JPH11346075A - Input/output unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an input/output unit which is enhanced in flexibility of system constitution and maintainability, white being subjected to a treatment which is carried out for an enhancement in a shielding effect and antistatic properties. SOLUTION: An input/output unit which is equipped with a backboard 12 with connectors 11 and mounted with a printed board 21 is provided with a metal plate 13 arranged in line with the backboard 12, a means 15 which grounds the metal plate 13, a shielding metal plate 23 provided at a position to confront the printed board 21, and an elastic contact means 24 which is mounted on the shielding metal plate 23 coming into electric contact with it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input / output unit for transmitting / receiving input / output signals to / from a field device used for industrial control equipment, and more particularly to an improvement which can be generally used for various field devices.

[0002]

2. Description of the Related Art An input / output unit is disclosed in JP-A-6-2445.
As disclosed in Japanese Patent Publication No. 70, a unique card corresponding to a combination of various input / output signals and input wiring forms is inserted into a nest formed by combining sheet metals and the like. Field devices are installed for instrumentation in the equipment industry, such as petrochemicals and steel, and come in a variety of input types, such as thermocouples, coaxial cables, and optical fibers. ), Digital type (status pulse), communication type (various protocols), etc. Thus, the input / output unit realizes various input / output functions by combining a card unit that performs signal processing and an interface unit that passes signals connected in various input forms to the card unit.

[0003]

In such an input / output unit, since the unit main body is mainly constituted by a molded product, the input / output unit is prevented from becoming an antenna for radiation noise and the nest itself is protected from the influence of static electricity. I will not receive it. However, there is a problem that it is difficult to electrically ground, is relatively weak against static electricity from the card, and electromagnetic waves pass through the nest against various radiated radio noises.

[0004] Therefore, in the conventionally used nest for sheet metal processing, the number of constituent members increases due to the reason of the manufacturing process. On the other hand, there is a problem that a member that is not electrically firmly joined does not serve as a ground for static electricity and also plays a role of an antenna against radiation noise. Therefore, it is necessary to securely assemble all the components of the nest electrically and mechanically, and as a whole, there are many problems such as weight, cost, and workability. In addition, as a countermeasure against static electricity,
The need to evaluate and compensate has arisen, leading to a cost increase.

[0005] Therefore, it is conceivable to cover the whole with a thin integrated sheet metal having a complicated shape inside the exterior mold case or to apply a conductive paint to the mold case as in the case of consumer products. However, it is desirable for the input / output unit to have good flexibility in system configuration and good maintainability for system changes / expansion. If the technology of consumer products is diverted as it is, flexibility and maintainability of the system configuration are sacrificed. . Further, the conductive coating is not only expensive but also undesirable from the viewpoint of environmental problems, and may be subject to various regulations in the future.

An object of the present invention is to provide an input / output unit which has good flexibility in system configuration and good maintainability while providing a shielding effect and measures against static electricity.

[0007]

According to another aspect of the present invention, there is provided an input / output unit including a back board having a connector and a printed circuit board mounted thereon. A metal plate 13 provided side by side with the backboard, and means 15 for grounding the metal plate, and a shield metal plate 23 provided at a position facing the printed circuit board; And a resilient contact means 24 electrically connected to the metal plate attached to the metal plate.

According to the configuration of claim 1 of the present invention, the shield metal plate acts as a shield plate against external electromagnetic waves as in claim 2, so that malfunction of the circuit against external noise is prevented. it can. Further, the shield metal plate acts as a shield plate for shielding electromagnetic waves radiated from the printed circuit board, thereby reducing radiation noise.

According to a fourth aspect of the present invention, when the shield metal plate is configured to flow static electricity charged on the card body to which the printed circuit board is fixed to the ground via the elastic contact means and the metal plate, measures against static electricity can be taken. Can be taken reliably. According to a fifth aspect of the present invention, when the shield metal plate is configured to be used for heat radiation of a heat-generating electronic component mounted on a printed circuit board,
Heat dissipation efficiency increases. Further, as in claim 6, the printed circuit board has a pin serving as a rotation axis with respect to the card body,
With the configuration using the lever, the printed circuit board can be easily mounted on the card body.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of the present invention, and is a front view of a nest main body 10 in a state where a card 20 is not mounted. In the figure, a nest body 10 is a housing molded of an epoxy resin or the like, and is provided with two chambers capable of accommodating two cards 20. The connector 11 connects to a printed circuit board 21 accommodated in a card 20 and is mounted on the backboard 12. The backboard 12 is provided with wiring for connecting the terminals of the connector 11.

The metal plate 13 appears on the front panel 15 side through the rectangular holes 12a formed in the back board 12, and here, four rectangular holes 12a are formed by one metal plate.
Is covered. The screws 14 are for attaching the nest body 10 to a larger casing, and are provided at four corners here. The front plate 15 is attached to the nest body 10.
The front panel 22 of the card body 20 is mounted on the front surface of the card body 20, or a terminal block is mounted.

FIG. 2 is a perspective view showing the structure of the metal plate 13. On the back board 12 of the nest body 10, the connector 11 is mounted on the upper side, while the metal plate 13 is mounted on the lower side. The screw connection part 17 is mechanically fixed by the screw 14, and the metal plate 1 is
3 is integrated.

FIGS. 3A and 3B are configuration diagrams of the card body, FIG. 3A is a side view, and FIG. The printed circuit board 21 has mounted thereon circuits necessary for signal input / output processing, and has a two-sheet configuration here. The front panel 22 has an end portion of the printed circuit board 21 fixed thereto, and is formed by resin molding or sheet metal processing. The shield metal plate 23 is screwed to the front panel 22 so as to face the printed board 21. The spring 24 has one end fixed to the shield metal plate 23 and the other end elastically contacting the metal plate 13. The electronic component 25 generates heat like a power transistor or a power diode. The electronic component 25 is mounted on the printed circuit board 21 and the surface of the electronic component 25 has the shield metal plate 2.
Contact 3

In the case where the electronic component 25 is divided into a plurality of parts or the height is low, a thermal compound or a thermal sheet is interposed between the heat-generating component 25 and the shield metal plate 23 to make the same. It is good to realize the function of. With this configuration, the printed circuit board 21 is compared with a case where a heat sink is individually mounted on the electronic component 25.
The mounting area can be reduced little.

FIG. 4 is a configuration diagram of the entire input / output unit, and is a cross-sectional view in the direction 4-4 in FIG. 1 in a state where the card body is mounted in each room. The shield metal plate 23 is connected to the front panel 2.
2 and the spring 24 are mechanically and firmly coupled to each other, and are also electrically connected with low resistance and large capacity. On the other hand, the metal plate 13 is fixed and connected to a panel or a cabinet or the like on which the nest main body 10 is mounted by using screws 14. When the card body 20 is inserted into the nest body 10, the spring 24 bends to electrically connect the metal plate 13 and the shield metal plate 23 with low resistance and large capacity. Therefore, the metal plate 13 and the shield metal plate 23 have the same potential. The extended metal plate 26 covers the surface of the printed circuit board 21 opposite to the surface covered by the shield metal plate 23.

With this configuration, the input / output unit protects the circuit on the printed circuit board 21 against static electricity generated from the environment in which the input / output unit is installed, static electricity received from the human body during maintenance work of the unit, and the like. The effect of external electromagnetic noise and radiation of electromagnetic noise from the printed circuit board 21 can be prevented by the electrostatic shielding effect of the plate 23. Further, according to the degree of static electricity and electromagnetic waves and the need, if the surface covering the printed circuit board 21 is attached to not only one surface but also both surfaces using the extended metal plate 26, further effects can be expected.

FIGS. 5A and 5B are explanatory views of attaching the printed circuit board 21 to the front panel 22. FIG. 5A shows a state in which the pin and the pin hole are engaged, and FIG. 5B shows a state in which the engaging portion is locked in the guide groove. ing. The front panel 22 has a screw hole 221 at the upper and lower ends, and a guide groove 225 and a component engaging hole 22 at the upper end. The connector hole 22 is located at the lower center.
3 are provided, and a pin 224 is provided at the lower end.

An electronic component 21 a such as an LED is provided on the upper edge of the printed circuit board 21 and engages with the component engaging hole 22. The front connector 27 is provided at the edge of the printed circuit board 21, and an external connector is mounted through the connector hole 223. Pin hole 28 is printed circuit board 21
The pin 224 is provided at the lower corner. The engaging portion 29 is a protrusion provided at the upper corner of the printed board 21 and engages with the guide groove 225.

In the device configured as described above, first, the pin 224 is engaged with the pin hole 28 to be pivotally supported, and is rotated in the direction of the arrow so that the engaging portion 29 is engaged with the guide groove 225. Then, the printed circuit board 21 is attached to the front panel 22. With this configuration, the printed circuit board 21 can be attached to the front panel 22 using pins and levers without using screws, so that the assembling work is simplified.

In the above embodiment, the nest body 1
Although the case of the two-room structure accommodating the card body 20 is shown in FIG. 0, the present invention is not limited to this, and may have a one-room structure or three or more rooms.

[0021]

As described above, according to the first aspect of the present invention, the back board 12 having the connector 11 is provided.
In the input / output unit to which the printed board 21 is mounted, the input / output unit has a metal plate 13 provided side by side with the back board, and a means 15 for grounding the metal plate, and is provided at a position facing the printed board. The shield metal plate 23 is provided, and the elastic contact means 24 attached to the shield metal plate and in electrical contact with the metal plate is provided.

Therefore, the shield metal plate acts as a shield plate against external electromagnetic waves as described in claim 2, so that malfunction of the circuit against external noise can be prevented.
Further, the shield metal plate acts as a shield plate for shielding electromagnetic waves radiated from the printed circuit board, thereby reducing radiation noise.

Further, when the shield metal plate is configured such that static electricity charged on the card body to which the printed circuit board is fixed flows to the ground via the elastic contact means and the metal plate, measures against static electricity can be taken. Can be taken reliably. According to a fifth aspect of the present invention, when the shield metal plate is configured to be used for heat radiation of a heat-generating electronic component mounted on a printed circuit board,
Heat dissipation efficiency increases. Further, as in claim 6, the printed circuit board has a pin serving as a rotation axis with respect to the card body,
With the configuration using the lever, the printed circuit board can be easily mounted on the card body.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, in which a card 20 is used.
Is a front view of the nest body 10 in an unmounted state.

FIG. 2 is a configuration perspective view of a metal plate 13;

FIG. 3 is a configuration diagram of a card body, (A) is a side view,
(B) is BB sectional drawing of a side view.

4 is a configuration diagram of the entire input / output unit, and is a cross-sectional view in the 4-4 direction of FIG. 1 in a state where a card body is mounted in each room.

FIG. 5 is an explanatory diagram for attaching a printed circuit board 21 to a front panel 22.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Nest main body 12 Backboard 13 Metal plate 14 Screw (also serves as grounding) 20 Card main body 21 Printed circuit board 22 Front panel 23 Shield metal plate 24 Spring (elastic contact means) 25 Heat generating electronic parts

Claims (6)

[Claims] 1. An input / output unit having a back board (12) having a connector (11) and having a printed board (21) mounted thereon, wherein a metal plate (13) provided alongside the back board.
And a means (15) for grounding the metal plate. The shield metal plate (23) provided at a position facing the printed board, and the metal plate attached to the shield metal plate is electrically connected to the shield metal plate. Elastic contact means (24) for contacting
An input / output unit comprising: 2. The input / output unit according to claim 1, wherein said shield metal plate acts as a shield plate against external electromagnetic waves. 3. The input / output unit according to claim 2, wherein said shield metal plate functions as a shield plate for shielding electromagnetic waves radiated from said printed circuit board. 4. The input / output unit according to claim 1, wherein said shield metal plate allows static electricity charged on a card body to which a printed circuit board is fixed to flow to ground via elastic contact means and the metal plate. . 5. The input / output unit according to claim 1, wherein said shield metal plate is used for radiating heat generated electronic components mounted on a printed circuit board. 6. The input / output unit according to claim 1, wherein the printed circuit board is mounted on a card body using a pin serving as a rotation axis and a lever.