Control device and control method

Abstract

To control the temperature of a controlled object such as a device or circuit more stably and reliably than ever before.SOLUTION: A control device performs control to lower the gain when a detected temperature of a control target that is adjustable in gain when outputting an electrical signal becomes equal to or higher than a first temperature, and to increase the gain when the detected temperature subsequently falls below the first temperature. Furthermore, when increasing the gain, the control device reduces the change over time of the gain compared to when decreasing the gain.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control device and a control method. [Background technology]

[0002] Conventionally, a high temperature protection circuit has been proposed that aims to smoothly suppress a temperature rise when it detects that the temperature of a device has reached a predetermined temperature value (for example, see Patent Document 1 below). When this high temperature protection circuit receives a high temperature warning signal, it lowers a predetermined threshold level for compressing the dynamic range of an audio signal, thereby compressing the dynamic range of the audio signal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-163240 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, simply compressing the range of volume when a high-temperature warning signal is received may not be reliable enough as a high-temperature protection circuit. For example, the temperature of a device to be controlled or monitored may vary in a complex manner depending on the output of the device exemplified by the audio signal. Therefore, a control device for a device exemplified by a high-temperature protection circuit or the like is required to provide stable and reliable control not only when a high-temperature warning signal is generated but also when the high-temperature warning signal is resolved.

[0005] An object of the disclosed embodiments is to quickly, stably and reliably control the temperature of a controlled object such as a device or circuit. [Means for solving the problem]

[0006] One aspect of the disclosed embodiment is exemplified by a control device. This control device is a control device that performs control to lower the gain when a detected temperature of a control target that is adjustable in gain when outputting an electrical signal is equal to or higher than a first temperature, and to increase the gain when the detected temperature subsequently falls below the first temperature. This control device is characterized in that when the gain is increased, the change in gain over time is smaller than when the gain is decreased. Effect of the Invention

[0007] Since the present control device reduces the change in gain over time when increasing the gain compared to when decreasing the gain, it is possible to reduce the possibility that the detected temperature of the controlled object will easily return to a state equal to or higher than the first temperature even in cases where increasing the gain causes a rapid rise in temperature of the controlled object. Therefore, the present control device can stably and reliably control the temperature of the controlled object, such as a device or circuit. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a system configuration diagram illustrating a control system according to the first embodiment. [Diagram 2] FIG. 2 is a timing chart illustrating the control of the amplifier IC by the microcomputer. [Diagram 3] FIG. 3 is a diagram illustrating a control process performed by a microcomputer. [Figure 4] FIG. 4 is a diagram illustrating an example of warning monitoring in detail. [Diagram 5] FIG. 5 is a diagram illustrating an embodiment according to the present control system. [Figure 6] FIG. 6 is a diagram illustrating an example of the configuration of a control system according to the second embodiment. [Figure 7] FIG. 7 is a diagram illustrating an example of the configuration of a control system according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] First embodiment (Configuration) A control device and a control method according to the first embodiment will be described with reference to Fig. 1 to Fig. 4. Fig. 1 is a system configuration diagram illustrating a control system 10 according to the first embodiment. The control system 10 has a microcomputer 1, an amplifier IC (Integrated Circuit) 2, and a speaker 3. In this 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 is also called an audio amplifier, and is subjected to temperature control by the microcomputer 1, and drives the speaker 3 to output sound.

[0010] The microcomputer 1 is also called a microcontroller, a microcomputer, or simply a computer. The microcomputer 1 has, for example, a CPU, a memory, and an interface. The CPU executes a computer program that is executable and deployed in the memory, and provides the function of a control device. The CPU is also called a processor. However, the CPU is not limited to a single processor, and may have a multiprocessor configuration. The CPU may be a single processor connected to a single socket, and may have a multicore configuration. Furthermore, at least a part of the processing of the microcomputer 1 may be provided by a dedicated processor such as a DSP (Digital Signal Processor), a GPU (Graphics Processing Unit), a numerical calculation processor, a vector processor, or an image processing processor, an ASIC (Application Specific Integrated Circuit), or the like. Furthermore, at least a part of the microcomputer 1 may be The microcomputer 1 may be a dedicated large scale integration (LSI) such as a field programmable gate array (FPGA), or other digital circuit. Also, at least a part of the microcomputer 1 may include an analog circuit.

[0011] Memory stores computer programs executed by the CPU, data processed by the CPU, etc. Memory can be classified into DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), etc. Access Memory), ROM (Read Only Memory), etc.

[0012] As described above, the microcomputer 1 has an interface and inputs a signal to the CPU from an external device, for example, the amplifier IC 2. The microcomputer 1 also outputs an output signal to an external device, for example, the amplifier IC 2, via the interface.

[0013] The amplifier IC2 amplifies an input signal and outputs it to an output device, such as the speaker 3. The input and output signals of the amplifier IC2 are, for example, sound or voice signals, and are called audio signals. The audio signals are amplified by the amplifier IC2 and drive the speaker 3.

[0014] The amplifier IC2 has a built-in temperature sensor and measures the temperature of the amplifier IC2. There is no limitation on the type, method, and configuration of the temperature sensor. The temperature sensor may include, for example, a thermistor, a resistance temperature detector, etc. The amplifier IC2 also has 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 called a first temperature) defined in the standard or specifications.

[0015] For example, in a normal state where the temperature measured by the temperature sensor does not reach the reference temperature, the first control circuit outputs a HI signal. Then, in a state where the temperature measured by the temperature sensor reaches the reference temperature, the first control circuit outputs a LO signal as an alarm signal. However, the alarm signal is not limited to an LO signal. That is, in the normal state described above, the first control circuit outputs a LO signal to terminal C2, and when the temperature measured by the temperature sensor reaches the reference temperature, the first control circuit outputs a LO signal to terminal C3. When this occurs, a HI signal may be output to terminal C2 as an alarm signal.

[0016] Moreover, the amplifier IC2 has a second control circuit that outputs a fault signal when the temperature measured by the temperature sensor reaches a limit temperature (also called the second temperature) defined in the standard or specifications. The limit temperature is a temperature higher than the reference temperature. When the temperature of the amplifier IC2 reaches the limit temperature, the amplifier IC2 stops amplifying. The operation of the second control circuit is similar to that of the first control circuit, and therefore a description thereof is omitted. That is, the first control circuit and the second control circuit differ in that the temperature compared with the measured temperature is the reference temperature and the limit temperature, but the operation of the circuit is similar. Note that the first control circuit and the second control circuit may be the same circuit.

[0017] In this embodiment, the amplifier IC2 has terminals C1 to C3 for transmitting and receiving signals to and from the interface of the microcomputer 1, or inputting signals to the interface of the microcomputer 1. The terminal C1 is a terminal for performing serial communication with the microcomputer 1 by I2C (Inter-Integrated Circuit). The microcomputer 1 reads values ​​of various registers of the amplifier IC2 through the terminal C1 by I2C communication. The microcomputer 1 also sets values, such as commands or control parameters, in various registers of the amplifier IC2 through the terminal C1 by I2C communication. For example, the microcomputer 1 sets the gain of the amplifier IC2 by I2C communication. Note that the communication method between the microcomputer 1 and the amplifier IC2 is not limited to I2C communication. The communication between the microcomputer 1 and the amplifier IC2 may be another communication method, such as SPI (Serial Peripheral Interface) communication.

[0018] Terminal C2 is called a warning terminal. When the temperature of amplifier IC2 reaches a reference temperature (first temperature) while amplifier IC2 is amplifying an audio signal, amplifier IC2 outputs a warning signal to terminal C2 by the first control circuit.

[0019] Terminal C3 is called a fault terminal. When the temperature of amplifier IC2 reaches the limit temperature (second temperature) while amplifier IC2 is amplifying an audio signal, amplifier IC2 outputs a fault signal to terminal C3 via the second control circuit, notifying the occurrence of a fault.

[0020] (Processing example) Fig. 2 is a timing chart illustrating the control of amplifier IC2 by microcontroller 1. In Fig. 2, the horizontal axis represents time, and the vertical axis illustrates an instruction value (also called a control amount) of the gain for amplifier IC2. Note that in Fig. 2, the vertical axis can also be understood to illustrate the gain in amplifier IC2. In this case, Fig. 2 can also be said to be a timing chart illustrating the operation of amplifier IC2.

[0021] In this example, for example, at timing T1 on the time axis (TIME), an alarm signal is input from terminal C2 of amplifier IC2 to microcomputer 1. In this embodiment, for example, when terminal C2 becomes LO, the alarm signal is turned on (also called asserted), and microcomputer 1 detects a valid alarm signal. If the temperature measured by the temperature sensor is equal to or higher than a reference value, amplifier IC2 maintains the alarm signal on.

[0022] When the microcontroller 1 detects an alarm signal, it writes an instruction (control amount) to the register of amplifier IC2 to reduce the gain by ΔG1. Amplifier IC2 then reduces the gain of the amplifier by ΔG1. The instruction (control amount) that the microcontroller 1 writes to amplifier IC2 may be a difference value (ΔG1) indicating the amount of change, or it may be the gain value itself (G1-ΔG1). Here, G1 is the gain of amplifier IC2 before the alarm signal is turned on. The microcontroller 1 also detects the state of amplifier IC2 at a period determined in advance by the system specifications or at a period determined by design (for example, ΔT1), and sets the control amount for amplifier IC2. This cycle is a cycle in which the microcomputer 1 may control the amplifier IC2, but it is also a cycle in which the state of the amplifier IC2 is detected, so it is also called a monitoring cycle.

[0023] 2, the alarm signal from terminal C2 of amplifier IC2 is still on at timing T2 when the next control is performed. Then, microcontroller 1 writes an instruction to further reduce the gain by ΔG1 to the register of amplifier IC2. When this control causes the temperature measured by the temperature sensor to fall below the reference value, amplifier IC2 turns off (also called negates) the alarm signal.

[0024] In this example, at timing T3, the alarm signal from terminal C2 of amplifier IC2 is turned off. In this embodiment, the microcontroller 1 does not change the gain of amplifier IC2 just because the alarm signal is turned off once. In FIG. 2, the gain immediately before timing T3 is maintained as is. Furthermore, in this example, the microcontroller 1 detects N consecutive times that the alarm signal is maintained off at timing T4. Therefore, the period ΔT2=ΔT1*N is the period from timing T2 when the alarm signal was last detected as on to timing T4 when the Nth off is detected. Here, * indicates multiplication.

[0025] In FIG. 2, the alarm signal from the terminal C2 of the amplifier IC2 is continuously maintained OFF N times during the periods ΔT2 from timing T4 to T5, from timing T5 to T6, and from timing T6 to T7. When the microcomputer 1 detects that the alarm signal is continuously maintained OFF N times during ΔT2, the microcomputer 1 writes an instruction (control amount) to increase the gain by ΔG2 to the register of the amplifier IC2 via the terminal C1 by I2C communication. Then, the amplifier IC2 increases the gain of the amplifier by ΔG2. Note that the instruction (control amount) that the microcomputer 1 writes to the amplifier IC2 may be the increase amount (ΔG2, a value indicating the difference value) or the gain value itself (G2+ΔG2). Here, G2 is the gain of the amplifier IC2 before the gain is increased by ΔG2. In this embodiment, the amount of decrease in gain ΔG1 is a value larger than the amount of increase ΔG2.

[0026] As described above, before the timing at which control is performed, the microcontroller 1 checks for an alarm signal at terminal C2 of amplifier IC2. That is, the microcontroller 1 checks for an alarm signal at terminal C2 of amplifier IC2 at each monitoring period ΔT1. However, when the microcontroller 1 checks that the alarm signal is off, it does not immediately increase the gain of amplifier IC2. That is, when the microcontroller 1 detects that the alarm signal is maintained off for N consecutive monitoring periods, it increases the gain of amplifier IC2. The microcontroller 1 performs the same check when increasing the gain at any of the timings T4, T5, T6, and T7.

[0027] N is an integer of 2 or more, and is a value determined by the characteristics, specifications, configuration, etc. of the amplifier IC2. For example, if the temperature characteristics of the amplifier IC2 are stable, or if the amplifier IC2 is relatively heat-resistant, N can be a relatively small number close to 1. Whether the temperature characteristics of the amplifier IC2 are relatively heat-resistant or not can be determined, for example, from the values ​​in the specifications of the amplifier IC2. In addition, an example of a case where the temperature characteristics of the amplifier IC2 are stable is when a heat dissipation component such as a heat sink or heat sink is installed on the amplifier IC2 with sufficient guaranteed performance. Conversely, if the temperature characteristics of the amplifier IC2 are unstable, or if the amplifier IC2 is relatively heat-sensitive, it is desirable to set N to a relatively large number far from 1.

[0028] In this way, when the microcomputer 1 increases the gain of the amplifier IC2, it can stably control the gain of the amplifier IC2 by checking that the alarm signal is off multiple times. On the other hand, when the microcomputer 1 decreases the gain of the amplifier IC2, it can directly control the gain of the amplifier IC2 by detecting that the alarm signal is on once. The gain is immediately reduced. This is because when the alarm signal is on, rapid control is desirable to protect amplifier IC2. However, when increasing the gain of amplifier IC2, stable control is more desirable than protecting amplifier IC2. The microcontroller 1 achieves both rapid protection and stable control of amplifier IC2 by changing the number of times it checks for the presence or absence of an alarm signal when the gain is increasing and when the gain is decreasing. The microcontroller 1 also achieves both rapid protection and stable control of amplifier IC2 by setting ΔG1, the amount of gain reduction, to a larger value than ΔG2, the amount of gain increase.

[0029] 3 is a diagram illustrating an example of a control process by the microcomputer 1. This process is started, for example, by turning on the power of an audio device equipped with the control system 10. Also, for example, this process is started by turning on the power of an accessory of a vehicle equipped with the control system 10.

[0030] In this process, the microcomputer 1 resets a variable X to 0 (S1). The variable X is a counter that counts the number of times N that the alarm signal is continuously detected as off. The microcomputer 1 also sets the gain (A) of the amplifier IC2 to an initial value (S2). In the following process, the current gain is set to A. By setting the initial value of the gain, the microcomputer 1 can initialize the amplifier IC2 to the same state, for example, every time the audio device is turned on or the vehicle accessory is turned on. In this embodiment, the gain (A) is not a gain that can be set by the user, but a gain that is controlled inside the amplifier IC2. For example, the amplitude (volume) of the output signal to the speaker 3 of the audio device is determined by multiplying the gain set by the user and the gain controlled inside the amplifier IC2. However, the gain controlled by the microcomputer 1 is not limited to such a gain controlled inside the amplifier IC2, and may be a gain that can be operated by the user. The gain that can be operated by the user is, for example, a volume indication value set by a knob, a scale, or the like.

[0031] Next, the microcomputer 1 waits for a period of time defined in the system specifications to elapse (S3). The process of S3 is called WAIT. WAIT allows the microcomputer 1 to stabilize the control system 10 after the control system 10 is powered on.

[0032] Next, the microcomputer 1 executes register monitoring (S4). Register monitoring is a process for reading the values ​​of the internal registers of the amplifier IC2 via I2C communication. By using register monitoring, the microcomputer 1 can implement fail-safe measures other than the processes implemented in S5 and S6 below.

[0033] Next, the microcomputer 1 executes fault monitoring (S5). Fault monitoring is a process of checking whether or not a fault signal is on at the terminal C3 of the amplifier IC2. When the fault signal is on, the microcomputer 1 forcibly terminates the process abnormally. In this embodiment, the description of the process of forcibly terminating the process abnormally is omitted.

[0034] Next, the microcomputer 1 executes warning monitoring (S6). Warning monitoring is a process that checks whether or not an alarm signal is ON at the terminal C2 of the amplifier IC2, and controls the amplifier IC2 according to the check result. Details of the warning monitoring will be described separately with reference to Fig. 4. As already described with reference to Fig. 2, the processes from S4 to S6 are repeatedly executed with a cycle of ΔT1 (NO in S7).

[0035] Here, NO in S7 means that the control system 10 including the microcomputer 1 is performing normal operation. That is, the microcomputer 1 detects the state of the amplifier IC2 at each monitoring period (every ΔT1) for monitoring the amplifier IC2 to be controlled. On the other hand, for example, when the power supply of an audio device incorporating the control system 10 is off or the power supply of an accessory of a vehicle incorporating the control system 10 is off (YES in S7), the microcomputer 1 ends the process.

[0036] FIG. 4 is a diagram illustrating the details of warning monitoring (S6 in FIG. 3). In this process, the microcomputer 1 determines whether or not the alarm signal is on at the terminal C2 of the amplifier IC2 (S60). If the alarm signal is on, the microcomputer 1 resets the variable X to 0 (S61). Note that the variable X has already been reset in S1 in FIG. 3, but it is also reset in the process in FIG. 4. The process in FIG. 4 is executed repeatedly with a period ΔT1, so when the alarm signal is on, the variable X is reset in preparation for the next process after the gain reduction.

[0037] Next, the microcomputer 1 determines whether the current gain (A) of the amplifier IC2 exceeds the lower limit of the gain defined in the specifications of the amplifier IC2 (S62). If the current gain (A) is equal to or lower than the lower limit of the gain (NO in S62), the microcomputer 1 returns from the warning monitoring to the processing in FIG. 3 (RETURN). If the current gain (A) is equal to or lower than the lower limit of the gain, the microcomputer 1 cannot turn on the alarm signal any more, i.e., it cannot respond to the temperature rise of the amplifier IC2. Therefore, the microcomputer 1 returns to the processing in FIG. 3 and executes abnormality processing by fault monitoring in S5.

[0038] On the other hand, if the current gain (A) exceeds the lower limit of the gain (YES in S62), the microcomputer 1 reduces the gain (A) by ΔG1 to A=A-ΔG1 and writes it to the register of the amplifier IC2 (S63). At this time, the microcomputer 1 may issue a warning (display, sound, etc.). That is, a warning is not essential and is an optional process. There is no limitation on the type of warning. For example, the microcomputer 1 may cause an LED (Light Emitting Diode) to emit light indicating a warning. Furthermore, the microcomputer 1 may output a voice or a warning sound including a warning message from the speaker 3 before the process of reducing the gain (A) in S63. Furthermore, if a display device is connected to the microcomputer 1, the microcomputer 1 may display an image including a warning message on the display device. Furthermore, if the microcomputer 1 is mounted on a vehicle, the microcomputer 1 may display an image including a warning message on an in-vehicle information processing device equipped with a display device, for example, a car navigation device. Then, the microcomputer 1 returns from the warning monitoring to the processing of FIG.

[0039] Furthermore, if the judgment in S60 is that the alarm signal is off, the microcomputer 1 judges whether or not the current gain (A) of the amplifier IC2 is less than the upper gain limit value defined in the specifications of the amplifier IC2 (S65). If the current gain (A) is equal to or greater than the upper gain limit value (NO in S65), the microcomputer 1 returns from the warning monitoring to the processing in FIG. 3 (RETURN). If the current gain (A) is equal to or greater than the upper gain limit value, the microcomputer 1 cannot increase the gain any further. Therefore, the microcomputer 1 returns the processing to FIG. 3. In other words, the current gain (A) is maintained as is.

[0040] On the other hand, if the current gain (A) has not reached the upper gain limit (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). If the variable X has not reached the specified value N (NO in S67), the microcomputer 1 returns from the warning monitoring to the process of FIG. 3 (RETURN). The microcomputer 1 RETRUNs to check whether the alarm signal is OFF for multiple (N) consecutive monitoring periods (ΔT1) until the variable X reaches the specified value N. Therefore, if the alarm signal is still OFF at the next warning monitoring after another period ΔT1 has elapsed, the determination in S67 is executed again.

[0041] On the other hand, if 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 this to the register of the amplifier IC2 (S69). In other words, the microcomputer 1 sets the amplifier IC2 so that its output increases. Then, the microcomputer 1 resets the variable X to 0 (S6A). Since the microcomputer 1 has executed control to increase the current gain (A), the control is repeated until the next time the gain is increased. Each time, the microcomputer 1 checks whether the alarm signal is turned off for a plurality of (N) consecutive monitoring periods (ΔT1) until the variable X reaches a specified value N from 0. For this purpose, the microcomputer 1 resets the variable X. Then, the microcomputer 1 returns from the warning monitoring to the process of FIG. 3 (RETURN).

[0042] (Example) 5 is a diagram illustrating an embodiment of the control system 10. FIG. 5 shows an audio output signal from the amplifier IC2 to the speaker 3, a fault signal (FAULT) at the terminal C3, and a fault signal (FAULT) at the terminal C4. The waveform of the warning signal (WARNING) in 2 observed by an oscilloscope (also called an oscillograph) In FIG. 5, the horizontal axis represents time. Three signals are displayed in the upper, middle and lower sections of FIG. 5. The upper section illustrates an example of a waveform G1 of an audio output signal from amplifier IC2 to speaker 3. In this embodiment, a sine wave is used as the audio output signal. The middle section illustrates an example of a waveform G2 of a fault signal (FAULT) of terminal C3. The lower section illustrates an example of a warning signal (FAULT) of terminal C2. The waveform G3 of the warning signal (WARNING) is shown in FIG. 5. Correspondingly, the gain is reduced (GAIN DOWN) and the audio output signal is gradually reduced. can be read.

[0043] In FIG. 5, the gain is increased (GAIN UP) in response to the section in which the warning signal is off (WARNING HI) following the section in which the warning signal is on (WARNING LO), and the audio output signal increases stepwise. It can be seen that the rate of change over time of the audio output signal when the gain is decreasing (rate of change in output decrease) is steeper than the rate of change over time of the audio output signal when the gain is increasing (rate of change in output increase). In other words, it can be seen that when the gain is increasing, the microcomputer 1 increases the gain by ΔG2 each time the alarm signal OFF (WARNING HI) is detected a specified number of times in succession. Note that, as already explained in FIG. 2, ΔG1 is a larger value than ΔG2.

[0044] (Effects of the first embodiment) As described above, the amplifier IC2 can be said to be an example of a control target capable of adjusting the gain 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 (first temperature), the amplifier IC2 turns on the alarm signal and outputs it to the terminal C2. When the alarm signal is turned on at the terminal C2, the microcomputer 1, which is an example of a control device, reduces the current gain (A) of the amplifier IC2 to (A=A-ΔG1). Here, the amount of reduction ΔG1 when the gain is reduced is greater than the amount of increase ΔG2 when the gain is increased. Thereafter, when the detected temperature falls below the reference temperature (first temperature), the amplifier IC2 turns off the alarm signal and outputs it to the terminal C2. Then, before increasing the current gain (A) of the amplifier IC2 to (A=A+ΔG2), the microcomputer 1 confirms by N times of monitoring that the detected temperature falls below the reference temperature (first temperature). As a result, in this embodiment, when the microcomputer 1 reduces the gain, the time change of the gain is larger than when the gain is increased. In other words, when the temperature of the amplifier IC2 reaches or exceeds the reference temperature (first temperature), the microcomputer 1 can execute control to quickly lower the temperature of the amplifier IC2. In this case, the microcomputer 1 can also achieve stable control by making the change in gain over time smaller when increasing the gain than when decreasing the gain.

[0045] Furthermore, when the temperature detected by the temperature sensor reaches a limit temperature (second temperature) higher than the reference temperature (first temperature), amplifier IC2 turns on a fault signal and outputs it to terminal C3. When the fault signal turns on at terminal C3, microcontroller 1 executes abnormality processing. That is, when amplifier IC2 reaches the limit temperature, microcontroller 1 stops normal processing and immediately responds to the abnormality. Therefore, when amplifier IC2 is in an abnormal state, microcontroller 1 can execute the next best processing.

[0046] In addition, when the temperature detected by the amplifier IC2 becomes equal to or higher than the reference temperature (first temperature), the microcomputer 1 Therefore, the microcomputer 1 can notify a user of an audio device having the control system 10, a vehicle having the control system 10, or the like, that the amplifier IC2 has reached a high temperature equal to or higher than the reference temperature (first temperature).

[0047] Also, the microcontroller 1 detects the state of the amplifier IC2, for example, an alarm signal, for each monitoring period (period ΔT1, for example) during which the microcontroller 1 monitors the amplifier IC2, which is an example of a control target. Then, when the microcontroller 1 detects that the detected temperature has fallen below the reference temperature (first temperature) in a number of consecutive monitoring periods, the microcontroller 1 performs control to increase the gain. That is, when increasing the gain, the microcontroller 1 checks the state of the amplifier IC2 multiple times and increases the gain of the amplifier IC2. By doing this, the microcontroller 1 can stably and reliably perform control when the gain is increased even when the temperature characteristics are unstable. On the other hand, as described above, when the microcontroller 1 detects even once that the detected temperature is in a state where it is above the reference temperature (first temperature), the microcontroller 1 reduces the gain. That is, the microcontroller 1 quickly reduces the gain in response to an increase in the detected temperature in the amplifier IC2, and increases the gain with stable control in response to a decrease in the detected temperature in the amplifier IC2. The microcontroller 1 realizes rapid protection of the amplifier IC2 and stable control of the gain by using different monitoring counts for the temperature rise phase and the temperature fall phase.

[0048] In addition, the microcontroller 1 can control the amplifier IC2 by using different values ​​for the gain decrease amount ΔG1 and the gain increase amount ΔG2. In this way, the microcontroller 1 can quickly protect the amplifier IC2 and achieve stable gain control by using different amounts of gain change depending on whether the temperature is rising or falling.

[0049] Moreover, the microcomputer 1 uses the same monitoring period ΔT1 in the control of the gain decrease and the control of the gain increase. Then, when the gain is increased, the microcomputer 1 can arbitrarily vary the duration width ΔT2=N*ΔT1 according to the count number N of the period. That is, the microcomputer 1 can flexibly set the amount of change in the gain decrease and the gain increase. Furthermore, the microcomputer 1 can flexibly control the amplifier IC2 with a desired value of N according to the thermal characteristics of the amplifier IC2 itself and the characteristics of heat dissipation parts such as a heat sink and a heat sink provided in the amplifier IC2. That is, the microcomputer 1 realizes a quick decrease in the gain when the temperature of the amplifier IC2 increases and a stable increase in the gain when the temperature of the amplifier IC2 decreases. That is, the microcomputer 1 of this embodiment can arbitrarily vary the decrease in the gain due to the decrease amount ΔG1 and the period ΔT1 and the increase in the gain due to the increase amount ΔG2 and the period ΔT2 according to the product specifications, etc.

[0050] <Second embodiment> A control system 10A according to a second embodiment will be described with reference to Fig. 6. In the above-described first embodiment, a control system 10 including a microcomputer 1 that determines the state of an amplifier IC2 from an alarm signal, a fault signal, or the like, and controls the gain of the amplifier IC2 is exemplified. In the above-described first embodiment, the amplifier IC2 has a function (e.g., a register) for accepting a gain setting. However, the processing of the control system 10 of the first embodiment can also be performed on a device that does not have a function for accepting a gain setting.

[0051] 6 is a diagram illustrating a configuration of a control system 10A according to the second embodiment. The control system 10A includes a microcomputer 1, an amplifier IC 2A, a speaker 3, and a DSP (Digital Signal Processor) 4.

[0052] The DSP4 is capable of SPI communication with the microcomputer 1, and is capable of I2S (Inter-IC Sound) communication with the amplifier IC2A. However, communication between the DSP4 and the microcomputer 1 is not limited to SPI communication. The DSP4 may be capable of I2C communication with the microcomputer 1.

[0053] The DSP 4 also decodes, for example, encoded and compressed music data, and outputs, for example, digital audio data in a PCM (Pulse Code Modulation) format from an I2S terminal C5. The encoded and compressed music data is input from the DSP4 to the amplifier IC2A. There is no limitation on the input source of the encoded and compressed music data input to the DSP4. For example, the DSP4 may read the music data via a communication interface connected to a communication network. The DSP4 may also read the music data from a DVD, a Blu-ray disc, a hard disk drive, etc. via an input / output interface.

[0054] Amplifier IC2A has a D / A (Digital-to-Analog) converter that converts digital audio data to analog data, and an amplifier with a fixed gain. In other words, amplifier IC2A does not have the function of accepting gain settings. In this configuration, DSP 4 adjusts the amplitude of the analog audio signal output from amplifier IC2A to speaker 3 by adjusting the number of bits of the digital audio data input to amplifier IC2A.

[0055] As in the first embodiment, the microcomputer 1 reads values ​​of various registers of the amplifier IC2A via the terminal C1 by I2C communication or the like. The microcomputer 1 may also set values, such as commands or control parameters, in various registers of the amplifier IC2A via the terminal C1 by I2C communication or the like. That is, the amplifier IC2A may have a register that can be set from the outside by I2C communication or the like. However, the amplifier IC2A is not provided with a register for setting a gain.

[0056] As in the first embodiment, the microcomputer 1 detects an alarm signal from the amplifier IC2A via the terminal C2. As in the first embodiment, the microcomputer 1 detects a fault signal from the amplifier IC2A via the terminal C3. In this embodiment, instead of instructing the amplifier IC2A to increase or decrease the gain, the microcomputer 1 instructs the DSP4 to increase or decrease the gain via SPI communication. That is, as in the warning monitoring process of FIG. 4 in the first embodiment, when the microcomputer 1 detects an alarm signal from the amplifier IC2A, it calculates the gain to be set in the amplifier IC2A and instructs the DSP4 of the calculated gain.

[0057] The DSP4 adjusts the number of bits of the digital audio data in response to a gain instruction from the microcomputer 1, and inputs the data to the amplifier IC2A. By adjusting the number of bits of the digital audio data in the DSP4, the microcomputer 1 can adjust the amplitude of the drive signal output from the amplifier IC2A to the speaker 3, even if the amplifier IC2A does not have a gain adjustment function.

[0058] As in the processing of the microcomputer 1 in the first embodiment, the microcomputer 1 and the DSP4 increase the time change of the gain when lowering the gain compared to when increasing the gain. Therefore, when the amplifier IC2A reaches the reference temperature (first temperature) or higher and the alarm signal is turned on, the microcomputer 1 can execute control to quickly lower the temperature of the amplifier IC2A. In this case, the microcomputer 1 etc. can realize stable control by decreasing the time change of the gain when increasing the gain compared to when lowering the gain. Furthermore, when the microcomputer 1 etc. detects that the detected temperature in the amplifier IC2A has fallen below the reference temperature (first temperature) (alarm signal off) in a plurality of consecutive monitoring periods, the microcomputer 1 etc. can perform control to increase the gain. By doing so, the microcomputer 1 etc. can stably execute control when the gain is increased even when the temperature characteristic is unstable. As described above, the DSP4 and the amplifier IC2A in this embodiment can be said to be an example of a control target whose gain can be adjusted when outputting an audio output signal, which is an electric signal.

[0059] <Third embodiment> A control system 10B according to a third embodiment will be described with reference to FIG. 7. In the first embodiment, the control system 10 including the microcomputer 1 that determines the state of the amplifier IC2 from an alarm signal, a fault signal, or the like, and controls the gain of the amplifier IC2 is exemplified. In the second embodiment, the control system 10A including the amplifier IC2A that does not have a function of accepting a gain setting is exemplified. That is, the control system 10A is exemplified in which the microcomputer 1 determines the state of the amplifier IC2A, and the DSP4 and the amplifier IC2A adjust the output amplitude of the drive signal to the speaker 3. In this embodiment, the control system 10B is exemplified in which the amplifier IC2B that does not have a temperature detection function and a communication function with the microcomputer 1 is exemplified.

[0060] 7 is a diagram illustrating a configuration of a control system 10B according to a third embodiment. In this embodiment, the control system 10B includes a microcomputer 1, an amplifier IC 2B, a speaker 3, and a DSP 4. In this embodiment, the configurations and operations of the microcomputer 1, the speaker 3, and the DSP 4 are similar to those in the second embodiment.

[0061] That is, the microcomputer 1 is connected to the DSP 4, for example, via SPI communication, etc. Also, the DSP 4 can adjust the number of bits of digital audio data via I2S communication and input the data to the amplifier IC2B.

[0062] Furthermore, amplifier IC2B converts digital audio data into an analog signal, amplifies the signal at a fixed gain, and drives speaker 3. However, amplifier IC2B does not have a built-in temperature sensor, unlike amplifier IC2 in the first embodiment and amplifier IC2A in the second embodiment. Furthermore, amplifier IC2B does not have a communication function for outputting an alarm signal and a fault signal and notifying the microcomputer 1, etc.

[0063] Therefore, in this embodiment, a temperature sensor 5 for measuring the temperature of the amplifier IC2B and a buffer circuit (BUFFER) 6 for converting the temperature data detected by the temperature sensor 5 into digital data and inputting it to the digital (AD IN) terminal C6 of the microcontroller 1 are provided.

[0064] In this embodiment, the microcomputer 1 detects the temperature state of the amplifier IC2B instead of the amplifier IC2B. That is, the microcomputer 1 monitors the temperature measured by the temperature sensor 5. When the temperature of the amplifier IC2B rises and reaches a reference temperature (first temperature) while the amplifier IC2B is amplifying an audio signal, the microcomputer 1 instructs the DSP4 to reduce the gain of the amplifier IC2B. In addition, when the microcomputer 1 detects that the temperature of the amplifier IC2B is maintained below the reference temperature (first temperature) N times in succession, it instructs the DSP4 to increase the gain of the amplifier IC2B. As in the second embodiment, the DSP4 adjusts the gain by adjusting the number of bits of the digital audio data and inputting it to the amplifier IC2B.

[0065] Furthermore, if the temperature of amplifier IC2B reaches a limit temperature (second temperature) while amplifier IC2B is amplifying the audio signal, microcontroller 1 stops the input of digital audio data to amplifier IC2B by DSP 4 and executes abnormality processing.

[0066] As in the first and second embodiments, the microcomputer 1 etc., when decreasing the gain, makes the change in gain over time larger than when increasing the gain. Therefore, when the amplifier IC2B reaches or exceeds the reference temperature (first temperature), the microcomputer 1 etc. can execute control to quickly lower the temperature of the amplifier IC2B. In this case, it can be said that the microcomputer 1 etc., when increasing the gain, makes the change in gain over time smaller than when decreasing the gain, thereby realizing stable control. Furthermore, when the microcomputer 1 etc. detects that the detected temperature of the amplifier IC2B has fallen below the reference temperature (first temperature) in multiple consecutive monitoring cycles, the microcomputer 1 etc. can execute control to increase the gain. In this way, the temperature Even if the gain characteristics are unstable, control can be stably performed when the gain increases. With the above configuration, the microcomputer 1 and the DSP 4 can quickly protect the amplifier IC2B and achieve stable gain control, as in the first and second embodiments.

[0067] <Other embodiments> In the first to third embodiments, the process of adjusting the output of the amplifier IC2 to the amplifier IC2B in the control system 10 to 10B, which is an audio system that drives the speaker 3, is exemplified. However, the process of the control system 10 to 10B is not limited to an audio system. That is, the process of the control system 10 to 10B can be applied to a system in general including a device whose temperature changes depending on an output signal, similar to the amplifier IC2 to the amplifier IC2B. For example, the process of the control system 10 to 10B may be applied to an amplifier circuit included in a control circuit of an air conditioner. The process of the control system 10 to 10B may be applied to an amplifier circuit included in a driver circuit that controls the brightness of an image output device. Furthermore, the process of the control system 10 to 10B may be applied to a transmission circuit or an amplifier circuit that controls the transmission power of a communication device.

[0068] In such an apparatus including an amplifier circuit, the microcomputer 1 etc., when lowering the gain, makes the change in gain over time larger than when increasing the gain. Therefore, when the temperature of the device such as the amplifier IC2 becomes equal to or higher than the reference temperature (first temperature), control can be executed to quickly lower the temperature of the amplifier IC2 etc. In this case, the microcomputer 1 etc., when increasing the gain, makes the change in gain over time smaller than when lowering the gain, thereby realizing stable control. Furthermore, when the microcomputer 1 etc. detects that the detected temperature in the amplifier IC2 etc. falls below the reference temperature (first temperature) in a plurality of consecutive monitoring cycles, the microcomputer 1 etc. may perform control to increase the gain. In this way, even when the temperature characteristics are unstable, the microcomputer 1 etc. can stably perform control when the gain is increased. Furthermore, the microcomputer 1 etc., by using different monitoring counts in the temperature rise phase and the temperature fall phase, can realize rapid protection of the amplifier IC2 etc. and stable gain control.

[0069] <Computer-readable recording medium> A program for causing a computer or other machine or device (hereinafter, referred to as a computer, etc.) to realize any of the above functions can be recorded on a recording medium readable by the computer, etc. Then, the computer, etc. can provide the function by reading and executing the program from the recording medium.

[0070] Here, a computer-readable recording medium refers to a recording medium that stores information such as data and programs electrically, magnetically, optically, mechanically, or chemically and can be read by a computer, etc. Among such recording media, those that can be removed from a computer, etc. include, for example, flexible disks, magneto-optical disks, CD (Compact Disc)-ROM (Read Only Memory), CD-R (Read) / W (Write), DV D (Digital Versatile Disc), Blu-ray Disc, flash memory and other memory cards. In addition, hard disks and ROMs are used as recording media fixed to computers. Furthermore, SSDs (Solid State Drives) are removable storage media. The present invention can be used as a recording medium that can be read and written on a computer or the like.

[0071] <Other> Furthermore, this embodiment includes the following aspects (hereinafter, referred to as supplementary notes). (Appendix 1) When a detected temperature of a controlled object, in which a gain for outputting an electrical signal is adjustable, is equal to or higher than a first temperature, the gain is lowered, and when the detected temperature falls below the first temperature, the gain is lowered. A control device that performs control to increase a gain, A control device that reduces the change in the gain over time when the gain is increased compared to when the gain is decreased. (Appendix 2) 2. The control device according to claim 1, wherein the control device stops the output of the controlled object when the detected temperature reaches a second temperature that is higher than the first temperature. (Appendix 3) 3. The control device according to claim 1, wherein the control device outputs a warning when the detected temperature of the controlled object becomes equal to or higher than the first temperature. (Appendix 4) 4. The control device according to claim 1, wherein a state of the control object is detected for each monitoring cycle in which the control object is monitored, and when the control device detects that the detected temperature has fallen below the first temperature in a plurality of consecutive monitoring cycles, the control device performs control to increase the gain. (Appendix 5) A control method, comprising: when a detected temperature of a control target having an adjustable gain for outputting an electrical signal is equal to or higher than a first temperature, a computer reduces the gain; and when the detected temperature falls below the first temperature, a computer then performs control to increase the gain, A control method in which the change in the gain over time is made smaller when the gain is increased than when the gain is decreased. (Appendix 6) The control method according to claim 5, wherein the computer stops the output of the controlled object when the detected temperature reaches a second temperature higher than the first temperature. (Appendix 7) 7. The control method according to claim 5, wherein the computer outputs a warning when the detected temperature of the controlled object becomes equal to or higher than the first temperature. (Appendix 8) The control method according to any one of appendixes 5 to 7, wherein the computer detects a state of the control object for each monitoring cycle in which the control object is monitored, and when the computer detects that the detected temperature has fallen below the first temperature in multiple consecutive monitoring cycles, performs control to increase the gain. [Explanation of symbols]

[0072] 1 Microcomputer 2, 2A, 2B Amplifier IC 3 Speakers 4 DSP 5 Temperature Sensor 6 Buffer Circuit

Claims

1. A control device that performs control such that, when a detected temperature of a controlled object that is capable of adjusting a gain when outputting an electrical signal is equal to or higher than a first temperature, the gain is decreased, and, thereafter, when the detected temperature falls below the first temperature, the gain is increased, A control device that reduces the change in the gain over time when the gain is increased compared to when the gain is decreased.

2. The control device according to claim 1 , wherein the output of the controlled object is stopped when the detected temperature reaches a second temperature that is higher than the first temperature.

3. The control device according to claim 1 , wherein a warning is output when the detected temperature of the controlled object becomes equal to or higher than the first temperature.

4. 2. The control device according to claim 1, wherein the control device detects a state of the controlled object for each monitoring cycle in which the controlled object is monitored, and when the control device detects that the detected temperature has fallen below the first temperature in multiple consecutive monitoring cycles, the control device increases the gain.

5. A control method, in which a computer performs control to reduce a gain when outputting an electrical signal, when a detected temperature of a control target that has an adjustable gain is equal to or higher than a first temperature, and thereafter, when the detected temperature falls below the first temperature, the computer performs control to increase the gain, A control method in which the change in the gain over time is made smaller when the gain is increased than when the gain is decreased.

6. The control method according to claim 5 , wherein the computer stops the output of the controlled object when the detected temperature reaches a second temperature that is higher than the first temperature.

7. The control method according to claim 5 , wherein the computer outputs a warning when the detected temperature of the controlled object becomes equal to or higher than the first temperature.

8. The control method according to claim 5, wherein the computer detects a state of the controlled object for each monitoring cycle in which the controlled object is monitored, and when the computer detects that the detected temperature has fallen below the first temperature in a plurality of consecutive monitoring cycles, the computer performs control to increase the gain.

Images