Alert system for detecting the presence of children in car seats using a pressure sensor and radio key fob.

Abstract

A Child Presence Detection Alert System for Car Seats, characterized by comprising: a. A Detection Module, configured to be integrated into a car seat (S), which includes: i. A pressure sensor, capable of detecting the presence of a child by their weight. ii. A radio transmitter module (TX), to emit a wireless "presence" signal when the pressure sensor detects weight. iii. A button cell battery, for powering the module. iv. A low battery alarm, capable of emitting an audible and / or wireless signal indicating a low battery level. b. An Alert Device (Keychain Receiver), portable and intended to be carried by a caregiver, which includes: i. A radio receiver module (RX), configured to listen to the signal from the radio transmitter module. ii. An alert unit, capable of generating an audible and / or vibrating alarm. iii. A button cell battery, for powering the keychain.

Description

Child presence detection alert system for car seats using a pressure sensor and radio key fob Technology sector The present invention falls within the field of personal safety and alert devices, specifically in the area of ​​safety accessories for child transportation in vehicles. Its main application focuses on preventing accidents caused by children being left inside cars, using presence detection technologies and short-range wireless communication. Background of the invention The problem of children accidentally left inside vehicles, especially in hot weather, poses a serious and sometimes fatal risk. Despite growing public awareness, these incidents continue to occur, highlighting the need for effective and accessible technological solutions. In the current state of the art, there are several approaches to addressing this problem: * Integrated systems in high-end vehicles: Some modern cars include occupant detection systems that can alert the driver if movement is detected in the back seat after the engine is turned off. These systems are often complex, expensive, and exclusive to certain vehicle models, which limits their widespread adoption. * Mobile apps and Bluetooth devices: Solutions have been developed that link a sensor in the car seat to an app on the driver's smartphone via Bluetooth. However, their reliability can be compromised by dependence on the mobile phone, battery life, connectivity issues, or the need for complex interactions with the app. * Devices with GPS or cellular connectivity: These offer remote tracking and alerting capabilities, but involve higher hardware costs and often monthly subscriptions, making them less accessible to the general public. This background demonstrates the existence of solutions that, while seeking to solve the same problem, often sacrifice simplicity and cost-effectiveness for greater functionality, or rely on infrastructures (such as smartphones or cellular networks) that are not always ideal for immediate and robust alerts at critical moments. The present invention seeks to overcome these limitations by offering an autonomous, low-cost, and highly reliable solution, without the need for complex pairings or external dependencies. Explanation of the invention The present invention relates to a Child Presence Detection System in Car Seats using a Pressure Sensor and Radio Keyring, designed to prevent children from being accidentally left inside vehicles. The system is based on direct wireless communication between a presence detection module, located in the child seat, and a portable, keyring-type alert device carried by the caregiver. The technical problem posed is the need for a child safety alert system that is inexpensive, universally compatible, easy to use, and highly reliable, without requiring the intervention of smartphones or other complex devices. The proposed solution consists of two main components that operate autonomously: * Detection Module: It consists of a thin mat or cushion that integrates a small pressure sensor. This sensor is sensitive to a child's weight, activating when it detects a load exceeding a predefined threshold (e.g., 5 kg). The module incorporates a small, low-power, short-range radio transmitter (TX) module (similar to those used in key finders), which emits a constant "presence" signal while detecting weight. The module is powered by a long-life coin cell battery (e.g., CR2032). Additionally, the detection module includes a low-battery alarm that, upon reaching a critical voltage level, emits a discreet beep and a specific "low battery" signal to the key fob. * Alert Device (Receiver Keyring): This is a compact and lightweight radio key fob, designed to be carried by a parent or caregiver. This key fob incorporates a radio receiver (RX) module that continuously listens for the signal emitted by the detection module. The key fob's alert logic is based on the loss of this signal. * If the key fob loses the signal from the detection module (indicating that the caregiver has moved away from the vehicle, exceeding the radio communication range), AND the detection module on the chair is still reporting presence (i.e., the pressure sensor is still detecting weight), the key fob immediately activates a loud audible alarm and / or vibration to alert the caregiver. * If the key fob is within communication range and receives the "presence" signal, or if the sensor on the chair is not detecting weight, the key fob remains silent. The key fob is also programmed to recognize and issue a specific alert (e.g., a different beep pattern or an LED indicator) when it receives a "low battery" signal from the detection module. The key fob is also powered by a coin cell battery. Advantages of the invention compared to the prior art: * Low Cost: By using inexpensive electronic components and short-range radio technologies, the manufacturing cost and, therefore, the final price for the consumer remains significantly low, making it accessible to a wide range of families. * Ease of Use: It requires no smartphone pairing, app downloads, or complex configurations. It's a "plug and play" system that works independently once installed and initially paired. * Reliability: Direct radio communication and the use of robust pressure sensors ensure consistent detection and alerting, making it less prone to connectivity problems or interference common in Bluetooth or Wi-Fi based systems. * Universality and Compatibility: The detection mat is adaptable to any existing car seat, regardless of the vehicle model or brand, making it a universal solution. * Compact and Discreet: Both the sensor module and the keyring are small in size, making it easy to integrate into the chair and portable by the caregiver. * Autonomous: It does not depend on the vehicle's battery or the car's electrical infrastructure, operating with its own long-life batteries. * Bidirectional Low Battery Alert: The system not only alerts about the presence of the child, but also proactively notifies about the low battery level of the sensor module, ensuring its maintenance. Preferred embodiment of the invention In a preferred embodiment of the invention, the Child Presence Detection Alert System in Car Seats comprises a Detection Module and an Alert Device (Receiver Keyring), which operate together by means of radio communication. The Detection Module is configured as a thin, flexible mat, approximately 5 mm thick and measuring about 20x20 cm, designed to be discreetly placed under the cover or padding of any child car seat. It can even be secured with Velcro strips if necessary. This mat is made of an abrasion-resistant and easy-to-clean technical fabric, internally encapsulating the pressure sensor. This sensor can be either resistive or capacitive, configured to detect a minimum weight, thus preventing false alarms from light objects. Integrated into one edge or the underside of the mat is a small, flat, sealed capsule (approximately 5x3x1 cm) that houses a mini electronic board with a low-power microcontroller and the radio transmitter (TX) module, operating on a short-range ISM (Industrial, Scientific, Medical) frequency (e.g., 1000).433 MHz or 868 MHz), and an accessible battery compartment for a CR2032 coin cell battery. A power management circuit monitors the battery voltage and, upon detecting a critical level, activates a piezoelectric micro-speaker integrated into the capsule to emit an audible beep and, simultaneously, sends a coded "low battery" signal to the key fob. The Alert Device (Receiver Keyring) features a compact and ergonomic design, similar to a modern car key, with approximate dimensions of 6 x 3.5 x 1.2 cm. Its casing is molded from high-quality ABS plastic. Internally, it contains a mini electronic board with a low-power microcontroller, a radio receiver (RX) module tuned to the detection module's frequency, a higher-volume piezoelectric speaker for the main alarms, and optionally, a small vibration motor. A single pairing button allows for initial connection to the detection module. The keyring is powered by a CR2032 coin cell battery, housed in an easily accessible compartment. The keyring includes a discreet multi-color LED to indicate status: green for active connection, flashing red for child in-car alarm, and yellow for low sensor battery alert. The system works as follows: * Pairing: After the initial installation of the mat, the key fob is paired only once with the detection module by pressing the pairing button. * Presence Detection: When the child is placed in the seat, the pressure sensor detects their weight. The microcontroller in the Detection Module processes this signal and, if the weight exceeds the threshold, activates the radio transmitter module to continuously send a "child present" signal to the key fob. * Keyring Monitoring: The Alert Device is in constant listening mode, receiving the "child present" signal. While this signal is received and the caregiver is within communication range (approximately 5-15 meters, adjustable depending on transmission power), the keyring remains in silent monitoring mode (possibly with a flashing green LED). * Alert Activation: If the key fob stops receiving a signal from the Detection Module (indicating that the caregiver has moved beyond the signal range of the vehicle), and the last status received from the Detection Module indicated "child present," then the key fob immediately activates a high-intensity audible alarm and / or vibration to alert the caregiver. The alarm stops when the key fob receives the signal again or when the pressure sensor on the car seat stops detecting weight (the child is removed). * Low Battery Alert: If the Detection Module's microcontroller detects a low battery voltage, it activates an audible alarm and sends a specific "low battery" signal to the Alert Device. Upon receiving this signal, the key fob emits a different beep pattern or illuminates a yellow LED to indicate to the caregiver that the sensor battery needs replacing. The invention is suitable for industrial application in the child safety and automotive sectors. It can be mass-produced using plastic injection molding and surface-mount device (SMD) electronic component assembly, resulting in low production costs. It is easily marketable as a standalone accessory or as an optional component in child car seats.

Claims

1. A Child Presence Detection Alert System for Car Seats, characterized by comprising: a. A Detection Module, configured to be integrated into a car seat (S), which includes: i. A pressure sensor, capable of detecting the presence of a child by their weight. ii. A radio transmitter module (TX), to emit a wireless "presence" signal when the pressure sensor detects weight. iii. A button cell battery, for powering the module. iv. A low battery alarm, capable of emitting an audible and / or wireless signal indicating a low battery level. b. An Alert Device (Keychain Receiver), portable and intended to be carried by a caregiver, which includes: i. A radio receiver module (RX), configured to listen to the signal from the radio transmitter module. ii. An alert unit, capable of generating an audible and / or vibrating alarm. iii. A button cell battery, for powering the keychain. 2.An alert system according to claim 1, characterized in that the detection module is presented as a thin, flexible mat, adaptable to the base of any car seat, encapsulating the pressure sensor and the radio transmitter module.

3. An alert system according to any of claims 1 or 2, characterized in that the pressure sensor is configured to detect a predefined minimum weight, preventing false alarms from light objects.

4. An alert system according to any of claims 1 to 3, characterized in that it comprises an alert unit configured to activate upon the absence of reception of the presence signal from the detection module linked to the detection status of the pressure sensor.

5. An alert system according to any of claims 1 to 4, wherein the alert unit (receiver key fob) is configured to emit a specific alert upon receiving a low battery signal from the detection module. 6.An alert system according to any of claims 1 to 5, characterized in that the radio transmitter module and the radio receiver module operate in a short-range ISM frequency band.

7. An alert system according to any of claims 1 to 6, characterized in that the alert device (receiver key fob) includes an indicator LED to visually communicate the system status, including active connection, child safety lock, and low sensor battery.