JPH0548367A - Device for preventing undesired radiation - Google Patents

Abstract

PURPOSE:To reduce undesired radiation with a simple work by providing a resistor for an impedance to a 3-terminal capacitor and using a coil and a capacitor so as to eliminate a waveform noise component. CONSTITUTION:Resistors 14, 15 for impedance matching are provided to both sides of a 3-terminal capacitor 1. A waveform of a fundamental signal inputted from a timing signal generating circuit 4 is smoothed by the resistor 14 and the waveform is shaped by coils 11, 12 and a capacitor 13. Then the noise component of the signal waveform appearing as the undesired radiation is eliminated by a loss due to the resistor 15, of ferrite. The resistors 14, 15 are selected by detecting a signal waveform at each position on a synchroscope by connecting a resistor of a proper resistance to the device and each resistance is selected so as to obtain a proper waveform. After the selected resistor 14 is fitted, the noise level characteristic is measured. When the resistor 14 for impedance matching is fitted to the capacitor 1 in this way, the undesired radiation caused in the adjustment is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unnecessary radiation preventing device for preventing unnecessary radiation generated from a harness (wiring bundle) connecting boards to each other.

[0002]

BACKGROUND OF THE INVENTION For example, a three-terminal capacitor 1 shown in FIG. 4A, a ring core ferrite 2 shown in FIG. It has been known.

As can be seen from the figure, the three-terminal capacitor 1 is composed of coils 11 and 12 and a capacitor 13, and, for example, when the clock pulse generated by the timing signal generating circuit 4 in the substrate 3 is sent to another substrate 5, the substrate 3 In order to prevent unnecessary radiation generated from the harness 6 connected to the connectors 31 and 51 of the board 5, the connector 31 of the board 3
Placed in front of.

The ring core ferrite 2 is directly attached to the harness 6 for the same purpose.

[0005]

In the above-mentioned three-terminal capacitor 1 and the ring core ferrite 2, in order to most effectively reduce the unnecessary radiation generated from the harness 6,
Each component must be selected according to the impedance of the signal path, and this selection work is performed by trial and error.

Therefore, there is a problem that it takes a long time to effectively reduce unnecessary radiation.

Therefore, the present invention solves the above-mentioned problems, and proposes an unnecessary radiation preventing device capable of effectively reducing unnecessary radiation with a simple operation.

[0008]

In order to solve the above problems, according to the present invention, an unnecessary radiation preventing device using a three-terminal capacitor is provided with a resistor for impedance matching on one side or both sides of the three-terminal capacitor. It is characterized by.

[0009]

In FIG. 1, the signal sent from the timing signal generating circuit 4 (FIG. 2 (a)) has a smooth waveform due to the resistor 14 (FIG. 2 (b)), and then the coil 11,
The waveform noise component is further removed by 12 and the capacitor 13 (FIG. 2C).

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a facsimile apparatus according to the present invention will be described in detail with reference to the drawings. The same parts as those described above are designated by the same reference numerals.

FIG. 1 shows the structure of an unnecessary radiation prevention apparatus according to the present invention. As can be seen from the figure, this unnecessary radiation prevention device is provided with resistors 14 and 15 for impedance matching on both sides of a conventional three-terminal capacitor 1 (FIG. 4).

For example, a basic signal input from the timing signal generating circuit 4 as shown in FIG. 2A is smoothed to some extent by the resistor 14 as shown in FIG. And the waveform is shaped by the capacitor 13, and then the loss due to the high resistance of ferrite causes
The noise component of the signal waveform appearing as unnecessary radiation is removed ((c) in the same figure).

The resistor 14 of such an unnecessary radiation prevention device,
To select 15, first, connect a resistor having an appropriate value, detect the signal waveform of each part with a synchroscope or the like, and select each resistor so that this signal waveform has an appropriate value.

FIG. 3 shows characteristics of noise levels measured before and after mounting the above-mentioned unnecessary radiation preventing device. As can be seen from the figure, this unwanted radiation prevention device can significantly reduce unwanted radiation.

In the above embodiment, the case where the resistors 14 and 15 are attached before and after the three-terminal capacitor 1 has been described, but the resistors may be attached to only one side. Also, the resistance 1
A variable type can also be used for 4 and 15.

[0016]

As described above, according to the present invention, a resistor for impedance matching is attached to one side or both sides of a three-terminal capacitor.

Therefore, according to the present invention, there is an effect that unnecessary radiation generated from a harness or the like can be prevented with a simple structure and an easy adjustment work.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an unnecessary radiation prevention device according to the present invention.

FIG. 2 is an explanatory diagram illustrating a signal waveform of each unit.

FIG. 3 is an explanatory diagram illustrating a noise level measurement result.

FIG. 4 is a configuration diagram of an unnecessary radiation prevention device according to a conventional example.

[Explanation of symbols]

 1 Three-terminal Capacitor 2 Ring Core Ferrite 3, 5 Board 4 Timing Signal Generation Circuit 6 Harness 11, 12 Coil 13 Capacitor 14, 15 Resistor 31, 51 Connector

Claims (1)

[Claims] 1. An unnecessary radiation preventing apparatus using a three-terminal capacitor, wherein a resistor for impedance matching is provided on one side or both sides of the three-terminal capacitor.