JPS5861583A - Device for preventing noise of electronic controller and method of producing same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a noise prevention device that prevents the propagation of noise generated from digital electronic equipment, particularly automotive digital electronic equipment, and which interferes with reception of communication equipment such as radios, and a method for manufacturing the same.

In recent years, due to the development of digital electronic technology, watches.

Digitalization of consumer electronics such as timers and various home appliances equipped with microcomputers is progressing rapidly.

On the other hand, technology for controlling engines and various electrical components using digital wired logic circuits or microcomputers is beginning to be adopted in automobiles as well.

Figure 1 shows an example of a schematic configuration of an automotive digital electronic device using a microcomputer, where l is a microprocessor, λ is a clock oscillator using a crystal resonator, and the microprocessor l is a clock oscillator using a crystal resonator. The oscillation output of the vibrator is waveform-shaped to obtain square wave clock pulses with rise and fall times of several n- to several tens of ms, respectively. 3 is a memory b 4'A ``''4'D is a control circuit, jA-jD is an A/D converter for exchanging signals with an external circuit.

It is an input/output interface group that includes various circuits such as a D/A converter and a sensor amplifier, and these memories, control circuits, and interface groups are connected to the clock pulse or memory control signal in order to synchronize the microprocessor. A logic type signal with a clock pulse is supplied. The digital block 6 consisting of the above-mentioned parts is housed in a metal case t together with a power supply section 7. riA~riD
1 is an input/output signal line, and 10 is a power supply line.

As shown in Figure 2, case l is installed in a place where the environmental conditions such as temperature and humidity inside the vehicle are relatively favorable, such as under the instrument panel or the seat, and is connected to the input/output signal line A. ~2D input/output signals of the digital block t, that is, input signals from various systems for calculating control parameters, and these signals are digitally processed to control the operation of the engine, various electrical components, actuators, etc. Transmitting control output signals.

The frequency of the signals originally transmitted by these input/output signal lines is θ to several tens of kHz, and these signal edges and power lines should be made of ordinary vinyl-coated wires (or bundled together with harnesses for other electrical equipment). , is normally wired in a concentrated manner. Because of this wiring condition, the input/output signal lines of digital electronic equipment and the harnesses of other electrical components, such as between the in-vehicle 2G// and the antennas lλ and lJ. It can be said that the harnesses /ji and /j that connect the are extremely tightly coupled in terms of high frequency through induction and electromagnetic radiation.

In addition, since digital electronic devices for automobiles and other electrical components use the same on-board battery 16 as a power source, and also use the vehicle body 77 as a common ground, digital electronic devices and various electrical components can be connected through these power lines and ground lines. It can be seen that there is a direct conductive coupling with the electrical equipment.

By the way, the frequency of several hundred kHz or more is usually used as a synchronous control signal for digital electronic devices such as microcomputers.
A square wave clock pulse of several MHz consists of a high-level (several V) fundamental wave and its harmonic components, and its frequency is distributed over a wide range of radio frequency bands, that is, from the frequency band to the FM%'ff band. The input/output signal line deA from the digital block 6 of the device can be considered as a noise source.
Due to the leakage of high frequency noise components of the clock pulse to ~riD and the power line 10, and the direct and indirect coupling between these input/output signals l5PA~riD and the power supply @/σ and the 2 geoharness or antenna, the radio reception output This causes problems such as deterioration of the signal-to-noise ratio and bead sound interference, resulting in a significant deterioration of received sound quality.

The following technical problems are shown in concrete examples. Figure 3 shows a digital electronic device for automobiles (in this example,
FIG. 2 is a frequency spectrum diagram in which noise generated by a radio antenna terminal (using a MHz clock) is measured by a field strength measuring device (intermediate frequency bandwidth to kHz) as a radio antenna terminal input voltage. Here, the horizontal axis is the frequency ME
is, and the vertical axis is the voltage dB at the antenna input terminal.
μV is shown. As shown in this figure, large waves are generated in the terminal voltage over a wide frequency range, representing noise generated by digital electronic equipment.

In order to prevent such noise, filter elements for high-rise W bypass are inserted into all input/output signal lines, power supply lines, etc. of digital electronic equipment, and this filter element is connected to the vehicle body or the metal case of the equipment. Noise suppression devices have been used that connect to a ground conductor pattern that is connected to a ground conductor pattern.

FIG. 4 shows an example of a conventional noise prevention device for digital electronic equipment used for automatic military purposes, where /9 is an input/output signal set and a power line, and 〃 is a ground line. The ground wire
Further, 2G is a connection hole provided at the end of the people output line etc. /9, and this connection hole 241 has a people output line /
9 are connected to each other. Furthermore, the two legs 2 provided on the capacitor n? A and 2FB
Among them, leg BA is connected to this connection hole 2da, and the other leg 2? B is connected to a ground conductor on the back surface of the board J via a connecting portion l provided on the printed circuit board U.

However, in the noise prevention device configured as shown in Figure 1, the ground conductor U is attached to the back side of the printed circuit board 1. It is difficult to print wires, power wires, and ground wires and connect them to the connector on the back side.

For this reason, if this type of noise prevention device is to be used, it will be limited to one in which printed strings are wired only on the top surface of the printed circuit board 1.

FIG. 5 shows an example of another noise prevention device.

Below, the same reference numerals are given to the same parts as shown in the figures, and detailed explanation thereof will be omitted.

In this example, the ground conductor board d is not directly attached to the printed circuit board 1 but is formed separately, and the ground conductor n is formed on the back side of the board J. In addition, connectors X are installed at both ends of the board J.
and 31, a connector pipe and a capacitor filter n are connected to the input/output line, etc./9+7- ground wire x, and a ground conductor n is connected to the capacitor filter n. Here, 3λ is a connection line that connects the end 33 of the input/output line 1 and the end 3 of the connector bin. By organizing the noise prevention device separately in this way, the assembly procedure becomes easier, and the ground conductor
Since the filter can have a sufficiently large area, a noise prevention filter effect can be obtained, but this results in a significant increase in cost. Furthermore, if the line for attaching the input/output line 1 to the capacitor filter n is routed in a complicated manner, the effect of inserting the filter n may be reduced. Furthermore, it becomes necessary to expand the space.

It is an object of the present invention to eliminate the above-mentioned drawbacks, to fully demonstrate the performance of a filter element for preventing the propagation of high frequency noise components to input/output lines in digital electronic equipment that is a noise source, and to provide a filter that can be installed easily. It is therefore an object of the present invention to provide a noise prevention device for an electronic control device that is compact and does not impair the degree of freedom in designing a circuit board pattern.Another object of the present invention is to propose a method for manufacturing such a noise prevention device. .

Hereinafter, the present invention will be described in detail based on the drawings.

Figure 1 shows an example of the components of the noise prevention device of the present invention.
Here, 100 is a connector, and a connector bin 10/ is projected from one side of the IQOA.

One end of the connector bin 10/ is connected to the signal lit/, and the other end is connected to the external device (
(not shown). 102 is a coglint board, and a connector bin 10 is provided at the center S of its surface.
A 29th pattern //J having a connection hole 101 through which / is passed and a capacitor electrode connection portion 1044 is provided.

Further, around the surface of the printed circuit board 102, a second land pattern //J is surrounded and a second land pattern //J is surrounded.
/j is electrically insulated IR2 ground pattern/(H
The protrusion 70 of the earth pattern tOS!
is a pattern for connecting capacitor electrodes, and one electrode 1 of a chip type capacitor/It as a filter element.
09 to this protrusion 101, and the other electrode 706
The positional relationship is such that B can be bonded to the connecting portion 104LK. Further, 107 is a conductor connected to the ground pattern 10jt, and as shown in FIG. Connect to the metal case for IH storage and the vehicle body using the conductor shown in .

Here, a chip type capacitor 10 used as a filter element
Considering the capacitance of 6 and the resonant frequency of the capacitor,
It is suitable to set the current to about 00 pF to 3000 pF, and good attenuation characteristics can be obtained in the floor zone of 7M broadcasting and television broadcasting bands. Further, in this example, a chip-type multilayer ceramic capacitor is used, which is small in size but has a relatively large capacity, and also has good high frequency characteristics.

Next, Section 7 describes the procedure for assembling the noise prevention device of the present invention.
Let me explain by looking at 8 different countries.

Here, ior is #! which mounted electronic circuit parts. The connector 100 is attached to the end of the printed circuit board 101. Next, each of the = nectabins 10/ which remains in the linear shape shown in FIG.

Pass it through the connection hole 103 provided in the 29th node pattern //J of the second printed circuit board 10, and attach the second printed circuit board 10 to the connector side surface /00k.

At this time, the conductor 107 attached to the first coglint board 10 is placed on the first ground pattern 105P previously formed on the first printed board IOr. After completing the installation of the 10th coglint board in this manner, bend the tip of the linear connector pin 10/downward as shown in FIG. ,
The first printed circuit board/(H) is connected by passing through the connection hole/10A of the Ml land pattern/10 provided on the H.Here, each land pattern/10 is connected to various signal wires, Each signal line 19 on the first printed circuit board IOr is connected to an external device via 10/.

Next, both electrodes 104 and 704 of the capacitor/It
B is the earth butter in the 10th coglint board/1
0! Temporary bonding is performed by arranging it so as to be in contact with the protrusion 561 ozh and the connecting portion 1044, respectively. Here, it is preferable to temporarily adhere the capacitor 106 using a heat-resistant adhesive tape or adhesive so that the capacitor 106 does not come off during the solder bath processing described later.

Next, a solder bath treatment (undering) process is performed. In the wiring process, between the poles 109 and/(74B of the capacitor 106 and the earth pattern protrusion 10!A and the tangential line 10da on the 10th coglint board 10,
2nd land pattern//J and 1st land pattern
between pin/10 and connector bin 10/, and conductor 1
07 and the first ground pattern 109 by soldering. Thereafter, the ground conductor /// is connected to the first printed circuit board lθryr using the screw //2 to constitute the noise prevention device of the present invention.

In the noise prevention device configured in this way, the ground circuit is provided over a wide area and is formed to have low impedance, so that the chip type multilayer ceramic capacitor fO6 as a filter element can effectively function as a bypass effect against high frequencies. be able to.

Figure 7 shows the electric current Efl1 at the antenna input terminal when the noise prevention device of the present invention shown in Figure 7 is applied to a digital electronic device that generates noise at the level shown in Figure 3.
Indicates the bar value. In this experiment, toooo was used as a filter element.
Using a pF OaI layer semicircular capacitor equipped with an lθ book bag, noise was measured using an electric field strength f measuring device in the same manner as in the example shown in FIG.

As shown in this figure, the level of the sharp spectrum 2m that appears at each specific frequency seen in Figure 3 has been reduced, and the terminal voltage has reached the level of 2 kunds over a wide frequency range, As a result, it can be seen that harmful noise leakage and infiltration from other sources have been eliminated from the radio and equipment itself.

FIG. 2 shows another embodiment of the present invention.
The same reference numerals are used for the same parts as in the figure and FIG. 7.

In this example, the first printed circuit board toy and the second printed circuit board 1 are
Connector pin 10/K between 0 and 2, with a bead L made of ferrite inserted through it.
An LC filter can be constructed using the high-frequency inductance and resistance of the ferrite bead/20, which has a low electrical resistance, and as shown in FIG. Possession is further improved. Therefore, the effect of removing noise down to lower frequency bands can be obtained.

FIG. 1θ shows still another embodiment of the present invention, in which the connector bins 10/ are arranged in two rows: upper bins 1otU and lower bins 10/L.
It was applied to In general, such a double-row pin connector 10 has a complicated circuit configuration and a large number of input/output lines.
This is particularly effective for electronic equipment using 0D, since it is difficult to mount a large number of filter elements n on the pattern of the printed circuit board I, as described with respect to the conventional example shown in FIG. q. Regarding the assembly procedure, etc.,
There is no particular difference from the example shown in FIG.

As explained above, according to the present invention, high frequency components of clock pulses used in digital electronic equipment leak to the outside via input/output signal lines and power supply lines, and become noise that interferes with reception of in-vehicle radios, etc. In order to prevent this, a 21st lint board having a second land pattern and a first ground pattern through which the connector pin passes is attached to the side surface of the connector on the printed circuit board side. Since a chip-type capacitor with excellent high-frequency noise removal ability is provided as a filter element between the corando pattern, a complete noise prevention device can be obtained while ensuring a low impedance of the ground turn.

In addition, in the present invention, the filter element is provided in contact with the connector that serves as the entrance and exit for noise radio waves as well as the signal, so compared to the conventional example in which the filter element is provided on the printed circuit board, the noise between the input and output lines is reduced. The induction can be suppressed to a lower level, and the filter effect can be effectively exerted without loss.
It is also possible to prevent radio wave interference that would cause devices to operate or control functions to stop due to the intrusion of external noise.

Furthermore, if the connector pin penetrates the ferrite bead, an LC filter can be formed, so that the generation of noise can be more effectively prevented.

Furthermore, according to the method of the present invention, the two noise prevention devices of the present invention can be obtained at low cost.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing an example of the configuration of conventional digital electronic equipment for automobiles, Figure 2 is an explanatory diagram showing the relative positions of electronic equipment and electrical components in automobiles, and Figure 3 is a conventional example that does not include a noise prevention device. Figure 1 is a frequency spectrum diagram showing the measured noise from digital electronic equipment for automobiles, and Fig. 1 is a perspective view showing the configuration of two examples of conventional noise prevention devices installed in digital electronic equipment for automobiles. Fig. 7 is a perspective view showing the components of the noise prevention device of the present invention, Fig. 7 is an assembled perspective view thereof, and Fig. 7 is a spectrum diagram of measuring noise from a digital electronic device equipped with the noise prevention device of the present invention. FIG. 2 and FIG. 10 are perspective views showing the structure of another embodiment of the noise prevention device of the present invention together with a printed circuit board equipped with the same. l...Microprocessor, λ...Lipsock oscillator, J-...Memory, Reference A-
*p...control circuit, jmu~jD...input/output interface group, 6...digital block. 7...Power supply section, r...Metal case 2P
A~DeD-・Input/output signal line, 10...Power line, //
-...Radio, /2. /J・-antenna, ivy, /j...Harness, 14...Battery, n...Body, 19...Signal line, power line, X...Ground wire, 1...Printed circuit board . n...7-x conductor, 2F...capacitor, nm, 2
7B--leg, 3-connection hole, B-connector, m...; nectabin. 1... Connection part, l... Board, M, j/
−、・Connector knob. 32... Connection It, n*J dream... End, too, tooD...; Necta, 100 people...
・Side side, 10/...Connector bin, 10/A
・-Tip. 10/U, 10/L...Connector bin, 10 pieces...
・Second printed circuit board, 103-... Connection hole, 10e... Connection part,
lθ! ...#! coarse pattern. / OjA... protrusion, 104... capacitor, 109, 104B-... electrode, 107...
,conductor. toy...first printed circuit board, 109...first ground pattern, /10...first land pattern, l10fi,...connection hole, ///...ground conductor, /lco...・Screw, //J・
... 1st land pattern, /, 20... Ferrite bead. Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Scope of Claims] 1) A first printed circuit board on which electronic circuit components are mounted and a first land pattern and a WJl ground pattern to which a connector bin is connected are formed. It holds the connector bin through which various signal lines respectively connected to the runt nozzles on the first printed circuit board are connected to external devices, and also connects the connectors mounted on the first printed circuit board and the connectors. A pin is attached to the surface of the connector protruding toward the signal line side, forming a second land pattern having a connection hole through which the connector pin passes and a capacitor electrode connection part, and forming a second land pattern around the second land nozzle. a second printed circuit board on which a first ground pattern is electrically insulated from the second corando pattern; and a Tegg-type capacitor interposed between the second ground pattern and the first ground pattern. A noise prevention device for an electronic control device, characterized in that: 2. In the noise prevention device according to claim 1, a ferrite is provided in the connector bin between the I!l printed circuit board and the first printed circuit board. A noise prevention device for an electronic control device, characterized in that a bead is attached. 3) A first printed circuit board on which electronic circuit components are mounted and a first land pattern and a first ground pattern to which a connector bin is connected are formed; It holds connector bins for connecting various signal lines respectively connected to the land patterns on the first printed circuit board to external devices, and
a second land pattern having a connector mounted on a printed circuit board, a connection hole through which the connector bin passes through the connector, and a capacitor electrode connection portion, the connector bin being attached to the surface of the connector protruding toward the signal line side; and a second printed circuit board having a second ground pattern formed around the second corando pattern and electrically insulated from the second land pattern, and between the second land pattern and the first ground pattern. In manufacturing a noise prevention device having a chip type capacitor interposed in the sl! attaching the first coblint board to the connector by penetrating it through the connection hole of the two-land pattern, and bending the connector pin to connect it to the first land butter of the first printed board;
Next, after temporarily attaching both electrodes of the chip-type capacitor to the capacitor electrode connection part and the second ground pattern, the chip-type capacitor is attached to the capacitor electrode connection part and the second earth pattern by a seeding process. !
In addition to interposing a solid layer between the coarse pattern and the coarse pattern,
A method for manufacturing a noise prevention device for an electronic control device, comprising electrically connecting the connector bin to the second wind pattern and the twelfth wind pattern, respectively.