JPS6139693B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in input switches for household electrical appliances such as washing machines.

Washing machines are generally used in harsh environments such as bathrooms and outdoors, so unlike other home appliances, when implementing electronic control, sufficient consideration must be given to moisture resistance and drip resistance. It is. Also, since washing machines generate vibration during the dehydration process, consideration must be given to vibration resistance. In order to meet the specifications of these washing machines, we carry out a coating process. With this coating process,
By applying an insulating coating to the entire controller that incorporates resistors, ICs, etc., it is possible to suppress power leakage within an acceptable range to prevent malfunctions even if exposed to dew, etc. It has also been confirmed that the lifespan of ICs, etc. is extended, and this, together with the effect of fixing resistors and ICs, is an essential requirement for electronic washing machines. It is important that this coating process penetrates into every detail and forms a uniform coating in order to prevent the occurrence of pinholes, etc.
There is no way to configure a movable part on the controller. That is, if a movable part is provided, the coating liquid will penetrate into it and become fixed. Therefore, the first input switch method for washing machines is to have no moving parts on the controller and to withstand coating treatment.

Secondly, since it is a home appliance, it is necessary to supply a low-cost, high-performance controller.To do this, the control circuit, including the switch, must be integrated on a single board to reduce the number of soldered wires. This is very important. The second condition is to incorporate the input switch on a single board to achieve one-board design. To satisfy the first and second conditions above, reed switches with contacts sealed inside a glass tube have conventionally been used, but as described below, reed switches have problems such as ease of handling. It was hot.

A conventional input switch will be explained below with reference to FIGS. 1 to 4. FIG. 1 shows a plan view and FIG. 2 shows a front view. 1 is the display plate, "wash",
Characters such as "Rinse" and "Dehydration" are printed and displayed, and the plurality of input keys 2 are restrained from being pushed out by the push spring 17 and held in a fixed position. ing. input key 2
Eight pieces of different shapes are arranged and are slidably attached to the switch base 3 to form a push button, which is held by a display plate 1, which is fixed with screws 4. switch base 3
The parts held between the display plate 1 and the display plate 1 are separated from circuit parts as key parts and are assembled in the final step of assembling the electronic timer.

5 is a printed board, on which a buzzer 6, a transformer 7, a triax 8, a heat dissipation fin 9 are installed, and a resistor 19, an IC 20, etc. are also installed and soldered. A reed switch 18 as an input switch is also included therein, and is electrically connected to the circuit through a copper foil pattern by soldering. A flameproof plate 10 is disposed on the bottom surface of the switch base 3 and is made of a metal plate to prevent the spread of fire in the event that an element on the printed board 5 catches fire. Reference numeral 11 denotes a bush, which is used to ensure a uniform distance between the switch base 3 and the printed circuit board 5, and is used by engaging with a spacer 12, and serves as a guide tube when fixed with screws 22. Butsuyu 1
1. The coating process is performed while the spacer 12 is engaged with the printed board 5. The controller and key parts are engaged at any position, and the reed switch 18 is placed directly below the input key 2. This state is called an electronic timer assembly.

FIG. 3 is a cross-sectional view of the electronic timer component incorporated into the panel. Reference numeral 13 indicates a plastic panel base, which is partially covered with a decorative plate 14 and partially covered with a dust cover 15. The display plate 1 is arranged inside the dust cover 15. Input keys 2 for washing, rinsing, dehydration, etc. are provided. A permanent magnet 16 is fixed to the bottom of the input key 2. The input key 2 and the switch base 3 are engaged with each other at the concave and convex portions, and the input key 2 is biased toward the display plate 1 by a push spring 17. When the input key 2 is pressed, the input key 2 resists the pressure of the push spring 17.
The signal can be input by approaching the reed switch 18 on the printed board 5. On the printed board 5, a timer circuit is constructed by a resistor 19, an IC 20, etc., which are incorporated in addition to the reed switch 18. Reference numeral 21 denotes a timer cover, which is fixed with cover screws 22 to prevent dust, water vapor, etc. from adhering to the back surface after the electronic timer assembly is fixed to the panel.

Although not shown in FIG. 3, the electronic timer assembly is fixed to the panel base 13 with screws, and is connected to the switch base 3 to prevent water from reaching the printed board 5 against water entering from the top of the panel. The ribs of the panel base 13 seal water. In addition, the engaging and sliding portion between the input key 2 and the switch base 3 is
Since the cylindrical portion is configured to overlap, water is prevented from entering. FIG. 4 shows details of the reed switch 18 attachment part, and the reed switch 18 consists of a glass tube 18a and a pair of lead pieces 1.
8, which is inserted into a hole in the printed board 8 and soldered. A coating material 23 is coated so that a uniform coating is applied to the entire printed board 5.

In the above-mentioned conventional structure, the film deposited by the coating process does not adhere to the contact portions of the reed switch 18, and the movement of the reeds is not restricted. Also, a permanent magnet 1 that magnetizes the lead
B can be switched by being close to the reed switch 18, and has the advantage that the switch can be configured without being affected by coating. Since the reed switch 18, which serves as a contact point of the switch, is assembled and soldered onto the printed circuit board 5, there is no wiring such as lead wires to the switch, and a single board is achieved. Therefore, although the washing machine satisfies the two conditions as described above, it has the following drawbacks and needs to be improved.

First, since it is made of a glass tube, it is easily broken. As shown in FIG. 1, if one-board construction is promoted, heavy parts such as transformers will be incorporated into the printed board 5, and therefore the amount of deflection of the printed board 5 will tend to increase. If the deflection is transmitted to the reed switch 18, the glass tube may break, so care must be taken especially when carrying it. Second
Although the reed switch 18 is manufactured on an automated production line, it has the disadvantage that it is significantly more expensive than input switches used in, for example, television receivers and desktop computers.

FIG. 6 shows a cross section of a main part of a conventional rubber contact switch. The principle is that 25 comb-shaped copper foil patterns are arranged, and a pressurized conductive rubber 27 is placed as a bridge between them.
Switching is performed using the seat. Rubber contacts have the characteristic that their electrical resistance does not decrease unless pressure is applied.
The seventh graph shows pressure on the horizontal axis and resistance on the vertical axis.
As shown by curve A in the figure, when a pressure of 0.5 to 1 kg/cm ² is applied, it becomes a conducting wire. This rubber contact is used in desktop electronic computers and the like, and is generally used on a board exclusively for switches, as shown in FIG.

24 is a phenol plate, and a copper foil 25 is printed on the surface.The copper foil 25 is usually gold plated, but the copper is oxidized and the contact resistance with the rubber contact is high. This is due to the fact that it requires gold plating treatment that does not oxidize. 26 is a space seat,
The copper foil 25 and the pressurized conductive rubber 27 are interposed in a portion where contact is not desired, and only the input key portion is configured to be electrically connected by pressurization. Therefore,
Square holes are made only in the areas with numbers and symbols on the printed sheet 28 shown in FIG. 6, and the pressurized conductive rubber 2
7 and the copper foil 25 are configured to be in contact with each other. However, in the conventional structure described above, the board on which the rubber contact switch is attached and the board on which the resistor, IC, transformer, etc. are attached are formed separately, which has the drawback of increasing the number of parts and the number of work steps.

The present invention has been made in view of the above-mentioned situation, and an object of the present invention is to provide an input switch that can reduce the number of parts, reduce the number of work steps, be easy to handle, and improve functionality.

The input switch of the present invention includes an input key consisting of a plurality of push buttons dotted and protruding from a panel surface, a switch base that holds the input keys so as to protrude from the panel surface via a push spring, and the input key A printed board is provided with a switch that is operated by pressing, a resistor, an IC, a transformer, etc. and is covered with a coating material, and the switch is a comb-shaped conductor provided on the printed board, a conductive rubber sheet that is bonded via an adhesive applied around the conductor, is formed so as to press the conductor when facing and in contact with the input key, and is covered with the coating material; It is composed of

Hereinafter, one embodiment of the input switch of the present invention will be described with reference to FIG. 8, with the same parts as those in the conventional art being denoted by the same reference numerals and explanations of the same parts being omitted. FIG. 8 is a sectional view of a panel portion corresponding to FIG. 3, and the bottom of the input key 29 is a push rod, and unlike the input key 2 of FIG. 3, a permanent magnet is not provided. Reference numeral 30 denotes pressurized conductive rubber sheets, which are individually bonded to the printed board 5, one for each switch. Printed board 5 to which pressurized conductive rubber sheet 30 is adhered
As in FIG. 3, expensive components such as a resistor 19 and an IC 20 are fixed and mounted on the surface by soldering, and the reed switch 18 is replaced with a pressurized conductive rubber sheet 30. Incidentally, the conductive portion of the copper foil 25 is formed as shown in FIG.

FIG. 9 is an enlarged view of the adhesive portion of the pressurized conductive rubber sheet 30, in which the pressurized conductive rubber sheet 30 is cut into a round shape and adhered with an adhesive 31 applied to the outer peripheral side. Compared to the configuration shown in FIG. 5, the configuration is simplified without the space sheet 26 and print sheet 28. The procedure for assembling the switch in this example is as follows:
Unlike the procedure for the conventional reed switch 18, this work is performed as a pretreatment before installing the resistor 19 and IC 20. The order is: (1) Treat the substrate with a primer. (2) Screen apply adhesive 31 to the board. (3) Glue the round pressurized conductive rubber sheet 30. (4) Pressure treatment. Primer treatment is performed to increase the adhesion between the substrate and adhesive. The material of the pressurized conductive rubber sheet 30 is silicone rubber, and an adhesive that can reliably bond the silicone rubber and phenol resin substrates is required.

In FIG. 9, a copper foil 25 and a pressurized conductive rubber sheet 30 are shown.
Although the illustration shows that there is a gap between the copper foil 25 and the pressurized conductive rubber sheet 30, the thickness of the copper foil 25 is approximately 35 μm, and depending on the degree of adhesion of the adhesive 31, the copper foil 25 and the pressurized conductive rubber sheet 30 may have a gap between them.
may come into contact, but conduction will not occur unless pressure is applied. After all the circuit elements are assembled on the printed board 5, the coating process is performed. Therefore, the entire body is covered with the coating material 23 to prevent malfunctions. A washing machine has a large main body unlike a desktop computer, etc., so if the keys are crowded together as shown in FIG. 6, the operability becomes poor, so it is necessary to distribute the keys as shown in FIG. 1. Therefore, the pressurized conductive rubber sheet 30
By effectively reducing the size of the conductive rubber, the amount of expensive pressurized conductive rubber used can be reduced. Since the round pressurized conductive rubber sheet 30 is used and only the contact portions are pressurized by the input key 29, the space sheet 26 is not necessary, and the printed sheet 28 is not required. Since the display plate 1 and the decorative plate 14 are available as substitutes, they are also unnecessary.

Since it is configured as described above, it satisfies the two conditions described above as an input switch.
That is, it is clear from the above explanation that it can withstand coating treatment and can be integrated into one board. The stroke is the clearance between the tip of the push rod of the input key 29 and the pressurized conductive rubber sheet 30, but sufficient performance can be obtained with 1 to 2 mm, compared to the 3 to 4 mm required in the conventional example, so accuracy during assembly can be improved. Atup is no longer necessary. In the conventional reed switch 18, the bush 11 is used to ensure the ON stroke due to hysteresis, and the coating material 23 may adhere to the top surface of the bush 11 during the coating process, making it impossible to obtain a uniform height. In order to exclude
The coating process was performed by applying masking tape, and it was necessary to remove the coating material 23 after it had solidified. However, according to the configuration of this embodiment, even some variations can be tolerated, so masking processing and the like can be omitted, simplifying the work.

By considering the shape of the push rod at the end of the input key 29, the necessary pressure of the pressurized conductive rubber can be obtained with a force of 100 to 200 g, so the influence of the operating force on the printed board 5 can be almost ignored. Small enough to do. Since the amount of air trapped by the adhesive 31 between the printed board 5 of the input switch section and the pressurized conductive rubber sheet 30 is very small, it is necessary to confine the air during heating during soldering work and during drying after coating. There is no need for the air to expand and peel off the adhesive.

No. 10 shows another embodiment. In Fig. 9, a pressurized conductive rubber sheet 30 pressed into a circular shape is used, but since the pressurized conductive rubber itself is very expensive, it is made into smaller chips, and the auxiliary piece 33 is molded from silicone rubber. A pressurized conductive rubber chip 34 is attached, which has the advantage of reducing costs. FIG. 11 shows the auxiliary piece 33 to which the pressurized conductive rubber chip 34 is attached, and 33a is a hole made on the outer periphery of the auxiliary piece 33 for venting the gas generated when the adhesive 31 hardens. be.
33b is an adhesive reservoir for adhesive 31 and auxiliary piece 33
This is a part that increases the contact area of the contact area and at the same time stores excess adhesive 31 to prevent the adhesive 31 from flowing into the contact area. According to both examples in which the copper foil 25 portion was sealed with adhesive 31, it is clear that the contact portion is less likely to be oxidized or sulfurized by corrosive gas, so it is plated with a noble metal such as gold. The need to create a comb-shaped pattern has decreased, and the reliability level of conventional gold-plated products can be ensured by simply using copper foil or nickel plating, and inexpensive switches can be constructed.

Since the input switches of both embodiments are configured in this way, they can withstand the coating treatment required for washing machines, and since the connection wires of the switch section are integrated into the main board, they can be integrated into one board and are free. Can be wired. In addition, by using a rubber contact switch, functionality and reliability are improved, and the structure can be configured with a small number of parts, resulting in good workability.The application of adhesive before applying the pressurized conductive rubber sheet can be automated using screen printing technology. possible and reduce man-hours. In addition, the contact part of the input switch can be assembled in advance before circuit elements such as resistors are assembled, and since the height of the pressurized conductive rubber sheet is low, it is easy to insert other nearby parts. . Furthermore, unlike glass reed switches, it does not break, making it easier to handle, and controlling the operating distance is less troublesome, reducing the incidence of defects in the assembly. Since the switch portion is located on the component insertion surface of the printed board, masking for soldering is not required and the process can be shortened compared to the conventional case where a conductive rubber switch is bonded to the soldering surface of the element as a special example. Furthermore, since the contact portions are sealed, the occurrence of contact failure due to corrosive gas is reduced, and similar reliability can be obtained even with an inexpensive treatment that replaces plating with precious metals such as gold. Moreover, the stroke is reduced to 1 to 2 mm, improving operability, and the amount of air enclosed by the use of pressurized conductive rubber is small, so the incidence of adhesion defects during the work process is low.

As described above, the input switch of the present invention has the effects of reducing the number of parts, reducing the number of man-hours, being easy to handle, and improving functionality.

[Brief explanation of the drawing]

Figure 1 is a plan view of a conventional electronic timer assembly.
Figure 2 is a front view of Figure 1, Figure 3 is a vertical sectional view of the assembled product in Figure 1 installed on a panel, Figure 4 is a detailed view of the reed switch in Figure 3, and Figure 5 is a conventional Fig. 6 is a cross-sectional view of the main parts of the rubber contact switch shown in Fig. 5, Fig. 7 is an explanatory drawing of the pressure and resistance characteristics of the pressurized conductive rubber, and Fig. 8 is a diagram illustrating the installation state of the switch shown in Fig. 5. 9 is an enlarged view of part B in FIG. 8, FIG. 10 is a sectional view of a main part of another embodiment of the input switch of the present invention, and FIG. 11 is FIG. 10. A is a front view, B is a sectional view of A, and FIG. 12 is a detailed view of the copper foil pattern in FIGS. 8 and 10. 2...Input key, 3...Switch base, 5...
...Printed board, 7...Transformer, 13...Panel base, 17...Press spring, 19...Resistor, 20...
...IC, 23... Coating material, 25... Copper foil, 30
... Pressure conductive rubber sheet, 31 ... Adhesive, 33
...Auxiliary piece, 33a...Gas vent, 33b...
...Adhesive reservoir, 34...Pressed conductive rubber chip.

Claims (1)

[Scope of Claims] 1. An input key consisting of a plurality of push buttons dotted and protruding from a panel surface, a switch base that holds the input keys so as to protrude from the panel surface via a push spring, and the input key described above. A switch operated by pressing
In an input switch comprising a printed board provided with a resistor, an IC, a transformer, etc. and covered with a coating material, the switch is connected to a conductor formed in the shape of a comb blade provided on the printed board, and and a conductive rubber sheet that is adhered via an adhesive applied around the conductor and is formed to press the conductor when facing and in contact with the input key, and is covered with the coat. An input switch featuring: 2. An auxiliary piece in which the switch part has a pressurized conductive rubber chip disposed opposite to the conductor, and an annular adhesive reservoir surrounding the pressurized conductive rubber chip with a gas vent opening, and is covered with a coating material. 2. The input switch according to claim 1, wherein the input switch is formed by: and an adhesive applied between the adhesive reservoir and the printed board.