JPS6223049Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semi-fixed variable resistor with a locking device.

Among variable resistors, a semi-fixed variable resistor used for fine adjustment is particularly required to have stable settings after adjusting its resistance value, that is, the position of the slider contact. This semi-fixed variable resistor usually has a structure in which it slides on a resistance element while making contact with it through a slider contact. Therefore, the stability of the slider contact position after it is set depends on mechanical rattling, that is, displacement of the slider contact position due to vibrations and shocks applied from the outside, and the contact surface between the resistance element and the slider contact. This is largely affected by an increase in contact resistance due to oxidation, sulfurization, etc., or poor contact due to the intrusion of moisture, dust, etc. from the outside.

In order to improve stability after setting, various improvements have been made, such as increasing processing accuracy by removing mechanical play, stabilizing contact by using precious metal contacts, or placing the contact part in a sealed housing. has been carried out, but its reliability is still low. Therefore, for circuits that require higher reliability,
A semi-fixed variable resistor is not used, but a plurality of fixed resistors finely adjusted to the desired resistance value are often used. However, this requires additional time and adjustment to obtain the required resistance value, making it extremely costly.

On the other hand, it has been found that in order to improve the setting stability, it is sufficient to increase the contact pressure of the contact portion. However, most semi-fixed variable resistors are required to be extremely small, and the resistance element is installed in a small space, so most of them are wound type or film type. If so, the film thickness is thin, and in any case, the mechanical strength of the resistance element is not so large. Therefore,
Increasing the contact pressure may cause wire breakage during sliding, wear of the contacts, and increase in resistance due to wear of the resistive film. This results in the loss of .

An object of the present invention is to increase the pressure at the slider contact easily and without damaging the contact or the resistance element during vibration, thereby improving the setting stability after adjusting the resistance value. Therefore, in the present invention, during sliding, the contact pressure of the slider contact is set to a level that can obtain the output necessary for adjustment and can withstand the sliding life, and once the adjustment is completed, the contact pressure of the slider contact is The structure is such that a pressing force is applied to the contact point and the contact pressure is increased within the elastic limit of the slider spring. Hereinafter, the present invention will be specifically explained using the drawings.

FIG. 1 is a partial sectional view showing an example of a conventional semi-fixed variable resistor. A lid 2 is glued or caulked to the bottom opening of a housing 1 having a rectangular cross section, and a resistive element substrate 3 is mounted on the lid 2. The resistance element substrate 3 has a film resistor 4 and a fourth resistor.
A slip lead (collector) 5 shown in the figure is formed, and terminals 6a, 6b are drawn out from both terminal electrode portions 4a, 4b of the resistor 4. The output of the slider contact 7 is led out to the outside via a terminal by the collector. A screw 8 for driving a slider is attached to the housing 1 from the left side surface using a pin 9 so as to be rotatable and not to come out. A sealing O-ring 10 is provided to prevent moisture from entering through the gap between the drive screw 8 and the housing 1.
An adjustment driver groove 8a is provided in the head of the drive screw 8, and the screw 8 is rotated with a driver or the like when adjusting the slider contact position. A slider 11 is attached to the inside of the casing 1 so as to be movable laterally by engaging with a drive screw 8, and by turning the drive screw 8, the slider 11 is moved in the left-right direction. It is constructed so that the position of the slider contact 7 can be adjusted. As mentioned at the beginning, the conventional semi-fixed variable resistor described above has poor setting stability.

2 to 5 are diagrams showing a first embodiment of the present invention. In the figure, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and their explanation will be omitted. Figure 2 shows
FIG. 3 is a partial cross-sectional view of the same embodiment. As shown,
A locking shaft 12 is provided in the housing 1 in the same direction as the driving screw 8. Pin 9', O-ring 1
0' is the pin 9 used in the drive screw 8,
This is the same as the O-ring 10. An eccentric cam 13 slidable in the axial direction is attached to a locking shaft 12 having a locking screw at one end. The slider 14, which is moved by the rotation of the drive screw 8, is extended upward so that the eccentric cam 13 can slide together with the slider 14 and rotate in a direction perpendicular to the shaft. locking shaft 12 and eccentric cam 1
3 is provided with a cross-shaped groove 14' when viewed from above. The axial width of the cross-shaped groove 14' is such that the locking shaft 12 can rotate freely.
2, and smaller than the maximum width of the eccentric cam 13 so that the eccentric cam 13 can be pushed in the axial direction. The engaging portion between the locking shaft 12 and the eccentric cam 13 has a square cross section as shown in FIG.
2', but this is just one example, and a keyway or spline may be used.

FIG. 4 is a sectional view taken along line A-A' in FIG. The slider 14 is formed with a female thread 15 for moving it, and a relief 1 for the drive screw 8.
5' is provided to enable the slider 14 to move toward the resistor element. The slider contact 7 contacts and slides across the resistor 4 and the slip lead (collector) 5,
The resistance value between the terminal terminal 6a or 6b and the slider terminal 6c connected to the slip lead 5 is adjusted by rotating the drive screw 8.

FIG. 5 is a left side view of FIG. 2, showing the appearance of the locking shaft 12 and the drive screw 8. It is possible to provide alignment marks 16 and 16' on the locking shaft 12 and the housing 1 at the positions shown in the figure to indicate the locked state. In this example, as shown in FIGS. 3A and 3B, the alignment mark 1 of the locking shaft 12 is
When the 6 is at the bottom, it indicates that the lock is released, and when it is at the top, it indicates that the lock is completed.

When the semi-fixed resistor of the present invention configured as described above is used, it is mounted on a printed wiring board of an electronic circuit, and in the state shown in FIG. etc. to rotate the drive screw 8. By rotating the drive screw 8, the slider 14
The slider contact 7 attached to the slider moves and the resistance value changes. The contact pressure between the contact point 7 and the resistor 4 at this time is set to a necessary and sufficient value. When the desired resistance value or voltage value is reached, the rotation of the driving screw 8 is stopped. Next, install the locking shaft 12.
Rotate 180 degrees and align the alignment marks 16 and 16' as shown in FIG. 3B to complete the locking.
3A shows the locking shaft 12 when the lock is released, and FIG. 3B shows the locking shaft 12 when the lock is completed.
The positional relationship between the slider 14 and the eccentric cam 13 is shown.
When the locking is completed, the slider 1 is moved by the eccentric cam 13.
4 is pushed down by a predetermined distance d in the direction of the arrow. Therefore, the slider contact 7 attached to the lower part of the slider 14 is strongly pressed against the resistor 4 and the slip lead 5.

The pressing force of the eccentric cam 13 firstly increases the contact pressure of the slider contact 7 to minimize contact resistance and maintain a good contact state over a long period of time; It is mechanically fixed and has the effect of preventing mechanical play and displacement of the slider position due to external vibrations and shocks. In the above embodiment, the resistor 4
When a vapor-deposited metal film resistor was used, the value of the concentrated contact resistance during locking was approximately 1/4 of that of a conventional semi-fixed resistor, giving extremely good results.

FIG. 6 is a diagram showing a second embodiment of the present invention. This example is an example in which the resistor and slip lead are applied to a ring-shaped one. Figure 6A
6B is a sectional view taken along the line -' in FIG. Terminal '' and 7' indicate a slider contact. In this example, the drive screw 8 is a worm screw, and the slider 22 that engages with it is a worm pinion. The slider contact 7' is fixed to the worm pinion 22 and slides in an arc across the resistor 4' and the slip lead 5'.
FIG. 6B is an external view, and when the drive screw 8 is rotated and adjusted to the desired resistance value, the locking rotor 2
Rotate 3 in the direction of the arrow. The locking rotor 23 is provided with an arrow-shaped groove 24 for easy rotation.
Together with the mark 24' attached to the housing 1, it functions similarly to the alignment mark shown in FIG. Further, on the lower surface of the locking rotor 23, two serrated protrusions 26, 26 formed on the locking metal fitting 25 are received.
Two recesses 27, 27 are provided. Figure 6A
When the protrusion 26 is housed in the recess 27 as shown in the figure, it is in the unlocked state. When the locking rotor 23 is turned, the protrusion 26 is gradually pushed down and locked because the recess 27 is tapered. The slider contact 7' is strongly pressed against the resistance element side through the metal fitting 25 and the slider 22, and a locked state is established. 6th
Figures C and D are a perspective view and a side view of the locking fitting 25.

As explained above, according to the present invention, after adjusting the resistance value or voltage etc. with a predetermined contact pressure, the slider contact is strongly pressed against the resistance element with a predetermined pressing force, so that it can be used in a semi-fixed variable resistor. Long-term setting stability can be improved. Further, according to the present invention, the contact pressure can be set in advance and no tall parts are required, so it is suitable for a small semi-fixed variable resistor.

Although the shape and structure of the slider contacts have not been described in detail, they are of course symmetrical in structure so that the set resistance does not change during locking.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing a conventional example, FIGS. 2 to 5 are views showing a first embodiment of the present invention, and FIG. 6 is a view showing a second embodiment of the present invention. 1... Sealed housing, 4, 4'... Resistance element, 7, 7'...
Slider contact, 8...Slider drive rotor, 14, 2
2...Slider, 13,25...Lock means, 12,2
3... Locking means rotor, d... Predetermined distance.

Claims (1)

[Claims for Utility Model Registration] A resistive element, a slider having a contact that slides into contact with the resistive element, and a locking means for strongly pressing the slider contact against the resistive element are housed in a sealed casing. , the slider driving rotor and the lock means rotor are exposed from the housing, and the slider contact position is adjusted by the slider driving rotor to set the resistance value of the resistance element. After that, the lock means rotor is rotated by a predetermined angle so that the slider is pressed down against the resistor element by a predetermined distance from the position at the time of adjustment.