Sound source preprocessing circuit for sound source tracking table lamp

Abstract

The utility model relates to a sound source preprocessing circuit for a sound source tracking table lamp. A preprocessing circuit module comprises a sound acquisition unit, a signal amplification unit and a signal filtering unit. For a first preprocessing circuit module, a grid electrode of a first field effect transistor in a sound acquisition unit is connected with a first electret in a first microphone, and is connected to a first signal amplification unit through a first capacitor; in the first signal amplification unit, the base electrode of a first NPN type triode is connected with a first capacitor through a resistance voltage division circuit, and the collector electrode of the first NPN type triode is connected with a first signal filtering unit through a second capacitor. The first signal filtering unit comprises a second-order active band-pass filter constructed by an operational amplifier, the negative input end of the operational amplifier is connected with a second capacitor, and a filter circuit comprises a high-pass branch and a low-pass branch which are connected in parallel. Compared with the prior art, the utility model has the advantages of high accuracy, easy detection of weak signals, adaptation to human voice and the like.

Description

Technical Field

[0001] This utility model relates to the field of lighting equipment, and in particular to a sound source preprocessing circuit for a sound source tracking desk lamp. Background Technology

[0002] Most desk lamps on the market today only have passive lighting functions, meaning that changes in the illuminated area and the user's posture depend on the user's intervention. For example, in a dark room, the user must manually operate the lamp switch to generate a light source, and the lamp cannot provide an instantaneous lighting effect. Similarly, if the entire room is illuminated only by the desk lamp, the user's view may be obstructed if they move to an area not illuminated by the lamp.

[0003] To address this issue, a convenient follow-up lighting service is provided by automatically adjusting the lighting direction based on the location of sound sources in the environment. In existing technologies, sound source localization primarily relies on microphones to collect sound signals, which then drive a motor to adjust the lamp head's orientation. The method involves calculating the sound source location through geometric analysis using the microphone's position coordinates and the time delay of the received sound signal. However, such systems still have several limitations in practical applications. First, in complex environments, such as those with background noise, electromagnetic interference, or weak sound signals, the positioning accuracy and stability of existing systems significantly decrease. Due to the lack of effective signal optimization methods, weak signals are easily drowned out by noise, leading to misjudgment or missed detection of sound source locations. Second, existing technologies lack targeted processing of the frequency characteristics of sound source signals, making it difficult to effectively distinguish between human voice frequencies and environmental noise, further reducing positioning reliability. Finally, existing desk lamps typically directly convert sound signals into drive signals, resulting in inaccurate sound source localization. Therefore, improving the intelligence level of sound source tracking desk lamps, enhancing their anti-interference capabilities in complex environments, and accurately locating sound sources to make the lamp's following action more precise are technical problems that need to be solved. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology by providing a sound source preprocessing circuit for a sound source tracking desk lamp. It uses a microphone array to detect the sound source of human speech in the room to locate the user's position, thereby realizing intelligent tracking lighting for the user, optimizing the lighting effect, and adding a preprocessing circuit before the sound source signal processing to improve the quality of the sound source signal and avoid misjudgment or omission due to weak signal, thus providing solid computational support for sound source tracking.

[0005] The objective of this utility model can be achieved through the following technical solutions:

[0006] According to one aspect of this utility model, a sound source preprocessing circuit for a sound source tracking desk lamp is provided, comprising a microphone array module consisting of four microphones, each microphone being connected to a DSP processing module via a preprocessing circuit module.

[0007] The preprocessing circuit module includes a sound acquisition unit, a signal amplification unit, and a signal filtering unit. In the first preprocessing circuit module, the gate of the first field-effect transistor in the sound acquisition unit is connected to the first electret in the first microphone and to the first signal amplification unit via a first capacitor. In the first signal amplification unit, the base of the first NPN transistor is connected to the first capacitor via a resistor divider circuit, and the collector of the first NPN transistor is connected to the first signal filtering unit via a second capacitor. The first signal filtering unit includes a second-order active bandpass filter constructed from an operational amplifier. The negative input terminal of the operational amplifier is connected to the second capacitor. The filter circuit includes a parallel high-pass branch and a low-pass branch. The output terminal of the operational amplifier is connected to the DSP processing module.

[0008] Furthermore, the second, third, and fourth preprocessing circuits have the same structure as the first preprocessing circuit, forming four independent processing links.

[0009] Furthermore, the voltage divider circuit in the first signal amplification unit includes a second resistor and a fourth resistor connected in series.

[0010] Furthermore, the second resistor is connected to VCC, and the fourth resistor is grounded.

[0011] Furthermore, the high-pass branch in the first signal filtering unit includes a third capacitor and a seventh resistor, with a cutoff frequency of 3400Hz. The two ends of the third capacitor are respectively connected to the negative input terminal of the operational amplifier and the fifth resistor, and the two ends of the seventh resistor are respectively connected to the negative input terminal and the output terminal of the operational amplifier.

[0012] Furthermore, the low-pass branch in the first signal filtering unit includes a fifth resistor and a fourth capacitor, with a cutoff frequency of 300Hz. The two ends of the fifth resistor are respectively connected to the second capacitor and the third capacitor, and the two ends of the fourth capacitor are respectively connected to the third capacitor and the output terminal of the operational amplifier.

[0013] Furthermore, the drain of the first field-effect transistor in the sound acquisition unit is connected to VCC through a second resistor, and the source of the first field-effect transistor is grounded.

[0014] Furthermore, the collector of the first NPN transistor in the first signal amplification unit is connected to VCC through a third resistor, and the emitter of the first NPN transistor is grounded.

[0015] Furthermore, the negative input of the operational amplifier is also grounded through a sixth resistor.

[0016] Furthermore, the four microphones of the microphone array module are arranged in a uniform ring.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) Improve weak signal recognition capability: By setting up an independent three-level preprocessing circuit, the sound is collected, the signal is amplified and then filtered. The current amplification characteristics of the first NPN transistor are used to amplify the microphone output signal. At the same time, the DC component is filtered out by the coupling capacitor, which effectively enhances the strength and signal-to-noise ratio of the original sound source signal and avoids misjudgment or missed judgment due to weak signal.

[0019] (2) Accurate extraction of human voice frequency band features: A second-order active bandpass filter with specific parameters is used, with the high-pass branch cut off at 300Hz and the low-pass branch cut off at 3400Hz. This filter specifically removes low-frequency noise below 300Hz and high-frequency interference above 3400Hz, while retaining the core frequency band signal of human voice in the 300-3400Hz range. This ensures that the sound source signal input to the DSP processing module has effective features from the source.

[0020] (3) Enhance the reliability of the sound source localization system: Based on the hardware design of four symmetrical preprocessing links and the sixth resistor of the operational amplifier negative input grounding resistor, a stable signal conditioning channel is formed to eliminate environmental noise and inherent circuit interference, providing a highly consistent and low-distortion multi-channel time difference signal for subsequent sound localization calculation, and ensuring the accuracy of azimuth angle calculation. Attached Figure Description

[0021] Figure 1 This is a circuit diagram of the sound source preprocessing circuit used in a sound source tracking desk lamp.

[0022] The following are the labels in the diagram: Q11, first electret MOSFET; Q12, first field-effect transistor; Q13, first NPN transistor; C11, first capacitor; C12, second capacitor; C13, third capacitor; C14, fourth capacitor; R11, first resistor; R12, second resistor; R14, fourth resistor; R15, fifth resistor; R16, sixth resistor; R17, seventh resistor. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present utility model.

[0024] The sound source tracking desk lamp can locate the source based on sound signals, thereby driving a motor to actively follow the voice and illuminate the lamp. Before determining the sound source's location, a pre-processing circuit is specifically designed to amplify and filter the sound signal, ensuring an accurate and robust identification signal for subsequent sound source location calculations. The DSP processing module calculates the azimuth angle of the sound source relative to the desk lamp, then converts this azimuth angle into a motor drive signal. This causes the No. 5 motor at the bottom of the lamp to rotate according to the azimuth angle, thus achieving the sound source tracking lighting function.

[0025] like Figure 1 As shown, this is a sound source preprocessing circuit for a sound source tracking desk lamp, consisting of a microphone array module with four microphones. Each microphone is connected to the DSP processing module through the preprocessing circuit module.

[0026] The preprocessing circuit module includes a sound acquisition unit, a signal amplification unit, and a signal filtering unit. In the first preprocessing circuit module, the gate of the first field-effect transistor Q12 in the sound acquisition unit is connected to the first electret condenser Q11 in the first microphone, and is connected to the first signal amplification unit through the first capacitor C11. The second resistor R12 is connected to VCC, and the fourth resistor R14 is grounded. In the first signal amplification unit, the base of the first NPN transistor Q13 is connected to the first capacitor C11 through a resistor divider circuit, and the collector of the first NPN transistor Q13 is connected to the first signal filtering unit through the second capacitor C12. The voltage divider circuit in the first signal amplification unit includes the second resistor R12 and the fourth resistor R14 connected in series. The first signal filtering unit includes a second-order active bandpass filter constructed from an operational amplifier. The negative input terminal of the operational amplifier is connected to the second capacitor C12. The filter circuit includes a high-pass branch and a low-pass branch connected in parallel, and the output terminal of the operational amplifier is connected to the DSP processing module. The high-pass branch in the first signal filtering unit includes a third capacitor C13 and a seventh resistor R17, with a cutoff frequency of 3400Hz. The two ends of the third capacitor C13 are connected to the negative input terminal of the operational amplifier and the fifth resistor R15, respectively. The two ends of the seventh resistor R17 are connected to the negative input terminal and the output terminal of the operational amplifier, respectively. The low-pass branch in the first signal filtering unit includes a fifth resistor R15 and a fourth capacitor C14, with a cutoff frequency of 300Hz. The two ends of the fifth resistor R15 are connected to the second capacitor C12 and the third capacitor C13, respectively. The two ends of the fourth capacitor C14 are connected to the third capacitor C13 and the output terminal of the operational amplifier, respectively. The voltage divider circuit in the first signal amplification unit includes a second resistor R12 and a fourth resistor R14 connected in series. The drain of the first field-effect transistor Q12 in the sound acquisition unit is connected to VCC through the second resistor R12, and the source of the first field-effect transistor Q12 is grounded. The collector of the first NPN transistor Q13 in the first signal amplification unit is connected to VCC through the third resistor R13, and the emitter of the first NPN transistor Q13 is grounded. The negative input of the operational amplifier is also grounded through the sixth resistor R16.

[0027] The remaining second, third, and fourth preprocessing circuits have the same structure as the first preprocessing circuit, forming four independent processing links. The four microphones of the microphone array module are arranged in a uniform ring.

[0028] The DSP processing module circuit of this utility model is existing technology, and its specific circuit structure and working principle will not be described in detail here.

[0029] In this embodiment, the sound acquisition module's acquisition function primarily relies on the first electret condenser Q11. The first electret condenser Q11 has a diaphragm on top and a metal plate below, with a certain amount of permanent charge injected between them, equivalent to a capacitor with a variable capacitance. When the diaphragm senses sound waves, it vibrates, causing the distance between the diaphragm and the metal plate of the first electret condenser Q11 to shorten. Since the capacitance value is related to the distance between the plates, the capacitance of the first electret condenser Q11 also changes, increasing. Furthermore, since the charge is the product of capacitance and voltage, when the plate distance shortens, the voltage of the first electret condenser Q11 decreases. Even further, the voltage change of the first electret condenser Q11 causes a change in the output impedance and voltage of the first field-effect transistor Q12, thereby converting the sound signal into an electrical signal. Additionally, a coupling capacitor, the first capacitor C11, is added to the sound acquisition module to filter out the inherent DC signal of the circuit.

[0030] The electrical signal output from the first sound acquisition module serves as the input to the signal amplification module, flowing to the first NPN transistor Q13. The first NPN transistor Q13 is an NPN transistor with current amplification capabilities; its collector current is equal to the base current. β times ( β >1), and β The magnitude depends on the doping concentration ratio of the emitter to the base. Resistors R12 and R14 are used to adjust the voltage so that the base voltage of the first NPN transistor Q13 is greater than 0.7V, thus putting the transistor in the on state. The signal amplification module amplifies the input base current and outputs the amplified signal at the collector of the first NPN transistor Q13. Subsequently, this signal passes through the second capacitor C12, which blocks DC and passes AC, to filter out the DC component and provide a processed AC signal for subsequent modules.

[0031] The first signal filtering module is used to retain useful frequency signals and filter out other noise. This sound source tracking lamp is based on indoor human voice localization, and the human voice frequency band is typically 300-3400Hz. Therefore, the filtering module is designed as a bandpass filter with cutoff frequencies of 300Hz and 3400Hz. The signal filtering module is built based on an operational amplifier and is a second-order active bandpass filter. By calculating the high-pass and low-pass cutoff frequencies, the impedance values ​​of the fifth resistor R15, the seventh resistor R17, the third capacitor C13, and the fourth capacitor C14 can be obtained. Typically, the low-pass filter capacitor is chosen to be 1000pF, and the high-pass filter capacitor is chosen to be 0.1uF; therefore, R15 = 10kΩ, R17 = 1kΩ, C13 = 0.01μF, and C14 = 0.001μF. Current flows from the signal amplification module to the negative input terminal of the operational amplifier, while the positive input terminal is grounded. The fifth resistor R15 and the fourth capacitor C14 are low-pass filters, allowing signals below 3400Hz to pass through; the third capacitor C13 and the seventh resistor R17 are high-pass filters, allowing signals above 300Hz to pass through. Taking the intersection of these two sets of filters allows signals in the 300~3400Hz frequency range to pass through, while other frequencies such as low-frequency white noise and high-frequency electromagnetic noise are filtered out. The final filtered signal is then input to the chip in the DSP processing module.

[0032] In this embodiment, the circuit is used in a sound source tracking desk lamp. Specifically, a microphone array is set in the lamp holder, consisting of four electret microphone sensors arranged in a circular, evenly spaced pattern to collect external sound signals. The PB0-PB3 pins of the DSP processing module chip are interrupt pins. When the lamp is turned on, timers on each pin are activated, and external signals trigger timer interrupts. Each electret microphone outputs a pre-processed sound source signal to the PB0-PB3 pins of the DSP processing module chip through a pre-processing circuit. When a sound signal is generated at the chip's input pin, triggering a level flip, the timer is interrupted and the current time is recorded. Because the sound source signal arrives at any two microphone sensors at different times, the trigger times of the two interrupt pins are also different, resulting in a time difference, which is the time delay. τ .according to τ The TDOA algorithm can be used to solve for the azimuth angle of the sound source. The coordinates of the sound source can be obtained through geometric analysis using the coordinates of the four microphones and the sound time delay.

[0033] The signal amplification circuit in this embodiment can enhance weak signals, improve the signal-to-noise ratio, and enable the chip to identify signals more accurately, avoiding misjudgment or missed judgment due to weak signals. Filtering can effectively remove interference components, retain useful signal characteristics, and further improve signal quality, making the chip's judgment of signal time sequence more accurate. Especially in complex environments, it can filter out interference factors such as environmental noise, making the signal clearer and more stable, thereby improving the accuracy and stability of time sequence judgment.

[0034] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this utility model, and these modifications or substitutions should all be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A sound source preprocessing circuit for a sound source tracking desk lamp, characterized in that, The microphone array module consists of four microphones, each of which is connected to the DSP processing module via a preprocessing circuit module. The preprocessing circuit module includes a sound acquisition unit, a signal amplification unit, and a signal filtering unit. In the first preprocessing circuit module, the gate of the first field-effect transistor (Q12) in the sound acquisition unit is connected to the first electret condenser (Q11) in the first microphone, and is connected to the first signal amplification unit via a first capacitor (C11). In the first signal amplification unit, the base of the first NPN transistor (Q13) is connected to the first capacitor (C11) via a resistor divider circuit, and the collector of the first NPN transistor (Q13) is connected to the first signal filtering unit via a second capacitor (C12). The first signal filtering unit includes a second-order active bandpass filter constructed from an operational amplifier. The negative input terminal of the operational amplifier is connected to the second capacitor (C12). The filter circuit includes a parallel high-pass branch and a low-pass branch. The output terminal of the operational amplifier is connected to the DSP processing module.

2. The sound source preprocessing circuit for a sound source tracking desk lamp according to claim 1, characterized in that, The second, third, and fourth preprocessing circuits have the same structure as the first preprocessing circuit, forming four independent processing links.

3. The sound source preprocessing circuit for a sound source tracking desk lamp according to claim 1, characterized in that, The voltage divider circuit in the first signal amplification unit includes a second resistor (R12) and a fourth resistor (R14) connected in series.

4. The sound source preprocessing circuit for a sound source tracking desk lamp according to claim 3, characterized in that, The second resistor (R12) is connected to VCC, and the fourth resistor (R14) is grounded.

5. The sound source preprocessing circuit for a sound source tracking desk lamp according to claim 1, characterized in that, The high-pass branch in the first signal filtering unit includes a third capacitor (C13) and a seventh resistor (R17), with a cutoff frequency of 3400Hz. The two ends of the third capacitor (C13) are connected to the negative input terminal of the operational amplifier and the fifth resistor (R15), respectively. The two ends of the seventh resistor (R17) are connected to the negative input terminal and the output terminal of the operational amplifier, respectively.

6. The sound source preprocessing circuit for a sound source tracking desk lamp according to claim 1, characterized in that, The low-pass branch in the first signal filtering unit includes a fifth resistor (R15) and a fourth capacitor (C14), with a cutoff frequency of 300Hz. The two ends of the fifth resistor (R15) are connected to the second capacitor (C12) and the third capacitor (C13), respectively. The two ends of the fourth capacitor (C14) are connected to the third capacitor (C13) and the output terminal of the operational amplifier, respectively.

7. The sound source preprocessing circuit for a sound source tracking desk lamp according to claim 1, characterized in that, The drain of the first field-effect transistor (Q12) in the sound acquisition unit is connected to VCC through the second resistor (R12), and the source of the first field-effect transistor (Q12) is grounded.

8. The sound source preprocessing circuit for a sound source tracking desk lamp according to claim 1, characterized in that, The collector of the first NPN transistor (Q13) in the first signal amplification unit is connected to VCC through the third resistor (R13), and the emitter of the first NPN transistor (Q13) is grounded.

9. A sound source preprocessing circuit for a sound source tracking desk lamp according to claim 1, characterized in that, The negative input of the operational amplifier is also grounded through a sixth resistor (R16).

10. The sound source preprocessing circuit for a sound source tracking desk lamp according to claim 1, characterized in that, The four microphones of the microphone array module are arranged in a uniform ring.

Images