Information processing device and control method

Abstract

The output level of the audio signal is adjusted according to the impedance of the sound source. The present invention includes a controller and an audio system, and when the controller detects a connection between the audio system and a sound source, the controller measures an output level of a test signal to be output to the sound source, and determines an output gain of an audio signal to be output from the audio system to the sound source based on the output level. The embodiment of the present application can be realized as an information processing device or a control method.

Description

[Technical field]

[0001] The present application relates to an information processing device and a control method, for example, for controlling the output level of an audio signal. [Background technology]

[0002] Information processing devices such as PCs (Personal Computers) and smartphones are usually capable of acquiring content desired by a user via a network and presenting the acquired content. The acquired content may include audio. When audio is presented in a public place, the presented audio may propagate to the surrounding area and cause discomfort to others. To avoid this, a wearable sound source such as headphones or earphones may be used when playing audio.

[0003] On the other hand, various sound sources have been widely used. The impedance varies greatly depending on the model of the sound source. For example, the average impedance of headphones is about 30 to 40 Ω, but headphones with high impedance exceeding 100 Ω are also widely used. Such differences in impedance affect the output level of the audio signal provided from the information processing device. For example, even when connected to the same information processing device, the output level of the audio signal tends to decrease as the impedance of the headphones increases. An audio playback device has been proposed that allows volume adjustment when the sound source to which the audio is output is switched.

[0004] For example, the audio playback device described in Patent Document 1 is described as having a built-in speaker, an external output means to which an external audio output device can be connected, a volume operation means for a user to operate the volume of an audio signal, a volume adjustment means for adjusting the volume of the audio signal in response to user operation of the volume operation means, and switching the output destination of the audio signal to the external output means when an external audio device is connected to the external output means, and switching to the built-in speaker when an external audio output device is not connected to the external output means, thereby performing different volume control depending on the output destination of the audio signal. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-69925 A Summary of the Invention [Problem to be solved by the invention]

[0006] The audio reproducing device described in Patent Document 1 adjusts the volume by switching the output destination of the audio signal to either the external output means or the built-in speaker depending on whether an audio output device is connected to the external output means. In the volume adjustment, the acquired audio signal is amplified by an amplification factor according to a volume value input by a user operation. However, the fact that the impedance of the audio output device connected to the external output means is diverse has not been fully taken into consideration. [Means for solving the problem]

[0007] The present application has been made to solve the above-mentioned problems, and an information processing device according to one aspect of the present application includes a controller and an audio system, and when the controller detects a connection between the audio system and a sound source, it measures an output level of a test signal to be output to the sound source, and determines an output gain of an audio signal to be output from the audio system to the sound source based on the output level.

[0008] In the above information processing device, the controller may determine the output gain based on an impedance of the sound source corresponding to the output level, a rated power consumption of the sound source, and an internal resistance of the audio system.

[0009] In the above information processing device, the controller may determine a maximum voltage of the audio signal based on an impedance of the sound source, a maximum power consumption of the sound source, and the internal resistance.

[0010] In the above information processing device, the test signal may have a frequency component higher than the audible band.

[0011] The information processing device may include a rectifying element that rectifies the test signal and outputs a rectified signal, and a low-pass filter that extracts a low-pass signal from the rectified signal, and the controller may measure an output level of the low-pass signal.

[0012] In the above-mentioned information processing device, the low-pass filter may include a resistive element and a storage element in parallel with the controller, and the controller may detect the output level after a predetermined time has elapsed since output of the test signal, and the predetermined time may be greater than the product of the resistance value of the resistive element and the capacitance of the storage element.

[0013] A control method according to another aspect of the present application is a control method for an information processing device including a controller and an audio system, wherein when the controller detects a connection between the audio system and a sound source, the controller executes a step of measuring an output level of a test signal to be output to the sound source, and a step of determining an output gain of an audio signal to be output from the audio system to the sound source based on the output level. Effect of the Invention

[0014] According to the embodiment of the present application, the output level of the audio signal can be adjusted according to the impedance of the sound source. [Brief description of the drawings]

[0015] [Figure 1] 1 is a perspective view showing an example of an external configuration of an information processing device according to an embodiment of the present invention; [Diagram 2] 1 is a schematic block diagram illustrating an example of a hardware configuration of an information processing device according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a schematic block diagram showing an example of a hardware configuration for adjusting an output level according to the embodiment. [Figure 4]FIG. 4 is a diagram illustrating an example of a setting table according to the embodiment. [Diagram 5] 11 is a diagram showing an example of setting impedance and maximum output voltage for each model of sound source. FIG. [Figure 6] 4 is a flowchart illustrating volume control according to the present embodiment. [Figure 7] 2 is a circuit diagram showing a configuration example of a processing circuit according to the present embodiment. FIG. [Figure 8] FIG. 4 is a diagram showing an example of a change over time in a detected output level. [Figure 9] FIG. 11 is a diagram showing another example of a change over time in the detected output level. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present application will be described with reference to the drawings. First, an overview of an information processing device 1 according to this embodiment will be described. FIG. 1 is a perspective view showing an example of the external configuration of the information processing device 1 according to this embodiment. In the example of FIG. 1, the information processing device 1 is configured as a notebook personal computer (notebook PC: Personal Computer).

[0017] The information processing device 1 includes a first housing 101 and a second housing 105, which are joined together using hinge mechanisms 121a and 121b. The hinge mechanisms 121a and 121b are fixed to one side of the first housing 101 and the second housing 105, respectively. One of the first housing 101 and the second housing 105 is rotatable relative to the other with one side of the first housing 101 and the second housing 105 as a rotation axis. That is, the angle θ (referred to as the "opening angle" in this application) between the main surface of the first housing 101 and the main surface of the second housing 105 is variable.

[0018] A display 103 is disposed on the main surface of the first housing 101, occupying most of the surface. A keyboard 107, a touch pad 109, and a power button 113 are disposed on the main surface of the second housing 105. With such an arrangement, the information processing device 1 is used in a state in which the first housing 101 and the second housing 105 are open. The open state means that one of the main surface of the first housing 101 and the main surface of the second housing 105 is open and not covered by the other. In the open state, the opening angle θ is typically within a range of 90° to 180°.

[0019] An audio terminal 124a is provided on the side surface of the second housing 105. The audio terminal 124a is connected to an input / output terminal of an audio device in a detachable manner by an external force. The audio terminal 124a has a shape that allows it to be fitted to an input / output terminal of the audio device, and in a state where it is fitted to the input / output terminal, it allows input and output of audio signals to and from the information processing device 1. In the example of FIG. 1, the audio terminal 124a has an audio jack. The audio device is headphones 44h, and includes an audio plug as an input / output terminal. The audio plug is inserted into a hollow portion of the audio terminal 124a, and audio signals are input and output between the audio terminal 124a and the audio terminal 124a.

[0020] The audio device includes a sound source 44 (FIG. 2). The sound source 44 generates sound according to an audio signal input to the device. The sound source 44 includes an electroacoustic transducer (e.g., a speaker) that generates mechanical vibrations according to an audio signal that is an electric signal. The audio device may include a sound receiving element (e.g., a microphone) that receives sound arriving at the device. The audio device may include a sound receiving element separate from the sound source 44, or the sound receiving element may be shared as the sound source 44. The sound source 44 may be one, or two or more. The sound source 44 may be configured as a wearable device that is worn in contact with or in close proximity to each ear. Typical sound sources 44 that can be worn on the human body include headphones 44h and earphones.

[0021] In general, the electrical impedance of the sound source 44 (sometimes simply referred to as "impedance" in this application) varies greatly depending on the model. When an audio signal is output to the sound source, the output level of the audio signal provided to the sound source varies depending on the impedance. The higher the impedance of the sound source 44, the lower the output level of the audio signal from the signal source tends to be. As will be described later, the information processing device 1 measures the impedance of the sound source 44 when detecting a connection with the sound source. The information processing device 1 determines that the higher the measured impedance, the higher the output level of the audio signal. This reduces the volume difference between models, regardless of the impedance of the sound source 44.

[0022] Next, a hardware configuration example of the information processing device 1 according to the present embodiment will be described. Fig. 2 is a schematic block diagram showing a hardware configuration example of the information processing device 1 according to the present embodiment. The information processing device 1 includes a CPU 11, a main memory 12, a GPU (Graphic Processing Unit) 13, a display 103, a PCH (Platform Controller Hub) 21, a BIOS (Basic Input Output System) memory 22, an auxiliary storage device 23, a USB (Universal Serial Bus) connector 24, a WLAN (Wireless Local Area Network) card 25, an audio system 26, an EC (Embedded Controller) 31, an input device 32, a power supply circuit 33, a battery 34, and a processing circuit 36.

[0023] The CPU 11 is a processor that is the core of a system device included in the information processing device 1. The CPU 11 is a processor that can execute various arithmetic processes instructed by commands written in various programs. The CPU 11 executes processes instructed by various programs, such as an OS (Operating System), a BIOS, firmware, and application programs (referred to as "apps" in this application). The CPU 11 executes the OS and provides functions such as resource management, execution management of various programs, input / output control, and file management in the computer system that constitutes the core of the information processing device 1, i.e., the host system. Note that executing a process instructed by a command written in a program is sometimes called "executing a program" or "running a program."

[0024] The main memory 12 is a writable memory used as a read area for the executable program of the processor or as a work area for writing processing data for the executable program. The main memory 12 is composed of, for example, a plurality of DRAM (Dynamic Random Access Memory) chips. The executable programs include an OS, various drivers for operating hardware such as peripheral devices, various services / utilities, applications, etc.

[0025] The GPU 13 is a processor that mainly executes real-time image processing. The GPU 13 processes drawing commands from the CPU 11, and writes drawing information obtained by the processing to a video memory (not shown). The GPU 13 reads out the drawing information from the video memory, and outputs it to the display 103 via the CPU 11 as display data indicating the drawing information (image processing). The drawing information notified to the display 103 constitutes the display screen.

[0026] The CPU 11 executes a graphic driver on the OS to control the operation of the GPU 13 and realizes image processing instructed by the OS, an application, or other programs. The number of GPUs 13 is not limited to one, and may be multiple. The GPU 13 may share some of the processing with the CPU 11 and execute parallel arithmetic processing other than image processing. The CPU 11, the main memory 12, and the PCH 21 form a computer system, that is, a host system, which is the core of the information processing device 1. In other words, the computer system of the information processing device 1 includes a system device as hardware, and software such as an OS and schedule tasks.

[0027] Display 103 displays a display screen based on display data output from CPU 11. Display 103 may be, for example, any of a liquid crystal display (LCD) and an organic light emitting diode (OLED) display.

[0028] The PCH 21 includes one or more bus controllers and can be connected to a plurality of devices to input and output various data. The bus controller may be, for example, any one of USB, Serial ATA (Advanced Technology Attachment), SPI (Serial Peripheral Interface) bus, PCI (Peripheral Component Interconnect) bus, PCI-Express bus, and LPC (Low Pin Count), or any combination thereof. The plurality of devices to be connected include, for example, the BIOS memory 22, the auxiliary storage device 23, the USB connector 24, the WLAN card 25, the audio system 26, and the EC 31.

[0029] The BIOS memory 22 stores firmware for controlling the operation of the BIOS, the EC 31, and other devices. The BIOS is firmware for performing basic input and output of system devices. In this application, the BIOS may also include firmware defined according to the specifications defined in the Unified Extensible Firmware Interface (UEFI). The BIOS memory 22 includes an electrically rewritable non-volatile memory. As such a non-volatile memory, for example, an Electrically Erasable Programmable Read Only Memory (EEPROM) and a flash Read Only Memory (FLASH ROM) can be used.

[0030] The auxiliary storage device 23 continuously stores various data. The stored data includes various programs that can be executed by the CPU 11 and the GPU 13, parameters, data used in various processes, and data acquired by various processes. The auxiliary storage device 23 may be, for example, any one of an HDD (Hard Disk Drive) and an SSD (Solid State Drive). The auxiliary storage device 23 includes various non-volatile memories. For example, a flash memory is used as the non-volatile memory. The various programs may include, for example, any one of an OS, a driver, firmware, an application, and the like, or any combination thereof.

[0031] The USB connector 24 is a connector for connecting various peripheral devices using USB. The WLAN card 25 is connected to a wireless LAN or to another network via a wireless LAN, enabling various data to be wirelessly transmitted and received between the connected device and the network.

[0032] The audio system 26 is capable of acquiring, recording, reproducing, and outputting audio data under the control of the host system. For example, the audio system 26 converts an analog audio signal input from a microphone (not shown) connected to the audio system 26 into digital audio data (Analog-to-digital (AD) conversion). The audio system 26 reads out designated audio data from a storage medium in which audio data is stored in advance. The audio system 26 acquires designated audio data from another device. The storage medium from which audio data is acquired may be a storage medium provided in the audio system 26, the auxiliary storage device 23, or another device. The audio system 26 stores the acquired audio data in the storage medium. The audio system 26 converts the acquired digital audio data into an analog audio signal (Digital-to-Analog (DA) conversion). When presenting audio, the audio system 26 outputs the converted analog audio signal to the sound source 44. An audio terminal 124a (FIG. 1) may be installed in the audio system 26.

[0033] The operations of audio system 26, i.e., acquisition, recording, playback, and output, are directed by instructions written in an application or other program executed by the host system. Audio system 26 may include one or both of an encoder (coder) that encodes the acquired audio data using a predetermined audio encoding method and a decoder (decoder) that decodes the acquired digital audio data using a predetermined audio decoding method. The encoder and decoder may be integrated into a single codec. A microphone and a speaker (not shown) may be built in or may be separate from the information processing device 1. The built-in speaker may also be selected as one of the sound sources 44 by a user operation.

[0034] The EC 31 is a one-chip microcomputer that monitors and controls the status of various devices (peripheral devices, sensors, etc.) regardless of the operating state of the host system that is the core of the information processing device 1. The EC 31 includes a processor separate from the CPU 11, a RAM separate from the main memory 12, a ROM, an A / D (Analog-to-Digital) input terminal for multiple channels, a D / A (Digital-to-Analog) output terminal, a timer, and an input / output interface (not shown). The EC 31 executes predetermined firmware to fulfill its functions.

[0035] An input device 32, a power supply circuit 33, a processing circuit 36, and other devices are connected to the input / output interface of the EC 31 by wires. The EC 31 is capable of controlling the operations of these devices. The input / output interface may be connected to various devices so as to be capable of wirelessly transmitting and receiving data. The input device 32 may be wirelessly connected to the EC 31 using the input / output interface. The input / output interface may realize a wireless connection using, for example, a short-range wireless communication method defined in IEEE802.15.1.

[0036] The EC 31 monitors the usage environment of the information processing device 1 based on various electric signals input to the EC 31. The EC 31 judges whether or not the sound source is connected based on the potential of the signal cable connecting the audio system 26 and the sound source 44. Here, the EC 31 can detect the potential difference between the signal line and a reference potential line (ground line) that is part of the signal cable, and judge whether or not the detected potential difference is equal to or greater than a predetermined reference value of the potential difference.

[0037] When EC 31 determines that the sound source 44 is connected, it measures the impedance of the sound source 44. Here, EC 31 causes the audio system 26 to output a test signal to the sound source 44. At this time, EC 31 measures the output level obtained by passing the test signal output from the audio terminal 124a to the sound source 44 through the processing circuit 36. EC 31 can calculate the impedance of the sound source 44 based on the measured output level and the internal impedance of the audio system 26. EC 31 notifies the host system of the calculated impedance. The host system determines the gain of the audio signal output from the audio system 26 to the sound source 44 so that the gain increases as the impedance notified from the EC 31 increases. Thus, the higher the impedance of the sound source 44, the higher the output level of the audio signal.

[0038] The input device 32 detects a user's operation and outputs an operation signal generated in response to the detected operation to the EC 31. Examples of the input device 32 include a keyboard 107 and a touch pad 109. The input device 32 may further include a touch sensor. The touch sensor may overlap the display 103 forming the display unit and be configured as a touch panel.

[0039] The power supply circuit 33 supplies power required for the operation of each device included in the information processing device 1 in accordance with the control of the EC 31. Devices to which power is supplied include peripheral devices as well as system devices. Peripheral devices connected to the USB connector 24 may also be recipients of power. The operating voltage of a device may differ for each individual device. The various devices may include devices that require multiple voltage stages. The multiple voltage stages may include a reference voltage as well as an operating voltage.

[0040] The power supply circuit 33 includes a converter that converts the voltage of the power supplied to the power supply circuit 33 itself, and a power supply unit that supplies the voltage-converted power to the battery 34. When power is supplied from an AC adapter (not shown), the power supply unit supplies the power remaining unused in each device to the battery 34. When power is not supplied from the AC adapter, or when the power supplied from the AC adapter is insufficient to cover the power consumed by each device, the power discharged from the battery 34 is supplied to each device as operating power.

[0041] As the converter, for example, one or more DC / DC converters are used. The multiple DC / DC converters may be used separately for each voltage after conversion. Furthermore, a first type converter that is a part of the multiple DC / DC converters may be connected to a system device or a device whose operating state may vary depending on the operating mode of the system device. The first type converter may control the power to be supplied based on the operating mode notified by the EC 31. A second type converter that is another part of the multiple DC / DC converters may be connected to a device that operates regardless of the operating mode of the system device. The second type converter may be capable of steadily supplying a constant power. Examples of devices that operate regardless of the operation mode of the system device include the EC 31, the processing circuit 36, and the sound source 44.

[0042] The battery 34 stores the power supplied from the power supply circuit 33 under the control of the power supply circuit 33. The battery 34 discharges a part of the stored power to the power supply circuit 33. A secondary battery is used as the battery 34. The secondary battery is a storage battery that can be charged and discharged. The secondary battery is, for example, a lithium ion battery. The AC adapter converts AC power supplied from an external power source into DC power with a constant voltage, and supplies the converted power to the power supply circuit 33. The AC adapter includes a mounting fixture that allows the AC adapter to be detachably attached to a housing of the information processing device 1 including the power supply circuit 33. The mounting fixture includes an interface that can transmit both power and data according to a predetermined standard. For example, USB Type-C can be used as the predetermined standard.

[0043] The processing circuit 36 ​​is connected between the audio system 26 and the EC 31, and includes a rectifying element for rectifying the test signal input from the audio system 26, and a low-pass circuit for extracting low-frequency components of the rectified test signal. The processing circuit 36 ​​outputs an output signal output from the low-pass circuit to the EC 31. The EC 31 can detect the potential of the output signal input from the processing circuit 36 ​​as the output level of the test signal supplied to the sound source 44.

[0044] Next, a method for adjusting the output level of an audio signal will be described in more detail. Fig. 3 is a schematic block diagram showing an example of a hardware configuration related to the adjustment of the output level according to this embodiment. In the example of FIG. 3, the audio system 26 includes a built-in codec 26c. As an example of the sound source 44, a headphone 44h is used, and it is assumed that the headphone 44h is connected to the audio terminal 124a. When the headphone 44h is connected to the audio terminal 124a, the speaker corresponding to each ear of the headphone 44h is electrically connected to the codec 26c using a signal cable of the audio channel corresponding to the ear. The codec 26c is connected to the CPU 11 and operates under the control of the CPU 11. The codec 26c is connected to the CPU 11 according to, for example, the HDA (High Definition Audio) standard. The codec 26c converts digital audio data input from the CPU 11 into an analog audio signal. The analog audio signal is sent to the audio terminal 124a using one signal cable for each audio channel. The one signal cable includes two conductors. One of the two conductors is connected to a reference potential point (GND) and functions as a reference potential line, and the other conductor functions as a signal line that transmits a substantial audio signal. The audio signal represents an audio waveform by the change in potential over time. In Fig. 3, R1 indicates the internal resistance of audio system 26. Audio system 26 may include an amplifier (not shown) that amplifies the audio signal, and the volume may be adjustable. In general, the higher the amplification rate of the audio signal by the amplifier, the smaller the internal resistance R1.

[0045] The EC31 has two audio signal terminals. The signal line connected to one of the audio signal terminals, HP_DET, is connected to a pull-up resistor R pEC31 is electrically connected to the reference potential line and one end of the switch 124s via the audio terminal 124a. The other end of the switch 124s is electrically connected to the other end of the reference potential line. The switch 124s is a mechanical switch, and is built in or adjacent to the audio terminal 124a. When the audio plug is inserted into the audio terminal 124a, the terminal of the switch 124s contacts both ends and short-circuits (switch ON). In this state, when the audio plug is removed from the audio terminal 124a, the terminal of the switch 124s separates from both ends and is insulated (switch OFF). Therefore, the EC31 monitors the potential of the audio signal terminal HP_DET and the signal line. The EC31 judges whether or not the measured potential is equal to or lower than a predetermined detection threshold when no audio signal is output to the headphones 44h. The EC31 can judge that the headphones 44h are connected to the audio terminal 124a when the absolute value of the potential difference is equal to or lower than the detection threshold. When the absolute value of the potential difference exceeds the reference value, the EC 31 can determine that the headphones 44h have been disconnected from the audio terminal 124a. When the headphones 44h are not connected, the potential at the audio signal terminal HP_DET becomes significantly higher than the reference potential.

[0046] When the EC 31 determines that the headphones 44h are connected, it notifies the CPU 11 of the connection to the headphones 44h. When the CPU 11 is notified of the connection to the headphones 44h by the EC 31, it outputs an audio signal having known characteristics as a test signal for each audio channel to the audio system 26. The test signal output from the codec 26c is attenuated by the internal resistor R1 and is supplied to the headphones 44h via the audio terminal 124a and also to the EC 31 via the processing circuit 36.

[0047] The EC 31 is preset with an amplitude V1 and a frequency f1 of the output voltage of the test signal. An audio signal having a frequency component of a higher frequency (for example, 20.5 kHz) than an audible frequency (typically, 20 Hz to 20 kHz) may be applied as the frequency f1. The test signal may be a sine wave of the frequency. As a result, even if a sound based on the test signal is presented to a user wearing the headphones 44h, the presented sound is not perceived. Strictly speaking, an impedance difference occurs between an audio signal having a frequency component of an audible frequency and a test signal having a higher frequency component. However, the frequency dependency of the impedance is not as significant as the dependency due to the structure of the sound source.

[0048] The processing circuit 36 ​​includes a rectifying element and a low-pass filter (LPF). The rectifying element rectifies the test signal input from the audio system 26, and outputs the rectified signal obtained by the rectification to the low-pass filter. The low-pass filter has a low-pass characteristic that passes more of the frequency components of the rectified signal input from the rectifying element as the frequency components with lower frequencies are passed, and outputs the rectified signal after passing to the EC 31 as a low-pass signal. The low-pass characteristic can also be regarded as temporal smoothing. The low-pass characteristic may be set for the low-pass signal so that the DC component of the rectified test signal is mainly left. The EC 31 measures the potential V_DET of the test signal input from the processing circuit 36. The measured potential V_DET corresponds to the output level V2 of the test signal output from the audio system 26. In the example of FIG. 3, the test signal is input to an input terminal of an AD converter (ADC) included in the EC 31 and converted into a digital signal. A potential V_DET is obtained which indicates the real value transmitted by the converted digital signal.

[0049] The EC31 calculates the impedance R of the headphones 44h based on the measured output level V2, the internal resistance R1 of the audio system 26 and the output voltage V1 that are preset. L It is possible to estimate the impedance R Lis obtained by multiplying the internal resistance R1 by the ratio V2 / (V1-V2) of the output voltage V1 to the output level V2. This relationship is expressed as the ratio of the output voltage V1 to the output level V2 depending on the internal resistance R1 and the impedance R L The total impedance R1+R L and impedance R L This is because it is equivalent to the ratio of

[0050] EC31 is the calculated impedance R L is notified to the CPU 11. A setting table showing the relationship between the impedance of the sound source and the output gain corresponding to the adjusted output voltage is preset in the CPU 11. The CPU 11 refers to the setting table and calculates the impedance R L An output gain corresponding to the above is determined, and the determined output gain is set in the audio system 26. The output gain corresponds to a ratio of an output voltage of an audio signal to be output to a predetermined reference output voltage (hereinafter referred to as a "reference output voltage") of the codec 26c. The audio system 26 multiplies the signal value of each sample constituting the audio signal converted by the DA conversion by the set output gain. The audio system 26 outputs an audio signal including the multiplied value obtained by the multiplication to the audio terminal 124a as a volume-adjusted audio signal.

[0051] The setting table may describe the maximum output voltage in association with the impedance. In this case, the CPU 11 refers to the setting table and calculates the impedance R LThe CPU 11 further specifies a maximum output voltage corresponding to the default output voltage specified as described above. The CPU 11 determines an output gain corresponding to the specified default output voltage as described above, and sets the determined output gain to the audio system 26. On the other hand, the CPU 11 sets the specified maximum voltage to the audio system 26. The audio system 26 adjusts the amplitude of the audio signal so that the voltage value indicating the audio signal after the volume adjustment does not exceed the set maximum voltage. The audio system 26 outputs the audio signal after the amplitude adjustment to the audio terminal 124a. This prevents the supply of an audio signal with power exceeding the maximum output voltage to the headphones 44h.

[0052] The power consumption P of the audio signal supplied to the headphones 44h and the output voltage U from the codec 26c have the relationship expressed by the formula (1). According to the formula (1), the output voltage U is determined by the internal resistance R1 of the audio system 26 and the impedance R L The sum of this and impedance R L The audio terminal 124a multiplies the voltage of the audio signal output from the codec 26c by the square root of the ratio of the power consumption P to the internal resistance R1 and impedance R L It can also be considered as an output point that divides the impedance R L The square root of the ratio of the power consumption P to the rated power consumption P corresponds to the current I supplied to the headphones 44h. The default output voltage corresponds to a voltage value U calculated using equation (1) for the rated power consumption P of the headphones 44h.

[0053] The default output gain is 44Ω, with the impedance R of the headphones at 44Ω. L It is calculated by dividing the default output voltage U corresponding to the impedance R by the reference output voltage corresponding to the reference impedance. L is determined based on the output voltage V1 of the test signal, the measured output level V2, and the internal resistance R1 of the audio system 26. The default output gain is the impedance R L, is determined based on the rated power consumption P of the headphones 44h and the internal resistance R1 of the audio system 26. The maximum voltage corresponds to a voltage value U calculated using equation (1) for the maximum power consumption P allowed for the headphones 44h. In other words, the maximum voltage corresponds to the impedance R L , is determined based on the maximum power consumption P of the headphones 44h and the internal resistance R1 of the audio system 26.

[0054]

number

[0055] 4 is a diagram showing an example of a setting table according to the present embodiment. The setting table shown in FIG. 4 includes an output level V_DET (unit: V), an impedance R L (unit: Ω), maximum output voltage V max (V) and a resistor value set for each output level V_DET. This output level V_DET corresponds to the above-mentioned output level V2. With a constant internal resistance R1 and output voltage V1, the impedance R L increases, and the impedance R L The rate of increase of the maximum output voltage V max , and the output gain G also increases. As the output level V_DET increases, the rate of increase in the output gain G relative to the increase in the output level V_DET also tends to increase. L The increase in the maximum output voltage V max is roughly proportional to the output gain G.

[0056] FIG. 5 shows an example of the impedance and maximum output voltage settings for each model of headphones 44h. Four models of headphones with different structures were measured. The output level of the test signal and the headphone output (power consumption) were fixed at V1 and P, respectively, regardless of the model. The internal resistance R1 of the audio system 26 was also fixed. The measured impedance R L,1 ~R L,4 The minimum value R varies greatly depending on the model. L,1 and maximum R L,4 In the example of FIG. 5, the detection threshold differs for each model, but the detection threshold may be a common constant value regardless of the model.

[0057] The rated power consumption may be common regardless of the model of the headphones 44h as described above, or may differ depending on the model. The maximum output voltage may be common regardless of the model of the headphones 44h as described above. When one or both of the rated power consumption and the maximum output voltage differ depending on the model, a setting table may be set in advance for each model in the CPU 11 or the audio system 26. When the headphones 44h are connected to the audio system 26, the headphones 44h may output a notification signal indicating model information indicating the model of the headphones 44h to the EC 31, and the EC 31 may notify the CPU 11 of the model information indicated by the notification signal. The CPU 11 may select a setting table corresponding to the notified model information, and determine the output gain and the maximum output voltage using the selected setting table.

[0058] Next, an example of volume control according to this embodiment will be described below. Fig. 6 is a flowchart illustrating volume control according to this embodiment. (Step S102) The EC 31 monitors the voltage of the audio signal output from the audio terminal 124a, and judges whether or not the headphones 44h are connected based on the voltage. If it is judged that the headphones are connected (step S102, headphones detected, YES), the process proceeds to step S104. If it is judged that the headphones are not connected (step S102, headphones detected, NO), the process of step S102 is repeated. (Step S104) The CPU 11 outputs a test signal having a frequency higher than the audible band from the codec 26c included in the audio system 26 to the audio terminal 124a.

[0059] (Step S106) The EC 31 measures the output level of the test signal input from the audio terminal 124a via the processing circuit 36. The measured output level depends on the impedance of the headphone 44h. The EC 31 notifies the CPU 11 of the measured output level. (Step S108) The CPU 11 refers to the setting table, determines a maximum output voltage corresponding to the output level notified by the EC 31, and sets the determined maximum output voltage as the maximum output voltage of the audio signal output from the audio system .

[0060] (Step S110) The CPU 11 refers to the setting table, determines an output gain corresponding to the output level notified by the EC 31, and sets the determined output gain as the output gain in the audio system . (Step S112) The audio system 26 adjusts the volume of the audio signal decoded by the codec 26c based on the set output gain, and outputs the audio signal after the volume adjustment to the headphones 44h via the audio terminal 124a. Then, the process of FIG. 6 ends.

[0061] Next, a configuration example of the processing circuit 36 ​​according to this embodiment will be described. Fig. 7 is a circuit diagram showing a configuration example of the processing circuit 36 ​​according to this embodiment. In Fig. 7, the reference signal line is omitted. It is also assumed that the headphone 44h is connected to the audio terminal 124a. The processing circuit 36 ​​includes a rectifier D2, resistors R2 and R3, and a storage element C2. The rectifier D2 and the resistor R2 are connected in series. The resistor R2 is connected in series with the resistor R2 and the storage element C2. The resistor R2 and the storage element C3 are connected in parallel with each other and with the EC31.

[0062] The rectifying element D2 rectifies the audio signal input from the audio system 26, passing a forward component with a positive potential and blocking a reverse component with a negative potential. The rectifying element D2 outputs the forward component as a rectified audio signal to one end of the resistor element R2. The rectifying element D2 is, for example, a diode. The rectified audio signal is input to one end of the resistor R2 from the rectifier D2. The resistor R2 passes the input audio signal through an electrical resistance value R2 and outputs the signal from the other end to one end of the storage element C2, one end of the resistor R3, and the input end of EC31. An audio signal is input to one end of each of the storage element C2 and the resistor element R3 from the other end of the resistor element R2. The other ends of each of the storage element C2 and the resistor element R3 are electrically connected to the reference potential point. Therefore, the storage element C2 and the resistor element R3 form an RC circuit in parallel with EC31.

[0063] With this configuration, the processing circuit 36 ​​functions as a low-pass filter having low-pass characteristics for the forward component obtained by the rectifying element D2. The capacitance C2 and the resistance R3 are set so that the time constant, which is the product of the capacitance C2 of the storage element and the resistance R3 of the resistive element, is sufficiently larger than the reciprocal of the frequency of the main component of the test signal. The forward component obtained by the rectifying element D2 is smoothed over time, and mainly the DC component is supplied to the EC31.

[0064] The output level V(t) of the test signal output from the codec 26c with a constant amplitude increases over time and approaches a constant value E. As shown in FIG. 8, the output level V(t) is expressed as E(1-e -1 / R3C2), and the difference with E decays exponentially with the time constant R3C2. Figure 9 shows the output level V(t) when E = 1V, R3 = 300kΩ, and C2 = 100nF. The output level V(t) is initially 0V, and does not immediately reach E = 1V immediately after the test signal is output. It becomes 0.9V when the elapsed time t from the start of the test signal output becomes 0.69ms. Therefore, EC31 detects the output level after a time sufficiently longer than the time constant R3C2 (for example, 2.3R3C2 or more) has passed since the start of the test signal output.

[0065] In the above description, the CPU 11 refers to the setting table to determine the output gain or maximum power corresponding to the measured output level, but the present invention is not limited to this. The CPU 11 may calculate the output gain or maximum power from the output level using a preset formula. In the above description, the CPU 11 (i.e., the host system) and the EC 31 are used as controllers that execute volume control, and the processes are shared between them, but the present invention is not limited to this. Either the host system or the EC 31 may execute the processes related to the volume control collectively without sharing them.

[0066] In the above description, the information processing device 1 is configured as a notebook PC, but the present invention is not limited to this. The information processing device 1 may be configured as, for example, a mobile phone or a tablet terminal device. The information processing device 1 may also have a built-in sound source separate from the sound source 44 that is detachable using the audio terminal 124a. In this case, when the host system detects the connection of the sound source 44 to the audio terminal 124a, it disconnects the built-in sound source. When the host system detects the removal of the sound source 44 from the audio terminal 124a, it reconnects to the built-in sound source.

[0067] As described above, the present embodiment includes a controller (for example, a host system, EC 31) and an audio system 26. When the controller detects a connection between the audio system 26 and the sound source 44, the controller measures the output level of a test signal to be output to the sound source 44. The controller determines the output gain of an audio signal to be output from the audio system to the sound source 44 based on the measured output level. The controller may determine the output gain based on, for example, the impedance of the sound source 44 corresponding to the output level, the rated power consumption of the sound source 44, and the internal resistance of the audio system.

[0068] With this configuration, when the sound source 44 is connected to the audio system 26, the output level of the test signal output to the sound source 44 is measured. The output gain of the audio signal output from the audio system 26 to the sound source 44 is determined based on the measured output level. Here, the controller determines the output gain of the audio signal so that the higher the measured output level, the larger the output gain becomes. Since the lower output level is compensated for as the impedance of the sound source 44 connected to the audio system 26 becomes higher, the difference in output level depending on the type of sound source 44 is reduced.

[0069] The controller may also determine the maximum voltage of the audio signal based on the impedance of the sound source 44, the maximum power consumption of the sound source, and the internal resistance. The audio system 26 controls the voltage of the audio signal output from itself so that it does not exceed the maximum voltage, thereby preventing an audio signal having an excessive voltage exceeding the maximum voltage from being input to the sound source 44. Therefore, the sound source 44 is protected.

[0070] The test signal may have frequency components above the audible range. Even if the sound source 44 is attached and a sound based on the test signal is presented, the listener does not perceive the presented sound. Therefore, the listener does not experience discomfort due to the presentation of the sound based on the test signal.

[0071] The information processing device 1 may include a rectifying element that rectifies the test signal and outputs a rectified signal, and a low-pass filter that extracts a low-pass signal from the rectified signal. The controller may measure the output level of the low-pass signal. With this configuration, the DC component of the rectified signal obtained by rectifying the test signal is obtained as the main component, and the output level of the rectified signal is measured. Therefore, the power of the test signal can be estimated from the output level measured with this simple configuration.

[0072] The low-pass filter may include a resistive element and a storage element in parallel with the controller. The controller may detect the output level a predetermined time after the output of the test signal. The predetermined time is a value greater than the product of the resistance value of the resistive element and the capacitance of the storage element. Since a sufficient amount of time has passed since the start of the output of the test signal and an output level approximating a constant value is detected, the output level of the DC component is detected more accurately than immediately after the start of the output of the test signal.

[0073] Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to the above embodiment, and the present invention also includes designs that do not deviate from the gist of the present invention. The configurations described in the above embodiment can be combined in any combination. [Explanation of symbols]

[0074] 1...information processing device, 11...CPU, 12...main memory, 13...GPU, 21...PCH, 22...BIOS memory, 23...auxiliary storage device, 24...USB connector, 25...WLAN card, 26...audio system, 26c...codec, 31...EC, 32...input device, 33...power supply circuit, 34...battery, 36...processing circuit, 44...sound source, 44h...headphones, 101...first housing, 103...display, 105...second housing, C2...power storage element, D2...rectifier element, R2, R3...resistor element

Claims

1. Equipped with a controller and audio system, The controller: when detecting a connection between the audio system and a sound source, Measure the output level of the test signal output to the sound source; An output gain of an audio signal output from the audio system to the sound source is Determined based on the impedance of the sound source corresponding to the output level, the rated power consumption of the sound source, and the internal resistance of the audio system. Information processing device.

2. The controller: determining a maximum voltage of the audio signal based on the impedance of the sound source, the maximum power consumption of the sound source, and the internal resistance of the sound source; The information processing device according to claim 1 .

3. A controller, an audio system, a rectifying element that rectifies the test signal to be output to the sound source and outputs a rectified signal; a low-pass filter for extracting a low-pass signal from the rectified signal; the test signal has a frequency component higher than the audible range; The low pass filter is A resistor element and a capacitor element are connected in parallel with the controller, The controller: measuring an output level of the low-pass signal after a predetermined time has elapsed since the start of output of the test signal; An output gain of an audio signal output from the audio system to the sound source is Based on the output level, The predetermined time is greater than the product of the resistance value of the resistive element and the capacitance of the power storage element. Information processing device.

4. A method for controlling an information processing device including a controller and an audio system, comprising: The controller: when detecting a connection between the audio system and a sound source, measuring an output level of a test signal output to the sound source; An output gain of an audio signal output from the audio system to the sound source is determining the output level based on the impedance of the sound source, the rated power consumption of the sound source, and the internal resistance of the audio system. Control methods.

5. A controller, an audio system, a rectifying element that rectifies the test signal to be output to the sound source and outputs a rectified signal; a low-pass filter that extracts a low-pass signal from the rectified signal, the test signal has a frequency component higher than the audible range; The low pass filter is A resistor element and a capacitor element are connected in parallel with the controller, The controller: measuring an output level of the low-pass signal after a predetermined time has elapsed since the start of output of the test signal; An output gain of an audio signal output from the audio system to the sound source is determining based on the output level, The predetermined time is greater than the product of the resistance value of the resistive element and the capacitance of the power storage element. Control methods.

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