JP2004355568A - Electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent generation of electromagnetic waves from differential signal lines for transmitting a differential signal; and to easily form the differential signal lines paired with each other into the same wiring length in a wiring board. <P>SOLUTION: Signal wires 11 and 12 paired with each other for connecting terminals of a transmission circuit (USB controller) 4 formed on the wiring board 3 to those of a connector 5 and for transmitting differential signals are installed in a relationship at a predetermined distance on a first surface of the wiring board 3 and on a second surface facing to the first surface through at least one board. Thereby, the differential signals transmitted through the paired signal wires 11 and 12 interfere with each other to negate the generation of electromagnetic waves. By arranging the signal wires 11 and 12 so as to partially set their wiring paths at symmetrical positions by interlaying at least one board, wiring patterns having the same length can be easily formed as compared with the case where the wiring lengths of the paired signal wires are uniformed by forming a folding part on the same surface of the board. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic device including a wiring board on which signal wiring for transmitting a differential signal is provided.
[0002]
[Prior art]
As an electronic apparatus including a wiring board on which signal wiring for differential signals is provided, there is an electronic apparatus disclosed in Japanese Patent Application Laid-Open No. H11-163873. This electronic device includes a connector having terminals that are divided into two types according to a difference in structure, a signal transmission circuit for transmitting data signals to and from other units via the connector, and a signal transmission circuit and the connector. A wiring board provided with signal wirings connecting them, and for specific signal wirings that need to be matched in delay amount, they are connected to the same type connector terminal and paired with each other. A pair of signal wires for transmitting a differential signal is formed on the same surface of a wiring board with a wiring pattern having the same wiring length.
[0003]
[Patent Document 1]
JP 2001-22486 A
[Problems to be solved by the invention]
In the electronic device described in Patent Document 1, when a high-speed data signal composed of a differential signal is transmitted to a pair of signal lines provided on the same surface of a wiring board, a data signal transmitted through the signal line is transmitted. There is a possibility that electromagnetic waves will be generated due to this, causing operation failure of peripheral devices, but no particular measures have been taken in this regard.
[0005]
In the electronic device, the wiring lengths of the pair of differential signal lines provided on the same surface of the wiring board are adjusted by providing a folded portion in the wiring pattern and adjusting the wiring length. However, in reality, there is no room for providing the folded portion in the wiring pattern on the wiring board due to the arrangement position of other mounting components provided on the wiring board and the wiring space on the board, and the pair of differential signal lines has In some cases, it is difficult to make the wiring lengths the same.
[0006]
The present invention solves the conventional problems, prevents generation of electromagnetic waves from a differential signal line through which a differential signal is transmitted, and easily forms a pair of differential signal lines on a wiring board. It is an object of the present invention to provide an electronic device that can be provided with the same wiring length.
[0007]
[Means for Solving the Problems]
An electronic device of the present invention includes a connector having a predetermined terminal, a signal transmission circuit for transmitting a signal to another device via the connector, a wiring board on which the signal transmission circuit and the connector are mounted, and the wiring A pair of signal lines for connecting the transmission circuit provided on the substrate and the terminals of the connector and transmitting a differential signal, wherein the pair of signal lines includes a first surface of the wiring substrate and a pair of signal lines. The first surface is provided on a second surface via at least one substrate with a predetermined distance relationship in which differential signals transmitted through the pair of signal wires interfere with each other to cancel generation of electromagnetic waves. It is characterized by being able to.
[0008]
According to the electronic device configured as described above, the pair of signal wirings that connect the transmission circuit provided on the wiring board and the terminal of the connector and transmit the differential signal are formed on the first surface of the wiring board and the signal wiring. The first surface is provided on the second surface via at least one substrate at a predetermined distance, so that differential signals transmitted through the pair of signal wires interfere with each other to generate electromagnetic waves. Will be canceled.
[0009]
Further, in the electronic device, the pair of signal wirings may be configured such that the first substrate surface of the wiring substrate and the first substrate surface are at least at a second substrate surface via at least one substrate. It is characterized in that a part of the wiring path is arranged at a symmetrical position with one substrate interposed, and the wiring lengths have the same value.
[0010]
In the electronic device configured as described above, the pair of signal wirings is configured such that at least one substrate is formed on the first surface of the wiring substrate and on the second surface via the at least one substrate. Since a part of the wiring path is arranged at a symmetrical position in the middle, a folded portion is provided on the same surface of the substrate as in the conventional case and the wiring length of the pair of signal wirings is made equal to that of a wiring pattern of the same length. It is easy to form.
[0011]
Further, in the electronic device, the pair of signal lines is a pair of data signal lines based on a USB standard.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0013]
FIG. 1 shows a configuration of a signal interface unit used in an electronic device according to an embodiment of the present invention.
[0014]
The electronic device 1 is, for example, a printer device, and a USB controller 4 is mounted on a printed wiring board 3 provided in the device main body 2. The USB controller 4 controls data communication based on the USB standard, and transmits and receives serial signals to and from an external device such as a personal computer via the connector 5. A jack 6 of a connector 5 is mounted on the printed wiring board 3, and a plug 8 of a USB cable 7 is attached to the jack 6, whereby the electronic device 1 and an external device are connected via the USB cable 7. And are communicably connected.
[0015]
Data signals are transmitted and received between the electronic device 1 and the external device based on the USB standard. The USB cable 7 connecting the electronic device 1 and the external device has two data lines (signal lines) (D +, D-) and two power supply lines (VBus, GND), for a total of four signal lines, and the USB data uses two data lines D + and D- as shown in FIG. The signal is transmitted by an inverted differential signal.
[0016]
The jack section 6 of the connector 5 includes four terminals 9 a to 9 d to which four signal lines of the USB cable 7 are connected via the plug section 8. Each of the four terminals 9a to 9d of the jack portion 6 is connected to a wiring pattern of a corresponding predetermined signal wiring formed on the printed wiring board 3 formed of a double-sided board.
[0017]
That is, the signal wiring 10a is connected to the terminal 9a of the USB cable 7 to which the power supply line VBus is connected. The signal wiring 10a is connected to a power supply circuit block (not shown) of the electronic device 1 to enable power supply from an external device to the electronic device 1.
[0018]
A signal wiring 10b is connected to a terminal 9d of the USB cable 7 to which the power supply line GND is connected. The signal wiring 10b is wired to a predetermined position on the printed wiring board 3 and is grounded.
[0019]
The terminals 9b and 9c of the USB cable 7 to which the two data lines D + and D- are respectively connected are connected to one ends of signal wirings 11 and 12, and the other ends of the pair of signal wirings 11 and 12 are connected to the other ends. Each is connected to the USB controller 4.
[0020]
As shown in FIG. 1, the signal wiring 11 is arranged such that its main wiring portion 11c is linearly connected between the USB controller 4 and the jack section 6 on the front surface side of the double-sided printed wiring board 3. And both ends 11 a and 11 b are connected to the jack unit 6 and the USB controller 4, respectively. On the other hand, the signal wiring 12 is arranged such that a main wiring portion 12c linearly connects the USB controller 4 and the jack section 6 to the back surface of the printed wiring board 3 which is a double-sided board. Both ends 12a and 12b of the signal wiring 12 are exposed to the front side of the printed wiring board 3 through through holes 14 and 15 provided near the jack 6 and the USB controller 4, respectively, and are connected to the jack 6 and the USB controller 4. Have been.
[0021]
The two signal wirings 11 and 12 have both ends 11 a, 11 b, 12 a and 12 b on both sides of the main wiring portions 11 c and 12 c which are most of the wiring paths except for the vicinity of the jack section 6 and the USB controller 4. It is arranged symmetrically via the substrate 3 on the front and back of the substrate. Therefore, by providing the signal wirings 11 and 12 in such a relationship, as shown in FIGS. 1 and 3, the main wiring portion 11c of the signal wiring 11 formed on the front side of the double-sided printed wiring board 3 and the back side thereof The main wiring portions 12c of the signal wirings 12 formed on the front and back surfaces of the substrate 3 are vertically overlapped with the substrate 3 interposed therebetween.
[0022]
A pair of signal wirings 11 and 12 for transmitting differential signals arranged symmetrically (overlapping) on the front and back of the substrate 3 via the substrate 3 are transmitted over the signal wirings 11 and 12 at the distance. The USB differential signals are provided within a predetermined distance that can interfere with each other and cancel the generation of electromagnetic waves.
[0023]
The pair of signal wires 11 and 12 have a wiring length of a wiring pattern from the terminals 9 b and 9 c of the jack section 6 of the connector 5 to the USB controller 4, that is, a main wiring portion 11 c in order to adjust the amount of signal delay. , 12c plus both end portions 11a, 11b, 12a, 12b are made equal in length. In FIG. 1, the main wiring portions 11c and 12c are formed in a straight line on the substrate 3. However, when the main wiring portions 11c and 12c cannot be formed in a straight line due to the relationship with other mounted components on the substrate 3, a curved line is formed. And an appropriate pattern shape. Also in this case, the wiring portions 11c and 12c of the signal wirings 11 and 12 are provided at symmetrical positions via the substrate 3, and have the same wiring length.
[0024]
When forming a pair of signal wirings on the same surface of a wiring board, even if the paired signal wirings are simply arranged in parallel, if the wiring pattern includes a curve, the wiring length is set to the same value. It is difficult. In this case, in order to make the wiring lengths of the signal wirings the same, the wiring lengths are made uniform by providing a folded portion in the wiring pattern of one of the signal wirings. In some cases, there is a limitation in providing the folded portion.
[0025]
However, according to this embodiment, the pair of signal wirings 11 and 12 are formed symmetrically with the substrate interposed between the front and back surfaces of the double-sided wiring substrate 3, thereby providing a folded portion in a part of the wiring pattern. Since it is not necessary to make the shapes of the wiring patterns different on the same substrate surface, it is possible to easily form a pair of wiring patterns having the same wiring length.
[0026]
As described above, in the electronic device of the present embodiment, the pair of signal wires for transmitting the data signal composed of the differential signal has a predetermined distance relationship between the front and back surfaces of the double-sided printed wiring board, and has the same wiring length. Thus, in USB communication in which a high-speed serial signal is transmitted through signal wiring, generation of electromagnetic waves can be prevented due to mutual interference between differential signals of both signal wirings.
[0027]
Next, FIG. 4 shows another embodiment according to the present invention.
[0028]
In the above-described embodiment, the main wiring portions 11c and 12c of the pair of signal wires 11 and 12 are provided symmetrically on the front and back of the substrate 3 so as to overlap at the same position on the front and back of the substrate 3. In this embodiment, as shown in FIG. 4, main wiring portions 11c and 12c of both signal wirings 11 and 12 are provided in parallel at a distance L1. In this case, the distance L1 is in the range of the above-mentioned predetermined distance, and the distance at which the differential signals interfere with each other is set. Also in this case, the wiring lengths of both signal wirings 11 and 12 are made equal. In the same manner as in the above-described embodiment, the signal wires 12 disposed on the back surface of the board 3 are brought out to the front side of the board 3 by through holes at both ends of the signal wires, and are respectively connected to the USB controller 4 and the jack. It is connected to a predetermined terminal of the unit 6.
[0029]
The above embodiment is the case of a single-layer double-sided wiring board, but can also be applied to a case where the printed wiring board is a multilayer board.
[0030]
FIG. 5 is a cross-sectional view of a main part of the multilayer printed wiring board 13 including the boards 13a, 13b, and 13c.
[0031]
As shown in FIG. 5, a pair of signal wirings 11 and 12 having the same wiring length are formed on predetermined surfaces of the substrate 13a and the substrate 13c. The distance between the two signal wirings 11 and 12 is set to L2, and this distance is within the above-mentioned predetermined distance.
[0032]
Also in the embodiments of FIGS. 4 and 5, it is possible to prevent the generation of electromagnetic waves due to the mutual interference between the differential signals of the two signal lines, and to provide a pair of signal lines on different surfaces of the substrate. Thus, the wiring length of the pair of signal wirings can be easily set to the same value.
[0033]
Next, FIG. 6 shows various examples in which a pair of signal wirings for transmitting differential signals is provided on a multilayer printed wiring board. The boards 13a, 13b, and 13c that constitute the multilayer printed wiring board 13 are laminated, but are illustrated separately for explanation.
[0034]
FIG. 6 shows six examples, and the leftmost example is one in which a pair of signal wirings 21 and 22 are provided on the front and back surfaces of the uppermost double-sided board 13a. In the second example from the left, a pair of signal wires 31 and 32 are provided on the upper surface of the uppermost substrate 13a and the upper surface of the inner substrate 13b. In the third example from the left, a pair of signal wires 41 and 42 are provided on the surface of the uppermost substrate 13a and the lower surface of the inner substrate 13b. In the third example from the right, a pair of signal wires 51 and 52 are provided on the upper surface of the uppermost substrate 13a and the upper surface of the lowermost substrate 13c.
[0035]
In the second example from the right, a pair of signal wires 61 and 62 are provided on the surface of the uppermost substrate 13a and the lower surface of the lowermost substrate 13c. In the example at the right end, a pair of signal wirings 71 and 72 are provided on the upper and lower surfaces of the inner double-sided board 13b. In any of these examples, the distance between one signal wiring 21, 31, 41, 51, 61, 71 of the pair of signal wirings and the other signal wiring 22, 32, 42, 52, 62, 72 is The predetermined distance relationship is ensured.
[0036]
In this manner, even in a multilayer printed wiring board, by arranging a pair of signal wirings at the predetermined distance on the board constituting the multilayer printed wiring board, a differential signal transmitted through both signal wirings is provided. The generation of electromagnetic waves can be prevented by the mutual interference effect, and by providing a pair of signal wires on different surfaces of the substrate, the wire lengths of the pair of signal wires can be easily set to the same value.
[0037]
【The invention's effect】
As described above, according to the present invention, a pair of signal wires through which a differential signal is transmitted is provided with a predetermined signal in which the differential signals transmitted through the pair of signal wires interfere with each other to cancel the generation of an electromagnetic wave. By providing the distance, it is possible to prevent the generation of electromagnetic waves and prevent the electromagnetic waves from causing an operation failure to peripheral devices. Further, the pair of differential signal lines can be easily provided on the wiring board with the same wiring length.
[0038]
The pair of signal wires for transmitting the differential signal are provided on the first surface of the wiring board and the second surface on the second surface via at least one substrate. By arranging a part of the wiring path at a symmetrical position with two substrates therebetween, the wiring length of the pair of signal wirings can be easily set to the same value, and the delay amount of the differential signal can be adjusted. Can be.
[Brief description of the drawings]
FIG. 1 is an exemplary view showing a configuration of a signal interface unit of an electronic device according to an embodiment of the present invention.
FIG. 2 is a waveform diagram of a data signal.
FIG. 3 is a sectional view of a printed wiring board provided with a pair of signal wirings according to the embodiment.
FIG. 4 is a cross-sectional view of a printed wiring board provided with a pair of signal wirings according to another embodiment.
FIG. 5 is a cross-sectional view of a printed wiring board provided with a pair of signal wirings according to still another embodiment.
FIG. 6 is a cross-sectional view of a printed wiring board provided with a pair of signal wirings according to still another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electronic equipment 2 ... Device main body 3 ... Printed wiring board 4 ... USB controller 5 ... Connector 6 ... Jack part 7 ... USB cable 8 ... Plug parts 9a-9d ... Terminals 10a, 10b, 11, 12, 21, 22, 31 , 32, 41, 42, 51, 52, 61, 62, 71, 72 ... signal wiring 13 ... printed wiring boards 14, 15 ... through holes

Claims (3)

A connector having a predetermined terminal, a signal transmission circuit for transmitting a signal to and from another device via the connector, a wiring board on which the signal transmission circuit and the connector are mounted, and the transmission provided on the wiring board A circuit and a pair of signal wires that connect between terminals of the connector and transmit differential signals,
The pair of signal wirings includes a first surface of the wiring substrate and a second surface on at least one substrate interposed between the first surface of the wiring substrate and a differential signal transmitted through the pair of signal wirings. An electronic device provided with a predetermined distance relationship in which generation of electromagnetic waves is canceled by interference with each other. The signal wiring of the pair is formed by wiring the first surface of the wiring substrate and the first surface between the at least one substrate and a second surface via at least one substrate. 2. The electronic device according to claim 1, wherein a part of the path is arranged at a symmetrical position, and the wiring lengths have the same value. The electronic device according to claim 1, wherein the pair of signal lines is a pair of data signal lines based on a USB standard.

Images