Control apparatus and control method

Abstract

A control device includes a circuit configured to: perform control to decrease a gain when a detected temperature of a control target is equal to or higher than a first temperature, and then increase the gain when the detected temperature becomes lower than the first temperature, the gain being adjustable when an electrical signal is output; and such that the time variation of the gain when the gain is increased is smaller than the time variation of the gain when the gain is decreased.

Description

Technical Field

[0001] The present disclosure relates to a control device and a control method. Background Art

[0002] Related art discloses a high-temperature protection circuit that aims to keep the temperature rising steadily when it detects that the temperature of a device reaches a specified temperature (for example, see Japanese Patent Application Laid-Open No. 2017-163240). When receiving a high-temperature warning signal, the high-temperature protection circuit reduces a specified threshold level for compressing the dynamic range of an audio signal and compresses the amplitude range of the volume of the audio signal.

[0003] However, when receiving a high-temperature warning signal, simply compressing the amplitude range of the volume may not be sufficient to ensure the reliability of the high-temperature protection circuit. For example, the temperature of a device to be controlled or monitored can change in a complex manner depending on the output of the device (exemplified by an audio signal).

[0004] Therefore, a control device of a device (exemplified by the high-temperature protection circuit) needs stable and reliable control not only when generating a high-temperature warning signal but also when eliminating the high-temperature warning signal.

[0005] An object of an embodiment of the present disclosure is to quickly, stably, and reliably control the temperature of a control target such as a device or a circuit. Summary of the Invention

[0006] One aspect of an embodiment of the present disclosure takes a control device as an example. The control device includes a circuit configured to: perform control to reduce a gain when the detected temperature of a control target is equal to or higher than a first temperature, and then increase the gain when the detected temperature becomes lower than the first temperature, where the gain is adjustable when an output electrical signal is output; and cause the time change of the gain when increasing the gain to be smaller than the time change of the gain when decreasing the gain.

[0007] Since the time change of the gain when increasing the gain is made smaller than the time change of the gain when decreasing the gain, even when the temperature of a controlled object rapidly rises by increasing the gain, the control device is less likely to easily return the detected temperature of the controlled object to a state equal to or higher than the first temperature. Therefore, the control device can stably and reliably control the temperature of a control target such as a device or a circuit. Brief Description of the Drawings

[0008] Exemplary embodiments of the present disclosure will be described in detail based on the following drawings, in which:

[0009] Figure 1 is a system configuration diagram showing a control system according to a first embodiment;

[0010] Figure 2 is a timing chart showing the control of the amplifier IC by the microcomputer;

[0011] Figure 3 shows the control process executed by the microcomputer;

[0012] Figure 4 shows the details of the warning monitoring;

[0013] Figure 5 shows an example of the control system;

[0014] Figure 6 shows the configuration of the control system according to the second embodiment; and

[0015] Figure 7 shows the configuration of the control system according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] First Embodiment (Configuration)

[0017] will be described with reference to Figures 1 to 4 a control device and a control method according to the first embodiment. Figure 1 is a system configuration diagram showing a control system 10 according to the first embodiment. The control system 10 includes a microcomputer 1, an amplifier integrated circuit (IC) 2, and a speaker 3. In the control system 10, the microcomputer 1 operates as a control device and controls the amplifier IC 2 as a control target. The amplifier IC 2 (also referred to as an audio amplifier) receives temperature control by the microcomputer 1 and drives the speaker 3 to output sound.

[0018] The microcomputer 1 is also referred to as a microcontroller or a computer. The microcomputer 1 includes, for example, a CPU, a memory, and an interface. The CPU executes a computer program loaded in the memory in an executable manner and provides a function as a control device. The CPU is also referred to as a processor. The CPU is not limited to a single processor and may have a multi-processor configuration. The CPU may be a single processor connected by a single socket and may have a multi-core configuration. At least a part of the processing of the microcomputer 1 may be provided by a dedicated processor (e.g., a digital signal processor (DSP), a graphics processing unit (GPU), a numerical data processor, a vector processor, or an image processing processor, an application specific integrated circuit (ASIC), etc.). At least a part of the microcomputer 1 may be a dedicated large-scale integrated circuit (LSI), such as a field programmable gate array (FPGA) or other digital circuits. At least a part of the microcomputer 1 may include an analog circuit.

[0019] The memory stores computer programs executed by the CPU, data processed by the CPU, etc. The memory is a dynamic random access memory (DRAM), a static random access memory (SRAM), a read-only memory (ROM), etc.

[0020] As described above, the microcomputer 1 includes an interface and inputs signals from external devices such as the amplifier IC 2 to the CPU. The microcomputer 1 outputs output signals to external devices such as the amplifier IC 2 via this interface.

[0021] The amplifier IC 2 amplifies, for example, an input signal and outputs the amplified signal to an output-side device such as the speaker 3. The input signal and the output signal of the amplifier IC 2 are, for example, sound or audio signals and are referred to as audio signals. The audio signal is amplified by the amplifier IC 2 to drive the speaker 3.

[0022] The amplifier IC 2 includes a temperature sensor therein that measures the temperature of the amplifier IC 2. The type, method, and configuration of the temperature sensor are not limited. The temperature sensor can include, for example, a thermistor or a thermally sensitive resistor. The amplifier IC 2 also includes a first control circuit that outputs an alarm signal to the terminal C2 when the temperature measured by the temperature sensor reaches a reference temperature (also referred to as the first temperature) defined by a standard or specification.

[0023] The first control circuit outputs a HI signal, for example, in a normal state where the temperature measured by the temperature sensor does not reach the reference temperature. When the temperature measured by the temperature sensor reaches the reference temperature, the first control circuit outputs a LO signal as the alarm signal. The alarm signal is not limited to the LO signal. That is, the first control circuit can output a LO signal to the terminal C2 in a normal state and can output a HI signal to the terminal C2 as the alarm signal when the temperature measured by the temperature sensor reaches the reference temperature.

[0024] The amplifier IC 2 also includes a second control circuit that outputs a fault signal when the temperature measured by the temperature sensor reaches a limit temperature (also referred to as the second temperature) defined by a standard or specification. The limit temperature is higher than the reference temperature. When the temperature of the amplifier IC 2 reaches the limit temperature, the amplifier IC 2 stops its amplification function. The operation of the second control circuit is the same as that of the first control circuit, so its description is omitted. That is, the first control circuit and the second control circuit are different in terms of whether the temperature compared with the measured temperature is the reference temperature or the limit temperature, while they are the same in terms of the operation of the circuit. The first control circuit and the second control circuit can be the same circuit.

[0025] In this embodiment, the amplifier IC 2 includes terminals C1 to C3 for sending signals to, receiving signals from, and inputting signals to the interface of the microcomputer 1. Terminal C1 performs serial communication with the microcomputer 1 via the Inter-Integrated Circuit (I2C). The microcomputer 1 reads the values of various registers of the amplifier IC 2 via terminal C1 through I2C communication. The microcomputer 1 sets the values (e.g., commands or control parameters) in various registers of the amplifier IC 2 via terminal C1 through I2C communication. For example, the microcomputer 1 sets the gain of the amplifier IC 2 through I2C communication. The communication method between the microcomputer 1 and the amplifier IC 2 is not limited to I2C communication. Communication between the microcomputer 1 and the amplifier IC 2 can be performed through other communication methods such as Serial Peripheral Interface (SPI) communication.

[0026] Terminal C2 is called the warning terminal. When the temperature of the amplifier IC 2 reaches the reference temperature (first temperature) while the amplifier IC 2 is amplifying an audio signal, the amplifier IC 2 outputs an alarm signal to terminal C2 through the first control circuit.

[0027] Terminal C3 is called the fault terminal. When the temperature of the amplifier IC 2 reaches the limit temperature (second temperature) while the amplifier IC 2 is amplifying an audio signal, the amplifier IC 2 outputs a fault signal through the second control circuit to notify the fault to terminal C3.

[0028] Process Example

[0029] Figure 2 is a timing diagram showing the control of the amplifier IC 2 by the microcomputer 1. In Figure 2 , the horizontal axis represents time, and the vertical axis represents the command value (also called the control amount) of the gain of the amplifier IC 2. In Figure 2 , it can be understood that the vertical axis represents the gain of the amplifier IC 2. In this case, Figure 2 it can also be said to be a timing diagram showing the operation of the amplifier IC 2.

[0030] In this example, for example, at timing T1 on the time axis (TIME), an alarm signal is input from terminal C2 of the amplifier IC 2 to the microcomputer 1. In this embodiment, for example, when terminal C2 is LO, the alarm signal is turned on (also called asserted), and the microcomputer 1 detects a valid alarm signal. When the temperature measured by the temperature sensor is equal to or higher than the reference value, the amplifier IC 2 keeps the alarm signal on.

[0031] When an alarm signal is detected, the microcomputer 1 writes an instruction (control amount) for reducing the gain by ΔG1 into the register of the amplifier IC 2. Then, the amplifier IC 2 reduces the gain of the amplifier by ΔG1. The instruction (control amount) written by the microcomputer 1 into the amplifier IC 2 can be the difference (ΔG1) indicating the change amount or the gain value (G1 - ΔG1) itself. Here, G1 is the gain of the amplifier IC 2 before the alarm signal is turned on. The microcomputer 1 detects the state of the amplifier IC 2 at a period (e.g., ΔT1) predetermined according to the specifications of the system or at a period determined in the design, and repeats setting the control amount of the amplifier IC 2. This period is the period during which the microcomputer 1 can control the amplifier IC 2 and is also the period for detecting the state of the amplifier IC 2, so it is also called the monitoring period.

[0032] In Figure 2 the example, the alarm signal from terminal C2 of the amplifier IC 2 remains on even at the timing T2 for the next control. Then, the microcomputer 1 writes an instruction for further reducing the gain by ΔG1 into the register of the amplifier IC 2. According to this control, when the temperature measured by the temperature sensor is lower than the reference value, the amplifier IC 2 turns off (also called invalidates) the alarm signal.

[0033] In this example, the alarm signal from terminal C2 of the amplifier IC 2 is turned off at the timing T3. In the present embodiment, the microcomputer 1 does not change the gain of the amplifier IC 2 by turning off the alarm signal only once. In Figure 2 it, the gain immediately before the timing T3 remains the same. Further, in this example, the microcomputer 1 detects that the alarm signal remains off continuously N times at the timing T4. For this reason, the period ΔT2 from the timing T2 when the alarm signal was last detected as being on to the timing T4 when the Nth turn-off was detected is ΔT2 = ΔT1 * N. Here, * represents multiplication.

[0034] In Figure 2In each time period ΔT2 from timing T4 to T5, from timing T5 to T6, and from timing T6 to T7, the alarm signal from terminal C2 of amplifier IC 2 remains off continuously for N times. In this way, when it is detected that the alarm signal remains off continuously for N times during ΔT2, the microcomputer 1 writes an instruction (control amount) for increasing the gain by ΔG2 to the register of amplifier IC 2 via terminal C1 by I2C communication. Then, amplifier IC 2 increases the gain of the amplifier by ΔG2. The instruction (control amount) written to amplifier IC 2 by microcomputer 1 can be the increase amount (ΔG2, the value indicating the difference) or the gain value (G2 + ΔG2) itself. Here, G2 is the gain of amplifier IC2 before the gain is increased by ΔG2. In this embodiment, ΔG1, which is the decrease amount of the gain, is greater than ΔG2, which is the increase amount.

[0035] As described above, the microcomputer 1 checks the alarm signal at terminal C2 of amplifier IC 2 before the timing of performing control. That is, for each cycle ΔT1 (which is the monitoring cycle), the microcomputer 1 checks the alarm signal at terminal C2 of amplifier IC 2. When the alarm signal is checked to be off, the microcomputer 1 does not immediately increase the gain of amplifier IC 2. That is, the microcomputer 1 increases the gain of amplifier IC2 when it is continuously detected that the alarm signal remains off within N monitoring cycles. When increasing the gain at any one of the timings T4, T5, T6, and T7, the microcomputer 1 performs the same check.

[0036] N is an integer of 2 or greater, and is determined by the characteristics, specifications, configuration, etc. of amplifier IC 2. For example, when the temperature characteristics of amplifier IC 2 are stable, or when amplifier IC 2 is relatively heat-resistant, N can be a relatively small number close to 1. Whether the temperature characteristics of amplifier IC 2 are relatively heat-resistant can be determined according to, for example, the value in the specifications of amplifier IC 2. In addition, the case where a heat radiation component such as a heat radiation plate or a heat sink is installed in amplifier IC 2 in a manner that fully guarantees performance is exemplified as the case where the temperature characteristics of amplifier IC 2 are stable. On the other hand, when the temperature characteristics of amplifier IC 2 are unstable, or when amplifier IC 2 is relatively less heat-resistant, it is desirable that N is a relatively large number far from 1.

[0037] In this way, when increasing the gain of the amplifier IC 2, the microcomputer 1 can stably control the gain of the amplifier IC 2 by checking the turning-off of the alarm signal multiple times. On the other hand, when decreasing the gain of the amplifier IC 2, the microcomputer 1 immediately decreases the gain upon detecting the turning-on of the alarm signal once. This is because: when the alarm signal is turned on, rapid control is desired to protect the amplifier IC 2. However, when increasing the gain of the amplifier IC 2, stable control is more desired than protecting the amplifier IC 2. The microcomputer 1 achieves both rapid protection and stable control of the amplifier IC 2 by changing the number of times of checking for the presence or absence of the alarm signal in the case of increasing gain and in the case of decreasing gain. The microcomputer 1 also achieves both rapid protection and stable control of the amplifier IC 2 by making ΔG1, which is the amount of decrease in gain, greater than ΔG2, which is the amount of increase in gain.

[0038] Figure 3 The control process executed by the microcomputer is shown. For example, when the power supply of the audio device equipped with the control system 10 is turned on, this process starts. For example, when the auxiliary power supply of the vehicle equipped with the control system 10 is turned on, this process starts.

[0039] At this time, the microcomputer 1 resets the variable X to 0 (S1). The variable X is a counter that counts the number N of consecutive detections of the turning-off of the alarm signal. The microcomputer 1 sets the gain (A) of the amplifier IC 2 to the initial value (S2). In the following process, the current gain is A. For example, every time the power supply of the audio device is turned on or every time the auxiliary power supply of the vehicle is turned on, by setting the initial value of the gain, the microcomputer 1 can initialize the amplifier IC 2 to the same state. In this embodiment, the gain (A) is not the gain that can be set by the user, but the gain controlled inside the amplifier IC 2. For example, the amplitude (volume) of the output signal to the speaker 3 of the audio device is defined by multiplying the gain set by the user by the gain controlled inside the amplifier IC 2. The gain controlled by the microcomputer 1 is not limited to the gain controlled inside the amplifier IC 2, and can be the gain that can be operated by the user. The gain that can be operated by the user is, for example, the volume indication value set by a knob, scale, etc.

[0040] Next, the microcomputer 1 waits for a period defined by the system specifications to pass (S3). The process of S3 is called WAIT. By WAIT, the microcomputer 1 can stabilize the control system 10 after the control system 10 is powered on.

[0041] Next, the microcomputer 1 performs register monitoring (S4). Register monitoring is a process of reading the values of the registers inside the amplifier IC 2 through I2C communication. The microcomputer 1 can perform fail-safe different from the processes performed through register monitoring in S5 and S6 described below.

[0042] Next, the microcomputer 1 performs fault monitoring (S5). Fault monitoring is a process of checking whether the fault signal is on at the terminal C3 of the amplifier IC 2. When the fault signal is on, the microcomputer 1 forcibly and abnormally ends the process. In this embodiment, the description of forcibly and abnormally ending the process is omitted.

[0043] Next, the microcomputer 1 performs warning monitoring (S6). Warning monitoring is a process of checking whether the alarm signal is on at the terminal C2 of the amplifier IC 2 and controlling the amplifier IC 2 according to the check result. The details of warning monitoring will be described separately. As described with reference to Figure 4 separately. As described with reference to Figure 2 already described, the processes from S4 to S6 are repeatedly executed at a period ΔT1 ("No" in S7).

[0044] Here, the case of "No" in S7 is the case where the control system 10 including the microcomputer 1 is performing normal operation. That is, the microcomputer 1 detects the state of the amplifier IC 2 in each monitoring cycle (each ΔT1) for monitoring the amplifier IC 2 as the control target. On the other hand, for example, when the power supply of the audio device equipped with the control system 10 is turned off or the auxiliary power supply of the vehicle equipped with the control system 10 is turned off ("Yes" in S7), the microcomputer 1 ends the process.

[0045] Figure 4 Shows the details of warning monitoring ( Figure 3 S6 in). In this process, the microcomputer 1 determines whether the alarm signal is on at the terminal C2 of the amplifier IC 2 (S60). When the alarm signal is on, the microcomputer 1 resets the variable X to 0 (S61). The variable X is reset in Figure 3 S1 of, and is also reset in Figure 4 the process of. Since the process of Figure 4 is repeatedly executed at a period ΔT1, when the alarm signal is on, the variable X is reset to prepare for the next process after the gain reduction.

[0046] Next, the microcomputer 1 determines whether the current gain (A) of the amplifier IC 2 exceeds the lower limit value (S62) of the gain defined by the specifications of the amplifier IC 2. When the current gain (A) is equal to or less than the lower limit value of the gain ("No" in S62), the microcomputer 1 returns from the warning monitoring to Figure 3 the process of ("Return"). When the current gain (A) is equal to or less than the lower limit value of the gain, the microcomputer 1 cannot respond to the turning on of the alarm signal, that is, the temperature rise of the amplifier IC 2. Therefore, the microcomputer 1 returns the process to Figure 3 and performs an abnormal process through the failure monitoring in S5.

[0047] On the other hand, when the current gain (A) exceeds the lower limit value of the gain ("Yes" in S62), the microcomputer 1 decreases the gain (A) by ΔG1, sets A = A - ΔG1, and writes the gain (A) into the register of the amplifier IC 2 (S63). At this time, the microcomputer 1 can issue a warning (display, sound, etc.). That is, the warning is not necessary and can be omitted. The type of warning is not restricted. For example, the microcomputer 1 can turn on a light-emitting diode (LED) indicating a warning. Before the process of decreasing the gain (A) in S63, the microcomputer 1 can output a sound including a warning message or a warning tone from the speaker 3. When a display device is connected to the microcomputer 1, the microcomputer 1 can display an image including a warning message on the display device. When the microcomputer 1 is installed on a vehicle, the microcomputer 1 can display an image including a warning message on an information processing device (e.g., a car navigation device) in the vehicle including the display device. Then, the microcomputer 1 returns from the warning monitoring to Figure 3 the process of ("Return").

[0048] When it is determined in S60 that the alarm signal is off, the microcomputer 1 determines whether the current gain (A) of the amplifier IC 2 is less than the upper limit value of the gain defined by the specifications of the amplifier IC 2 (S65). When the current gain (A) is equal to or greater than the upper limit value of the gain ("No" in S65), the microcomputer 1 returns from the warning monitoring to Figure 3 the process of ("Return"). When the current gain (A) is equal to or greater than the upper limit value of the gain, the microcomputer 1 cannot further increase the gain. Then, the microcomputer 1 returns the process to Figure 3 . That is, the current gain (A) remains as it is.

[0049] On the other hand, when the current gain (A) has not reached the upper limit value of the gain (Yes in S65), the microcomputer 1 increments the variable X by 1 (S66). Then, the microcomputer 1 determines whether the variable X has reached the specified value N (S67). When the variable X has not reached the specified value N (No in S67), the microcomputer 1 returns from the warning monitoring to the Figure 3 process of (“return”). Before the variable X reaches the specified value N, the microcomputer 1 executes “return” to check whether the alarm signal has been continuously off within multiple (N) monitoring periods (ΔT1). Therefore, when the period ΔT1 elapses again and the alarm signal remains off even during the next warning monitoring, the determination in S67 is executed again.

[0050] On the other hand, when the variable X reaches the specified value N (Yes in S67), the microcomputer 1 increases the current gain (A) by ΔG2 (S68), sets A = A + ΔG2, and writes the gain A into the register of the amplifier IC 2 (S69). That is, the microcomputer 1 sets the output of the amplifier IC 2 to increase. Then, the microcomputer 1 resets the variable X to 0 (S6A). The microcomputer 1 executes control to increase the current gain (A) and checks whether the alarm signal has been continuously off within multiple (N) monitoring periods (ΔT1) until the variable X reaches the specified value N from 0 again before the next gain increase. For this purpose, the microcomputer 1 resets the variable X. Then, the microcomputer 1 returns from the warning monitoring to the Figure 3 process of (“return”).

[0051] Example

[0052] Figure 5 An example of the present control system 10 is shown. Figure 5 Waveforms obtained by observing the audio output signal from the amplifier IC 2 to the speaker 3, the fault signal (“fault”) of the terminal C3, and the alarm signal (“warning”) of the terminal C2 with an oscilloscope (also called an oscillograph) are shown. In Figure 5 , the horizontal axis represents time. In Figure 5 , three signals are shown in the upper, middle, and lower parts. The upper part shows the waveform G1 of the audio output signal from the amplifier IC 2 to the speaker 3. In this embodiment, a sine wave is used as the audio output signal. The middle part shows the waveform G2 of the fault signal (“fault”) of the terminal C3. The lower part shows the waveform G3 of the alarm signal (“warning”) of the terminal C2. In Figure 5 , it can be seen that in accordance with the part where the alarm signal is on (“warning = LO”), the gain decreases (“gain reduction”) and the audio output signal decreases step by step.

[0053] In Figure 5As can be seen, in line with the turn-off portion of the alarm signal ("Warning HI") immediately following the turn-on portion of the alarm signal ("Warning LO"), the gain increases ("Gain Increase") and the audio output signal increases gradually. The rate of change of the audio output signal over time when the gain decreases (the rate of change of the output decrease) is steeper than the rate of change of the audio output signal over time when the gain increases (the rate of change of the output increase). That is, in the case of an increasing gain, it can be seen that whenever the alarm signal turn-off ("Warning HI") is detected continuously N (a specified value) times, the microcomputer 1 increases the gain by ΔG2. As Figure 2 already described, ΔG1 is greater than ΔG2.

[0054] Effect of the First Embodiment

[0055] As described above, the amplifier IC 2 can be regarded as an example of a control target whose gain can be adjusted when outputting an audio output signal (which is an electrical signal). When the temperature detected by the temperature sensor is equal to or higher than the reference temperature (the first temperature), the amplifier IC 2 turns on the alarm signal and outputs the alarm signal to terminal C2. When the alarm signal is turned on at terminal C2, the microcomputer 1, as an example of a control device, reduces the current gain (A) of the amplifier IC 2 to (A = A - ΔG1). Here, the decrease amount ΔG1 when reducing the gain is greater than the increase amount ΔG2 when increasing the gain. Thereafter, when the detected temperature is lower than the reference temperature (the first temperature), the amplifier IC 2 turns off the alarm signal and outputs the alarm signal to terminal C2. Then, before increasing the current gain (A) of the amplifier IC 2 to (A = A + ΔG2), the microcomputer 1 checks by monitoring N times that the detected temperature is lower than the reference temperature (the first temperature). Therefore, in this embodiment, the microcomputer 1 makes the temporal change of the gain (as an example, such as the rate of change) when reducing the gain larger than the temporal change of the gain when increasing the gain. That is, when the temperature of the amplifier IC 2 is equal to or higher than the reference temperature (the first temperature), the microcomputer 1 can perform control to quickly reduce the temperature of the amplifier IC 2. In this case, it can also be said that the microcomputer 1 can achieve stable control by making the temporal change of the gain when increasing the gain smaller than the temporal change of the gain when reducing the gain.

[0056] When the temperature detected by the temperature sensor reaches the limit temperature (the second temperature) higher than the reference temperature (the first temperature), the amplifier IC 2 turns on the fault signal and outputs the fault signal to terminal C3. When the fault signal is turned on at terminal C3, the microcomputer 1 performs an abnormal process. That is, when the temperature of the amplifier IC 2 reaches the limit temperature, the microcomputer 1 stops the normal process and immediately responds to the abnormality. Therefore, the microcomputer 1 can perform a sub-optimal process in the abnormal state of the amplifier IC 2.

[0057] When the detected temperature of the amplifier IC 2 is equal to or higher than the reference temperature (first temperature), the microcomputer 1 outputs a warning (display, sound). Accordingly, the microcomputer 1 can notify the user of an audio device including the control system 10, a vehicle equipped with the control system 10, etc. that the temperature of the amplifier IC 2 is equal to or higher than the reference temperature (first temperature).

[0058] In addition, for monitoring the amplifier IC 2 as an example of a control target, the microcomputer 1 detects the state (e.g., alarm signal) of the amplifier IC 2 for each monitoring period (e.g., period ΔT1). When the microcomputer 1 detects that the temperature detected in a plurality of consecutive monitoring periods is lower than the reference temperature (first temperature), the microcomputer 1 performs control to increase the gain. That is, when increasing the gain, the microcomputer 1 checks the state of the amplifier IC 2 a plurality of times and increases the gain of the amplifier IC 2. In this way, even when the temperature characteristics are unstable, the microcomputer 1 can stably and reliably perform the control when increasing the gain. On the other hand, as described above, when the microcomputer 1 detects that the detected temperature exceeds the reference temperature (first temperature) even once, the microcomputer 1 decreases the gain. That is, the microcomputer 1 rapidly decreases the gain in response to an increase in the temperature in the detected amplifier IC 2, and increases the gain by stable control in response to a decrease in the temperature in the detected amplifier IC 2. The microcomputer 1 achieves rapid protection of the amplifier IC 2 and stable control of the gain by selectively using different numbers of monitoring times in the case of temperature increase and temperature decrease.

[0059] Furthermore, the microcomputer 1 can control the amplifier IC 2 by using different values as the gain decrease amount ΔG1 and the gain increase amount ΔG2. In this way, the microcomputer 1 achieves rapid protection of the amplifier IC 2 and stable control of the gain by selectively using the change amount of the gain in the case of temperature increase and temperature decrease.

[0060] The microcomputer 1 uses a cycle ΔT1 that is the same as the monitoring cycle to perform control for decreasing gain and control for increasing gain. When increasing the gain, the microcomputer 1 can freely change the cycle ΔT2 = N * ΔT1 by the counted number N of the cycles. That is, the microcomputer 1 can flexibly set the change amount of the gain when considering both gain decrease and gain increase. In addition, the microcomputer 1 can flexibly control the amplifier IC 22 with a desired N value according to the thermal characteristics of the amplifier IC 2 itself and the characteristics of the heat radiation components (for example, the heat radiation plate and the heat sink provided in the amplifier IC). That is, the microcomputer 1 realizes rapid gain decrease when the temperature of the amplifier IC 2 rises and stable gain increase when the temperature of the amplifier IC 2 drops. That is, the microcomputer 1 according to the present embodiment can freely change the gain decrease caused by the decrease amount ΔG1 and the cycle ΔT1 and the gain increase caused by the increase amount ΔG2 and the cycle ΔT2 according to the product specifications and the like.

[0061] Second Embodiment

[0062] will be described with reference to Figure 6 the control system 10A according to the second embodiment. The first embodiment illustrates the control system 10 including the microcomputer 1 that determines the state of the amplifier IC 2 based on an alarm signal, a failure signal, etc. and controls the gain of the amplifier IC 2. In the first embodiment, the amplifier IC 2 has a function (for example, a register) for receiving a gain setting. However, the process of the control system 10 according to the first embodiment can be executed on a device without a function for receiving a gain setting.

[0063] Figure 6 The configuration of the control system 10A according to the second embodiment is shown. The control system 10A includes a microcomputer 1, an amplifier IC 2A, a speaker 3, and a digital signal processor (DSP) 4.

[0064] The DSP 4 can perform SPI communication with the microcomputer 1 and can perform integrated circuit built-in audio bus (I2S) communication with the amplifier IC 2A. The communication between the DSP 4 and the microcomputer 1 is not limited to SPI communication. The DSP 4 can perform I2C communication with the microcomputer 1.

[0065] The DSP 4 decodes, for example, encoded and compressed music data and inputs digital audio data in, for example, pulse code modulation (PCM) format to the amplifier IC 2A from the terminal C5 of the I2S. The input source of the encoded and compressed music data input to the DSP 4 is not limited. For example, the DSP 4 can read music data via a communication interface connected to a communication network. The DSP 4 can read music data from a DVD, a Blu-ray disc, a hard disk drive, etc. via an input and output interface.

[0066] The amplifier IC 2A includes a digital-to-analog (D / A) converter that converts digital audio data into analog data and an amplifier with a fixed gain. That is, the amplifier IC 2A does not have a function to receive gain settings. With this configuration, the DSP 4 adjusts the amplitude of the analog audio signal output from the amplifier IC 2A to the speaker 3 by adjusting the number of bits of the digital audio data input to the amplifier IC 2A.

[0067] Similar to the first embodiment, the microcomputer 1 reads the values of various registers of the amplifier IC 2A via the terminal C1 by I2C communication or the like. The microcomputer 1 can set the values (e.g., commands or control parameters) in various registers of the amplifier IC 2A via the terminal C1 by I2C communication or the like. That is, the amplifier IC 2A may include registers for I2C communication or the like that can be set from the outside. Registers for gain setting may not be provided in the amplifier IC 2A.

[0068] Similar to the first embodiment, the microcomputer 1 detects an alarm signal from the amplifier IC 2A at the terminal C2. Similar to the first embodiment, the microcomputer 1 detects a fault signal from the amplifier IC 2A at the terminal C3. In this embodiment, the microcomputer 1 instructs the DSP 4 to increase or decrease the gain by SPI communication, rather than instructing the amplifier IC 2A to increase or decrease the gain. That is, similar to the Figure 4 warning monitoring process according to the first embodiment, when detecting an alarm signal from the amplifier IC 2A, the microcomputer 1 can calculate the gain to be set in the amplifier IC 2A and instruct the DSP 4 with the calculated gain.

[0069] The DSP 4 can adjust the number of bits of the digital audio data according to the gain instruction from the microcomputer 1 and input the digital audio data to the amplifier IC 2A. With such a process, even when the amplifier IC 2A does not have a gain adjustment function, the microcomputer 1 can adjust the amplitude of the drive signal output from the amplifier IC 2A to the speaker 3 by adjusting the number of bits of the digital audio data in the DSP 4.

[0070] Similar to the process of the microcomputer 1 according to the first embodiment, the microcomputer 1 and the DSP 4 cause the temporal change in the gain to be larger when decreasing the gain than when increasing the gain. Therefore, when the temperature of the amplifier IC 2A is equal to or higher than the reference temperature (the first temperature) and the alarm signal is on, the microcomputer 1 can perform control to rapidly decrease the temperature of the amplifier IC 2A. In this case, it can also be said that the microcomputer 1 or the like can achieve stable control by making the temporal change in the gain when increasing the gain smaller than the temporal change in the gain when decreasing the gain. In addition, when it is detected that the temperature of the amplifier IC 2A detected in a plurality of consecutive monitoring periods is lower than the reference temperature (the first temperature) (the alarm signal is off), the microcomputer 1 or the like can perform control to increase the gain. In this way, even when the temperature characteristics are unstable, the microcomputer 1 or the like can stably perform the control when increasing the gain. As described above, the DSP 4 and the amplifier IC 2A according to the present embodiment can also be referred to as examples of control targets whose gain can be adjusted when outputting an audio output signal (which is an electrical signal).

[0071] Third Embodiment

[0072] Reference will be made to Figure 7 Describe the control system 10B according to the third embodiment. The first embodiment illustrates the control system 10 including the microcomputer 1 that determines the state of the amplifier IC 2 based on an alarm signal, a failure signal, etc. and controls the gain of the amplifier IC 2. The second embodiment illustrates the control system 10A including the amplifier IC 2A that does not receive the function of setting the gain. That is, the second embodiment illustrates the control system 10A in which the microcomputer 1 determines the state of the amplifier IC 2A, and the DSP 4 and the amplifier IC 2A adjust the output amplitude of the drive signal to the speaker 3. The present embodiment illustrates the control system 10B including the amplifier IC 2B that does not have a temperature detection function or a communication function with the microcomputer 1.

[0073] Figure 7 Shows the configuration of the control system 10B according to the third embodiment. In the present embodiment, the control system 10B includes the microcomputer 1, the amplifier IC 2B, the speaker 3, and the DSP 4. In the present embodiment, the configurations and operations of the microcomputer 1, the speaker 3, and the DSP 4 are the same as those of the microcomputer 1, the speaker 3, and the DSP 4 in the second embodiment.

[0074] That is, the microcomputer 1 is connected to the DSP 4 through, for example, SPI communication or the like. In addition, the DSP 4 can adjust the number of bits of the digital audio data through I2S communication and input the digital audio data into the amplifier IC 2B.

[0075] The amplifier IC 2B performs D / A conversion on the digital audio data, and then amplifies the digital audio data with a fixed gain to drive the speaker 3. However, unlike the amplifier IC 2 according to the first embodiment and the amplifier IC 2A according to the second embodiment, the amplifier IC 2B does not include a temperature sensor therein. The amplifier IC 2B does not have a communication function of outputting an alarm signal and a failure signal or notifying the alarm signal and the failure signal to the microcomputer 1 or the like.

[0076] In this embodiment, a temperature sensor 5 and a buffer circuit ("buffer") 6 are provided. The temperature sensor 5 measures the temperature of the amplifier IC 2B. The buffer circuit ("buffer") 6 converts the temperature data detected by the temperature sensor 5 into digital data and inputs the digital data to the digital (AD IN) terminal C6 of the microcomputer 1.

[0077] In this embodiment, the microcomputer 1 detects the temperature state of the amplifier IC 2B instead of the amplifier IC 2B. That is, the microcomputer 1 monitors the temperature measured by the temperature sensor 5. When the temperature of the amplifier IC 2B rises and reaches a reference temperature (first temperature) while the amplifier IC 2B is amplifying the audio signal, the microcomputer 1 instructs the DSP 4 to decrease the gain of the amplifier IC 2B. When it is continuously detected N times that the temperature of the amplifier IC 2B remains lower than the reference temperature (first temperature), the microcomputer 1 instructs the DSP 4 to increase the gain of the amplifier IC 2B. Similar to the second embodiment, the DSP 4 adjusts the number of bits of the digital audio data and inputs the digital audio data to the amplifier IC 2B, thereby adjusting the gain.

[0078] In addition, when the temperature of the amplifier IC 2B reaches a limit temperature (second temperature) while the amplifier IC 2B is amplifying the audio signal, the microcomputer 1 stops inputting the digital audio data to the amplifier IC 2B through the DSP 4 and performs an abnormal process.

[0079] Similar to the first and second embodiments, the microcomputer 1 or the like causes the temporal change in the gain to be larger when decreasing the gain than when increasing the gain. Therefore, when the temperature of the amplifier IC 2B is equal to or higher than the reference temperature (the first temperature), the microcomputer 1 or the like can perform control to rapidly decrease the temperature of the amplifier IC 2B. In this case, it can also be said that the microcomputer 1 or the like can achieve stable control by making the temporal change in the gain when increasing the gain smaller than the temporal change in the gain when decreasing the gain. Further, when it is detected that the temperature of the amplifier IC 2B detected in a plurality of consecutive monitoring periods is lower than the reference temperature (the first temperature), the microcomputer 1 or the like can perform control to increase the gain. In this way, even when the temperature characteristics are unstable, the microcomputer 1 can stably perform the control when increasing the gain. According to the above configuration, as in the first and second embodiments, the microcomputer 1 and the DSP 4 can achieve rapid protection of the amplifier IC 2B and stable control of the gain.

[0080] Other embodiments

[0081] The first to third embodiments illustrate the process of adjusting the output of the amplifier IC 2 to the amplifier IC 2B to drive the speaker 3 in the control systems 10 to 10B as audio systems. However, the processes of the control systems 10 to 10B and the like are not limited to audio systems. That is, similar to the amplifier IC 2 to the amplifier IC 2B, the processes of the control systems 10 to 10B can be applied to all systems including devices whose temperature changes according to the output signal. For example, the processes of the control systems 10 to 10B can be applied to an amplifier circuit provided in a control circuit of an air conditioner. The processes of the control systems 10 to 10B can be applied to an amplifier circuit provided in a driver circuit that controls the brightness of an image output device. Further, the processes of the control systems 10 to 10B can be applied to a transmission circuit or an amplifier circuit that controls the transmission power of a communication device.

[0082] In a device including such an amplifier circuit or the like, a microcomputer 1 or the like causes the time change of the gain to be larger when decreasing the gain than when increasing the gain. Therefore, when the temperature of a device such as an amplifier IC 2 is equal to or higher than a reference temperature (first temperature), the microcomputer 1 can perform fast control to lower the temperature of the amplifier IC 2. In this case, it can also be said that the microcomputer 1 or the like can achieve stable control by causing the time change of the gain to be smaller when increasing the gain than when decreasing the gain. Further, when it is detected that the temperature of the amplifier IC 2 or the like detected in a plurality of consecutive monitoring periods is lower than the reference temperature (first temperature), the microcomputer 1 or the like can perform control to increase the gain. In this way, even when the temperature characteristics are unstable, the microcomputer 1 or the like can stably perform the control when increasing the gain. The microcomputer 1 or the like can achieve fast protection of the amplifier IC 2 or the like and stable control of the gain by selectively using different numbers of monitoring times in the case of temperature increase and temperature decrease.

[0083] Computer-readable recording medium

[0084] A program that causes a computer or another machine or device (hereinafter referred to as a computer or the like) to implement one of the above functions can be recorded on a non-transitory computer-readable recording medium. The function can be provided by causing the computer or the like to read and execute the program on the recording medium.

[0085] Here, a computer-readable recording medium refers to a recording medium that stores information such as data and programs by an electrical, magnetic, optical, mechanical, or chemical operation and can be read by a computer or the like. Among such recording media, removable media from a computer or the like include, for example, memory cards such as floppy disks, magneto-optical disks, compact disc read-only memories (CD-ROMs), CD read / write (CD-R / W), digital versatile discs (DVDs), Blu-ray discs, and flash memories. Recording media fixed in a computer or the like include hard disks, ROMs, etc. A solid-state drive (SSD) can be used as a recording medium removable from a computer or the like, or as a recording medium fixed to a computer or the like.

[0086] Other

[0087] This embodiment includes the following aspects (hereinafter referred to as appendices).

[0088] Appendix 1:

[0089] A control device including a circuit configured to:

[0090] Execute control to decrease the gain when the detected temperature of the control target is equal to or higher than a first temperature, and then increase the gain when the detected temperature becomes lower than the first temperature, where the gain is adjustable when an electrical signal is output; and

[0091] Cause the time variation of the gain to be smaller when increasing the gain than when decreasing the gain.

[0092] Appendix 2:

[0093] The control device according to Appendix 1, wherein,

[0094] The circuit is configured to: stop the output of the control target when the detected temperature reaches a second temperature, where the second temperature is higher than the first temperature.

[0095] Appendix 3:

[0096] The control device according to Appendix 1 or 2, wherein,

[0097] The circuit is configured to: output a warning when the detected temperature of the control target is equal to or higher than the first temperature.

[0098] Appendix 4:

[0099] The control device according to any one of Appendix 1 to Appendix 3, wherein,

[0100] The circuit is configured to: detect the state of the control target within each monitoring period for monitoring the control target, and perform control to increase the gain when the temperature detected in a plurality of consecutive monitoring periods becomes lower than the first temperature.

[0101] Appendix 5:

[0102] A control method executed by a computer, comprising:

[0103] Execute control to decrease the gain when the detected temperature of the control target is equal to or higher than a first temperature, and then increase the gain when the detected temperature is lower than the first temperature, where the gain is adjustable when an electrical signal is output; and

[0104] Cause the time variation of the gain to be smaller when increasing the gain than when decreasing the gain.

[0105] Appendix 6:

[0106] The control method according to Appendix 5, further comprising:

[0107] Output a warning when the detected temperature of the control target is equal to or higher than the first temperature.

[0108] Appendix 7:

[0109] According to the control method described in Appendix 5 or 6, it further includes:

[0110] When the temperature of the control target detected is equal to or higher than the first temperature, output a warning.

[0111] Appendix 8:

[0112] According to the control method described in any one of Appendix 5 to Appendix 7, it further includes:

[0113] Detect the state of the control target within each monitoring period for monitoring the control target, and perform control to increase the gain when it is detected that the temperature detected in multiple consecutive monitoring periods is lower than the first temperature.

Claims

1. A control device comprising a circuit, the circuit being configured to: performing control to reduce a gain when a detected temperature of a control target is equal to or higher than a first temperature, and then increase the gain when the detected temperature becomes lower than the first temperature, the gain being adjustable when an electrical signal is output; and The time variation of the gain when the gain is increased is made smaller than the time variation of the gain when the gain is decreased.

2. The control device according to claim 1, wherein: The circuit is configured to stop output of the control target when the detected temperature reaches a second temperature, wherein the second temperature is higher than the first temperature.

3. The control device according to claim 1, wherein: The circuit is configured to output a warning when the detected temperature of the control target is equal to or higher than the first temperature.

4. The control device according to claim 1, wherein: The circuit is configured to detect a state of the control target in each monitoring period for monitoring the control target, and to control to increase the gain when the temperature detected in a plurality of consecutive monitoring periods becomes lower than the first temperature.

5. A control method executed by a computer, comprising: performing control to reduce a gain when a detected temperature of a control target is equal to or higher than a first temperature, and then increase the gain when the detected temperature is lower than the first temperature, the gain being adjustable when an electrical signal is output; as well as The time variation of the gain when the gain is increased is made smaller than the time variation of the gain when the gain is decreased.

6. The control method according to claim 5, further comprising: When the detected temperature reaches a second temperature higher than the first temperature, output of the control target is stopped.

7. The control method according to claim 5, further comprising: When the detected temperature of the control target is equal to or higher than the first temperature, a warning is output.

8. The control method according to claim 5, further comprising: The state of the control target is detected in each monitoring period for monitoring the control target, and control is performed to increase the gain when it is detected that the temperature detected in a plurality of consecutive monitoring periods is lower than the first temperature.

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