JP4300781B2 - Interface circuit unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an interface circuit unit including a circuit that converts an analog signal into a digital signal and outputs the digital signal, and more particularly, to an interface circuit unit that prevents noise output from a digital cable from leaking into the analog cable. .
[0002]
[Prior art]
When a circuit that converts an analog signal into a digital signal and outputs the signal is provided on one circuit board, an analog circuit unit as described in Patent Document 1 is used to prevent noise caused by the digital signal from leaking into the analog signal. The digital circuit part is separated using a shield plate.
[0003]
[Patent Document 1]
Japanese Utility Model Publication No. 5-90997
[Problems to be solved by the invention]
When the cable connected to the circuit board is only analog as in Patent Document 1, the digital circuit portion can be surrounded by a shield plate. However, when the digital cable is connected to the circuit board, noise generated from this cable Is a problem. In particular, when the analog cable and the digital cable have to be arranged so as to overlap in a plane due to a problem in the configuration of the circuit board, there is a problem that noise generated from the digital cable is likely to leak into the analog cable.
[0005]
Therefore, an object of the present invention is to provide a structure capable of suppressing noise leaking into an analog cable when the analog cable and the digital cable are arranged so as to overlap in a plane.
[0006]
[Means for Solving the Problems]
The present invention provides a first circuit board having an analog output unit, a second circuit board having an analog input unit and a digital output unit, and the first and second circuit boards. Metal mounting boards that are fixed to each other at intervals, an analog cable that connects the analog output section and the analog input section through an interval area of the circuit board, and a plane that is connected to the digital output section and that is flat with the analog cable. A digital cable arranged with a general overlap, and the first circuit board and the second circuit board are spaced apart from each other so that there is no planar overlap on one surface of the mounting board. fixed Te, the spacing region, the opening to contact the sides of the mounting substrate is provided, characterized in that to derive the said digital cable on the back side of the mounting substrate through the opening
[0007]
According to a second aspect of the present invention, the opening is formed in a region that avoids a planar overlap with the analog cable.
[0008]
According to a third aspect of the present invention, a tunnel-shaped passage portion for arranging the digital cable is formed adjacent to the opening of the mounting substrate.
[0009]
According to a fourth aspect of the present invention, the analog output section of the first circuit board and the analog input section of the second circuit board face each other across the tunnel-shaped passage section. The first and second circuit boards are fixed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a state in which the upper surface cover of the interface circuit unit is removed, and FIG. 2 is a perspective view of the mounting substrate.
[0011]
In the interface circuit unit 1, the first circuit board 3 and the second circuit board 4 are fixed to one surface of the mounting board 2 with a gap region 5 therebetween so that there is no planar overlap. . Various signal terminal portions 6 and 7 such as an analog signal input / output, a video signal input, a composite video output, and an RS232C signal input / output, and a power supply terminal 8 are arranged on the lower side and the right side of the unit 1. The unit 1 includes a lower plate 9 on which various signal terminal portions 6 and power supply terminals 8 are arranged on the lower side, and the lower plate 9 is fixed to the mounting substrate 2 with screws. The right side plate of the unit 1 on which various signal terminal portions 7 are arranged is formed by bending the mounting substrate 2.
[0012]
A metal cover 10 (see FIG. 3) is attached so as to cover the first and second circuit boards 3 and 4. The metal cover 10 and the mounting substrate 2 also function as a shield plate by being connected to the ground potential.
[0013]
The first circuit board 3 is a circuit that exclusively handles analog signals, and is fixed to the mounting board 2 so as to occupy one side of the unit 1 in the left-right direction. The second circuit board 4 is a circuit that handles both an analog signal and a digital signal in order to perform a digitization process for digitizing an analog signal and a scaling process for changing the size of an image. The first circuit board 3 is fixed to the mounting board 2 in an area other than the area occupied by the first circuit board 3.
[0014]
The first circuit board 3 includes a connector 11 as an analog output unit that outputs an analog signal supplied via a terminal 7. The second circuit board 4 includes a connector 12 as an analog input unit to which an analog signal supplied from the first circuit board 3 is input. These connectors 11 and 12 are arranged to face each other with the interval region 5 interposed therebetween so as to be connected to each other by an analog cable 13 passing over the interval region 5.
[0015]
In the second circuit board 4, a connector 14 as a digital output unit is disposed on the same side edge as the side edge provided with the analog output connector 12. One end of a digital cable 15 is connected to the connector 14. The digital cable 15 is configured by a cable suitable for a digital interface, and in this example, a plurality of twisted pairs for transmitting a parallel-serial converted data signal, a clock signal, etc. with a reduced amplitude are used. The other end of the digital cable 15 is pulled out from the lower side of the unit so as to be connected to a digital device, for example, a digital input liquid crystal display device.
[0016]
At this time, since the digital cable 15 passes under the analog cable 13, the digital cable 15 and the analog cable 13 are arranged with a planar overlap. In order to prevent noise leakage from the digital cable 15 arranged with a planar overlap to the analog cable 13, a shielding member is arranged between the two. A part of the mounting substrate 2 was used as the shielding member. An opening 16 that communicates the front and back of the mounting substrate 2 is provided at a position corresponding to the interval region 5 of the mounting substrate 2. The opening 16 is formed in a region that avoids a planar overlap with the analog cable 13. Here, an opening 16 is formed at a position adjacent to the digital output connector 14.
[0017]
Since the digital cable 15 is pulled out to the back side of the unit 1 through the opening 16 and the metal mounting board 2 is interposed at the crossing position of the analog cable 13 and the digital cable 15, the mounting board 2 functions as a shield plate. Therefore, the function of the shield plate between the digital cable 15 and the analog cable 13 can be achieved using the existing parts, and the number of parts can be reduced.
[0018]
A tunnel-shaped passage portion 17 in which the digital cable 15 is disposed adjacent to the opening 16 is formed at a position corresponding to the interval region 5 of the mounting substrate 2. As shown in FIG. 2, the passage portion 17 has a convex shape from the back side to the front side of the substrate 2, and the length of the passage portion 17 is longer than the width of the analog cable 13 and its connectors 11 and 12. Also long enough. The height of the passage portion 17 is set such that the digital cable 15 drawn from the opening 16 to the back side of the unit 1 can be stored without protruding to the back side of the unit 1. Since the passage portion 17 is arranged corresponding to the interval region 5, the height of the passage portion 17 can be set relatively freely without being restricted by the substrates 3 and 4. Therefore, although the height of the passage portion 17 is set higher than the substrates 3 and 4, it may be set lower than the substrates 3 and 4.
[0019]
Since the tunnel-shaped passage portion 17 functions as a storage portion for storing the digital cable 15 in addition to the function of the shield plate between the digital cable 15 and the analog cable 13, the number of parts can be further reduced. .
[0020]
The analog cable 13 is disposed across the tunnel-shaped passage portion 17. Accordingly, the connectors 11 and 12 are also fixed at positions facing each other with the tunnel-shaped passage portion 17 interposed therebetween.
[0021]
On the upper side of the second circuit board 4, a dip switch 18 and a temperature sensor 19 for performing various settings are arranged. Since the setting dip switch 18 is disposed on the side opposite to the side on which the input / output terminal 6 is disposed on the substrate 4, the setting operation is hindered by the input / output terminal 6 and various cables connected thereto. Can be prevented.
[0022]
As shown in FIG. 3, the unit 1 thus configured is used by being mounted on the back of a digital display device, in this example, a liquid crystal display device 20 having a digital input.
[0023]
【The invention's effect】
As described above, according to the present invention, when an analog cable and a digital cable are arranged so as to overlap in a plane, noise leaking into the analog cable can be suppressed. And the structure can be realized by using existing parts, and the configuration can be simplified.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of the present invention.
FIG. 2 is a perspective view of a mounting substrate according to the embodiment.
FIG. 3 is a perspective view of an apparatus equipped with a unit of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Interface circuit unit 2 Mounting board 3 1st circuit board 4 2nd circuit board 5 Space | interval area | region 11 Connector 12 Connector 13 Analog cable 14 Connector 15 Digital cable 16 Opening 17 Passage part

Claims (4)

A first circuit board having an analog output section; a second circuit board having an analog input section and a digital output section; and a metallic mounting board for fixing the first and second circuit boards with a space therebetween. An analog cable that connects the analog output unit and the analog input unit through an interval region of the circuit board, and a digital cable that is connected to the digital output unit and arranged with a planar overlap with the analog cable. The first circuit board and the second circuit board are fixed to each other on the one surface of the mounting board at a distance so that there is no planar overlap. An interface circuit unit characterized in that an opening for connecting the front and back sides of the mounting board is provided, and the digital cable is led out from the opening to the back side of the mounting board. 2. The interface circuit unit according to claim 1, wherein the opening is formed in a region avoiding a planar overlap with the analog cable. 3. The interface circuit unit according to claim 1, wherein a tunnel-shaped passage portion for arranging the digital cable is formed adjacent to the opening of the mounting substrate. The first and second circuit boards are fixed so that the analog output section of the first circuit board and the analog input section of the second circuit board face each other across the tunnel-shaped passage section. The interface circuit unit according to claim 3.

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