This paper explores the development of a car reversing anti-collision voice prompter that integrates a reflective near-infrared sensor with a voice recording and playback system. When a vehicle is in reverse, if an object or person is within a specific distance behind the car, infrared light emitted by the sensor will reflect off the object and be captured by the receiving component. This signal is then converted into an electrical signal, amplified, demodulated, and processed to generate a control signal that activates the voice module. The system alerts the driver about obstacles behind the car, enhancing safety by compensating for blind spots in the rearview mirror. The compact design, low cost, and ease of installation make this device ideal for automotive applications.
Introduction
With the rapid advancement of technology, new materials, processes, and devices have emerged to improve efficiency, reduce labor, enhance safety, and conserve resources. Infrared sensors, particularly those using near-infrared technology, have become essential in various fields. The use of infrared in remote controls began as early as 1972, and since the 1990s, near-infrared sensors have been widely applied in automation, security, and vehicle systems. These sensors typically operate at a wavelength of 940nm and rely on both transmission and reception for effective detection.
The voice prompt system described in this paper utilizes the TX05D reflective infrared sensor for object detection during reversing. When a vehicle is backing up, especially in tight spaces like parking garages, the sensor detects nearby objects and triggers the voice module to alert the driver. This system helps overcome the limitations of rearview mirrors, which often leave blind spots. The voice recording and playback component, such as the ISD1420, allows for high-quality audio storage and playback, with a long lifespan and easy re-recording. It supports 100,000 recording cycles and retains data for over 100 years without power. The system is powered by a 12V battery and a 6V voltage regulator, making it convenient and reliable for daily use.
Key features of the system include strong anti-interference capabilities, stable performance, and a detection range of up to 1.2 meters, making it suitable for automotive environments. Its compact size, simple wiring, and robust construction ensure ease of installation and long-term operation.
1 Module Structure and Working Principle
1.1 Reflective Near-Infrared Sensor TX05D
The TX05D is a fully integrated sensor module with dimensions of 46mm × 32mm × 17mm. It includes an indicator LED and a sensitivity adjustment hole, allowing users to fine-tune the detection range. The red LED indicates the working status—normally off, but it lights up when a reflector is detected. The sensor uses a 1.5m double-core shielded cable, with the red wire connected to the positive power supply and the white wire serving as the output. The shielding is grounded within the detection area. If an object is present, the output voltage rises; otherwise, it remains low. The operating voltage ranges from 5V to 12V, with a maximum current of 30mA and a detection range of up to 1.2 meters.
When activated, the TX05D emits modulated infrared signals at 38kHz. If an object reflects the signal, the receiver captures it, converts it into an electrical signal, and processes it through amplification, demodulation, and shaping. The final output is a high-level signal, which can trigger the voice module. The built-in modulation and anti-jamming features help minimize interference from ambient light or other sources.
1.2 Voice Recording and Playback Component ISD1420
The ISD1420 is a single-chip voice recording and playback module based on advanced US ISD technology. It includes a noise-canceling microphone preamplifier, automatic gain control, and a highly stable clock oscillator. This ensures clear audio quality, long-term memory retention, and excellent durability. The component operates on a 4.5–6.5V power supply, with a quiescent current of 0.5mA and a working current of 25mA. It supports recording times of 10–20 seconds and can store information permanently, even after power loss. With a capacity of 100,000 recordings, it offers long-term reliability and flexibility. It can be used with a standard electret microphone and a 8–16Ω speaker, making it easy to integrate into various systems.
2 Wiring Diagram of the Reversing Anti-Collision Voice Prompter
The system consists of a near-infrared sensor (TX05D), a voice module (ISD1420), and a power supply. A 7806 voltage regulator (IC1) provides stable power, while the TX05D (IC2) serves as the sensing unit. The ISD1420 (IC3) handles the voice functions. A relay (KS) is used to control the playback circuit. The TX05D is mounted on the rear of the vehicle, aligned to detect objects behind the car. When the car is in reverse, the backup light turns on, activating the system automatically. This ensures that the driver receives timely warnings when obstacles are detected.
3 Operation Process
3.1 Recording
Once the system is powered on, it enters a low-power standby mode. To start recording, the user presses and holds the REC button. The LED indicator lights up, signaling that the system is in recording mode. The driver can speak instructions or messages, and the content is stored until the memory is full or the button is released. This feature allows for personalized voice alerts tailored to specific driving conditions.
3.2 Playback
Playback can be initiated by pressing the PLAY button or using a dedicated switch. The system continuously loops the recorded message until the object is no longer detected. When the TX05D senses an obstacle, it sends a signal to activate the relay, which connects the voice module to the playback circuit. Once the object moves away, the relay de-energizes, stopping the playback. This ensures that the driver receives continuous feedback while reversing, significantly improving safety and reducing the risk of collisions.
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