JPS584161Y2 - variable resistor - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a variable resistor used in a volume control circuit of an audio device.

As is well known, a variable resistor has a resistor 1 as shown in Figure 1.
A low resistance part (silver bar part) 2 is provided at the end of the low resistance part 2.
It is common to have a structure in which the sliding limit point of the mover 3 is determined at , and the terminal 4 is attached.

FIG. 2 shows an equivalent circuit in a state where the movable element 3 of this variable resistor is located at the sliding limit point.

In Figure 2, R1 is the resistance of resistor 1, R2 is the resistance of low resistance part 2, R3 is the contact resistance between low resistance part 2 and terminal 4, and R
4 is the resistance of the terminal 4, and R5 is the combined resistance of the contact resistance between the low resistance portion 2 and the movable element 3 and the resistance of the movable element 3.

Resistors R3 and R4 are very small and can be ignored when considering the circuit, but resistor R2 becomes a problem.

That is, when a variable resistor is used, for example, in a volume control circuit and the volume is minimized, that is, when the movable element 3 is located at the sliding limit point on the ground side, the voltage of the movable element 3 becomes zero (ground potential). Instead, a divided voltage by the resistor R2 appears, causing so-called sound leakage.

This is particularly a problem in high-output amplifiers.

Conventionally, the residual resistance of the variable resistor is reduced by using a material with low specific resistance for the low resistance part 2, thereby increasing the maximum attenuation (residual) of the variable resistor, or the movable element 3 and the terminal 4 are The above problem is attempted to be solved by increasing the maximum attenuation by bringing the two into contact at the sliding limit point.

However, there is a limit to reducing the residual resistance by using a material with low specific resistance for the low resistance portion 2 as in the former case.

For example, with a total resistance of 10, a Q 24φ type carbon film ordinary grade variable resistor has a specification of -120 dB, and an actual measurement value of -120 dB.
The limit is about 130 dB.

In addition, the latter case not only requires special parts, but also has the disadvantage that the touch at the final end of the mover operation is poor.

The present invention aims to eliminate the above-mentioned drawbacks and provide a variable resistor that has a simple structure and can increase the maximum attenuation amount without deteriorating the feel when operating the mover. .

The present invention provides a low resistance part at the end of the resistor, defines the sliding limit point of the mover in this low resistance part, and in a variable resistor with a terminal attached, the terminal is connected to the sliding limit of the mover. It is characterized by being located electrically closer to the resistor than the limit point.

The present invention will be explained below based on the illustrated embodiments.

3 and 4 show an embodiment of the present invention, in which a low resistance part 2 is provided at one end of the resistor 1, and the sliding limit point of the movable element 3 is determined in this low resistance part 2. Attaching the terminal 4 is the same as in the conventional method (FIG. 1), but in this embodiment, a notch 7 that reaches the terminal 6 is made from the side edge of the low resistance section 5 at the other end opposite to the side from which the terminal 6 protrudes. The low resistance portion 5 is divided into two regions 5A and 5B with this notch 7 as a boundary, and the sliding limit point of the movable element 3 is set in the region 5B away from the resistor 1.

That is, the two regions 5A and 5B of the low resistance section 5 are connected via the terminal 6.

FIG. 5 shows an equivalent circuit of the variable resistor having the structure shown in FIG. 5 when the movable element 3 is located at the sliding limit point.

In FIG. 5, R1 is the resistance of the resistor 1, R21 is the resistance of the region 5A of the low resistance section 5, and R22 is the resistance of the region 5A of the low resistance section 5.
The resistance of B, R3 is the contact resistance between the low resistance part 5 and the terminal 6, R6
is the resistance of the terminal 6, and R5 is the combined resistance of the contact resistance of the region 5B of the low resistance portion 5 and the movable element 3, and the resistance of the movable element 3.

Since the resistors R3 and R6 are very small as mentioned above, the maximum attenuation is very large, -20% compared to the conventional one.
It is improved by about dB.

Therefore, when this variable resistor is used in a volume adjustment circuit and the volume is minimized, the two regions 5A and 5 of the low resistance section 5
The potential at the boundary point A of B becomes approximately zero (ground potential), and the potential of the movable element 3 becomes the same potential as that of the boundary point A, so that there is no noise.

This is effective when the resistance of the audio variable resistor is reduced.

In the above embodiment, the resistance section 5 is divided into two regions 5A and 5B by the cut 7 (high resistance section), but instead of a cut, a high resistance section similar to the resistor 1 is used to divide the resistance section 5 into two regions 5A, 5B. 5B may be electrically separated, and the terminal 6 may be located at the boundary point between the terminals 6 and 5B, and the manufacturing process is easy since all that is required is to change the printing of the low-resistance portion.

FIG. 6 shows another embodiment of the present invention, in which a terminal 6 is attached to a portion of the low resistance section 5' near the resistor 1, and the terminal 6 is
The sliding limit point of the movable element 3 is defined in a region 5C on the edge side of the low resistance portion 5' beyond the point.

Even with this structure, the equivalent circuit is the same as that of the above embodiment, and there is an advantage that the maximum attenuation can be increased without cutting into the low resistance part or providing a high resistance part.

However, the low resistance part 5' needs to be larger in size than the low resistance part 5 in the embodiment shown in FIG. 3, and in the case of the same resistance value, it becomes slightly larger.

In each of the above embodiments, this is applied only to the low resistance part on one side of the resistor, but it may be applied to both sides.If it is used on the input side, the insertion loss of the variable resistor will be reduced when the load impedance is sufficiently large. can be reduced (to the order of 0 or several dB).

Further, in the above description, a rotary variable resistor is illustrated, but the present invention is also applicable to a linear sliding variable resistor.

As described above, according to the present invention, it is possible to increase the maximum attenuation amount, and the structure is simple and the cost is almost the same as the conventional one, since it is possible to increase the maximum attenuation amount by simply adding a little modification to the low resistance part. There are advantages.

[Brief explanation of the drawing]

Fig. 1 is a front view showing an example of a conventional variable resistor, Fig. 2 is an equivalent circuit diagram of the same variable resistor with the movable element located at the sliding limit point, and Fig. 3 is a variable resistor according to the present invention. FIG. 4 is an enlarged view of the main parts, FIG. 5 is an equivalent circuit diagram, and FIG. 6 is a front view of the main parts of another embodiment of the present invention. 1...Resistor, 2...Low resistance part, 3...
...Mover, 4゜6...Terminal, 5,5'
・・・・・・Low resistance part, 5A, 5B, 5C・・・・・・
Each area of the low resistance part, 7...notches.

Claims (2)

[Scope of utility model registration request] (1) A low resistance part is provided at the end of the resistor, and the sliding limit point of the movable element is determined in this low resistance part, and in a variable resistor with a terminal attached, the terminal is connected to the sliding limit of the movable element. A variable resistor characterized by being located electrically closer to the resistor than the point. (2) Attach the terminal so that it protrudes from one side of the low resistance part, and provide a high resistance part that reaches the terminal from the other side edge of the low resistance part,
The variable resistor according to claim 1, wherein the sliding limit point of the movable element is defined at the edge side of the low resistance part beyond the high resistance part.