JPS5843280Y2 - Housing structure of electronic equipment - Google Patents

Description

[Detailed explanation of the invention] This invention mainly uses internal electronic components that are easily affected by noise or are a source of noise, such as electronic desktop calculators (hereinafter referred to as calculators) and electronic digital clocks. The present invention relates to a housing structure of an electronic device having the following.

BACKGROUND ART Recently, advances in integrated circuit technology and electronic display technology have made it possible to manufacture electronic devices in a small size and at low cost, and as a result, the use of electronic devices in tools used in daily life is rapidly expanding.

By the way, in this type of portable electronic device,
Electrical products equipped with oscillation circuits such as televisions and radios,
In some cases, it is placed near electrical products such as power tools that have contact circuits, and in such cases, conventional electronic devices of this type do not give much consideration to the electrical shielding of electronic devices. However, there is a risk of mutual interference with other types of electrical products, that is, there is a problem that noise may be imparted to the electrical products, or the electronic equipment may malfunction due to the noise of the electrical products.

For example, in the case of a calculator, a method is often used in which a pulse signal is used to advance the digits of the display device, and the display device is driven by time-division operation using pulse control, and this pulse signal generally has a frequency of several KHz to several tens of KHz. The pulse signal has a peak value of about 30 V at a repetition frequency of 1, but a wide range of harmonic components contained in the pulse signal are radiated to the outside as radio waves, eliminating the cause of the above-mentioned disturbance.

Similar problems also exist in electronic digital clocks.

The purpose of the present invention is to solve the above problems, namely:
It is an object of the present invention to provide a casing structure for an electronic device that prevents the radiation of radio waves to the outside and prevents malfunction of the device due to external radio waves, particularly a simple and robust casing structure of this type.

Hereinafter, the present invention will be explained based on an illustrated embodiment.

1 and 2 show a calculator having a housing structure according to the present invention, in which a circuit board 1 shown in FIG. 3 is fixed inside a box-shaped case 18 with windows 19a and 19b. The front side of the case 18 houses a battery compartment 20, and a connector 21 for external power supply is attached to the end of the case 18, and a key frame 1 is mounted on the circuit board 1.
1 is installed.

In addition, the bottom plate of this case 18 is hollowed out according to the shape of the circuit board 1, so that a hollow opening 19C is formed in the bottom plate of the case.
The peripheral edge of the hollow opening 19C and the peripheral edge of the circuit board 1 are sealed together, and this sealing allows the circuit board 1 to also serve as at least a part of the bottom plate of the case 18.

The case 18 is made of a conductive material such as a metal plate, a resin plate containing conductive fine powder, or a resin plate coated with a conductive film, and
The periphery of the circuit board 1 is tightly sealed to the periphery of the opening 19C on the bottom of the case 18, so that the circuit board 1 and is electrically connected.

Next, the circuit board 1 is made of a so-called enamel board, in which an enameled film 1b made of glass material is fused to a metal plate 1a such as an iron plate, and the base portion of the metal plate 1a remains as appropriate on the periphery. is in contact with the case 18, and conductivity is maintained between the case 18 and the case 18.

On the enamel film 1b surface of the circuit board 1, there are circuit patterns 2 (2a, 2b) and contact patterns 3 (3a, 3).
b) A conductive film forming the end of the circuit pattern 2 and forming the connection land 5 to which the terminals of each circuit component described later are attached is printed and deposited by screen printing or the like, and is further fired. It is fixed.

Therefore, these circuit patterns 2 (2a, 2b),
The following circuit parts are attached to the contact patterns 3 (3a, 3b) and the connection land 5 to form the following circuit parts that constitute the circuit parts of the circuit board. It is.

(1) The display circuit unit 8 includes a display device 13° (2) The arithmetic processing circuit unit 7 includes a LS 12° (3) The power supply circuit unit 9 includes a converter 14, a capacitor array 15, and a resistor group 16
, power switch 17, etc.

(4) In the keyboard circuit section 4, each key top 10° is held by the key frame 11 and bridges each contact pattern 3 (3a, 3b). Note that the circuit patterns 2a and 2b intersect. Overlapping wiring part A
In this method, a glass insulating layer 6 having a lower melting point than the wax coating surface 1b is deposited on one circuit pattern 2a by screen printing or the like, and the other circuit pattern 2b is formed on it. Like the other circuit patterns 2, it is printed and fired using a screen printing method or the like to form a multilayered structure.

By the way, in the above-described structure of the calculator, except for the structure method in which the case 18 is made of a conductive material and the case 18 is electrically connected to the circuit board 1, this is only one example of the structure of the calculator. The housing structure of the present invention can be easily applied not only to calculators having a different structure from the above, but also to electronic watches and other electronic devices in general. It is sufficient to cover the circuit portion including the components with a conductive case 18 and to electrically connect it to the circuit board 1 in the manner described above.

Now, the operation of the calculator with the above configuration is similar to that of a general calculator, and by pressing the required key tops 10,
The arithmetic processing unit 7 performs the commanded calculation and displays the result of the calculation on the display device 13 of the display unit 8.

However, in the case of this calculator, as is clear from its housing structure, the circuit part is sufficiently electromagnetically shielded from the outside by the case 18, so harmonics emitted from the electronic circuit, etc. are absorbed by the case 18 and do not escape to the outside, and radio waves that hit the device from the outside are absorbed by the case 18 and almost never reach the electronic circuit.

As described above, according to the housing structure of the electronic device of the present invention,
Since the circuit part is covered with a conductive case, the electronic circuit is sufficiently shielded from the outside, thereby preventing radio wave interference to external electrical products and preventing electronic equipment from malfunctioning due to external radio waves. This has the effect of increasing the operability, reliability, and usability of electronic equipment.

In addition, in this invention, since the circuit board is an enamel board, the bottom of the circuit board becomes a part of the metal plate that constitutes the enamel board as a whole, that is, it becomes a conductive material, and electrically conducts electricity to the circuit part on the enamel film on the surface. This has the effect of making shielding easier and more reliable.

Further, the electrical connection between the case and the circuit board can be easily and reliably made by using the peripheral edge of the back or side surface of the circuit board made of a hollow plate where the metal plate portion is exposed.

Furthermore, it has sufficient mechanical strength, is extremely strong and stable against changes in external conditions, and has good heat dissipation effects.The surface is smooth, making it possible to perform precise screen printing to increase circuit density. effective.

Moreover, in the case of the present invention, the bottom plate of the conductive case is hollowed out, and the conductive metal plate part of the enamel circuit board is sealed to the periphery of the hollow opening, so that the case and the board are not connected to each other. Electrical shielding structure is direct and reliable,
In addition, it is extremely easy to manufacture and assemble.Since the circuit board mentioned above is part of the bottom plate of the case, the case with this type of electrically shielded structure can be made lightweight and thin, and the structure is simple and robust. There are effects that can be achieved depending on the shape.

[Brief explanation of the drawing]

FIGS. 1 and 2 are a front view and a side view of a case portion of an electronic device housing structure showing an embodiment of the present invention;
FIG. 3 is a schematic diagram of a substrate used in the same embodiment. 1... Circuit board, 1a... Metal plate, 1
b...... Wax film, 18... Case, 19C... Hollow opening.

Claims (1)

[Scope of utility model registration request] In a housing structure for an electronic device that includes a circuit board and a case that covers at least a circuit portion of the circuit board, the circuit board is made of enamel made by fusing a vitreous enamel film to the surface of a conductive metal plate. The case is formed of a plate, and the case is formed of a conductive material, and the bottom plate portion thereof is formed hollow according to the shape of the circuit board, so that a hollow opening is formed in the bottom plate of the case,
At least the peripheral edge of the hollow opening of the case and a portion of the conductive metal plate constituting the circuit board are sealed to each other, and the metal plate portion of the circuit board and the case are bonded to each other at this sealed portion. are electrically connected to each other so that a circuit portion of the circuit board on the waxy film is electrically shielded, and the sealing allows the circuit board to be connected to at least a portion of the bottom plate of the case. A housing structure for an electronic device characterized by having a configuration that is used for both.