JP2010185724A - Disconnection detection circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a disconnection detection circuit that has a simple configuration and is highly versatile. <P>SOLUTION: The disconnection detection circuit 10 includes: a voltage generation section 11 for supplying a signal at a prescribed voltage to a first terminal 23 of signal lines 303, 304 for connecting a first terminal 23 and a second terminal 24 while being disposed along cables (signal lines 301, 302) of which disconnection is detected; and a voltage change detection section 12 for detecting the disconnection of the cables by detecting a voltage change in the second terminal 24. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a disconnection detection circuit.

  Conventionally, as a disconnection detection circuit that detects disconnection of a signal cable that connects an external device such as a speaker and a main unit, there is one disclosed in Patent Document 1, for example. In the disconnection detection circuit of Patent Document 1, an equivalent circuit having the same impedance as that of the speaker is provided, and disconnection occurs if the voltage difference between the signal flowing through the speaker and the signal flowing through the equivalent circuit is equal to or greater than a predetermined value. To detect this.

JP 2003-274491 A

  However, according to the disconnection detection circuit of Patent Document 1 described above, a circuit for comparing the voltage value between when the signal is passed through the speaker and when the signal is passed through the equivalent circuit is required. There is a drawback that becomes larger. In addition, since the impedance of the equivalent circuit must be the same value as that of the speaker, there is a problem that correct disconnection detection cannot be performed for speakers having different impedances.

  The present invention has been made in view of the above points, and an object thereof is to provide a disconnection detection circuit having a simple configuration and high versatility.

  The present invention has been made to solve the above problems, and the disconnection detection circuit of the present invention is arranged along a cable to be detected for disconnection, and is a signal line that connects between a first terminal and a second terminal. Voltage generating means for supplying a signal of a predetermined voltage to the first terminal, and voltage change detecting means for detecting disconnection of the cable by detecting a voltage change of the second terminal. And

  In the disconnection detection circuit according to the present invention, in the above configuration, the voltage change detection unit detects that the cable is disconnected when the voltage of the second terminal changes from the predetermined voltage to zero. Features.

  Moreover, the disconnection detection circuit of this invention is provided with the control means which operates an alerting | reporting apparatus, when the disconnection of the said cable is detected in the said structure.

  According to the present invention, the disconnection of the cable can be detected by detecting the change in the voltage generated in the path of the signal line provided along the cable to be detected for disconnection. In other words, the present invention uses a configuration for detecting a change in voltage, and thus the configuration is simpler than using a comparison circuit for comparing voltage values. Further, the present invention does not depend on impedance because it is not a configuration for comparing voltage values, and therefore is highly versatile.

It is a block diagram for demonstrating the disconnection detection circuit by one Embodiment of this invention. It is a block diagram for demonstrating the disconnection detection circuit by one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a configuration diagram for explaining a disconnection detection circuit according to an embodiment of the present invention. In FIG. 1, a semiconductor device 100 is an IC (integrated circuit) having a predetermined arithmetic processing function, and includes a processing unit 14 and a disconnection detection circuit 10.

  The processing unit 14 is an electronic circuit composed of various circuit elements for realizing the function as the semiconductor device 100. In the present embodiment, the processing unit 14 is an audio processing circuit that generates an electrical signal for driving the external speaker 111. It is configured as. The speaker driving electrical signal generated by the processing unit 14 has a positive (+) output supplied to the external terminal 21 of the semiconductor device 100 and a negative (−) output supplied to the external terminal 22.

  One end of a positive (+) signal line 301 is connected to the external terminal 21 of the semiconductor device 100, and one end of a negative (−) signal line 302 is connected to the external terminal 22. The positive (+) signal line 301 and the negative (−) signal line 302 form a signal cable for transmitting an electric signal for driving the speaker to the external speaker 111. The other end of the positive (+) signal line 301 is connected to a positive (+) input terminal (not shown) of the speaker 111, and the other end of the negative (−) signal line 302 is connected to the negative side ( -) Connected to an input terminal (not shown).

  With such a configuration, during normal times when the signal cable is not disconnected, sound based on sound processing by the processing unit 14 is emitted from the speaker 111.

  The disconnection detection circuit 10 is a circuit that detects whether or not the signal cable is disconnected, and includes a voltage generation unit 11 and a voltage change detection unit 12.

The voltage generator 11 always generates a signal of a predetermined steady voltage (high level) while the semiconductor device 100 is operating, and supplies the signal to the external terminal 23 of the semiconductor device 100.
The voltage change detection unit 12 is a voltage appearing at the external terminal 24 of the semiconductor device 100 (which is a voltage value corresponding to the high level generated by the voltage generation unit 11 depending on whether or not the signal cable is disconnected as described below). , One of the zero voltage values) is measured and the voltage change is detected. For example, the voltage change detection unit 12 can be configured to use an AND circuit having two inputs of the voltage of the external terminal 24 and a predetermined voltage. That is, the output of the AND circuit changes to reflect the change in the voltage of the external terminal 24.

  One end of a signal line 303 is connected to the external terminal 23 of the semiconductor device 100, and one end of a signal line 304 is connected to the external terminal 24. The signal lines 303 and 304 are provided along the signal cable. Preferably, the signal lines 303 and 304 are formed integrally with the signal cable (to form one signal cable). The other ends of the signal lines 303 and 304 are short-circuited at the short-circuit portion 310. In addition, if the short circuit part 310 is arrange | positioned inside the speaker housing | casing 112 which accommodated the speaker 111, even if a signal cable is disconnected at any location, a disconnection detection is possible.

  A signal supplied from the voltage generator 11 to the external terminal 23 of the semiconductor device 100 is transmitted to the external terminal 24 through the signal lines 303 and 304, and the voltage is measured by the voltage change detector 12. During normal times when the signal cable is not disconnected, the voltage of the external terminal 24 indicates a voltage value corresponding to the high level generated by the voltage generator 11. On the other hand, when the signal cable is disconnected (at least one of the signal lines 303 and 304 is disconnected), the voltage of the external terminal 24 shows a voltage value of zero.

  The voltage change detection unit 12 detects that the signal cable is disconnected when detecting that the measurement voltage has changed from the voltage value corresponding to the high level to zero. When the measured voltage does not change and continues to indicate a voltage value corresponding to the high level, the voltage change detection unit 12 can determine that the signal cable is not disconnected.

  Thus, according to the present embodiment, a signal of a predetermined voltage is supplied from one end (external terminal 23) of the shorted signal lines 303 and 304, and a change in the voltage at the other end (external terminal 24) is detected. Detect signal cable breaks. That is, since the disconnection detection circuit 10 of this embodiment uses a configuration for detecting a change in voltage, the configuration is simpler than using a comparison circuit for comparing voltage values. Moreover, since the disconnection detection circuit 10 of this embodiment is not a structure which compares a voltage value, it does not depend on the impedance (of the speaker 111), Therefore, versatility is high.

  As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the scope of the present invention. It is possible to

  For example, as shown in FIG. 2, the control unit 13 that operates the external notification device 113 connected to the external terminal 25 based on the disconnection detection result by the voltage change detection unit 12 in the disconnection detection circuit 10A in the semiconductor device 100A. By providing, it may be possible to notify that a disconnection has occurred in the signal cable. As an example of the notification device 113, it is conceivable to use a lamp (notification by light), a display device (notification by video or the like), an auxiliary speaker (notification by sound), or the like. In addition, as the notification device 113, a communication device using a communication line such as a telephone line or the Internet may be used to notify a remote place.

  Moreover, the speaker 111 shown in FIGS. 1 and 2 is merely an example of a device connected to the semiconductor devices 100 and 100A by a signal cable, and does not limit the present invention. For example, the signal cable described above may be applied as a signal cable for connecting a video reproduction device such as a DVD player and a video display device such as a liquid crystal monitor.

  In addition, in a configuration in which a device that operates by receiving a signal of a predetermined voltage instead of the speaker 111 is connected to the semiconductor devices 100 and 100A by a signal cable, a circuit for supplying the signal of the predetermined voltage is generated. The unit 11 can also be used.

  Further, the voltage value when the voltage change detecting unit 12 detects the disconnection may not be zero, and the voltage change detecting unit 12 changes the voltage measured at the external terminal 24 from the voltage value corresponding to the high level by a predetermined value or more. It is good also as a structure which detects that the disconnection of the signal cable had arisen when it was detected. As a result, it is possible to detect a situation where the resistance value of the signal line is extremely increased although the signal cable is not physically cut as a substantial disconnection.

  Further, a light emitting means such as a light emitting diode is used in place of the voltage generating section 11, a light receiving means such as an optical sensor (photodiode) is used in place of the voltage change detecting section 12, and an optical fiber is used in place of the signal lines 303 and 304. It is good also as the structure used.

  DESCRIPTION OF SYMBOLS 10,10A ... Disconnection detection circuit 11 ... Voltage generation part 12 ... Voltage change detection part 13 ... Control part 14 ... Processing part 21-25 ... External terminal 100, 100A ... Semiconductor device 111 ... Speaker 112 ... Speaker housing 113 ... Notification apparatus 301-304 ... Signal line 310 ... Short-circuit part

Claims (3)

Voltage generating means for supplying a signal of a predetermined voltage to the first terminal of the signal line arranged along the cable to be detected for disconnection and connecting between the first terminal and the second terminal;
Voltage change detecting means for detecting disconnection of the cable by detecting a voltage change of the second terminal;
A disconnection detection circuit comprising:   2. The disconnection detection circuit according to claim 1, wherein the voltage change detection unit detects that the cable is disconnected when the voltage of the second terminal changes from the predetermined voltage to zero.   The disconnection detection circuit according to claim 1, further comprising a control unit that activates a notification device when disconnection of the cable is detected.

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