JPH0351860Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Field of the Invention> This invention relates to a digital switch used in a code signal extraction circuit, etc.

<Prior art and its problems> Generally, in this type of switch, when setting a desired number on the display means exposed on the front part of the switch case, the operation part provided on the front part side is pressed with a finger. Since it is designed for direct operation (touch operation), it is extremely vulnerable to discharge due to static electricity. In other words, the electric charge accumulated due to friction of the human body is discharged from the operation part, such as a push button, through the gap in the switch case and into the interior when a finger touches the operation part during the above operation. There is a risk of damaging the integrated circuit elements of the device and causing loss of switch function. Of course, even if the information is mechanical, the same result will occur if the information is transmitted to the CPU of the control device through an internal mechanism or the like.

For this reason, it has been proposed to change the push button of the operation unit to a smaller one that cannot be operated directly with a finger, and to configure it so that it can be operated with a special pen-like tool with a sharp tip. Difficult to use.

<Purpose of the invention> This invention was made to solve the above-mentioned problems with the conventional switch, and the purpose is to provide an easy-to-manufacture digital switch that can protect circuits and elements from static electricity during operation and is easy to use. It is said that

<Structure and effect of the invention> The digital switch according to this invention has a frame-shaped earth plate formed by a pair of U-shaped pieces and a pair of touch connection pieces that connect the corresponding tips of both U-shaped pieces. A pair of lateral grooves into which the U-shaped pieces are fitted are provided near the operating section on the front side of the switch case, and each of the touch connection pieces is provided between corresponding ends of the lateral grooves. Part is fitted 1
A pair of vertical grooves are provided, each piece of the earth plate is fitted into the corresponding groove, and the outer end of each touch connection piece is exposed on both outer surfaces of the switch case, and the outer ends of the touch connection pieces are exposed on both outer surfaces of the switch case, and are arranged adjacent to each other. The present invention is characterized in that the touch connection pieces of a plurality of arranged switch cases come into contact with each other and are connected to a ground circuit.

In this invention, by connecting the ground plate to the ground circuit, the ground plate can prevent electric charges from the human body during touch operations from discharging into the switch case, thereby protecting the circuit and elements. Especially when multiple digital switches are installed in parallel,
Since each earth plate can be touch-connected,
The connection structure is simple, and since the touch connection is made outside the switch case, there is no risk of noise entering the internal circuit.

<Description of Examples> Examples of this invention will be described below with reference to the drawings.

FIG. 1 and FIG. 2 each show an example of a digital switch according to this invention. In the figure, 1 is a switch case, and the case body 2
and base 3. A display window 4 is formed in the front wall 1a of the switch case 1, and a digital display, for example, a 7 segment
The numerical display on the LED display 5 is made visible. 6 is an addition push button set at the bottom of the display window 4, 7 is a subtraction push button set at the top of the display window 4, and 8 and 9 are mechanical switches provided corresponding to the push buttons 6 and 7, respectively. be. Both push buttons 6 and 7 constitute an operating section 10 for rewriting a set value of a reversible preset counter, which will be described later, while looking at the numerical value displayed on the display 5.

Reference numeral 11 denotes a status indicator disposed between the mechanical switch 8 and the indicator 5, which is composed of an LED or the like. 12 is a through hole formed in the front wall 1a corresponding to the status indicator 11, and 13 is a first printed wiring board on which the indicators 5, 11 and input switches 8, 9 are mounted. A second printed wiring board 14 is electrically connected to the first printed wiring board 13 via a flexible board 15, and is equipped with an integrated circuit element 16 and other electrical components (not shown). . The integrated circuit element 16 includes a reversible preset counter that displays the output and signal status on each display 5, 11, a drive circuit for each display 5, 11,
It constitutes a pulse generation circuit for adding or subtracting a reversible preset counter, a latch circuit for holding a signal, and an input/output circuit (none of which is shown). 17 is a connecting connector, 18 is a second
A wrapping terminal 19 is fixed to the rear end of the printed wiring board 14, and a filter is detachably mounted on the front wall 1a side facing the display window 4 and the through hole 12.

On the front wall 1a of the switch case 1, there is a third
As shown in the figure, horizontal grooves 20, 20 are formed near the display 5 side of each push button 6, 7, and each horizontal groove 20, 20 is provided with a pair of frame-shaped earth plates 21. U-shaped pieces 21a, 21a are fitted. A pair of connecting pieces 21b, 2 connecting the ends of the U-shaped pieces 21a, 21a.
1b are vertical grooves 2 formed on the side surfaces of the switch case 1, that is, on the outer surfaces of the case body 2 and the cover 3.
2 and 22, respectively, and one connecting piece 2
1b is removably locked to filter locking protrusions 23, 23 provided near the vertical groove 22 (FIG. 4). 19a is an engagement groove provided in the filter 19 and engaged with the projection 23.

As shown in FIG. 5, each side end of the connecting pieces 21b, 21b is exposed on the outer surface of the switch case 1 and is configured as a touch connecting piece 24.

In the above configuration, for example, the data written by the CPU is displayed numerically on the display 5, but if the operator sees the numerical value on the display 5 and finds that it differs from the set value, he or she presses the push button 6 or 7. It can be corrected by manipulation.

When the push button 6 or 7 is operated, the charge accumulated in the operator's body tends to discharge into the switch case 1, but since the ground plate 21 is installed near the push button 6 or 7, If the plate 21 is connected to the ground circuit via the touch connection piece 24, the charge will be discharged onto the ground plate 21 and will flow, for example, to ground. Therefore, the display 5 and the integrated circuit element 1
There is no fear that the push buttons 6 and 7 will be destroyed by static electricity, and in other words, the push buttons 6 and 7 can be touched without anxiety without using special tools.

By the way, as shown in FIG. 6, a plurality of switches 61 ₁ to 61 ₄ are often arranged in parallel and used, and in this case, end plates 62 and 63 are attached to both the left and right sides. In that case, if one end plate 62 is provided with an external lead body 71 connected to the ground circuit and in contact with the touch connection piece 24 as shown in FIG. 7, each digital switch 61 ₁ to 61 ₄ can be When arranged in parallel, each ground plate 21 is touch-connected via each touch connection piece 24, and each ground plate 21 is touch-connected via each touch connection piece 24 on the left end side and the lead body 71.
are commonly grounded. That is, the work of connecting the earth plates 21 to each other can be omitted, and the connection part can be simplified and the work can be made easier. Of course, the left end touch connection piece 24 may be directly connected to the ground circuit.

Furthermore, since the earth plates 21 are touch-connected outside the switch case 1, there is no fear of interference with the internal circuitry due to static electricity noise, contributing to stabilization of operation.

Note that the shape of the ground plate 21 is not limited to the above shape as long as it has the U-shaped piece portion 21a, and can be changed as appropriate.

Furthermore, although the above embodiment has been explained using an electronic type as an example, even if it is a mechanical type in which a slider is attached to a rotary number disc that operates by clicking, by adopting the above configuration, the control equipment side can be This prevents the negative effects of static electricity on the CPU, etc.

[Brief explanation of the drawing]

Figures 1 and 2 are a side sectional view and a bottom sectional view, respectively, showing an example of the digital switch according to this invention, Figure 3 is a perspective view showing the earth plate and its mounting part, and Figure 4 is a view with the filter removed. 5 is an enlarged sectional view showing the touch connection piece at one end of the earth plate, FIG. 6 is a front view showing a state in which multiple digital switches are installed side by side, and FIG. FIG. 3 is an explanatory diagram of the connection state of ground plates when digital switches are arranged in parallel. 1... Switch case, 1a... Front part, 10
...Operation unit, 21...Earth plate, 21a...
...U-shaped piece, 24...Touch connection piece.

Claims (1)

[Scope of utility model registration request] A frame-shaped earth plate is constructed from a pair of U-shaped pieces and a pair of touch connection pieces that connect the corresponding ends of both U-shaped pieces, and is located near the operating section on the front side of the switch case. a pair of lateral grooves into which the U-shaped pieces are fitted, and a pair of vertical grooves into which the touch connection pieces are fitted between corresponding ends of the lateral grooves; Each piece of the earth plate is fitted into the corresponding groove, and the outer end of each touch connection piece is exposed on both outer surfaces of the switch case, and the plurality of switch cases are arranged adjacent to each other. A digital switch characterized in that each touch connection piece of the digital switch is configured such that each of the touch connection pieces comes into contact with each other and is connected to a ground circuit.