JP6637633B1 - Signal processing circuit and alarm - Google Patents

Abstract

Provided is a signal processing circuit and an alarm which can appropriately handle two audio signals with a small number of components. A signal processing circuit includes an amplifying unit having a first input terminal and a second input terminal for amplifying a signal received at each input terminal, wherein the first input terminal has a first input terminal. Upon receiving the audio signal SS1, the second input terminal 2b receives the second audio signal SS2 when the first input terminal 2a does not receive the first audio signal SS1, and the first input terminal 2a further includes: The amplifier 2 receives the reference signal SSr including the signal corresponding to the noise signal superimposed on the second audio signal SS2, and suppresses the amplification of the noise signal using the reference signal SSr in the amplification of the second audio signal SS2. The alarm device 100 includes at least a detection unit 103, a notification unit 104, and an audio signal processing unit 111. The audio signal processing unit 111 functions in the same manner as the signal processing circuit 1. [Selection diagram] FIG.

Description

  The present invention relates to a signal processing circuit and an alarm device, and more particularly to a signal processing circuit that outputs a signal based on each of two audio signals, and an alarm device that emits audio based on each of the two audio signals.

  Inside various electric devices, many electric signals are generated or received by elements or functional blocks constituting the electric devices, transmitted and received between the elements or between the functional blocks, and / or amplified by the respective elements. A predetermined function is realized by performing various processes such as the above. Therefore, the electrical signal is required to have the intended signal level at the intended time. However, the electrical signals in various electrical devices include, for example, an increase in the operating speed of central processing units such as microcomputers, an increase in internal current due to the expansion of applications of electrical devices, and the development of information and communication technology that provides various communications. Accordingly, unintended noise may be superimposed. Therefore, a process of canceling the noise may be performed so as not to cause such a problem due to the noise. For example, in Patent Literature 1, noise based on external noise is intentionally generated, and this noise is subtracted from a transmission signal before transmission on a transmission side. The receiving side can receive the signal as a noise-free signal.

  On the other hand, there is an alarm device that is a kind of various electric devices that monitors the surrounding environment and notifies the user of an abnormality by announcing the abnormality by voice when an abnormality occurs. For example, a sound signal that is a source of sound emitted from a speaker or the like in the alarm device is mainly generated in the alarm device, amplified to a desired amplitude as appropriate, and converted into sound by the speaker. For example, Patent Document 2 discloses an alarm device in which the gain of an audio amplifier that amplifies an audio signal is increased and the volume of a speaker is increased in accordance with switching from a main battery to an auxiliary battery.

JP-A-9-270575 JP 2011-14063 A

  In an electric device, not only one but also two or more audio signals are generated, and each of them may be subjected to a process for canceling noise or a process such as amplification as described above. In an alarm device, two audio signals may be generated. When a processing circuit such as noise cancellation or amplification is provided for each of the two or more audio signals, the circuit of the electric device may be complicated, and its size or cost may be increased. In particular, in the case of audio signals, a signal processing circuit such as an amplifier circuit may be complicated and an additional sound generator such as a speaker may be required.

  The present invention has been made in view of such circumstances, and a signal processing circuit capable of performing predetermined processing on two or more audio signals with a small number of components, and each of the two or more audio signals. It is an object of the present invention to provide an alarm device capable of appropriately generating a sound based on a small number of components.

  A signal processing circuit according to an embodiment of the present invention includes an amplification unit that includes a first input terminal and a second input terminal, and amplifies a signal received at each of the first input terminal and the second input terminal. The first input terminal receives a first signal that is a voice signal including information to be emitted as voice, and the second input terminal is configured to receive the first signal by the first input terminal, Receiving a second signal that is a voice signal including information to be emitted as voice, the first input terminal further receiving a reference signal including a signal corresponding to a noise signal superimposed on the second signal; The amplification unit suppresses the amplification of the noise signal using the reference signal in the amplification of the second signal.

  The first input terminal and the second input terminal may receive the first signal and the second signal respectively generated from different signal sources.

  One of the first input terminal and the second input terminal may include a PWM signal demodulation circuit.

  The amplifying unit may have a first gain for the reference signal and a second gain different from the first gain for the second signal.

  The alarm device of one embodiment of the present invention is an alarm device that detects a change in the surrounding environment and notifies the user of the change, and a detection unit that detects a change in the surrounding environment, and information inside or outside the alarm device. And a sound signal processing unit that processes a sound signal that is a source of sound emitted from the notifying unit. The sound signal processing unit includes a first input terminal and a second input terminal. And an amplifying unit for amplifying a signal input to each of the first input terminal and the second input terminal, wherein the first input terminal has a first input terminal based on data held in the alarm device. An audio signal is input, and when the first audio signal is not input to the first input terminal, a second audio signal based on information from outside the alarm is input to the second input terminal. The first input terminal further superimposes on the second audio signal. Reference signal comprising a signal corresponding to the sound signal is input, the amplifier unit suppresses amplification of the noise signal using the reference signal in the amplifier of the second audio signal.

  A first control unit that controls the issuance of an alarm from the alarm device; and a second control unit that controls communication between the alarm device and an external device, wherein the first control unit includes the detection unit Outputting the first audio signal based on the detection result, and the second control unit generates and outputs the second audio signal based on the information obtained by the communication, and outputs the reference signal. You may.

  The first control unit may stop outputting the second audio signal and the reference signal by the second control unit when outputting the first audio signal.

  According to the present invention, predetermined processing can be performed on two or more electric signals with a small number of components. Further, according to the present invention, in the alarm device, sound based on each of the two or more sound signals can be appropriately emitted with a small number of components.

1 is a block diagram schematically illustrating a signal processing circuit according to an embodiment of the present invention. 1 is a circuit diagram illustrating a configuration example of a signal processing circuit according to an embodiment of the present invention. FIG. 3 is a diagram illustrating an example of an output circuit of a second signal received by the signal processing circuit according to the embodiment of the present invention. FIG. 3 is a diagram illustrating an example of input / output signals of a signal processing circuit according to an embodiment of the present invention. It is a block diagram showing other examples of the signal processing circuit of one embodiment of the present invention. It is a block diagram showing an example of composition of an alarm of one embodiment of the present invention.

  Hereinafter, a signal processing circuit according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows a signal processing circuit 1 according to one embodiment.

  As shown in FIG. 1, the signal processing circuit 1 includes an amplifier 2. The amplification unit 2 includes a pair of input terminals 20 including a first input terminal 2a and a second input terminal 2b. The first input 2a receives the first signal S1, and the second input 2b receives the second signal S2. The second input terminal 2b receives the second signal S2 when the first input terminal 2a does not receive the first signal S1. The first input 2a further receives the reference signal Sr. The reference signal Sr is a signal including a signal corresponding to a noise signal superimposed on the second signal S2 (hereinafter, also referred to as a “pseudo-noise signal”).

  The first and second input terminals 2a and 2b may be physical “terminals” to which wiring is connected or connectors are connected, and the first and second input terminals 2a and 2b may be amplifying units on a wiring board on which the amplifying unit 2 is mounted. 2 may be used. In addition, the first input terminal 2a or the second input terminal 2b “receives” the first signal S1, the second signal S2, or the reference signal Sr when each input terminal receives each signal directly input to each input terminal. In addition to receiving, as described below, each input terminal receives a signal based on each signal input to an input circuit provided at each input terminal.

  In the example of FIG. 1, the first input terminal 2a is provided with a first input circuit 11 and a third input circuit 13, while the second input terminal 2b is provided with a second input circuit 12. The first signal S1 is input to the input terminal 2c (third input terminal) of the first input circuit 11, the second signal S2 is input to the input terminal 2d (fourth input terminal) of the second input circuit 12, and the reference signal Sr is input to the input terminal 2e (fifth input terminal) of the third input circuit 13. The first input terminal 2a receives the first signal S1 via the first input circuit 11, and receives the reference signal Sr via the third input circuit 13. The second input terminal 2b receives the second signal S2 via the second input circuit 12.

  Each of the first to third input circuits 11 to 13 is, for example, for AC coupling the pair of input terminals 20 and the signal sources of the first and second signals S1, S2 and the reference signal Sr. And / or an electric resistor for adjusting the gain of the amplifier 2 as described later. The internal configuration of each of the first to third input circuits 11 to 13 is not limited to these, and each input circuit can be configured by an arbitrary circuit element. However, in the present embodiment, even when the first terminal 2a and / or the second terminal 2b is provided with any one of the first to third input circuits 11 to 13, the connection to the first terminal 2a and the second terminal 2b is made. No switching element that blocks the input of each signal is arranged in each input circuit. For example, no switching element such as a transistor or a multiplexer is arranged between the input terminal 2c of the first input circuit 11 and the input terminal 2e of the third input circuit 13 via the first input terminal 2a of the amplifier 2.

  The amplifier 2 amplifies each of the first signal S1 and the second signal S2. Note that “amplification” includes conversion of a signal level with an amplification factor of 1 or less. The amplification unit 2 suppresses amplification of a noise signal superimposed on the second signal S2 using the reference signal Sr in amplification of the second signal S2. That is, in the present embodiment, each of the first signal S1 and the second signal S2 can be amplified by one amplifying unit (amplifying unit 2), and a noise signal superimposed on the second signal S2 is not intended. Amplification can be suppressed. The details will be described below.

  The pair of input terminals 20 of the amplifying unit 2 are so-called differential input type input terminals. The amplifying unit 2 amplifies the difference between signals input to the first input terminal 2a and the second input terminal 2b. It is composed of an amplifier circuit. The first input terminal 2a receives the first signal S1 and further receives the reference signal Sr. That is, the first input terminal 2a is shared by the first signal S1 and the reference signal Sr, and is also used as an input terminal for receiving these two signals. The first input terminal 2a receives the reference signal Sr when there is no input of the first signal S1 (when not receiving the first signal S1). On the other hand, as described above, the second input terminal 2b receives the second signal S2 when the first input terminal 2a does not receive the first signal S1. The first input 2a can receive the reference signal Sr when the second input 2b receives the second signal S2.

  The reference signal Sr is a signal in which a pseudo noise signal corresponding to a noise signal (hereinafter, also referred to as “target noise signal”) included in the second signal S2 is superimposed on a signal (DC signal) of a certain level. Here, “corresponding to” the target noise signal means that the target noise signal is at least substantially synchronized with the target noise signal and has the same polarity as the target noise signal with respect to the sign of the signal level. The pseudo noise signal and the target noise signal may have substantially the same signal level, or may have different signal levels. Further, the pseudo noise signal may have a signal level different from the signal level of the target noise signal by a predetermined ratio. The generation of the pseudo noise signal will be described below.

  Noise is superimposed on the second signal S2 by various factors. For example, due to a fluctuation in the potential of a power supply line inside an electric device in which the signal processing circuit 1 is used, a noise signal due to the fluctuation in the potential of the power supply line may be superimposed on a signal output by receiving power supply from the power supply line. is there. Further, a noise signal may be superimposed on the second signal S2 due to an electric field or a magnetic field inside or outside the electric device in which the signal processing circuit 1 is used. Therefore, for example, the reference signal Sr including the pseudo noise signal is generated by the circuit element that shares the power supply with the circuit element that generates the second signal S2 (for example, an integrated circuit device (IC) that generates the second signal S2). Can be. Alternatively, the pseudo noise signal may be generated by a circuit element placed under a specific electromagnetic environment together with the circuit element generating the second signal S2, and the reference signal Sr including the pseudo noise signal may be output from the circuit element. .

  The amplifier 2 amplifies the difference between the reference signal Sr received at the first input terminal 2a and the second signal S2 received at the second input terminal 2b. Since the reference signal Sr includes the pseudo noise signal, the target noise signal corresponding to the pseudo noise signal is subtracted from the second signal S2 through the differential amplification of the amplification unit 2. As a result, when the signal to be amplified in the second signal S2 is amplified, unintentional amplification of the target noise signal is suppressed. Further, it is more preferable that the target noise signal is substantially eliminated through the amplification of the second signal S2 by the amplifier 2. Therefore, an amplified signal of the second signal S2 with little noise can be obtained.

  On the other hand, the first input terminal 2a receives the first signal S1 when the reference signal Sr is not received and the second signal S2 is not received by the second input terminal 2b. When the first input terminal 2a receives the first signal S1, the second signal S2 is at 0 V or the ground potential. Therefore, the amplifier 2 amplifies the first signal S1. Thus, the first signal S1 is also amplified by the amplifier 2.

  In the present embodiment, the amplifying unit 2 amplifies each of the first signal S1 and the second signal S2 in a time-sharing manner, and in particular, in the amplification of the second signal S2, amplifies the difference from the reference signal Sr. Therefore, as described above, each of the first signal S1 and the second signal S2 can be amplified by one amplifying unit (amplifying unit 2), and the target noise signal is amplified when the signal to be amplified is amplified. Can be suppressed.

  In the example of FIG. 1, the first input terminal 2a and the second input terminal 2b receive the first signal S1 and the second signal S2 generated by different signal sources, respectively. The first signal S1 is generated by a first signal source G1, and the second signal S2 is generated by a second signal source G2. The reference signal Sr is generated by the second signal source G2 together with the second signal S2. The first signal source G1 and the second signal source G2 may be any electric component or functional module that can generate an electric signal. For example, one of the first signal source G1 and the second signal source G2 may be a central processing unit (main CPU) that controls the operation of an electric device in which the signal processing circuit 1 is used, and the first signal source G1 and the second signal source G2. The other of the two signal sources G2 may be a sub CPU that assists or backs up the main CPU. Further, for example, one of the first signal source G1 and the second signal source G2 is a microcomputer that controls the overall operation of the electric device, and the other is a specific function (for example, a communication function, a display function, (A memory control function). In the example of FIG. 1, the amplification unit 2 outputs the amplified signals of the first signal S1 and the second signal S2 to an output destination element Eo having an arbitrary function.

  The first signal S <b> 1 and the second signal S <b> 2 may be signals including arbitrary information as long as the signal level such as the amplitude is amplified by the amplification unit 2. The first and second signals S1 and S2 may be digital signals or analog signals. For example, the first and second signals S1 and S2 are audio signals having frequencies in an audible band including information to be emitted as audio from a speaker or the like. The first and second signals S1 and S2 may be audio signals including information related to audio collected by a microphone or the like. When the first and second signals S1 and S2 are audio signals, the output destination element Eo may be, for example, a sound generator such as a speaker. Note that the first and second signals S1 and S2 may be video signals including information relating to an image captured by an imaging device or information relating to an image displayed on a display device, and include temperature, humidity, specific gas, It may be a detection signal of a sensor that detects light, odor, or the like.

  The amplification unit 2 is mainly configured by a differential amplifier circuit as described above. The differential amplifier circuit constituting the amplifier 2 may be a single-ended output differential amplifier circuit or a differential amplifier circuit having a differential output. For example, the amplifier 2 is configured by a differential amplifier classified as a class D amplifier having high power efficiency. A differential amplifier integrated as an IC may be used as the differential amplifier circuit constituting the amplifier unit 2, and the amplifier unit 2 including the differential amplifier circuit is formed by a combination of a plurality of transistors. Is also good.

  FIG. 2 illustrates an example of a specific configuration of the signal processing circuit according to the embodiment. In the example of FIG. 2, the amplification unit 2 is mainly configured by a differential amplifier 21 having a pair of differential outputs (a positive output terminal 21a and a negative output terminal 21b). The first input terminal 2a of the amplifier 2 is a positive input terminal (non-inverting input terminal) of the differential amplifier 21, and the second input terminal 2b is a negative input terminal (inverting input terminal) of the differential amplifier 21. . As in the example of FIG. 1, the first input terminal 2a is provided with a first input circuit 11 and a third input circuit 13, and the second input terminal 2b is provided with a second input circuit 12.

  The first input circuit 11 includes a first resistor R1, the second input circuit 12 includes a second resistor R2, and the third input circuit 13 includes a third resistor R3. Further, each of the first to third input circuits 11, 12, and 13 includes a capacitor C. The first to third resistors R1, R2, R3 are each connected in series with the capacitor C. The DC components in the first signal S1, the second signal S2, and the reference signal Sr can be cut off by disposing the capacitor C in series in each input circuit. For example, in the reference signal Sr, only the pseudo noise signal component in the reference signal Sr is input to the first input terminal 2a.

  A fourth resistor R4 is connected to the differential amplifier 21 as a feedback resistor between the first input terminal 2a (positive input terminal) and the negative output terminal 21b, and the second input terminal 2b (negative input terminal) is connected to the positive output terminal. The fifth resistor R5 is connected as a feedback resistor between the terminal 21a. An output signal whose amplitude is the potential difference between the positive output terminal 21a and the negative output terminal 21b is output to the output destination element Eo.

  In the example of FIG. 2, the amplification unit 2 in the case where the open loop gain of the differential amplifier 21 is sufficiently larger than 1 and (r1 // r3) is substantially equal to r2 and r4 is substantially equal to r5. The gain will be described. Note that r1 to r5 are resistance values of the first to fifth resistors R1 to R5, respectively, and (r1 // r3) is a combined resistance of the first resistor R1 and the third resistor R3. In general, the open-loop gain of the differential amplifier is much larger than 1, and when the above-described substantially equal relation between the resistance values is satisfied, the balance of the feedback on both the positive and negative sides of the differential amplifier is balanced. A stable amplification operation can be obtained.

  Under the above conditions, the amplification factor A1 (first gain) of the amplification unit 2 with respect to the signal (reference signal Sr) input to the third input circuit 13 is 0 V in the first input circuit 11 and the second input circuit 12. In the case where 0V is input to the second and third input circuits 12 and 13, the amplification unit 2 for the signal input to the first input circuit 11 when the input is input is approximately equal to (r4 / r3). Is approximately equal to (r4 / r1)). That is, the signal levels of the signals input to the first to third input circuits 11, 12, and 13 are Vi1, Vi2, and Vi3, respectively, and the signals of the signals output from the positive output terminal 21a and the negative output terminal 21b. When the levels are Vo1 and Vo2, respectively, (Vo1−Vo2) = A1 × (Vi3−Vi2) = A1 × Vi3. Similarly, when 0 V is input to the first input circuit 11 and the third input circuit 13, the amplification factor A2 (second gain) of the amplifier 2 with respect to the signal input to the second input circuit 12 is (r2 / R5), and (Vo1-Vo2) = A2 × Vi2. Thus, the amplification unit 2 can have the first gain (amplification factor: r4 / r3) for the reference signal Sr and the second gain (amplification factor: r2 / r5) for the second signal S2.

  The amplification unit 2 in the present embodiment may have different first and second gains. The reason will be described with reference to FIG. FIG. 3 shows an example of the configuration of an output circuit B of an arbitrary circuit element (not shown) that outputs the second signal S2. In the output circuit B of FIG. 3, a voltage dividing resistor Ra (resistance value ra) and a voltage dividing resistor Rb (resistance value rb) are connected in series between a power supply line Vd (potential Vdd) and GND. Then, the AC signal S20 generated so as to swing around the unspecified reference voltage is output via the capacitor Cc and further via the midpoint between the voltage dividing resistors Ra and Rb. An output signal (second signal S2) that swings around a potential determined by (Vdd × rb) / (ra + rb) = Vt2 is output. At this time, if the noise N1 is included in the power supply line Vd, the noise N2 may also be superimposed on the second signal S2. However, the noise N2 has a level attenuated by rb / (ra + rb) with respect to the noise N1. Therefore, even if the noise N2 based on the noise N1 is superimposed on the second signal S2, the second signal S2 may include the noise N2 smaller than the noise N1 of the power supply line Vd.

  On the other hand, when the reference signal Sr is output from the circuit element that outputs the second signal S2, for example, the power line Vd itself in the circuit element can be output as the reference signal Sr simply via the buffer. By doing so, the reference signal Sr can include noise (pseudo noise signal) having substantially the same magnitude as the noise N1 included in the power supply line Vd. However, in this case, as described above, since the second signal S2 can include noise (target noise signal) smaller than the noise N1 of the power supply line Vd, the amplification unit 2 performs the same operation on the second signal S2 and the reference signal Sr. When there is a gain, the target noise signal may not be appropriately eliminated. Therefore, the amplification unit 2 may have first and second gains different from each other by a difference corresponding to a difference in magnitude between the pseudo noise signal of the reference signal Sr and the target noise signal of the second signal S2. . As described above, when the amplification unit 2 has the first gain and the second gain that are different from each other, a circuit element (not shown) that outputs the second signal S2 and the reference signal Sr causes, for example, the reference signal Sr May be omitted.

  In the output circuit B shown in FIG. 3, when the resistance value ra of the voltage-dividing resistor Ra and the resistance value rb of the voltage-dividing resistor Rb are substantially the same, the second signal S2 is centered on a potential approximately half of the potential Vdd. Swing. Then, the level of the noise N2 (target noise signal) superimposed on the second signal S2 is approximately の of the level of the noise N1 (a pseudo noise signal that can be included in the reference signal Sr) included in the power supply line Vd. In that case, the amplification unit 2 may have a first gain that is approximately half the amplification factor of the second gain. The present invention is not limited to this, and the first gain and the second gain may have a difference in the amplification factor according to the difference in signal level between the target noise signal and the reference noise signal. When the signal level of the pseudo noise signal is X times larger than the signal level of the target noise signal, the gain of the second gain may be N times larger than the gain of the first gain.

  As described above, the first gain and the second gain can be adjusted by the resistance values r1 to r5 of the first to fifth resistors R1 to R5. For example, when the resistance value r4 and the resistance value r5 are substantially the same, the resistance value r3 is a value X times the resistance value r2 so that the gain of the first gain is approximately 1 / X of the gain of the second gain. There may be. For example, when the signal level of the pseudo noise signal is twice the signal level of the target noise signal, the resistance value r3 may be approximately twice the resistance value r2.

  On the other hand, as described above, in order to maintain the balance of the differential amplifier 21, it is preferable that (r1 // r3) and r2 be substantially equal to each other in the example of FIG. Therefore, for example, when the resistance value r3 is twice the resistance value r2, the resistance value r1 may be approximately twice the resistance value r2, that is, substantially the same as the resistance value r3. As described above, when the reference signal Sr including the pseudo noise signal having a signal level approximately twice that of the target noise signal is generated, the balance of the positive and negative feedbacks of the differential amplifier 21 is maintained while the target noise signal is balanced. The gain setting that can be sufficiently eliminated can be realized by selecting a simple resistance value.

  FIG. 4 shows an example of a waveform of an input / output signal of the signal processing circuit 1 of the present embodiment. 4, a signal (first signal S1) input to the first input circuit 11 (see FIG. 2), a signal input to the second input circuit 12 (second signal S2), and An example of each signal (reference signal Sr) input to the third input circuit 13 is shown. 4 shows an example of the output signal So of the amplifying unit 2 at the bottom of FIG.

  In the example of FIG. 4, the first signal S1 is an AC signal that swings around the potential Vt1, and the second signal S2 is an AC signal that swings around the potential Vt2. The second signal S2 includes a noise signal that is unintentionally superimposed, that is, a target noise signal Snt whose amplification is suppressed in the signal processing circuit of the present embodiment. The reference signal Sr is a signal of a constant level having the potential Vt3, but includes a pseudo noise signal Snp corresponding to the target noise signal Snt. Note that the potential Vt3 (eg, 3.3 V) is approximately twice the potential Vt2 (eg, 1.65 V), and the pseudo noise signal Snp has a signal level approximately twice that of the target noise signal Snt. In addition, the amplifier 2 that outputs the output signal So illustrated in the example of FIG. 4 has the first gain that is approximately の of the gain of the second gain, as described above.

  In the first period T1 in FIG. 4, the first signal S1 is input. That is, the first input terminal 2a receives the first signal S1 via the first input circuit 11 (see FIG. 2). On the other hand, the second signal S2 received by the second input terminal 2b is 0V. Therefore, the first signal S1 is amplified by the amplifier 2, and an output signal So1 based on the first signal S1 is output. In the first period T1, for example, the constant potential of the potential Vt2 may be input to the second input circuit 12, and the constant potential of the potential Vt3 may be input to the third input circuit 13.

  In the second period T2, the first signal S1 is not input. The output source (not shown) of the first signal S1 outputs 0V. Then, in a period T21 of the second period T2, the second signal S2 is input. That is, the second input terminal 2b receives the second signal S2 via the second input circuit 12. Further, the reference signal Sr is input in the period T21. That is, the first input terminal 2a receives the reference signal Sr via the third input circuit 13. Therefore, the amplifier 2 amplifies the difference voltage between the reference signal Sr and the second signal S2. Note that the DC component of the reference signal Sr can be cut off by the capacitor C (see FIG. 2) in the third input circuit 13.

  At this time, since the amplifying unit 2 has the first gain that is about 1/2 of the gain of the second gain, the pseudo noise signal Snp is relatively generated in relation to the target noise signal Snt. Decay. As a result, the target noise signal is removed from the second signal S2 by a pseudo noise signal having substantially the same signal level as the target noise signal. Then, as shown in FIG. 4, preferably, an output signal So2 based on the second signal S2, on which the noise signal is not substantially superimposed, is output. In this way, amplification of the target noise signal is suppressed, and only the signal to be amplified is mainly amplified.

  In FIG. 4, in the third period T3, the first signal S1 is input similarly to the first period T1, and the second signal S2 and the reference signal Sr are not input. The amplifier 2 outputs an output signal So1 based on the first signal S1.

  FIG. 5 is a block diagram showing another example of the signal processing circuit of the present embodiment. In the example of FIG. 5, the first input terminal 2a includes a demodulation circuit 3. The demodulation circuit 3 in the example of FIG. 5 includes a capacitor Cd and a resistor Rd, and is connected to the first input terminal 2a via the first input circuit 11. The demodulation circuit 3 converts a digital signal into an analog signal by charging / discharging the capacitor Cd via the resistor Rd. For example, the first signal S1 modulated into a digital signal (PWM signal) by pulse width modulation (PWM) is demodulated into an analog signal. The provision of the demodulation circuit 3 makes it possible to amplify each of the digital signal (first signal S1) such as a PWM signal and the second signal S2 which is an analog signal by using one amplifier 2. When the second signal S2 is a digital signal such as a PWM signal, the demodulation circuit 3 may be provided at the second input terminal 2b. In that case, a demodulation circuit equivalent to the demodulation circuit provided at the second input terminal 2b is provided at the first input terminal 2a via the third input circuit 13. The signal processing circuit 1 of the example of FIG. 5 has a configuration similar to that of the signal processing circuit 1 of the example of FIG. In the example of FIG. 5, the same components as those in FIG. 2 are denoted by the same reference numerals as those in FIG. 2, and the description thereof will be omitted.

  In the above description with reference to FIGS. 1 to 5, an example has been described in which the first input terminal 2a receives the reference signal Sr including the pseudo noise signal. In the signal processing circuit 1 of the present embodiment, the second input terminal 2b may further receive a second reference signal including a signal corresponding to a noise signal superimposed on the first signal S1. Then, in the amplification of the first signal S1 in the amplification unit 2, the amplification of the noise signal superimposed on the first signal S1 may be suppressed using the second reference signal.

  Next, an alarm device according to an embodiment of the present invention will be described with reference to FIG. FIG. 6 is a block diagram showing an example of the configuration of the alarm device 100 according to the embodiment of the present invention.

As shown in FIG. 6, the alarm device 100 includes a detection unit 103 that detects a change in the surrounding environment,
A notification unit 104 that emits a sound based on information inside or outside the alarm 100, a first control unit 101 that controls the generation of an alarm, and a second control that controls communication between the alarm 100 and an external device Ei. A control unit 102 and an audio signal processing unit 111 are provided. The alarm device 100 detects a change in the surrounding environment, notifies the user of the change, and issues an alarm to prompt the user to take appropriate action when an abnormality occurs. The audio signal processing unit 111 processes the audio signals (the first audio signal SS1 and the second audio signal SS2) that are the source of the sound emitted by the notification unit 104.

  The audio signal processing unit 111 includes the signal processing circuit 1 according to the embodiment described with reference to FIGS. That is, the audio signal processing unit 111 includes the amplification unit 2 having the first input terminal 2a and the second input terminal 2b, and amplifying the signal input to each of the first input terminal 2a and the second input terminal 2b. ing. In the example of FIG. 6, similarly to the signal processing circuit 1 of the example of FIG. 2, the first input terminal 2 a includes a first input circuit 11 and a third input circuit 13. The second input terminal 2b is provided with a second input circuit 12. Further, the first input terminal 2a includes a demodulation circuit 3 connected to the first input terminal 2a via the first input circuit 11, as in the example of FIG. The first audio signal SS1 is input to the first input terminal 2a via the first input circuit 11, and the second audio signal SS2 is input to the second input terminal 2b via the second input circuit 12. The reference signal SSr including a signal corresponding to a noise signal superimposed on the second audio signal SS2 is further input to the first input terminal 2a via the third input circuit 13. The amplifying unit 2 is, like the amplifying unit 2 in the signal processing circuit 1 exemplified in FIG. 1 and the like, a noise signal superimposed on the second audio signal SS2 using the reference signal SSr in the amplification of the second audio signal SS2. Suppress amplification.

  The signal processing circuit 1 included in the audio signal processing unit 111 in the example of FIG. 6 performs the first and second signals S1, S2, with respect to the first and second audio signals SS1, SS2 and the reference signal SSr. In addition, the function and operation of the reference signal Sr are the same as those of the signal processing circuit 1 in the example of FIG. The demodulation circuit 3 included in the audio signal processing unit 111 in FIG. 6 operates on the first audio signal SS1 in the same manner as the demodulation circuit 3 in the example in FIG. 5 on the first signal S1. Although the description of the signal processing circuit 1 included in the alarm device 100 is omitted, the description of the signal processing circuit 1 described with reference to FIGS. The processing unit 111) can be applied.

  As will be described later, the first audio signal SS1 is generated based on data held in the alarm device 100, and is input to the audio signal processing unit 111 (first input terminal 2a). The second audio signal SS2 is input to the audio signal processing unit 111 (the second input terminal 2b) when there is no input of the first audio signal SS2 to the first input terminal 2a. The first audio signal SS1 is input to the first input terminal 2a when there is no input of the second audio signal SS2 to the second input terminal 2b. The first input terminal 2a is shared by the first audio signal SS1 and the reference signal SSr. When the first audio signal SS1 is not input to the first input terminal 2a, the first input terminal 2a receives the first input signal 2r. It is input to terminal 2a. The reference signal SSr is input to the first input terminal 2a while the second audio signal SS2 is being input to the second input terminal 2b. The second audio signal SS2 is generated based on information from outside the alarm device 100, as described later.

The detection unit 103 includes various sensors that monitor a physical phenomenon in a monitoring target area around the alarm device 100 and output the result. The various sensors include, for example, various gas sensors for detecting carbon monoxide (CO) gas, methane gas (CH ₄ ) or propane gas (C ₃ H ₈ ), a temperature sensor including a thermistor, a humidity sensor, a smoke sensor, and an odor. A sensor or the like may be used, and the detection unit 103 may be configured by one or a plurality of sensors.

  The notification unit 104 includes, for example, a notification unit for notifying the user of the alarm device 100, such as a speaker and / or a buzzer, a light emitting diode (LED), and a display panel made of liquid crystal. The notification unit 104 issues a warning by emitting a sound and / or light based on the detection result of the detection unit 103, for example. The notification unit 104 may operate to notify a user or the like of a state of the alarm device 100 or a change in a monitoring area that does not lead to an alarm. In the alarm device 100 of the present embodiment, the notification unit 104 includes at least a sound generation device such as a speaker or a buzzer so as to transmit a warning or desired information to a user by voice. The information that is the source of the sound emitted from the notification unit 104 may be recorded in a storage device (not shown) inside the alarm device 100 as described below, or acquired from the outside of the alarm device 100. Is also good.

  The first control unit 101 includes, for example, a commercially available microcomputer or a semiconductor device such as an ASIC, and executes various types of information processing such as calculation, comparison, clocking, and storage according to a program built in the microcomputer. Then, the first control unit 101 in the present embodiment outputs the first audio signal SS1 based on the detection result of the detection unit 103. The first audio signal SS1 is generated, for example, based on information issued as an alarm when the detection unit 103 detects an abnormality in the surrounding environment. The information that is the source of the first audio signal SS1 is recorded, for example, in a storage device (not shown) provided in the first control unit 101 or the alarm 100. For example, storage devices have increased risk of “leak gas” (data 1), “Woo, woo, woo, fire” (data 2), and “pip, pip, pip, heat stroke” (Data 3), data that can be converted by the notification unit 104 is stored. When various toxic gases having a concentration equal to or higher than a predetermined threshold are detected by the detection unit 103, the first control unit 101 generates and outputs a first audio signal SS1 based on the data 1. For example, the first control unit 101 outputs a first voice based on the data 2 when the detection unit 103 detects a fire, and based on the data 3 when the detection unit 103 detects a temperature and a humidity equal to or more than the threshold, respectively. The signal SS1 may be generated and output.

  The first control unit 101 may output the first audio signal SS1 in the form of the aforementioned PWM signal. Since the audio signal processing unit 111 in the example of FIG. 6 includes the PWM signal demodulation circuit 3, the PWM signal is converted into an analog signal and input to the amplification unit 2. Note that when the first control unit 101 outputs an analog signal as the first audio signal SS1, the demodulation circuit 3 may not be provided.

  The second control unit 102 controls communication with an external device Ei in an arbitrary communication mode, and performs, for example, mutual conversion between a signal in the alarm 100 and a communicable signal. The second control unit 102 is configured by, for example, an integrated circuit device or an electric circuit including individual electric components. The second control unit 102 may communicate with a router or a LAN server via a wireless LAN, for example, or may communicate with various devices on the Internet via these relay devices. For wireless communication with an external device Ei, a short-range wireless communication technology such as Bluetooth (registered trademark) or various communication technologies based on a wireless LAN standard such as Wi-Fi (registered trademark) is used. Is also good. In this case, various communication modules packaged as a Bluetooth module or a Wi-Fi module may be used as the second control unit 102.

  The second audio signal SS2 is generated by the second control unit 102 based on information from outside the alarm 100. That is, the second control unit 102 generates and outputs the second audio signal 102 based on the information obtained by communicating with the external device Ei. For example, based on information obtained from various devices on the Internet, such as a cloud server, via the external device Ei, the second control unit 102 uses the voice data stored in the alarm device 100 to generate a second voice. The signal SS2 may be generated, or audio data may be obtained from various devices on the Internet, such as a cloud server, via the external device Ei to generate the second audio signal SS2. Further, the second control unit 102 may transmit the information acquired by the detection unit 103 to the external device Ei, and generate the second audio signal SS2 based on the information. For example, information on weather conditions, traffic conditions, current events, and the like may be acquired from an external device Ei, and the second audio signal SS2 may be generated based on the information. The second audio signal SS2 is converted into an analog signal by a D / A converter included in an integrated circuit device or a communication module included in the second control unit 102, and output from the second control unit 102, for example.

  The second control unit 102 generates the second audio signal SS2 which is, for example, an analog signal through communication with the outside in this manner. When communication with the outside is performed, the current flowing in the integrated circuit device and the communication module constituting the second control unit 102 changes every moment. Therefore, the potential of the power supply line inside the communication module or the like fluctuates, and as described above with reference to FIG. 3, a noise signal (target noise signal) may be superimposed on the second audio signal SS2. Therefore, the second control unit 102 outputs the reference signal SSr together with the second audio signal SS2. The reference signal SSr including a noise signal (pseudo noise signal) corresponding to the target noise signal uses, for example, the potential itself of a power supply line such as a communication module included in the second control unit 102 or a signal extracted from the power supply line. Generated by passing through a buffer.

  Further, as described with reference to FIG. 3, the second audio signal SS2 swings around a half of the potential of the power supply line by using a voltage dividing resistor in an output circuit such as a communication module. Can be output as In that case, the second audio signal SS2 may include a target noise signal having a noise level of the power supply line, that is, a signal level substantially equal to a signal level of the pseudo noise signal. As described above, the second control unit 102 generates and outputs the second audio signal SS2 and the reference signal SSr, and thus, as described above, the first gain having an amplification factor of approximately 1/2 of the second gain. Can effectively suppress amplification of the target noise signal. Furthermore, for each of the first resistor R1 and the third resistor R3 (see FIG. 2), the differential amplifier constituting the amplifying unit 2 is selected by simply selecting a resistance value that is approximately twice the resistance value of the second resistor R2. 21 (see FIG. 2) can balance the feedback on both the positive and negative sides to obtain a stable operation.

  The first control unit 101 stops the output of the second audio signal SS2 and the reference signal SSr by the second control unit 102 when the first audio signal SS1 is output. Therefore, as described above, the second audio signal SS2 is input to the second input terminal 2 when there is no input of the first audio signal SS1 to the first input terminal 2a. For example, when outputting a first audio signal SS1, a microcomputer or the like constituting the first control unit 101 outputs a signal for inhibiting or stopping the output of the second audio signal SS2 and the reference signal SSr from a predetermined output port. 2 to the control unit 102.

  For example, at the end of the period T21 in the example of each signal waveform in FIG. 4 referred to above, the first control unit 101 causes the second control unit 102 to stop outputting the second audio signal SS2 and the reference signal SSr. Is sent. The second controller 102 receives this signal from the first controller 101, and stops outputting the second audio signal SS2 and the reference signal SSr. After that, in the third period T3, the first audio signal SS1 is output from the first control unit 101.

  As described above, when the first control unit 101 controls the second control unit 102, it is necessary to issue an alarm when a sound based on the second sound signal SS2 relating to weather or the like is issued from the notification unit 104. In this case, the notification unit 104 properly emits a sound indicating an alarm. That is, the first control unit 101 determines the degree of urgency and stops the utterance based on the second audio signal SS2 even while the audio based on the second audio signal SS2 is being emitted, and stops the utterance based on the second audio signal SS2. The notification unit 104 is caused to perform the generation based on the signal SS1. Due to the nature of the alarm device, the alarm device 100 stores therein message data relating to its essential function (alarm function) and important function (equipment failure determination function). The first sound signal SS1 based on the data held in the alarm 100 has a higher urgency than the second sound signal SS2, and the sound based on the first sound signal SS1 is preferentially emitted. It should be noted that message data other than such essential functions and important functions may be stored in the alarm device 100, but it is more advantageous to appropriately obtain the data from the outside because it may involve a corresponding increase in cost. There is.

  Note that while outputting the second audio signal SS2, the second control unit 102 may report that the second audio signal SS2 is being output by sending a predetermined signal to the first control unit 101. . The interference between the two audio signals in the audio signal processing unit 111 can be more reliably prevented.

  In the alarm 100 of the present embodiment, noise is not generated when switching between the utterance based on the first audio signal SS1 and the utterance based on the second audio signal SS2, and even if the two signals interfere with each other, The software may be adjusted in the first control unit 101 and / or the second control unit 102 so as not to generate noise such as a burr. When the first control unit 101 outputs a signal prohibiting output of the second audio signal SS2 or the like, the second control unit 102 transmits the second audio signal SS2 or the like within a predetermined time (for example, 0.5 seconds). May be set to stop the output.

  In the above description, an example is described in which an audio signal based on data held in the alarm device 100 and an audio signal based on data acquired from the outside are input to the audio signal processing unit 111, but the present invention is not limited to this. When there are two inputs of the audio signal based on the data obtained from the outside, that is, the first audio signal SS1 is replaced with the data obtained from the outside in place of the audio signal based on the data held in the alarm 100. The technology of the present embodiment can be applied even when the audio signal is based on the audio signal. Also, regardless of whether the audio signal is an audio signal based on data held in the alarm device 100 or an audio signal based on data acquired from the outside, three or more audio signals are input to the audio signal processing unit 111. Even in such a case, the technology of the present embodiment is applicable.

  As described above, in the alarm device 100 of the present embodiment, two or more audio signals generated by signal sources different from each other are appropriately amplified in a time-division manner by the Can be emitted.

  It should be understood that the embodiments disclosed this time are illustrative in all aspects and not restrictive. The scope of the present invention is shown not by the description of the above-described embodiment but by the claims, and further includes all modifications (modifications) equivalent to the claims and within the scope.

REFERENCE SIGNS LIST 1 signal processing circuit 11 first input circuit 12 second input circuit 13 third input circuit 2 amplifying unit 21 differential amplifier 2 a first input terminal 2 b second input terminal 3 demodulation circuit 100 alarm 101 first control unit 102 second Control unit 103 Detecting unit 104 Notification unit 111 Audio signal processing unit Ei External device S1 First signal S2 Second signal SS1 First audio signal SS2 Second audio signal Sr, SSr Reference signal

Claims (7)

An amplifying unit that has a first input terminal and a second input terminal and amplifies a signal received at each of the first input terminal and the second input terminal;
The first input receives a first signal that is an audio signal including information to be emitted as audio,
The second input terminal receives a second signal that is an audio signal including information to be emitted as audio when the first signal is not received by the first input terminal;
The first input terminal further receives a reference signal including a signal corresponding to a noise signal superimposed on the second signal,
The signal processing circuit, wherein the amplification unit suppresses amplification of the noise signal using the reference signal in amplifying the second signal. The signal processing circuit according to claim 1, wherein the first input terminal and the second input terminal receive the first signal and the second signal respectively generated from different signal sources. 3. The signal processing circuit according to claim 1, wherein one of the first input terminal and the second input terminal includes a PWM signal demodulation circuit. 4. The amplifying unit according to claim 1, wherein the amplifying unit has a first gain for the reference signal and a second gain different from the first gain for the second signal. 5. Signal processing circuit. An alarm that detects a change in the surrounding environment and informs the user,
A detection unit for detecting a change in the surrounding environment;
A notification unit that emits a sound based on information inside or outside the alarm device,
An audio signal processing unit that processes an audio signal that is a source of sound emitted in the notification unit,
The audio signal processing unit includes an amplification unit that includes a first input terminal and a second input terminal, and amplifies a signal input to each of the first input terminal and the second input terminal.
A first audio signal based on data held in the alarm device is input to the first input terminal,
A second audio signal based on information from outside the alarm device is input to the second input terminal when the first audio signal is not input to the first input terminal;
A reference signal including a signal corresponding to a noise signal superimposed on the second audio signal is input to the first input terminal,
The alarm device, wherein the amplification unit suppresses amplification of the noise signal using the reference signal in amplification of the second audio signal. A first control unit that controls the issuance of an alarm from the alarm device; and a second control unit that controls communication between the alarm device and an external device,
The first control unit outputs the first audio signal based on a detection result of the detection unit,
The alarm device according to claim 5, wherein the second control unit generates and outputs the second audio signal based on the information acquired by the communication, and outputs the reference signal . The alarm device according to claim 6, wherein the first control unit stops the output of the second audio signal and the reference signal by the second control unit when the first audio signal is output.

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