JPH03288403A - Variable resistor - Google Patents

Abstract

PURPOSE:To offer a sliding-type variable resistor whose change in a resistance value between a brush and a terminal is small by a method wherein a conductive path which has been connected to an electrode of a resistance path and which is shorter than the resistance path is formed on a resistor substrate composed of an insulating substrate. CONSTITUTION:Electrodes 16a are provided at both ends. A conductive path 5 formed along a resistance path 16 whose one end is connected to either of the electrodes 16a is formed in the same length as the electrodes. Leg parts at both ends of a brush 15 fitted to a slider 10 come into sliding contact with the resistance path 16 and a conductive path 6; and a leg part 15a in the center comes into sliding contact with the conductive path 5 formed along the resistance path 16. Since the conductive path 5 is connected to the electrode 16a of the resistance path 16 in this manner, it is reduced that shaved-off powders of the resistance path by a sliding abrasion are deposited on the electrodes. Consequently, it is possible to obtain a sliding-type variable resistor in which the brush cannot run onto the shaved-off powders, for control use of a motor, for a sewing machine or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a variable resistor used for speed control of sewing machines and the like.

Prior Art The prior art will be explained with reference to an exploded perspective view of a sliding variable resistor shown in FIG. According to the figure: 1 is a resistor substrate made of an insulating substrate on which a resistance path 4 and a conductive path 6 are provided in parallel to the resistance path 4; 8 is an inner terminal attached to one end of the conductive path 6, and 14 is an inner terminal attached to the slider 10, and 8 is an inner terminal attached to the resistive path 4. The brush 12 bridges the conductive path 6 and comes into sliding contact with the brush, and numeral 12 has a long hole 13 on the top surface from which the lever 11 provided on the slider 10 projects. This is a cover that slidably holds the slider 10. That is, as is clear from the above structure, a conventionally known general slide type variable resistor is used for speed control.

Problems to be Solved by the Invention However, in conventional slide type variable resistors that control current using the rheostat method, the resistance path 4 is formed on the electrode 4a at the sliding end due to sliding wear between the brush 14 and the resistance path 4. The brush rides on the ground powder in the resistance path 4, which has a high resistance value, and the resistance value becomes high.The brush rides on the terminal electrode of a motor used to control the speed of a sewing machine, etc., and the resistance value increases. Ω
For circuits that cause the motor to stop under the following conditions, as the number of times the motor is used increases and shavings accumulate, the resistance value increases and the motor will not stop or the motor rotation may become unstable. The problem was that

Means for Solving the Problems In order to solve the above problems, the present invention provides a conductive path along the resistance path, one end of which is connected to the electrode of the resistance path, and a foot portion that slides on the conductive path on the brush. It was established.

Function: As described above, in the present invention, since the conductive path is provided and one end is connected to the electrode of the resistance path, the amount of powder on the resistance path due to guide wear is extremely reduced on the conductive path, and the brush rides on the powder. It is possible to provide a slide type variable resistor for long life use in motor controls of sewing machines and the like.

Embodiment An embodiment of the present invention will be explained using a slide type variable resistor shown in FIGS. 1 and 2. Figure 1 is an exploded perspective view, and Figure 2 is an exploded perspective view.
The figure is a sectional view. Note that parts that are the same as those in the prior art will be given the same numbers and will not be described further.

5 has electrodes 16a at both ends, and this electrode 16a
This is a conductive path provided along the resistance path 16 with one end connected to one of the electrodes, and is provided to have approximately the same length as the electrode. 15 is a brush attached to the slider 10, and the legs at both ends slide on the resistance path 16 and the conductive path 6,
The central leg portion 15a is configured to slide on the conductive path 5 provided along the resistance path 16.

FIG. 3 is a top view of a resistor board of a rotary variable resistor which is a convenient example. According to the figure, reference numeral 20 indicates an arc-shaped resistance path 21, electrodes 21a provided at both ends of the resistance path 21, and electrodes 21a provided at both ends of the resistance path 21.
a, and a conductive path 22 provided along the resistance path 21 continuously from the resistance path 21, and a conductive path 23 provided concentrically with the resistance path approximately at the center of the resistance path 21 on the surface thereof. body substrate, and a resistance path 21. A brush (not shown) that slides on the conductive path 22 and the conductive path 23, respectively.
The resistance value is adjusted by

Note that the length of the conductive path 5 or 22 provided along the resistance path 16 or 21 shown in the above embodiment is the end (in the case of a sliding type variable resistor, the end when the slider 10 is slid; The variable resistor may be set to an appropriate length that is at least longer than the fully turned position of the operating shaft (not shown).

Effects of the Invention As is clear from the above structure, the present invention provides a conductive path shorter than the resistance path connected to the electrode of the resistance path on a resistor substrate made of an insulating substrate, and the number of times of instruction is increased. Even if the wear between the brush and the resistive path accumulates on the terminal electrode and increases the resistance value, the amount of wear between the short conductive path and the brush is small. Since only the conductive parts are in sliding contact, the increase in resistance is also small, so the variation in resistance between the brush and the terminal is also small. Even when used for controlling the speed of a sewing machine, the motor may stop at the end or the motor rotation speed may change. This solves problems such as instability.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing one embodiment of a sliding variable resistor according to the present invention, FIG. 2 is a cross-sectional view of the same, and FIG. 3 is a rotary variable resistor according to another embodiment of the present invention. FIG. 4 is an exploded perspective view of a conventional sliding variable resistor. 1... Resistor board, 5... Conductive path, 6
...Conducting path, 15...Brush, 16...
...Resistance path.

Claims (1)

[Claims] At least a resistive path, a road conductive path provided parallel or concentrically to the resistive path, an electrode provided on the resistive path, and another conductive path connected at one end to this electrode and provided along the resistive path. A variable resistor comprising a resistor substrate formed thereon, and a brush having feet that slide on the resistance path, the conductive path, and another conductive path, respectively.