JPH01288000A - Shielding structure for circuit - Google Patents

Abstract

PURPOSE:To completely shield a noise source of an arbitrary shape in a narrow space by providing slits intermittent at a bent part, and exposing the part of a conductive layer to enclose a part required for shielding with a flexible printed board as a ground terminal. CONSTITUTION:A slit 1C to be bent is formed at the bent part of a shielded flexible board 1, and a window 1D for a connecting terminal is formed at a position opposite to the connecting terminal 2B of a board 2 for a flash light emitting device. A cutout part 1E for leads is formed at a position for passing the leads 2A of the board 2, the part of a Cu pattern 1A is exposed in the depth of the part 1E to provide a shielding terminal pattern 1B. The part surrounded by the slit 1C is brought into contact with the rear face of the board 2, the pattern 1B is connected to the ground pattern of the board 2, and the outside of the part surrounded by the slit 1C is bent to enclose the device 2. Thus, the whole periphery of a noise source of different shape is easily covered without necessity of a special space to shield the noise source from other signal system circuit.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a circuit shield for shielding a circuit portion that is a noise source for a circuit such as a board on which mounted components for a flashlight emitting device in a camera are mounted. Regarding structure.

(Prior art) Flash emitting devices use high voltage (approximately 3
00V), and a battery (about 3 to 6V) is the power source.
In order to obtain the necessary high voltage of 300V from the converter, a step-up circuit including a transformer is provided, which generates high-frequency oscillation using a DC power supply. This high frequency becomes noise to other circuits, and there is a great risk that noise will be input to other signal systems, and noise prevention measures are required to maintain the accuracy of other circuit operations. Traditionally, as a noise prevention measure, the noise source or the part where you want to block out external noise has been housed in a metal case. Because it is difficult to manufacture, the case becomes unnecessarily large in order to accommodate the entire board, making it difficult to accommodate it within the limited space of the camera. Therefore, when using a conventional metal case, it has been necessary to house only parts that generate particularly large noises (for example, a transformer, etc.).

Another idea is to separate the power supply circuit from the signal circuit as much as possible, but it is difficult to provide multiple spaces to house the circuits in cameras that are becoming more compact, and it also reduces noise. There is a problem in that the source circuit and the signal system circuit cannot be placed close to each other, which increases design constraints. Further, the noise source and the signal system are separated as much as possible and a shield plate or the like is placed at the boundary, but this method requires a large space and has the problem of being less effective in preventing noise.

(Problem to be Solved by the Invention) An object of the present invention is to provide a means for completely shielding a noise source of any shape in a narrow space where it is impossible to install it away from other circuits. means) consisting of a laminated sheet of a flexible insulating sheet and a conductive layer,
It has an outer shape that is an appropriately developed three-dimensional shape that circumscribes and encompasses the part that requires shielding, and has an intermittent slit in the bent part, and a lead or terminal part that is drawn out from the part that requires shielding. An opening is provided through which the conductive layer is exposed, and a portion of the conductive layer is exposed to serve as a ground terminal portion.A flexible printed circuit board is provided to cover the portion requiring the shield.

(Function) Since various circuit parts are mounted on the flashlight emitting device board, the three-dimensional outer shape is uneven and irregular, and in order to cover the whole body along the outer shape, the board must be flexible. Therefore, in the present invention, the outer periphery of the flashlight emitting device substrate on which the circuit components are mounted F6 is covered with an easily bendable shield flexible plate made of copper foil covered with a film. To this end, the above-mentioned shield flexible board is formed into a shape that appropriately develops the outer shape of the flashlight emitting device board, and a bending slit is formed in the bending part to make it easier to bend, so that the shape of the flashlight emitting device circuit board is adjusted. Since it can be lined up and covered all around, there is no need to provide a special space for shielding, unlike when shielding with a metal box, and there is no need to provide a lead to connect the circuit to be shielded with the outside. Windows and cutouts can be easily provided in three arbitrary positions on the shield flexible board so that wires and connection terminals can be drawn out of the shield flexible board. Further, by partially exposing the copper foil of the shield flexible board and connecting the exposed copper foil pattern to the ground pattern of the flashlight emitting device board, it is possible to further stabilize the shielding effect.

(Example) FIG. 1 shows an example of the present invention.
is a shield flexible substrate with a Cu shield pattern IA covered with a polyimide or polyester film.
In order to bend along the outer periphery of the flashlight emitting device substrate, a bending slit IC is provided at each bent portion so that it can be easily bent with a small bending radius, and the connection terminal 2B of the flashlight emitting device substrate is provided.
A connection terminal window ID is provided at a location facing the board, a lead wire notch IE is provided at a location where the lead wire 2A of the board passes through, and a Cu pattern IA is provided at the back of this lead wire notch IE.
A part of the shield is exposed and a shield terminal pattern IB is provided.
The part surrounded by the slit IC is brought into contact with the back surface of the flashlight emitting device board, the shield terminal pattern IB is connected to the ground pattern of the flashlight emitting device board 2, and the slit IC
Bend the outside of the part surrounded by to enclose the flashlight emitting device.

FIG. 2 shows a state in which the flashlight emitting device substrate 2 is covered with the above-mentioned shield flexible substrate 1. Pass the connection terminal 2B through the connection terminal window ID of the shield flexible board l,
Pass the lead wire 2A through the lead wire notch IE, bend the flexible board at each bend, and secure the ends of the flexible boards that are close to each other with tape, etc., to assemble the entire irregularly shaped flashlight device board 2 on which the circuit components are mounted. Make sure to cover it.

As shown in FIG. 3, the flashlight emitting device board 2, whose entire periphery is covered with the shield flexible board l, is mounted in a gap within the camera body away from the signal system chip component 7 of the camera control circuit. .

Note that the shield flexible substrate 1 used in the present invention
may be made of the same material as the flexible printed circuit board used for other circuits of the camera, or may be made of a different material.

Furthermore, depending on the shape of the substrate of the circuit that is the noise source, it is possible to form the bending portion without providing a slit or the like.

(Effects of the Invention) According to the present invention, it has become possible to easily cover the entire circumference of an irregularly shaped noise source without requiring a special space and to shield the noise source from the signal system circuit. , it became possible to make the shielding effect more stable with a simple device. Furthermore, since the flexible printed circuit board used in the present invention is generally provided with an insulating cover film, there is no problem even if the printed circuit board comes into contact with a conductive part on the circuit board, and therefore a more compact noise source. circuits can be shielded.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of the present invention, and FIG. 2 is a perspective view of the shield board of the above embodiment attached to a noise source.
FIG. 3 is a cross-sectional view of the shielded noise source installed in the device. l...Shield flexible board, IA...Cu pattern, IB...shield terminal pattern, IC...
・Bending slit, ID...window for connection terminal, IE...
・Notch for lead wire, 2...Substrate for flashlight emitting device, 2
A... Lead wire, 2B... Connection terminal, 3... Capacitor, 4... Outer cover, 5... PWB, 6...
・IC chip, 7... Signal system chip parts.

Claims (1)

[Claims] It is made of a laminated sheet of a flexible insulating sheet and a conductive layer, and has an outer shape that is an appropriate development of a three-dimensional shape that circumscribes and encompasses the part that requires shielding, and has intermittent slits in the bent part. A flexible printed circuit board is provided with an opening through which a lead or a terminal part drawn out from the part requiring shielding is passed through, and a part of the conductive layer is exposed and used as a ground terminal part to cover the part requiring shielding. A circuit shielding structure characterized by a structure in which: