A sharpness adaptive device for a cooled thermal imager

Abstract

This invention relates to the field of infrared imaging equipment technology, specifically a sharpness adaptive device suitable for cooled thermal imagers. It includes a temperature detection circuit, a distance input interface circuit, a data storage unit, a main control unit, a lens drive circuit, and a potentiometer. The temperature detection circuit and the distance input interface circuit are used to collect temperature signals and observe distance signals, respectively, and transmit them to the main control unit. The data storage unit stores a three-dimensional calibration table recording the relationship between temperature, distance, and focus. The main control unit determines the optimal focus position corresponding to the current temperature and distance based on the three-dimensional calibration table and generates a PWM control signal. The PWM control signal is transmitted to the lens drive mechanism via the lens drive circuit. The potentiometer is located on the lens and is used to provide feedback on the real-time position of the lens. This invention effectively suppresses focus drift caused by temperature changes through hardware-level closed-loop control, significantly improving the imaging stability and automation level of cooled thermal imagers in complex environments.

Description

Technical Field

[0001] This utility model relates to the field of infrared imaging equipment technology, specifically a sharpness adaptive device suitable for cooled thermal imagers. Background Technology

[0002] During operation, cooled infrared thermal imagers experience thermal expansion and contraction of the optical system and detector due to changes in ambient temperature, causing focus drift ("thermal drift") and resulting in blurred images. Current technologies mostly rely on manual focusing or simple autofocus mechanisms, lacking comprehensive compensation capabilities for temperature and observation distance, thus failing to achieve stable imaging over extended periods. While some high-end devices possess autofocus functionality, their control logic often depends on host computer software or independent algorithm modules, failing to integrate environmental perception, data lookup, and execution into a dedicated hardware circuit system. This leads to slow response, high cost, and poor reliability. Furthermore, in surveillance scenarios, existing devices cannot automatically trigger focusing upon target entry, impacting the efficiency of capturing critical information. Therefore, a device integrating environmental perception, local lookup, and closed-loop control is needed to improve the automation level and imaging stability of cooled thermal imagers. Utility Model Content

[0003] To address the shortcomings of existing technologies, this invention provides a sharpness adaptive device suitable for cooled thermal imagers. Through hardware-level closed-loop control, it effectively suppresses focus drift caused by temperature changes, significantly improving the imaging stability and automation level of cooled thermal imagers in complex environments.

[0004] To solve the aforementioned technical problem, the present invention adopts the following technical solution: a sharpness adaptive device suitable for a cooled thermal imager, comprising a temperature detection circuit, a distance input interface circuit, a data storage device, a main control unit, a lens drive circuit, and a potentiometer. The temperature detection circuit, distance input interface circuit, data storage device, and potentiometer are respectively connected to the input terminal of the main control unit, and the lens drive circuit is connected to the output terminal of the main control unit. The temperature detection circuit is used to collect the temperature of the thermal imager's interior and surrounding environment in real time and transmit it to the main control unit. The distance input interface circuit is used to collect the observation distance signal and transmit it to the main control unit. The data storage device stores a three-dimensional calibration table recording the relationship between temperature, distance, and focus. The main control unit determines the optimal focus position corresponding to the current temperature and distance based on the three-dimensional calibration table and generates a PWM control signal. The PWM control signal is transmitted to the lens drive mechanism via the lens drive circuit. The potentiometer is located on the lens and is used to collect the real-time position of the lens and transmit it to the main control unit.

[0005] Furthermore, the temperature detection circuit includes a temperature sensor and an interface J5. The temperature sensor is mounted on the optical cabin of the thermal imager and is connected to the input terminal of the main control unit via the interface J5.

[0006] Furthermore, the distance input interface circuit includes a laser rangefinder and interface J1, with the laser rangefinder connected to the input terminal of the main control unit via interface J1.

[0007] Furthermore, the lens driving circuit includes a level conversion chip, a lens driving chip, and an interface J4. Port B of the level conversion chip is connected to the output of the main control unit, port A of the level conversion chip is connected to the input of the lens driving chip, and the output of the lens driving chip is connected to the lens driving mechanism through interface J4.

[0008] Furthermore, the level conversion chip is model 74LVC4245, and the lens driver chip is model L293DD.

[0009] Furthermore, it also includes communication circuits, including WiFi communication circuits and 485 communication circuits. The WiFi communication circuit includes a WiFi interface J2, one end of which is connected to the main control unit, and the other end is connected to the peripheral module. The 485 communication circuit includes an RS-485 signal transceiver chip and an interface J3. The R and D pins of the RS-485 signal transceiver chip are connected to the main control unit, and the A and B pins of the RS-485 signal transceiver chip are connected to the peripheral module through the interface J3.

[0010] Furthermore, the peripheral modules communicate with the host computer.

[0011] The beneficial effects of this invention are as follows: This invention uses a temperature detection circuit to collect real-time temperature data of the thermal imager's interior and surrounding environment and transmits it to the main control unit. It also uses a distance input interface circuit to collect observation distance signals and transmit them to the main control unit. A three-dimensional calibration table recording the relationship between temperature, distance, and focus is stored in the data memory. The main control unit determines the optimal focus position corresponding to the current temperature and distance based on the three-dimensional calibration table and generates a PWM control signal. This PWM control signal is transmitted to the lens drive mechanism via the lens drive circuit, driving the lens to automatically adjust and achieve hardware-level compensation and maintenance of image sharpness. This process effectively suppresses focus drift caused by temperature changes, improves the imaging stability of the cooled thermal imager in complex environments, and has the advantages of compact structure, fast response, and easy integration. Furthermore, this invention solders all components onto a single double-layer PCB board, with dimensions suitable for the internal space of a standard thermal imager, and can be used as an independent module for replacement or upgrade. Attached Figure Description

[0012] Figure 1 The schematic diagram of the main control unit; Figure 2 This is the schematic diagram of interface J5; Figure 3 This is the schematic diagram of interface J1; Figure 4 This is a schematic diagram of a data storage device. Figure 5 This is the schematic diagram of a level conversion chip; Figure 6 This is a schematic diagram of a lens driver chip. Figure 7 This is the schematic diagram of interface J4; Figure 8 This is a schematic diagram of an RS-485 signal transceiver chip. Figure 9 The schematic diagrams are for interfaces J2 and J3; Figure 10 This is a schematic diagram of a potentiometer interface. Detailed Implementation

[0013] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0014] Example 1 This utility model discloses a sharpness adaptive device suitable for cooled thermal imagers, including a temperature detection circuit, a distance input interface circuit, a data storage device, a main control unit, a lens drive circuit, and a potentiometer. The temperature detection circuit, distance input interface circuit, data storage device, and potentiometer are respectively connected to the input terminal of the main control unit, and the lens drive circuit is connected to the output terminal of the main control unit. The temperature detection circuit is used to collect the temperature of the thermal imager's interior and surrounding environment in real time and transmit it to the main control unit. The distance input interface circuit is used to collect the observation distance signal and transmit it to the main control unit. The data storage device stores a three-dimensional calibration table recording the relationship between temperature, distance, and focus. The main control unit determines the optimal focus position corresponding to the current temperature and distance based on the three-dimensional calibration table and generates a PWM control signal. The PWM control signal is transmitted to the lens drive mechanism via the lens drive circuit. The potentiometer is located on the lens and is used to collect the real-time position of the lens and transmit it to the main control unit.

[0015] like Figure 1 As shown, the main control unit uses an STM32 microcontroller and has multiple I / O ports to connect to external devices, including temperature sensors, laser rangefinders, data storage devices, lens drive circuits, and communication circuits.

[0016] The temperature sensor is installed near the optical compartment of the thermal imager, such as... Figure 2 As shown, the temperature sensor is connected to the input terminal of the main control unit through interface J5. Specifically, terminal 1 of interface J5 is grounded, terminal 3 is connected to +3.3V, terminal 2 is connected to the input terminal PB1 of the main control chip U1, and terminal 2 is connected to pull-up resistor R17.

[0017] The distance input interface circuit includes a laser rangefinder and interface J1. The laser rangefinder is connected to the input terminal of the main control unit via interface J1. Figure 3 As shown, interface J1 supports the input of TTL level UART signals USART3_TX_IRIN and USART3_RX_IRIN from the laser rangefinder, and transmits the TTL level UART signals USART3_TX_IRIN and USART3_RX_IRIN to the USART receive pins 21 and 22 of the main control unit.

[0018] The data storage device stores a three-dimensional "temperature-distance-focus" lookup table written at the factory; the model number is AT24C512B. Figure 4 As shown, the SDA and SCL pins of the data storage are connected to the main control chip U1 via pull-up capacitors.

[0019] In this embodiment, the lens driving circuit includes a level conversion chip, a lens driving chip, and an interface J4, such as Figure 5 , 6 As shown in Figure 7, port B of the level conversion chip is connected to the output of the main control unit, port A of the level conversion chip is connected to the input of the lens driver chip, and the output of the lens driver chip is connected to the lens drive motor through interface J4.

[0020] In this embodiment, the level conversion chip is model 74LVC4245, and the lens driver chip is model L293DD. The 74LVC4245 is an eight-channel bus transceiver with tri-state outputs and a 3.3V to 5V shifter. In this embodiment, it converts the 3.3V PWM signal from the main control unit into 5V and then transmits it to the lens driver chip. The L293 is a high-current, half-step four-phase motor driver; that is, the lens driving component is a motor, which drives the lens according to the signal emitted by the L293DD.

[0021] This embodiment also includes a communication circuit, which includes a WiFi communication circuit and a RS-485 communication circuit, such as... Figure 9 As shown, the WiFi communication circuit includes a WiFi interface J2. One end of the WiFi interface J2 is connected to the serial communication interface (USART1_TX, USART1_RX) of the main control unit, supporting remote configuration and data upload. The other end is connected to a peripheral module that communicates with the main control unit. Figure 8 , 9As shown, the RS-485 communication circuit includes an RS-485 transceiver chip MAX3485 and interface J3. Pins R and D of the RS-485 transceiver chip are connected to the main control unit, while pins A and B are connected to peripheral modules via interface J3. Peripheral modules are those that need to communicate with the main control unit, such as a host computer or other modules (human-machine interface circuits).

[0022] like Figure 10 As shown, the potentiometer is connected to the main control unit via interface J6.

[0023] The working principle of this invention is as follows: After the device is powered on, the main control unit first completes system initialization and loads the pre-written "temperature-distance-focus" three-dimensional calibration table from the built-in calibration data memory (EEPROM). During operation, the temperature detection circuit collects real-time temperature changes inside the thermal imager and its surrounding environment, while simultaneously receiving observation distance signals from the laser rangefinder or external system through the distance input interface circuit. The main control unit looks up the corresponding optimal focus position based on the current temperature and distance parameters, generates a PWM control signal, and after level conversion, generates a control signal for the lens drive motor, driving the stepper motor to adjust the lens position. During adjustment, the potentiometer provides real-time feedback on the actual lens position, forming a closed-loop control to ensure accurate positioning. In addition, the device is equipped with a communication and human-machine interface circuit, supporting communication with a host computer via RS485 or Wi-Fi for remote configuration and status monitoring, and allowing users to manually set operating parameters. Through hardware-level closed-loop control, this device effectively suppresses focus drift caused by temperature changes, significantly improving the imaging stability and automation level of the cooled thermal imager in complex environments.

[0024] In this embodiment, all components are soldered onto a double-layer PCB board, with dimensions adapted to the internal space of a standard thermal imager, and can be used as an independent module for replacement or upgrade.

[0025] The above description is only the basic principle and preferred embodiment of this utility model. Any improvements and substitutions made by those skilled in the art based on this utility model shall fall within the protection scope of this utility model.

Claims

1. A sharpness adaptive device suitable for cooled thermal imagers, characterized in that: The system includes a temperature detection circuit, a distance input interface circuit, a data storage device, a main control unit, a lens drive circuit, and a potentiometer. The temperature detection circuit, distance input interface circuit, data storage device, and potentiometer are connected to the input terminals of the main control unit, while the lens drive circuit is connected to the output terminals of the main control unit. The temperature detection circuit is used to collect real-time temperature data of the thermal imager's interior and surrounding environment and transmit it to the main control unit. The distance input interface circuit is used to collect observation distance signals and transmit them to the main control unit. The data storage device stores a three-dimensional calibration table recording the relationship between temperature, distance, and focus. The main control unit determines the optimal focus position corresponding to the current temperature and distance based on the three-dimensional calibration table and generates a PWM control signal. The PWM control signal is transmitted to the lens drive mechanism via the lens drive circuit. The potentiometer, located on the lens, is used to collect the real-time position of the lens and transmit it to the main control unit.

2. The sharpness adaptive device for cooled thermal imagers according to claim 1, characterized in that: The temperature detection circuit includes a temperature sensor and an interface J5. The temperature sensor is installed on the optical cabin of the thermal imager and is connected to the input terminal of the main control unit through the interface J5.

3. The sharpness adaptive device for cooled thermal imagers according to claim 1, characterized in that: The distance input interface circuit includes a laser rangefinder and interface J1. The laser rangefinder is connected to the input terminal of the main control unit through interface J1.

4. The sharpness adaptive device for cooled thermal imagers according to claim 1, characterized in that: The lens driving circuit includes a level conversion chip, a lens driving chip, and an interface J4. Port B of the level conversion chip is connected to the output of the main control unit, and port A of the level conversion chip is connected to the input of the lens driving chip. The output of the lens driving chip is connected to the lens driving mechanism through interface J4.

5. The sharpness adaptive device for cooled thermal imagers according to claim 4, characterized in that: The level conversion chip is model 74LVC4245, and the lens driver chip is model L293DD.

6. The sharpness adaptive device for cooled thermal imagers according to claim 1, characterized in that: It also includes communication circuits, including WiFi communication circuits and 485 communication circuits. The WiFi communication circuit includes a WiFi interface J2, one end of which is connected to the main control unit and the other end is connected to the peripheral module. The 485 communication circuit includes an RS-485 signal transceiver chip and an interface J3. The R and D pins of the RS-485 signal transceiver chip are connected to the main control unit, and the A and B pins of the RS-485 signal transceiver chip are connected to the peripheral module through the interface J3.

7. The sharpness adaptive device for cooled thermal imagers according to claim 6, characterized in that: The peripheral module communicates with the host computer.

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