference junction compensator 3.
is installed. And printed circuit board 5
The terminals of reed relays 21 and 22 are on the pattern side.
t ₁ to _{t 8} are each soldered, etc., and the metal heat equalizing material 6 is connected to the changeover switches 21 and 22 of the printed circuit board 5.
A heat insulating material 7 made of resin is provided on the printed circuit board 5 so as to surround the terminals t ₁ to t ₈ with a space therebetween, and in contact with the outside thereof. Further, switches 21 and 22 and a cover 8 for the reference junction compensator 3 are provided on the component mounting surface side. The printed circuit board 5 is attached to a terminal board 10 via a partition post 9 or the like, and the terminal board 10 can be inserted into and removed from an instrument body (not shown) with the pattern surface of the printed circuit board 5 facing inward.

That is, the terminals t ₁ to _{t 8} of the changeover switches 21 and 22 mounted on the printed circuit board 5 are connected to the metal heat equalizing material 6
The heat is uniformed by the heat insulating material 7 made of resin, and the heat is uniformed as a whole.

In the above example, two changeover switches have been described, but the same applies to more than two switches.

[Effects of the invention] As described above, this invention is a printed circuit board for an input switch in which a heat equalizing material and a heat insulating material are provided on the terminals of the changeover switch mounted on the printed circuit board.

Therefore, the temperature difference between the terminals of a changeover switch such as a reed relay can be extremely reduced, so that unnecessary thermoelectromotive force is not generated, and inputs can be switched with high precision. In particular, it has a great practical effect when used for switching minute DC input signals.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are configuration explanatory diagrams showing one embodiment of this invention. 21, 22...Switching switch, 5...Printed circuit board, 6...Heat equalizing material, 7...Insulating material, _t1 to _t8 ...
terminal.

Claims (1)

[Scope of utility model registration request] A printed circuit board on which an input changer consisting of a changeover switch is mounted, a metal heat equalizing material provided on the printed circuit board to surround the entire changeover switch terminal with a space between the changeover switch terminals of this printed circuit board, and this equalization material. A printed circuit board for an input switch, comprising a resin heat insulating material provided on the printed circuit board in contact with and surrounding the outside of the heat material.