JPH0227621Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a variable attenuator with a built-in input coupling circuit for use in oscilloscopes and the like.

[Prior art]

As shown in Figure 2, the input coupling circuit connects the observed input signal applied to the input connector 2 to the input terminal of the vertical axis attenuator 3 of the oscilloscope by switching the input coupling switch 1 to either AC or DC coupling. Or it is a circuit connected to GND. When input coupling switch 1 is set to AC position, input connector 2
The input signal applied to the input signal is coupled through the coupling capacitor C ₁ to substantially block the DC component.
In the GND position, the input terminal of the attenuator 3 is grounded, and the coupling capacitor C ₁ is grounded through a high resistance R ₁ of, for example, 1 MΩ to discharge its charge.
In the DC position, the input signal is galvanically coupled to the input of the attenuator 3, coupling all frequency components from DC to high frequencies.

Conventionally, the input coupling switch 1 used in the above-mentioned input coupling circuit uses a lever switch or a slide switch provided outside the attenuator 3, or a switch contact on a printed circuit board outside the attenuator 3. The switch contacts are operated by a cam that operates in conjunction with a lever.

[Problem that the invention attempts to solve]

However, in the conventional input coupling circuit described above, the one in which the input coupling switch is provided outside the attenuator has the disadvantage that the signal path becomes long and unstable, which becomes an obstacle to improving frequency characteristics. Also,
The disadvantage of cam-operated devices is that they are complicated and expensive.

The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to provide an attenuator with an input coupling circuit that has a short signal path, can improve frequency characteristics, and is inexpensive.

[Means for solving problems]

In order to solve the above problems, the present invention provides a variable attenuator equipped with a rotary variable attenuator switch that operates in conjunction with a rotating shaft, which is fitted on the outside of the rotating shaft and rotates independently of the rotating shaft. In addition to providing a possible outer rotation shaft, the variable attenuator is provided with an input coupling switch that operates in conjunction with the rotation of the outer rotation shaft.

[Effect]

With the above configuration, the input coupling circuit can be formed on the same board as the attenuator using the input coupling switch, so the input signal path is shortened and the path is made uniform, so the frequency characteristics can be improved. It becomes possible to improve the performance.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 is a diagram showing the external appearance of a variable attenuator with an input coupling circuit according to the present invention, in which figure a is a side view and figure b is part A of figure a (input coupling circuit and attenuator part).
Fig. 3c is a bottom view, and Fig. 3c is a front view [viewed from the direction of arrow B in Fig. 3a]. As shown in the figure, the variable attenuator with input coupling circuit includes an input coupling switch 11, a variable attenuator switch 12 for switching attenuators, and a variable attenuator 13. As will be described in detail later, the shafts for operating the variable attenuator 13 have a multiple structure, and when the innermost rotating shaft 15 is rotated, the variable resistor 13 is operated, and the rotating shaft 16 located in the middle operates. When the lever is rotated, the variable attenuator switch 12 is operated, and the lever 17 is moved to the position B in Fig. 1c.
By rotating left and right as shown at positions D to D, the outermost shaft (described in detail later) rotates and the input coupling switch 11 is operated. Further, a shaft of a multiple structure for operating the input coupling switch 11, the variable attenuator switch 12, and the variable resistor 13 is rotatably attached to the support block 18 for the variable attenuator with an input coupling circuit. In the figure, 14 is a frame for housing a circuit board 23 on which an attenuator and an input coupling circuit are mounted, 24 is an input terminal connected to the input end of the input coupling circuit of the circuit board 23, and 25 is an attenuator. An output terminal 26 connected to the output end of the circuit is a ground terminal.

Furthermore, a groove 27 for rotating the lever 17 by a large amount is formed in the frame 14, and by providing the groove 27, the lever 17 can be rotated by a large rotation angle as shown in E of FIG. 1c. becomes possible. This is when installing the variable attenuator with input coupling circuit of the above structure in a synchroscope etc.
Lever 17 may be an obstacle to soldering work, etc.
This is to remove these obstacles by rotating the motor at a large rotation angle. Therefore, after the variable attenuator with input coupling circuit is mounted on a synchroscope or the like, a stopper for regulating the rotation range of the lever 17 to the rotation angle B to D is provided on the operation panel or the like.

FIG. 3 is a sectional view showing the structure of the multi-axis and the structure of the input coupling switch 11. As shown in the figure, in the multi-axis structure, a rotating shaft 16 is provided outside a rotating shaft 15, and a rotating shaft 1 is provided outside the rotating shaft 16.
9 is provided. Further, both the rotating shaft 16 and the rotating shaft 19 are rotatably supported by a support block 18. The lever 17 is fixed to one end of the rotating shaft 19, and the movable contact 20 of the input coupling switch 11 is fixed to the other end.
When the lever 17 is rotated left and right, the rotary shaft 19 rotates around the outer periphery of the rotary shaft 16, and the movable contact 20 is rotated about the axis of the multiple shafts. In addition, 22 in the figure is equipped with a ball 22a that fits into a groove 18a provided radially at a predetermined angle on the inner surface of the support block 18.
This is a holding mechanism for holding the rotating shaft 19 at a predetermined rotation angle.

FIG. 4 is a partial sectional view showing details of the holding mechanism 22. As shown in FIG. As shown in the figure, a disk 22c made of a resin material, a plate spring 22b made of an elastic metal material, and a lever 17 are fixed to the outer periphery of the rotating shaft 19 inside the support block 18. It is designed to rotate integrally by rotation. As mentioned above, grooves 18a are provided radially on the inner surface of the support block 18 at a predetermined angle, and a hole 22d in which the ball 22a slides is formed in the portion of the disc 22c that corresponds to the upper part of the groove 18a.
is formed, and the ball 22a is pushed toward the support block 18 by the plate spring 22b. Now when the lever 17 is rotated, the ball 22a will move into the groove 18.
When the ball 22a crosses the convex portion between the groove 18a and the groove 18a, the ball 22a is displaced as shown by the dotted line against the elastic force of the plate spring 22b, and when it reaches the position of the groove 18a, it is displaced again by the plate spring 22b. It is pushed and returns to the position indicated by the solid line, and the rotating shaft 19 is fixed at that position.

FIG. 5 is a diagram showing the structure of a movable contact. As shown in the figure, the movable contact has a movable contact pattern 20b made of a conductor on the surface of a thin disc 20a made of an insulating material such as resin. A hole 20c having a shape that fits around the outer periphery of the rotating shaft 19 is formed in the center.

FIG. 6 is a diagram showing the structure of a fixed contact electrically connected to and separated from the movable contact 20, in which FIG. 6a is a front view, and FIG. As shown in the figure, the fixed contact 21 has a structure in which a total of six fixed contact elements 21b are provided on the inner surface of a case 21a made of an insulating material such as a resin material. A hole 21c is formed in which the shaft 19 can freely rotate.

The input coupling switch 11 is assembled by arranging two fixed contacts 21 having the above structure, the movable contact 20 therein so that their inner surfaces face each other, and incorporating them into the rotating shaft 19. When the lever 17 is rotated left and right, the movable contact rotates in conjunction with the rotating shaft 19, and the contact pattern 20b is connected to the fixed contact element 21.
b or to separate the contact pattern 21b from the fixed contact element 21b.

In the variable attenuator with an input coupling circuit having the above structure, the input coupling circuit having the configuration shown in FIG. If the attenuator and the input coupling circuit are connected and arranged in the frame body 14, the attenuator and the input coupling circuit can be housed in the frame 14, and the pattern wiring that connects the terminal of the input coupling switch 11 and the input coupling circuit, the input of the attenuator and the output of the input coupling circuit can be housed. Since only a short pattern wiring is required to connect the two, the input signal path is short and uniform, and the frequency characteristics can be improved. Moreover, since these are housed within the metal frame 14 of the variable attenuator, the influence of noise and the like is reduced, and no special space is required to mount the input coupling circuit.

[Effect of idea]

As explained above, according to the present invention, an outer rotating shaft is provided which fits on the outer side of the rotating shaft and can rotate independently of the rotating shaft, and an input coupling switch is provided in conjunction with the rotation of the outer rotating shaft. Since it is provided in the variable attenuator, the path of the input signal can be shortened and made uniform, so that frequency characteristics are improved, space can be used effectively, and an excellent effect can be obtained in reducing the size of the device.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the external appearance of a variable attenuator with an input coupling circuit according to the present invention, in which Fig. 1a is a side view, Fig. 1b is a bottom view of part A in Fig. 1a, and Fig. 1c is a front view ( 2 is a circuit diagram showing an example of the configuration of the input coupling circuit, and FIG. 3 is a sectional view showing the structure of the multi-axis and the structure of the input coupling switch 11. , FIG. 4 is a partial sectional view showing details of the holding mechanism 22, FIG. 5 is a structural diagram showing an example of a pattern of movable contacts, FIG. 6 is a diagram showing the structure of a fixed contact, and FIG. , Figure b is a sectional view taken along the line A--A in Figure a. In the figure, 11...input coupling switch, 12...variable attenuator switch, 13...variable resistor, 14...
... Frame body, 15, 16, 19 ... Rotating shaft, 17 ...
Lever, 18... Support block, 20... Movable contact, 21... Fixed contact, 22... Holding mechanism.

Claims (1)

[Scope of utility model registration request] In a variable attenuator equipped with a rotary variable attenuator switch that operates in conjunction with a rotating shaft,
An outer rotating shaft is provided that fits on the outer side of the rotating shaft and is rotatable independently of the rotating shaft, and an input coupling switch that operates in conjunction with the rotation of the outer rotating shaft is provided within the variable attenuator. A variable attenuator with an input coupling circuit.