JP7079952B1 - Multi-stage attenuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a wide range of signal level attenuation by setting a configuration in which a multi-stage attenuator is mechanically and synchronously switched. SOLUTION: A common electrode and a plurality of divided electrode patterns are arranged concentrically, and sliding contacts 5 and 13 for connecting the common electrode and the divided electrode pattern by rotation of a shaft are provided. , A multi-stage attenuator composed of a first electrode substrate 1 and a second electrode substrate 2, and the divided plurality of electrode patterns 3, 4, etc. of the first electrode substrate are via resistors R11 and the like. The common electrode formed on the first electrode substrate is connected to an adjacent electrode pattern, and the electrode at the end of the plurality of electrode patterns 8, 9 and the like formed on the second electrode substrate. Of the plurality of electrode patterns connected to the pattern 8 and formed on the first electrode substrate, the electrode pattern 3 at the end is set as the input 14, and the common electrode formed on the second electrode substrate is output 15. It was configured to be. [Selection diagram] Fig. 1

Description

The present invention relates to a multi-stage attenuator used for adjusting the volume and the like in an audio device.

As a conventional mechanical attenuator, a so-called P-type attenuator is known in which resistors are connected in series and attenuated by the attenuation ratio of the resistors. In order to obtain N attenuations with the P-type attenuator, it is necessary to connect N + 1 resistors in series, and a switch capable of switching N contacts is required. For this reason, in this type of attenuator, only 20 to 30 switching attenuators have been put into practical use.
On the other hand, in audio equipment, a maximum attenuation amount of about -60 dB is required at 1 dB intervals, so that the attenuator by mechanical switching cannot meet the required specifications.

The attenuator disclosed in Patent Document 1 is configured so that a plurality of resistances in 10 dB steps and a plurality of resistances in 1 dB steps are switched by a switch controlled by a logic circuit to obtain a desired attenuation amount. ing. Here, the plurality of resistances in the 10 dB step and the plurality of resistances in the 1 dB step are connected via a buffer amplifier, and impedance conversion is performed to prevent the influence on the resistance of the next stage.

However, although relays and analog switches are used as digitally controlled switches, the resistance of the contacts becomes larger than that of mechanical switches, and the problem of distortion also arises. Further, when the resistance of the 10 dB step and the resistance of the 1 dB step are switched at the same time, if the timing of the switch is deviated even a little, there is a possibility that a large audible noise may be instantaneously generated, but such timing is easy to adjust. is not.

Further, in order to use the two attenuators of the 10 dB step and the 1 dB step, it is essential to insert a buffer amplifier between them in order to suppress an error in the amount of attenuation due to the parallel resistance in the subsequent stage. However, in the case of configuring a high-class audio device, a high-quality sound amplifier is installed after the sound quality controller, but as in Patent Document 1, a buffer amplifier may be further inserted inside the sound quality controller. As a whole, it was a factor of sound quality deterioration and was not a preferable configuration. The same problem is found in Patent Document 2.

Further, in recent years, a device has been developed in which these resistances are built in an IC (integrated circuit) and the switching is performed electronically by a relay, an analog switch, or the like (for example, PGA2320 manufactured by Texas Instruments). However, in these electronic devices, the contact resistance is several mΩ in the mechanical switch, whereas it is as large as several Ω to several tens Ω in the analog switch, and the internal resistance is non-linear, so that the signal is signaled. Has the drawback that it may cause distortion. Further, since digital control is performed, pulse noise is generated from a clock signal or the like, which tends to cause deterioration of sound quality.

Jitsukaisho 59-67032 Gazette Jikkai Sho 62-164414 Gazette

The problem to be solved is that attenuators that require a wide range of level adjustments at minute intervals for audio equipment are not practical for mechanical switching and deteriorate high sound quality with digital control. ..

The present invention is a mechanical switching attenuator composed of an electrode substrate for rough adjustment and an electrode substrate for fine adjustment, and has a configuration in which the electrode pattern provided on each electrode substrate can be switched in synchronization with the rotation of the shaft. That is the main feature.

Since the multi-stage attenuator of the present invention is mechanically switched, the resistance of the contacts is small and the influence of distortion is small as compared with the case of using an electronic device such as an analog switch. Noise due to switching timing from each stage can also be prevented. In addition, since a digital device such as a microcomputer is not required, no programming work is required, and pulse noise due to digital signals, clock signals, etc. is not mixed in principle, so that there is no concern about deterioration of sound quality due to these noises. Furthermore, since the components constituting the electrode pattern can be used in common, a wide range of level adjustment is possible with a small number of components.

It is explanatory drawing which shows the circuit structure of the multi-stage attenuator which concerns on this invention. It is explanatory drawing which shows the 1st electrode substrate of the multi-stage attenuator which concerns on this invention. It is explanatory drawing which shows the 2nd electrode substrate of the multi-stage attenuator which concerns on this invention. It is an enlarged explanatory view of the main part of the 2nd electrode substrate. It is a figure explaining the calculation method of the resistance value in the 1st electrode substrate.

The multi-stage attenuator is mechanically interlocked and switched, and the minimum number of parts enables adjustment of a wide range of signal levels while suppressing the generation of noise.

Hereinafter, the multi-stage attenuator of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory diagram showing a circuit configuration of a multi-stage attenuator according to the present invention, in which 1 is a first electrode substrate (for rough adjustment) constituting the multi-stage attenuator, and 2 is a second electrode substrate (fine). For adjustment). Reference numerals 3 and 4 are electrode patterns provided on the first electrode substrate 1, and the electrode pattern 3 is connected to the input terminal 14 and the resistor R11. The electrode pattern 4 is connected to the connection point between the resistance R11 and the resistance R12. That is, the adjacent electrode patterns are connected via a resistor. In the same manner below, the resistors are connected in series, and the electrode patterns are connected to each connection point. In this embodiment, the resistors are composed of six resistors R11 to R16 and six electrode patterns. The end of the last stand R16 is grounded.

Further, the first electrode substrate 1 is provided with a sliding contact 5 described later, and the terminal 6 connected to the common electrode 16 (FIG. 2) in contact with the sliding contact 5 is the second electrode substrate 2. It is connected to the terminal 7. The terminal 7 is connected to the electrode pattern 8 and the resistor R21 at the end, and the electrode pattern 9 to the last electrode pattern 10 are connected to the connection points from the resistor R22 connected in series with the resistor R21 to the subsequent R30, respectively. Has been done. That is, it is composed of 10 resistors R21 to R30 and 10 electrode patterns. The end of the last stand R30 is grounded.
Similar to the first electrode substrate 1, the second electrode substrate 2 is provided with a sliding contact 13, and the terminal 15 is connected to the common electrode 17 (FIG. 3) in contact with the sliding contact 13.

Since the sliding contact 5 of the first electrode substrate 1 and the sliding contact 13 of the second electrode substrate 2 are attached to a common rotating shaft 18 as described later, they rotate and slide in synchronization with each other. The contact 5 is configured to be in contact with the same electrode pattern 3 while the sliding contact 13 moves from the electrode pattern 8 to the last electrode pattern 10. Similarly, for the other five electrode patterns such as the electrode pattern 4, ten electrode patterns such as the electrode patterns 11 and 12 of the second electrode substrate 2 are correspondingly configured.

Here, the electrode pattern 11 is connected to the electrode pattern 8, and the electrode pattern 12 is connected to the electrode pattern 9. That is, in the 10 electrode patterns of the second electrode substrate 2 corresponding to the electrode pattern 4, the 10 electrodes from the electrode pattern 8 to the last electrode pattern 10 are directly formed without the adjacent electrode patterns passing through a resistor. It is connected to each pattern.
Hereinafter, similarly, in this embodiment, 50 electrode patterns are sequentially connected from the electrode pattern 8 to the last electrode pattern 10 by 10 each.

By doing so, each time the electrode pattern of the first electrode substrate 1 is switched, the electrode patterns connected to the resistors R21 to R30 are sequentially and repeatedly connected.
Therefore, in this embodiment, 60 electrode patterns (contacts) are formed on the second electrode substrate 2, but 10 resistors are actually arranged. Since 6 pieces are arranged on the first electrode substrate 1, the total number of resistances required is 16.

By using the terminal 14 as an input and the terminal 15 as an output, it is possible to configure an attenuator that performs mechanical switching with 60 contacts in this embodiment, and for audio equipment that requires a wide range of attenuation. Applicable.

FIG. 2 is an explanatory diagram showing a first electrode substrate 1 of the multi-stage attenuator according to the present invention, and 6 such as a common electrode 16 and an electrode pattern 3 concentrically centered on a shaft 18 on the first electrode substrate 1. Two electrode patterns are arranged. The shaft 18 can be rotated manually, and a sliding contact 5 is fixed to the shaft 18, the tip portion 19 thereof for connecting the common electrode 16 and six electrode patterns such as the electrode pattern 3. It is composed of conductors. Further, the terminal 14 for input is connected to the electrode pattern 3 at the end portion, and the terminal 6 is connected to the common electrode 16. By rotating the sliding contact 5 via the shaft 18, the common electrode 16 and six electrode patterns such as the electrode pattern 3 are switched and connected.

FIG. 3 is an explanatory diagram showing a second electrode substrate 2 of the multi-stage attenuator according to the present invention. In the figure, the common electrode 17, the electrode patterns 8, 9, and the like are arranged concentrically around the common shaft 18 as in the first electrode substrate 1. Further, the sliding contact 13 fixed to the shaft 18 also has a tip portion 20 connected to the common electrode 17 and 60 electrode patterns such as the electrode pattern 8 in the same manner as the sliding contact 5 of the first electrode substrate 1. be able to.

The first electrode substrate 1 and the second electrode substrate 2 are fixed around the shaft 18, and by rotating the shaft 18, the sliding contact 5 of the first electrode substrate 1 and the second electrode substrate 2 are fixed. The sliding contact 13 of 2 rotates synchronously so as to move the electrode pattern of the second electrode substrate 2 one by one toward the same direction. Each one electrode pattern of the first electrode substrate 1 is arranged in a positional relationship so as to overlap with the ten electrode patterns of the second electrode substrate 2, and the sliding contact 13 of the second electrode substrate 2 is arranged. While switching between these 10 electrode patterns, the sliding contact 5 of the first electrode substrate 1 rotates while being in contact with the same electrode pattern.

FIG. 4 is an enlarged explanatory view of a main part of the second electrode substrate 2, and the electrode pattern 8 at the end is connected to the terminal 7. Further, adjacent electrode patterns 8 and 9 are connected via resistors R21, R22 and the like, and the tenth electrode pattern 10 is grounded via the resistor R30. Here, the electrode pattern 8 is directly connected to the eleventh electrode pattern 11, the electrode pattern 9 is directly connected to the twelfth electrode pattern 12, and similarly, the tenth electrode pattern 10 is sequentially connected to the eleventh electrode pattern 10 thereafter. The electrode pattern 11 of the above is connected to the 21st electrode pattern, and is repeatedly connected to the 60th electrode pattern.
By doing so, it can be considered that the first electrode pattern 8 to the tenth electrode pattern 10 are repeatedly arranged five times, and 60 resistors are replaced by 10 resistors. be able to. Therefore, conventionally, in order to obtain 60 steps of attenuation from 0 dB to 59 dB at 1 dB intervals with a mechanical P-type attenuator, 60 resistors are required, which is difficult to put into practical use due to space problems and the like. However, by adopting the technique of the present invention, it can be realized with 16 resistors including the resistor used for the first electrode substrate 1, and a wide range of signal levels can be adjusted at minute intervals.

Next, the amount of attenuation in the multi-stage attenuator of this embodiment will be described. In the electrode pattern arranged on the first electrode substrate 1 corresponding to the attenuator of the first stage, the resistors R11 to R16 attenuate the electrodes from 0 dB to -10 dB, -20 dB, -30 dB, and so on at intervals of 10 dB. In the second electrode substrate 2 corresponding to the second-stage attenuator connected to the electrode pattern of the above, from 0 dB to -1 dB, -2 dB, -3 dB and so on at 1 dB intervals due to the resistors R21 to R30. Attenuated and the output is taken from each electrode pattern.
Therefore, in this embodiment, it is configured to obtain 60 steps of attenuation from 0 dB to −59 dB at 1 dB intervals.

As described above, when the terminal 6 of the first electrode board 1 and the terminal 7 of the second electrode board 2 are directly connected, a buffer amplifier or the like for impedance adjustment is not provided as in the conventional case. Therefore, when setting the attenuation amount of the first stage (first electrode substrate 1), it is necessary to obtain the resistance values of R11 to R16 in consideration of the influence of the resistance connected to the second stage (second electrode substrate 2). There is.

FIG. 5 is a diagram illustrating a method of calculating a resistance value in the first electrode substrate 1.
First, the resistance value of R11 to R16 is obtained by ignoring the resistance of the subsequent stage, and then the resistance of a constant resistance value (10 kΩ) is sequentially connected in parallel as the resistance of the subsequent stage, and at each connection point of R11 to R16. The resistance value is sequentially corrected to the optimum value from R12 so that the attenuation amount of the above becomes a predetermined attenuation amount. Then, since the attenuation value at each connection point also changes due to the change in the resistance value due to the correction, the resistance value is sequentially corrected in the same manner so as to have an appropriate attenuation amount from R12 again. This is repeatedly calculated using a computer, and repeated until the attenuation error is within the allowable range, and each resistance value is optimized. The optimization method of the present invention is not limited to this.
Further, in this embodiment, the case where the terminal 6 of the first electrode substrate 1 and the terminal 7 of the second electrode substrate 2 are directly connected has been described, but the connection can also be made via a buffer amplifier. In this case, the optimization as described above is not necessary.

Further, for example, when switching from -9 dB to -10 dB, the sliding contact 5 sliding on the first electrode substrate 1 is the electrode pattern 4, and the sliding contact 13 sliding on the second electrode substrate 2 is the electrode pattern. It is necessary to switch to 11 at the same time, but if the sliding contact 13 switches earlier, it switches in the order of −9 dB → 0 dB → 10 dB, and excessive noise is temporarily generated. Therefore, in this embodiment, the positions of the electrode patterns are staggered so that the sliding contact 5 always switches before the sliding contact 13 when switching at the same time.
That is, the sliding contacts are arranged so as to switch from the electrode pattern 3 to the electrode pattern 4 before switching from the electrode pattern 10 to the electrode pattern 11. After that, similarly, before the 20th, 30th, 40th, and 50th electrode patterns of the second electrode substrate 2 are switched to the next electrode pattern, the electrode pattern of the first electrode substrate 1 is the next electrode pattern. The electrode patterns are arranged so as to be slightly offset from the overlapping positional relationship so as to switch to.
It should be noted that the same effect can be obtained by a configuration in which the directions of the sliding contacts are changed to each other instead of shifting the position of the electrode pattern, and audible noise can be prevented.

Further, if the shaft 18 is rotationally driven by a stepping motor and each electrode pattern of the second electrode substrate 2 is arranged at a position that is an integral multiple of the drive angle of the stepping motor, for example, a multi-stage attenuator can be remotely controlled. When driving, control becomes easy. In this embodiment, the electrode pattern is arranged every 5.4 degrees, which is three times as large as the drive angle of the stepping motor of 1.8 degrees.
Further, by using a drive mechanism that combines a key groove and a key as the rotational drive of the shaft 18, the position accuracy of the rotation angle can be improved.
Further, in the present embodiment, the sliding contact 5 and the sliding contact 13 are rotationally driven by one common rotating shaft 18, but the present invention is not limited to this, and separate rotating shafts are provided. , Each can be configured to be rotationally driven via a timing pulley or timing belt.

By adopting the technique of the present invention, drive power is not required to switch the attenuation amount of the multi-stage attenuator, and not only for adjusting the volume of acoustic equipment but also in fields where signal level attenuation is required in a wide range. , Can be supplied as a single component and has high industrial applicability.

1 1st electrode board 2 2nd electrode board 3, 4 Electrode pattern 5, 13 Sliding contact 6, 7 Terminal 8, 9, 10, 11, 12 Electrode pattern 14 Input terminal 15 Output terminal 16, 17 Common electrode 18 shaft

Claims (8)

A first electrode substrate in which a common electrode and a plurality of divided electrode patterns are arranged concentrically, and a sliding contact for connecting the common electrode and the divided electrode pattern by rotation of a shaft is provided. A multi-stage attenuator composed of a second electrode substrate,
The plurality of divided electrode patterns of the first electrode substrate are connected to adjacent electrode patterns via resistors, and the common electrode formed on the first electrode substrate is the second electrode substrate. The second electrode pattern is input to the electrode pattern at the end of the plurality of electrode patterns formed on the first electrode substrate, which is connected to the electrode pattern at the end of the plurality of electrode patterns formed in the first electrode substrate. A multi-stage attenuator configured to output the common electrode formed on the electrode substrate. The multi-stage attenuator according to claim 1, wherein the sliding contact provided on the first electrode substrate and the second electrode substrate rotates in the same direction in synchronization with the rotation of the shaft. .. The divided plurality of electrode patterns of the second electrode substrate include a predetermined number of electrode patterns connected to adjacent electrode patterns via resistors, and a plurality of electrodes connected to each of these electrode patterns. The multi-stage attenuator according to claim 1, wherein the attenuator is composed of a pattern. The predetermined number of electrode patterns are arranged in a positional relationship overlapping with one of the divided electrode patterns of the first electrode substrate, and the plurality of electrode patterns connected to the predetermined number of electrode patterns are the first. The multi-stage attenuator according to claim 3, wherein the electrode substrate of 1 is arranged in a positional relationship overlapping with the other one of the divided electrode patterns. The predetermined number of electrode patterns and the plurality of electrode patterns connected to the predetermined number of electrode patterns are arranged in a positional relationship so as to overlap each of the divided electrode patterns of the first electrode substrate at a position shifted from each other. The multi-stage attenuator according to claim 4, wherein the attenuator is provided. The resistance value of the resistor connected to the electrode pattern of the first electrode substrate is predetermined so as to be connected to the electrode pattern of the second electrode substrate and have a predetermined attenuation amount. The multi-stage attenuator according to claim 1, which is characterized. The multistage according to claim 1, wherein the shaft is rotationally driven by a stepping motor, and each electrode pattern of the second electrode substrate is arranged at a position that is an integral multiple of the drive angle of the stepping motor. Attenuator. The multi-stage attenuator according to claim 1, wherein the rotation drive mechanism of the shaft is configured by combining a key groove and a key of the shaft.

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