JPH034076Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Purpose of the Invention] (Field of Industrial Application) The present invention relates to a control device for electrical appliances, and for example, to a control device for a kotatsu or the like using a microcomputer.

(Conventional technology) Thermal noise, shot noise,
Various types of noise, such as switching noise, noise caused by discharge, and noise caused by fluctuations in ground level, adversely affect the system by causing malfunctions. In particular, in recent years systems have progressed from analog systems to digital systems, and elements have shifted to transistors and ICs, resulting in lower power supply voltages and signal levels, which has significantly reduced the noise tolerance of electronic equipment. , noise removal becomes a problem.

In addition, noise includes vertical normal mode noise that appears superimposed between signal lines, and horizontal common mode noise that appears between each line and a reference point such as the ground.Normal mode noise can be detected by using a filter. However, in the case of common mode noise, the only way to remove it is to improve the balance of the circuit, and it is difficult to remove it.

FIG. 4 shows the transmission path of common mode noise in a conventional electronic control circuit.

1 is a commercial AC power source, and this commercial AC power source 1 is connected to a control device 3 including a control circuit 2 . Then, the noise enters the connection line from the noise source 4, passes through any part of the control circuit 2 of the control device 3, and flows to the ground via stray capacitance with the ground. Furthermore, it actually flows in the opposite direction due to the alternating current.

In order to make the control device 3 strong against common mode noise, a configuration is known in which the control device 3 is shielded with a conductive material such as metal. By shielding with a conductive material such as metal in this way, common mode noise will not enter the control circuit 2, but will flow into the stray capacitance with the ground through the conductive material such as a metal plate, which will prevent malfunctions due to noise in the control circuit 3. can be prevented.

(Problem to be solved by the invention) However, in the case of control devices that have openings for switches and displays, the case body has a complicated shape, and it is extremely difficult to form it from metal. Since it is very easy to mold the case body from synthetic resin, there is a demand for a control device that is resistant to noise and whose case body is formed from synthetic resin.

This invention was created in view of the above problems.
The control circuit section is less susceptible to noise, and
It is an object of the present invention to provide a control device for an electric appliance that improves heat dissipation from a heat generating element forming a control circuit section.

[Structure of the idea]

(Means for Solving the Problems) The control device for electrical appliances of the present invention has a control circuit section in which elements are arranged on a substrate and connected to a commercial AC power source, inside a case body made of a non-conductive material. A conductive plate that also serves as a heat dissipation plate is provided between the control circuit unit and the case body to insulate and attach a heat-generating element forming a part of the control circuit unit, and the commercial AC power supply and the conductive A capacitor is connected between the plates.

(Function) This invention allows common mode noise from a commercial AC power supply to flow from the capacitor between the commercial AC power supply and the conductive plate to the conductive plate, bypass the conductive plate to the ground via the ground's stray capacitance, and flow into the control circuit. In addition, the heat-generating elements that form part of the control circuit section radiate heat from the conductive plate, and have good heat dissipation.
Furthermore, since this heat-generating element is installed insulated, it is protected from noise.

(Embodiment) Hereinafter, an embodiment of the control device for electrical appliances of the present invention will be described with reference to FIGS. 1 to 3.

Reference numeral 11 denotes a case body made of synthetic resin, which is a non-conductive material, and includes an upper side member 12 and a lower side member 13.
A board 14 is housed within this case body 11. This board 14 includes an IC 15 and a transistor 1.
6, capacitor 17, function selection switch 19,
Elements such as a temperature control switch 20, a light emitting diode 21 for displaying functions that lights up in conjunction with the function selection switch 19, and a light emitting diode 22 for displaying temperature are arranged to constitute a control circuit section 23. Furthermore, a bypass capacitor 24 is provided on the substrate 14.

Reference numeral 25 denotes a conductive plate that also serves as a heat sink and has a circular opening 26 in the center. On the upper surface of this conductive plate 25, as shown in FIG. A heat generating element 45, such as a power transistor, which requires heat dissipation is installed without being affected in order to prevent noise from being applied to this element 45.

The conductive plate 25 is formed by inserting the opening 26 into the central shaft portion 27 provided on the lower side member 13 of the case body 11 and engaging the outer periphery with the surrounding frame 28 of the lower side member 13. support,
The central hole 30 of the substrate 14 is inserted into the central shaft portion 27 via the washer 29, and the plurality of protrusions 31 provided on the lower surface side member 13 are inserted into each hole 32 of the substrate 14. , the substrate 14 is fixed together with the conductive plate 25. In this way, the conductive plate 25 is interposed between the lower surface side member 13 and the substrate 14 on the lower surface side of the case body 11 .

Then, the power cord 34 to which the power plug 33 is connected and the control cord 36 to which the connection plug 35 is connected are connected to the control circuit section 23, and the power cord 34 and the control cord 3
A conductive plate 25 is connected to 6 via the bypass capacitor 24.

Further, a cord protector 37 encasing the power cord 34 and the control cord 36 is sandwiched between the upper surface side member 12 and the lower surface side member 13 of the case body 11.
is fixed with screws etc. Function selection pressers 38 and 3 formed on the upper surface side member 12
8 are opposed to the function selection switches 19, 19, and temperature control pressers 39, 39, which are also formed on the upper surface side member 12, are opposed to the temperature control switches 20, 20, and further, the upper surface side member The light emitting diode 21 for displaying the function and the light emitting diode 22 for displaying the temperature are made to face each of the 12 display windows 40. Note that a power switch 41 is provided at the periphery of the upper surface side member 12.

Next, the operation of the above embodiment will be explained.

While connecting the power plug 33 to an outlet (not shown) of the commercial AC power source 42,
5 to a controlled electrical appliance, such as a kotatsu. Then, turn on the power switch 41, select rapid heating, automatic control, etc. with the function selection pusher 38,
The temperature is set using the temperature control presser 39 for raising or lowering. At this time, elements of the function display light emitting diodes 21 corresponding to the corresponding functions emit light, and a number of temperature display light emitting diodes 22 corresponding to the corresponding temperature are lit. The control circuit section 23 then controls, for example, the temperature of the electrical appliance.

In this state, if common mode noise enters the power supply 42 from the noise source 43, it is sent to the conductive plate 25 via the capacitor 24 connected between the power supply 42 and the conductive plate 25, and is Capacity 4
4 to the ground, noise is prevented from flowing into the control circuit section 23.

In addition, a heat generating element 45 that requires heat radiation such as a triac or a power transistor forming a part of the control circuit section 23 is connected to a conductive plate 25 that also serves as a heat sink.
Since the heat generating element 45 is insulated and attached to the conductive plate 25, no noise is given to the heat generating element 45.
It is possible to reduce the number of parts and downsize the equipment.

As described above, by providing the conductive plate 25 between the substrate 14 and the lower side member 13 and connecting the capacitor 24 between the commercial AC power supply 42 and the conductive plate 25, even if the case body 11 is made of synthetic resin or the like, Noise is bypassed to the ground and does not flow to the control circuit section 23, so that the influence of noise can be reduced and malfunctions can be prevented.

[Effect of idea]

According to the present invention, a conductive plate is provided between the case body and the control circuit board, and a capacitor is connected between the commercial AC power supply, thereby bypassing noise to the ground and using a non-conductive synthetic resin. The case body can also protect the control circuit from noise, and
Heat is radiated from the heat-generating element that forms part of the control circuit section through a conductive plate that also serves as a heat sink, and since this heat-generating element is installed insulated from the conductive plate, there is no noise in the heat-generating element. This allows the number of heat dissipating members to be reduced, the number of parts to be reduced, and equipment to be downsized.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the device of the present invention, FIG. 2 is an exploded perspective view of the same, FIG. 3 is an equivalent circuit diagram of the same, and FIG. 4 is an equivalent circuit diagram of a conventional example. 11... Case body, 14... Board, 15-1
7, 19-22... element, 23... control circuit section,
24... Capacitor, 25... Conductive plate, 42...
Commercial AC power supply, 45... Heat generating element.

Claims (1)

[Scope of Claim for Utility Model Registration] A case body made of a non-conductive material, a control circuit part housed in the case body and having elements arranged on a board and connected to a commercial AC power source, and this control circuit part. and the case body, and a conductive plate that also serves as a heat sink to which a heat-generating element forming a part of the control circuit section is insulated and attached; and a conductive plate that is connected between the commercial AC power source and the conductive plate. 1. A control device for an electrical appliance, comprising: a capacitor; and a control device for an electric appliance.