JPS6256643B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a composite component for protecting speaker circuits and the like from overcurrent and overheating.

In a typical speaker circuit, as shown in FIG. 1, the output of an amplifier A is supplied to a speaker coil L via a variable resistor VR. However, in this circuit, there is no protection device in case, for example, amplifier A fails and a large amount of current flows into coil L, so there is a risk that speaker S may be destroyed by the abnormal current. It was hot.

From this, the present inventors, as shown in Figure 2,
I devised the idea of connecting a protective resistor, a positive temperature coefficient thermistor PTC, between amplifier A and variable resistor VR. And the overcurrent from amplifier A is
It is well controlled by the positive temperature coefficient thermistor PTC, and damage to the speaker S can be prevented.

However, after repeated experiments, we found that even though the positive temperature coefficient thermistor PTC was connected as shown in Figure 2, the speaker S was still sometimes destroyed. The present inventors further investigated the cause of this problem. As a result, it was found that the variable resistor VR may generate abnormal heat for some reason, causing an abnormal current to flow through the coil L. If this abnormal current is extremely large, it is not a problem because it can be controlled by the positive temperature coefficient thermistor PTC, but if an abnormal current occurs that is not large enough to be controlled by the positive temperature coefficient thermistor PTC, no protection can be provided. It was warm because I wasn't wearing it. In order to improve this drawback, attempts were made to select various characteristics of the positive temperature coefficient thermistor PTC, but the problem was that it was difficult to set the critical point of normality and abnormality, and it was difficult to achieve an appropriate design. Therefore, in reality, it is necessary to use additional fuses and thermostats to ensure safety, which significantly increases component costs. Note that when a fuse is used, once the fuse is activated, it cannot be reset, making it difficult to handle and replace. Furthermore, when a thermostat is used, there are problems in that it lacks reliability and generates noise due to the presence of contacts. Furthermore, since a positive temperature coefficient thermistor PTC is simply used, the wiring is not only complicated, but also has the disadvantage that miniaturization is not possible.

The present invention has been made in view of the above points, and in summary, a variable resistor and a positive temperature coefficient thermistor are thermally coupled, and a positive coefficient thermistor is attached to a slider of the variable resistor. The present invention aims to provide a composite component that can be connected in series and have a positive temperature coefficient thermistor detect and control both abnormal heat generation in a variable resistor and abnormal current flowing into the variable resistor. .

Embodiments of the composite part of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a top view, FIG. 4 is a bottom view, and FIG. 5 is a side sectional view.

In the figure, reference numeral 1 denotes an insulating substrate made of alumina porcelain or the like, and a through hole 2 for rotatably fixing a rotor shaft, which will be described later, is provided approximately at the center of the substrate 1. 3 is a resistor provided in a semicircular arc along the periphery of the through hole 2 on one plane of the insulating substrate 1; 4 and 5 are conductively connected to both ends of the resistor 3; External connection terminal electrodes 6 and 7 provided so as to lead out the resistor 3 to one end of the insulating substrate 1 are conductively connected to the electrodes 4 and 5 and project outward from the insulating substrate 1. The attached terminal board for external connection is fixed by caulking or the like through small holes 8 and 9 provided in the insulating substrate 1. The external connection terminal plates 6 and 7 may be further bonded with solder, or may be omitted if necessary. 10 has electrodes 11 on both planes,
A plate-shaped positive temperature coefficient thermistor having a numeral 12 is brought into surface contact with the other plane of the insulating substrate 1. Reference numeral 13 designates a through hole in the center of the PTC thermistor 10 for rotatably fixing a rotor shaft, which will be described later, and is provided so as to match the through hole 2 of the insulating substrate 1. Reference numeral 14 denotes a metal terminal plate disposed on the lower surface of the PTC thermistor 10, and is used to draw out the electrode 12 of the PTC thermistor 10 to the outside. This metal terminal plate 14
Also, a through hole 15 for rotatably fixing the rotor shaft, which will be described next, is provided in each of the through holes 2 and 13 described above.
It is set in accordance with the 16 is a rotor shaft having a protruding flange 17 formed on a part of its outer circumference;
One end is inserted through the through hole 15 of the metal terminal plate 14, the through hole 13 of the PTC thermistor 10, and the through hole 2 of the insulating substrate 1, respectively, and projects upward. That is, the rotor shaft 16 is inserted until the collar 17 comes into contact with the lower surface of the metal terminal plate 14. Reference numeral 18 denotes a fixing ring externally fitted near the end of the rotor shaft 16 projecting upward, and by pressing this onto the surface of the insulating substrate 1, the flange 17 is fixed.
It also integrates the whole. It is easy to understand that the rotor shaft 16 is rotatable in this state. 19 is the protruding rotor shaft 1
This is a connection terminal board whose one end is fitted onto the tip of the PTC thermistor 6 and which is led to the other side of the insulating substrate 1 so that the other end is connected to the electrode 11 of the PTC thermistor 10. The other end of the connection terminal plate 19 is connected to the insulating substrate 1 and the PTC thermistor 10 so that the connection terminal plate 19 does not interfere with the surface contact between the insulating substrate 1 and the PTC thermistor 10, that is, the thermal coupling. It is preferable that the contact surface be disposed over almost the entire area of the contact surface. Reference numeral 20 denotes a slider having one end externally fitted and fixed to the protruding end of the rotor shaft 16, and the other end elastically abutting against the resistor 3 on the insulating substrate 1. The slider 20 is electrically conductively connected to the connecting terminal plate 19 via a suitable spring washer 21 at the mounting portion of the rotor shaft 16. Of course, the connection may be made directly without using the spring washer 21.

In this way, a composite component in which a variable resistor and a positive temperature coefficient thermistor are integrated is obtained. In this composite component, a positive temperature coefficient thermistor 10 is attached to a slider 20 that slides on the resistor 3 of the variable resistor.
are connected in series via the connection terminal 19 and led out to the outside through the metal terminal plate 14. Note that reference numeral 22 in the figure is a locking piece with which the collar 17 is locked in order to suppress unnecessary rotation of the rotor shaft 16.

FIG. 6 is a side sectional view showing another example. The difference between this one and the previous example is that the slider 20
The point is that a connecting electrode 19' is provided on the insulating substrate 1 in place of the connecting terminal plate 19 used to connect the terminal and one electrode 11 of the positive temperature coefficient thermistor 10. The remaining points will be left to the previous example and will not be explained in detail.

FIG. 7 is a side sectional view showing still another example. In this example, the resistor 3 provided on the insulating substrate 1 is moved 180 degrees from the resistor 3 in the previous example across the through hole 2, and the tip of the slider 20 is stretched to form a positive temperature coefficient thermistor 1. The rotor shaft 16 is brought into contact with the electrode 11 of the rotor shaft 16, and is externally fitted and fixed to the other end of the rotor shaft 16. In this case, when the slider 20 is rotated, the slider 20 also slides on the electrode 11 of the positive temperature coefficient thermistor 10. In other words, the slider 20 has the functions of the connection terminal plate 19 and the connection electrode 19'. In this example, a metal terminal plate 14 is used to lead out the electrode 12 of the positive temperature coefficient thermistor 10.
is interposed between the insulating substrate 1 and the positive temperature coefficient thermistor 10.

FIG. 8 is a side sectional view showing still another example. This example has a structure in which a variable resistor and a positive temperature coefficient thermistor are loaded in case C, and resistor 3
The slider 20 sliding on the top is connected to the electrode 11 of the positive temperature coefficient thermistor 10 via a first coil spring 23, a connecting electrode (plate) 24 attached to the inner wall of the case, and a second coil spring 25. That will happen.

The above embodiments and drawings are merely shown to embody the present invention, and the present invention is not limited thereto. In short, the variable resistor and the positive temperature coefficient thermistor may be thermally coupled, and the shape and structure may be such that the positive coefficient thermistor can be connected in series with the slider of the variable resistor. It goes without saying that various design changes can be made from the embodiments and drawings. In other words, any design changes may be made without departing from the spirit of the present invention.

As described above, the composite component of the present invention allows the positive temperature coefficient thermistor to detect and control both the inflow of overcurrent into the variable resistor and abnormal heat generation of the variable resistor. It has the remarkable effect that it is compact and has excellent protection functions, and can be used as a device that does not require the use of other protective parts such as fuses and thermostats.

[Brief explanation of the drawing]

Figure 1 is a general speaker circuit diagram, Figure 2 is a speaker circuit diagram that is the premise of the present invention, and Figures 3 to 5.
The figure is a top view showing an embodiment of the composite part of the present invention;
The bottom view, side sectional view, and FIGS. 6 to 8 are all side sectional views showing other embodiments of the composite component of the present invention. DESCRIPTION OF SYMBOLS 1...Insulating substrate, 3...Resistor, 10...Positive characteristic thermistor, 16...Rotor shaft, 20...Slider.

Claims (1)

[Claims] 1. A plate-shaped positive temperature coefficient thermistor having a through hole in the center and having electrodes on both sides, and a through hole that is overlapped to be thermally coupled to the positive temperature coefficient thermistor and that matches the through hole of the positive temperature coefficient thermistor. a semicircular resistor provided around the through hole on one surface of the insulating substrate, terminals conductively connected to both ends of the resistor, and the positive characteristic A rotor shaft rotatably inserted into a through hole of the thermistor and an insulating substrate, a slider held by the rotor shaft and sliding on the resistor, and one electrode of the slider and the positive temperature coefficient thermistor. and a terminal conductively connected to the other electrode of the positive temperature coefficient thermistor.