JP2000357421A - Signal cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a USB-compatible signal cable capable of preventing defects such as malfunctions and operation failures particularly due to burst noises with a simple manner. SOLUTION: This signal cable is provided with a power source wire 5, a ground wire 6, a pair of signal wires 4a and 4b and a shield wire 7 for shielding. The signal cable is adopted wherein the signal wires 4a and 4b are stranded by a pitch of 2 cm per time or under and the shield wire 7 is a braided metal wire 7a covering the power source wire 5, the ground wire 6 and the signal wires 4a and 4b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal cable, and more particularly, to a signal cable which can connect a computer main body to peripheral devices or peripheral devices in accordance with the USB standard.

[0002]

2. Description of the Related Art Conventionally, personal computers (hereinafter, referred to as personal computers).
To build a system in which the PC and its peripheral devices are connected to each other, connect peripheral devices such as a keyboard device, mouse, and printer to the dedicated ports for each peripheral device provided on the personal computer. It was common to do.

On the other hand, recently, a personal computer having a terminal capable of connecting a personal computer main body and peripheral devices or peripheral devices in common has been provided. A system consisting of a personal computer and peripheral devices having the above terminals connects a keyboard device to the personal computer via a signal cable,
Further, a peripheral device such as a mouse and a printer is connected to a peripheral device common connection terminal provided in the keyboard device via another signal cable. In order to make such a connection, the keyboard device is provided with a socket for inserting a plug of a peripheral device. Plugs, sockets, signal cables, and the like that make this type of connection have been standardized as USB standards, and have recently attracted attention as USB-compatible peripheral devices.

[0004]

By the way, when a personal computer is used, input devices such as a keyboard device and a mouse are always operated by a user, and static electricity may be generated during use. In addition, static electricity charged in these devices sometimes causes discharge, and may adversely affect various electric signals exchanged between the personal computer body and the input device as static noise. In addition, burst noise may propagate from the power supply of the personal computer to the keyboard device via the signal cable, and the burst noise may also adversely affect various electric signals and cause the input device to malfunction.

For example, in the above USB compatible system, unlike a conventional system in which peripheral devices are connected to respective dedicated ports of a personal computer, a mouse is connected to a downstream side of a keyboard via a signal cable. When,
Not only data signals from the mouse but also address signals for the main body of the personal computer to recognize the presence of the mouse come and go as needed on this signal cable. In the case of the conventional system, even if burst noise or electrostatic noise enters the signal cable and the data signal becomes abnormal, if the data signal is exchanged again after resetting, normal operation is performed, and there is no particular problem. However, in the case of USB-compatible systems, if these noises cause the mouse address signal to be reset, the PC itself will not be able to recognize the mouse even though the mouse is connected downstream of the keyboard. However, there is a risk that operation with the mouse may become impossible. Under these circumstances, USB-compatible personal computers and their peripheral devices are required to have high resistance to burst noise and electrostatic noise.
The measures were urgently needed.

[0006] Further, in taking measures against these noises, from the viewpoint of avoiding an increase in the manufacturing cost of various peripheral devices, it is necessary to provide means capable of taking the measures as simple as possible without incurring much cost. Was desired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a USB-compatible signal cable that can prevent a malfunction such as a malfunction or a malfunction due to burst noise in a simple manner. And

[0008]

In order to achieve the above object, the present invention employs the following constitution. The signal cable of the present invention is for transmitting electric signals for connecting devices and exchanging them between the devices, and a power supply line, a ground line, and a pair of signal lines are connected to a shielding wire for shielding. The pair of signal lines are covered with each other at a pitch of 2 cm / 1 or less. Also,
It is preferable that the pair of signal lines be twisted together at a pitch of 0.3 cm / 1 to 2 cm / 1.

In such a signal cable, one of a pair of signal lines is used as a reference line and the other signal line is used as a data line, and various signals are generated by a change in a potential difference between the reference line and the data line. A so-called differential communication method for transmitting an electric signal is employed. Therefore, according to this signal cable, the tightness of the pair of signal lines (reference line and data line) is increased by twisting the pair of signal lines at a pitch of 2 cm / 1 or less, and one of the signal lines Even if burst noise enters a wire, the burst noise immediately propagates to the other signal line due to the action of electromagnetic induction, so that the potential difference between the pair of signal lines does not relatively change, causing abnormalities in various electrical signals. Never come.

[0010] The signal cable of the present invention is the signal cable described above, wherein the power supply line, the grounding line, and the pair of signal lines are at least once on a circular core made of a soft magnetic material. It is characterized by being wound.

In such a signal cable, a power supply line,
The inductor is formed by winding the ground line and the pair of signal lines at least once around the annular core, and the impedance of the power line, the ground line, and the pair of signal lines is increased. In this way, in this signal cable, the impedance of the power supply line connecting the devices becomes high, so that the burst noise is less likely to flow through the signal cable, and the possibility of causing abnormalities in various electric signals is further reduced. You. Since the shield wire is not wound around the annular core, the impedance of the shield wire is maintained at a low level, and the static electricity charged on one device can be quickly passed to the other device via the shield wire, and the Is prevented from being charged by static electricity, thereby reducing the generation of static noise, thereby reducing the adverse effects of burst noise.

Further, the signal cable of the present invention is the signal cable described above, wherein the shielded wire is a braided metal wire covering the power supply line, the ground line, and the pair of signal lines. It is characterized by the following.

In such a signal cable, since the shielded wire is a braided metal wire, the electric charge flowing through the shielded wire flows linearly along the longitudinal direction of the signal cable, thereby suppressing eddy current loss. And the impedance is reduced.
Through this signal cable, it is possible to quickly flow to the other device, preventing the device from being charged by static electricity, reducing the generation of electrostatic noise, and thereby reducing the adverse effect of burst noise. Become. Further, since the shielded wire is a braided metal wire, noise generated outside the signal cable is not shielded by the braided metal wire and does not adversely affect an electric signal flowing through the signal line.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
This will be described with reference to FIG. The signal cable of the present invention is for connecting, for example, a personal computer body conforming to the USB standard and a keyboard device, a USB plug is provided at one end and the other end is connected to the keyboard device, and the USB plug is connected to the personal computer. The personal computer is connected to the keyboard device by being inserted into a USB socket of the main body.

FIG. 1 shows a keyboard device connected to a personal computer (not shown) via the signal cable. This keyboard device 21 has a large number of key tops 2
, And a control circuit board 24 mounted with a control circuit for controlling the keyboard body 26 are housed in a case. The case is composed of an upper case 27 and a lower case 22 which are divided into upper and lower parts, and the keyboard body 26 is housed in a state exposed from the upper case 27 so that the key top 28 on the upper surface can be operated. USB sockets 25, 25, which are two USB connectors, are provided on the rear side below the keyboard body 26.
Is accommodated therein.

The control circuit board 24 is formed of a general printed wiring board. The signal cable 1 of the present invention is attached to a substantially central portion of the control circuit board 24.
Sockets 25, 25 are provided, respectively. As shown in FIGS. 1 and 2, the signal cable 1 of the present invention includes a pair of signal lines 4a and 4b, a power supply line 5, a ground line 6, and a shielding line 7 for shielding. A USB plug 3 is provided at one end. These signal lines 4a, 4b, power supply line 5, ground line 6, and shield line 7 are
It is connected to the lower surface of the control circuit board 24 by soldering, of which a conductor 32 is further connected to a connection portion between the board 24 and the shield wire 7, and a shield plate 2 described later.
The connection piece 34 at the end of the conductor 32 and the connection piece 34 at the tip of the conductor 32 are connected to each other.

FIG. 3 shows the internal structure of the signal cable 1. As shown in FIG. 3, in the signal cable 1, a pair of signal lines 4 a and 4 b are twisted together to form a pair, and are covered with an aluminum tape 13 together with a power supply line 5 and a ground line 6. Further aluminum tape 1
A shield wire 7, which is a braided metal wire 7a, is arranged on the outer periphery of 3, and the shield wire 7 (the braided metal wire 7a) is further covered with a sheath 14 made of a thermoplastic resin or the like.

Also, as shown in FIG.
Are shield terminals 8 having a substantially rectangular shape in cross section, and signal terminals 9 and 10 and power supply terminals 11 provided in the shield terminals 8.
And a shield terminal 8, a shield wire 7 (a braided metal wire 7 a) is connected to the shield terminal 8, signal wires 4 a and 4 b are respectively connected to the signal terminals 9 and 10, and a power wire is connected to the power terminal 11. Is connected to the ground terminal 12 and the ground wire 6
Is connected. The USB plug 3 is inserted into a USB socket of a personal computer (not shown), and the shield terminal 8, signal terminals 9, 10, power supply terminal 11, and ground terminal 12 are connected to the shield, signal, and power supply terminals of the personal computer. And a ground terminal.

The pair of signal lines 4a and 4b, the power line 5 and the ground line 6 are made of a conductor made of copper alloy such as oxygen-free copper, chromium copper, copper containing silver, or a conductor made of aluminum or aluminum alloy. With an insulating coating. Similarly, the shielded wire 7 may be made of a copper alloy such as oxygen-free copper, chromium copper, or copper containing silver,
It is made of aluminum or aluminum alloy.

One of the signal lines 4a and 4b is used as a reference line and the other is used as a data line, and various electric signals are transmitted based on a change in potential difference between the reference line and the data line. . The power supply line 5 is for supplying power from one device (the personal computer main body) to the other device (the keyboard device 21). Also, the shield wire 7
The static electricity charged on one device (keyboard device 21) side is released to the other device (computer body).

The signal cable 1 employs a so-called differential communication system in which various electric signals are transmitted based on a change in a potential difference between a pair of signal lines 4a and 4b (a reference line and a data line). Therefore, the pair of signal lines 4a, 4b
Are aligned with each other, the adhesion between the pair of signal lines 4a and 4b (the reference line and the data line) increases, so that even if burst noise enters one of the signal lines, the burst noise is Since the signal propagates immediately to the other signal line by the action of the induction, the pair of signal lines 4a, 4a
The potential difference between b does not change, and no abnormality occurs in various electric signals.

The pair of signal lines 4a and 4b are 2 cm /
It is preferred that they are twisted together at a pitch of not more than one time, and more preferably that they are twisted together at a pitch of 0.3 cm / 1 to 2 cm / 1. When the pitch exceeds 2 cm / 1, the adhesion between the signal lines 4a and 4b is reduced, and various electric signals exchanged by the signal lines 4a and 4b may be abnormal due to burst noise. Is not preferred. If the twisting pitch is less than 0.3 cm / one time,
Since the signal lines 4a and 4b are tightly fitted with each other and the flexibility of the signal cable 1 itself is reduced, it is not preferable.

Further, as shown in FIG.
In the connection portion between the power supply line 5 and the control circuit board 24,
, The ground line 6 and the signal lines 4a and 4b are wound by one turn around the annular core 15 made of a soft magnetic material. The shield wire 7 is not wound around the annular core 15. The annular core 15 is made of various ferrites such as MnZn ferrite and NiMn ferrite, Fe-Ni alloy, Fe-S
It is made of a soft magnetic alloy such as an i-alloy. In this way, the power supply line 5, the ground line 6, and the signal lines 4a and 4b are wound around the annular core 15 to form an inductor.

On the lower side of the control circuit board 24, LS
Various electronic components such as I and capacitor are mounted,
On the upper surface side, wirings, lands and the like made of a copper layer forming a control circuit by connecting terminals of these electronic components are formed. In the USB socket 25, a contact that contacts the plug is covered with a soft PVC (polyvinyl chloride) resin, and a metal frame ground portion (not shown, a ground terminal on the connector side) is fixed to an outer surface of the resin. I have.

The keyboard body 26 is a metal plate that sandwiches a housing 35 on which a plurality of key tops 28 are mounted, and a membrane switch 36 composed of two membrane sheets on which a switch circuit is printed and a spacer between the housing 35. 37. The metal plate 37 has two connecting portions 38 for fixing the keyboard main body 26 between the upper case 27 and the lower case 22. 27, and a position corresponding to the fastening portion 40 of the lower case 22. Further, a connection portion 41 having a through hole for connecting to a personal computer body side connection piece 34 of the shield plate 23 to be described later is provided at a substantially central portion on the rear edge side of the metal plate 37.

The lower case 22 includes a plurality of fixing portions 42 provided on the front edge side for fixing the upper case 27,
A socket groove 43 provided on the rear edge side for defining the fixing position of the SB socket 25, a stopper 44 provided on the rear edge side near the socket groove 43 and defining the fixing position of the USB socket 25, A fastening portion 40 protruding near the stopper 44 and the socket groove 43 and abutting on a later-described through portion 39 from the upper case 27 and fixing the upper case 27 and the lower case 22 is provided. Stopper 44
Acts as a rib for maintaining the structural strength of the rear edge of the lower case 22 while receiving the force when a connection plug such as a mouse is inserted into the USB socket 25.

The upper case 27 is provided with the fixing portion 4 of the lower case 22.
2 and a plurality of hook portions 45 fitted to the USB socket 2
5 and a through-hole 39 that penetrates through the through-hole of the connecting portion 46 and the through-hole of the connecting portion 38 of the keyboard body 26, contacts the fastening portion 40 of the lower case 22, and is fastened by the screw 47. .

The shield plate 23 is connected to the control circuit board 2
1 which was bent to cover various electronic components on 4
It is made of a stainless steel plate. The control circuit board 24 is designed to have a shape and dimensions that substantially match the control circuit board 24 so as to cover the entire control circuit board 24. Portions protruding from both ends of the shield plate 23 are socket-side connection pieces 47 which are formed by bending into a groove shape having the same shape as the socket groove 43 of the lower case 22. Socket 25
Is inserted, and in the assembled state, the socket-side connection piece 47 is inserted.
Is the socket groove 43 of the USB socket 25 and the lower case 22.
And the socket side connection piece 4
7 is pressed against the frame ground portion on the outer surface of the USB socket 25. Thus, the shield plate 23 and the USB socket 25 are electrically connected.

At a substantially central portion of the shield plate 23, a rectangular personal computer main body side connection piece 34 having a screw hole 48 is formed. Therefore, in the assembled state, the connection piece 3 of the shield plate 23 on the PC main body side is set.
4, the through-holes of the connecting portion 33 of the conductive wire 32 and the connecting portion 41 of the metal plate 37 are overlapped so as to coincide with each other, and these are screwed, so that the shield plate 23 is connected to the conductive wire 3.
2 is connected to the shielded cable 7 of the signal cable 1. Thus, the shield plate 23 is connected to the shield terminal of the personal computer via the shield line 7 of the signal cable 1.

When assembling the keyboard device 21 having the above structure, as shown in FIG. 1, the USB socket 25 connected to the control circuit board 24 is brought into contact with the connection portion 46 of the USB socket 25 to the fastening portion 40 of the lower case 22. In this state, the lower case 22 is fitted into a position regulated by the socket groove 43, the stopper 44 and the fastening portion 40. At this time, the shield plate 23 is arranged below the control circuit board 24, and the socket-side connection piece 47 of the shield plate 23 is inserted into the socket groove 43 of the lower case 22.
The USB socket 25 is fitted into the groove formed by the connector. On the upper side, a metal plate 37 is connected to the connection portion 46 of the USB socket 25.
The keyboard main body 26 is placed in a state where the connecting portion 38 of the keyboard abuts. As described above, the connection piece 34 of the shield plate 23 and the connection portion 3 of the conductor 32
3. The connecting portions 41 of the metal plate 37 are overlapped, and these are screwed. From above, hook portion 45 of upper case 7
To the fixing portion 42 of the lower case 22 and
The through portion 39 of the upper case 27 is connected to the connection portion 38 of the metal plate 37,
Lower case 22 through connection portion 46 of USB connector 25
Of the lower case 22 from below.
7 to fix the upper case 27 and the lower case 22 together.

In the above-described signal cable 1, the tightness of the pair of signal lines 4a and 4b is improved by twisting the pair of signal lines 4a and 4b at a pitch of 2 cm / 1 or less. Even if burst noise enters the signal line, the burst noise immediately propagates to the other signal line due to the action of electromagnetic induction, so that the potential difference between the pair of signal lines 4a and 4b does not relatively change.
There is no abnormality in various electrical signals.

Further, since the shielded wire 7 is the mesh metal wire 7a, the electric charge flowing through the shielded wire 7 flows linearly along the longitudinal direction of the signal cable 1, and an eddy current loss occurs. Since the impedance of the shield wire 7 is reduced without causing any trouble, the static electricity charged on the keyboard device 21 can be quickly passed through the signal cable 1 to the personal computer main body.
1 can be prevented from being charged by static electricity, the generation of static noise can be reduced, and the adverse effect of burst noise can also be reduced. Further, since the shield wire 7 is a braided metal wire 7a, even if any noise occurs outside the signal cable 1, the intrusion of noise is shielded by the braided metal wire 7a, and the signal wire 4a, The electric signal flowing through 4b is not adversely affected.

Further, since a pair of signal lines 4a and 4b and a power line 5 and a ground line 6 are wound around the annular core 15 to form an inductor, a pair of the power line 5 and the ground line 6 are formed. The impedance of each of the signal lines 4a and 4b increases,
Burst noise is less likely to flow through the signal cable 1, and the risk of causing various electrical signals to be abnormal due to the burst noise can be further reduced. Since the shield wire 7 is not wound around the annular core 15, the impedance of the shield wire 7 is maintained at a low level, and the static electricity charged on the keyboard device 21 can be quickly passed to the personal computer main body via the shield wire 7. That is, it is possible to prevent the keyboard device 21 from being charged by static electricity, reduce the generation of static noise, and further reduce the adverse effects of burst noise.

In the keyboard device 21 described above, since the control circuit board 24 is covered from below by the shield plate 23, electrostatic noise radiated from, for example, a desk or the like on the lower surface of the device is shielded by the shield plate 23. You. Further, since the connector side connecting piece 47 of the shield plate 23 is connected to the frame ground portion of the USB socket 25 and the personal computer main body side connecting piece 34 is connected to the shield wire 7 of the signal cable 1, the shield plate 3 allows static electricity to escape. Also acts as a route,
Static electricity that has entered from the USB connector 5 can be released to the shield terminal of the personal computer via the shield plate 3 and the signal cable 1. As described above, the shield plate 3 performs the two functions of the static electricity shield and the static electricity conduction path, so that the probability that the static electricity noise adversely affects the signal on the control circuit board 4 and the operation failure or the like occurs is sufficiently reduced. Can be. Further, since the shielded wire 7 of the signal cable 1 is configured as a braided metal wire 7a and is not wound around the annular core 15, the impedance of the shielded wire 7 is kept low, so that the keyboard device 2
The static electricity charged to 1 can be quickly released to the personal computer body.

[0035]

EXAMPLE A first burst transient test was carried out using the signal cable and keyboard device of the present invention shown in FIGS. 1 to 4 in accordance with the method defined by international standards. After connecting the personal computer to the signal cable and turning on the personal computer and keyboard, apply burst noise of various magnitudes from the power outlet of the personal computer to test whether the keyboard device malfunctions. did. Table 1 shows the burst noise voltage when the keyboard malfunctioned. The pitch at which the signal lines of the signal cable are twisted is set to 1.0 cm / time to 6 c.
m / 1 time.

As shown in Table 1, with respect to the standard value of 1 kV as the information processing equipment, a signal cable in which the pitch of the signal line exceeds 2 cm / one may cause malfunction even with noise of 1 kV or less. , The signal line pitch is 2cm /
In the signal cable of the present invention which is not more than one time, 1.2 kV
In the noise test, it was confirmed that the device had the capability of preventing malfunction and improved the resistance to burst noise. As described above, according to the signal cable of the present invention, the pair of signal wires are twisted at a pitch of 2 cm / 1 or less, the power wire, the ground wire, and the signal wire are wound around the annular core, and the shield wire is braided. By using a metal wire, it is possible to prevent malfunctions and malfunctions of peripheral devices due to burst noise.

[0037]

[Table 1]

[0038]

As described above in detail, in the signal cable of the present invention, the pair of signal lines are twisted together at a pitch of 2 cm / 1 or less. Therefore, even if burst noise enters one of the signal lines, the burst noise immediately propagates to the other signal line due to the action of electromagnetic induction, so that the potential difference between the pair of signal lines is relatively small. There is no change, and the risk of causing abnormalities in various electric signals can be reduced.

In the signal cable according to the present invention, since the power supply line, the ground line, and the pair of signal lines are wound at least once around an annular core made of a soft magnetic material to form an inductor, The impedance of the line, the ground line, and the pair of signal lines is increased, and burst noise is less likely to flow through the signal cable, thereby reducing the risk of causing various electrical signals to be abnormal due to the burst noise. Also, since the shield wire is not wound around the annular core, the impedance of the shield wire is kept low,
Through this shielded wire, it is possible to quickly flow the static electricity generated in one device to the other device, prevent the device from being charged by static electricity, reduce the occurrence of static noise, and further reduce burst The risk of causing abnormalities in various electrical signals due to noise can be reduced.

Further, in the signal cable of the present invention, since the shield wire is a braided metal wire covering the power supply line, the ground wire, and the pair of signal wires, the electric charge flowing through the shield wire is reduced by the signal cable. Flow straightly along the longitudinal direction of the device and reduce impedance without eddy current loss, allowing static electricity generated in one device to flow quickly to the other device through this signal cable. It is possible to reduce the occurrence of static electricity noise by preventing the equipment from being charged by static electricity,
Further, the risk of causing abnormalities in various electric signals due to the burst noise can be reduced. Also, since the shield wire is a braided metal wire, noise generated outside the signal cable is shielded by this braided metal wire,
There is no adverse effect on the electric signal flowing through the signal line.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a configuration of a keyboard device.

FIG. 2 is a front view showing a signal cable according to the embodiment of the present invention.

FIG. 3 is a perspective view showing an internal structure of the signal cable shown in FIG. 2;

FIG. 4 is an enlarged perspective view showing a connection portion between the signal cable and the keyboard device shown in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Signal cable 3 USB plug 4a, 4b Signal wire 5 Power supply wire 6 Ground wire 7 Shield wire 7a Braided metal wire 15 Ring core 21 Keyboard device 23 Shield plate (conductor plate) 24 Control circuit board 25 USB connector (common connection for peripheral devices) Connector) 26 Keyboard body 28 Key top 34 PC body side connection piece 47 Connector side connection piece

Claims (3)

[Claims] 1. A signal cable for connecting devices and transmitting an electric signal to be exchanged between these devices, wherein a power line, a ground line, and a pair of signal lines are a shielding wire for shielding. And the pair of signal lines is 2 cm / 1
A signal cable that is twisted together at a pitch of less than one turn. 2. The cable according to claim 1, wherein the power line, the ground line, and the pair of signal lines are wound at least once around an annular core made of a soft magnetic material. . 3. The signal cable according to claim 1, wherein the shield wire is a braided metal wire covering the power line, the ground line, and the pair of signal lines. .