Camera temperature measurement system

Abstract

Title: Temperature measurement system for a camera The subject of the invention is a temperature measurement system (1) for a camera, the measurement system comprising: a camera module (2) comprising a camera (3) and a temperature sensor (4), in particular a thermistor, sensitive to the temperature of the camera; an electronic control module (6); a wired connection (7) configured to connect the camera module (2) to the electronic control module (6), this wired connection (7) being capable of both transporting data from the camera (3) and enabling communication with the temperature sensor (4). Figure for the abstract: Fig. 1

Description

Title of the invention: Temperature measurement system of a camera

[0001] The present invention relates to a temperature measurement system of a camera.

[0002] Cameras (especially infrared cameras) are currently in use and their temperature needs to be known because if the temperature rises excessively, some camera functions must be interrupted. To know the camera temperature, a digital temperature sensor is used. Such a digital temperature sensor is a component that can be bulky and generally has a relatively high cost.

[0003] The present invention aims in particular to propose a solution for measuring the temperature of the camera which overcomes the above drawbacks.

[0004] The invention thus relates to a system for measuring the temperature of a camera, the measuring system comprising: - a camera module comprising a camera and a temperature sensor, in particular a thermistor, sensitive to the temperature of the camera; - an electronic control module (or ECU); - a wired connection configured to connect the camera module to the module electronic control unit (or ECU), this connection being capable of both transporting data from the camera and enabling communication with the temperature sensor

[0005] The invention proposes to use a discrete and passive component which is in particular a thermistor, of small size and less expensive than a digital sensor, in particular a digital sensor which uses an I2C type bus. The fact of using the same wired connection for both the video data from the camera and for carrying out the temperature measurement makes it possible to simplify the temperature measurement system.

[0006] If a thermistor is used in the present invention, the cost is reduced. Such a component (thermistor) is also compact.

[0007] The invention makes it possible to avoid having an additional wire dedicated to temperature measurement. The invention makes it possible to share the transmission of video data and the temperature measurement of the camera on the same link. The wired connection, of the data bus type, for the transfer of video data (for example at 2 gigahertz) is pre-existing.

[0008] According to one aspect of the invention, the wired connection is of the high-speed type, allowing video data from the camera to be passed.

[0009] According to one aspect of the invention, the wired connection is a coaxial cable, for example with an impedance of 50 ohms.

[0010] According to one aspect of the invention, the camera module comprises a housing and the electronic control module comprises a housing, and the wired connection, in particular a coaxial cable, is configured to make the electrical connection between these two housings.

[0011] According to one aspect of the invention, the camera module comprises an optical sensor for capturing video images in the infrared, and a serializer connected to the optical sensor for converting the parallel video data into serial data for transmission over the wired link, in particular a coaxial cable. The optical sensor is part of the camera.

[0012] According to one aspect of the invention, the electronic control module comprises a deserializer configured to receive data from the wired link, in particular a coaxial cable, and deserialize this data.

[0013] Thus the wired connection, in particular a coaxial cable, ensures communication between the serializer of the camera module and the deserializer of the electronic control module.

[0014] According to one aspect of the invention, the electronic control module comprises an analog-digital converter configured to carry out a measurement, in particular a voltage measurement, on the wired connection so as to be able to determine the temperature of the camera.

[0015] The voltage on the wired connection (which includes the coaxial cable) is measured, a voltage which is the DC component of the video bus.

[0016] According to one aspect of the invention, the voltage Vb is determined according to the divider bridge formula: Vb = Rntc / (Rup + Rntc) * Vref with Rntc being the resistance of the thermistor, and Rup being the resistance. The resistance Rntc varies depending on the temperature in the camera module.

[0017] According to one aspect of the invention, a microprocessor in the electronic control module is configured to provide a temperature value from the voltage measured by the analog-to-digital converter.

[0018] According to one aspect of the invention, the microprocessor is configured to control the analog-digital converter depending on whether or not it is necessary to take the temperature measurement.

[0019] According to one aspect of the invention, the microprocessor is configured to close a switch when it is necessary to make a temperature measurement, and to open the switch in the absence of a temperature measurement.

[0020] According to one aspect of the invention, capacities are present on the wired link.

[0021] This is useful because a thermistor (which serves as a temperature sensor) is polarized, and since the thermistor varies the DC voltage of the data bus, it is necessary to get rid of this DC voltage. The two capacitors are used to isolate the high-speed part from the DC voltage of the bus to keep only the high-frequency component.

[0022] According to one aspect of the invention, the camera is an infrared camera with an infrared source (for example an LED) for illuminating the target.

[0023] According to one aspect of the invention, the infrared source is controlled by a pilot or driver.

[0024] According to one aspect of the invention, the camera module comprises a power management integrated circuit (or PMIC in English) connected to the optical sensor and to the serializer.

[0025] According to one aspect of the invention, the ground of the coaxial cable is isolated from the power ground on the camera, this makes it possible to avoid a ground offset and therefore ensure the necessary precision of the analog voltage measurement carried out.

[0026] According to one aspect of the invention, the temperature measurement system of a camera is configured to be installed on a motor vehicle.

[0027] The invention also relates to a method for measuring the temperature of a camera, the method comprising the following steps: - provide a camera module comprising a camera and a temperature sensor, in particular a thermistor, sensitive to the temperature of the camera; - provide a wired connection configured to connect the camera module to an electronic control module, this wired connection being capable of both transporting data from the camera and enabling communication with the temperature sensor; - measure a voltage on the wired connection to determine the temperature of the camera.

[0028] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and several exemplary embodiments given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which:

[0029] [Fig.l] [Fig.l] is a schematic representation of the temperature measurement system according to an exemplary implementation of the invention.

[0030] The features, variants and different embodiments of the invention may be combined with each other, in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined which do not include than a selection of features described subsequently in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the prior art.

[0031] [Fig.l] shows a temperature measuring system 1 of a camera, the measuring system 1 comprising: - a camera module 2 comprising an optical camera sensor 3 and a temperature sensor 4, here a thermistor, sensitive to the temperature of the camera 3; - an electronic control module 6, or ECU in English; - a wired link 7 configured to connect the camera module 2 to the module control electronics 6, this wired connection 7 being capable of both transporting data from the camera 3 and enabling communication with the temperature sensor 4 in order to access the temperature data using the thermistor 4.

[0032] In the present invention, the camera 3 designates the optical part, i.e. the optical sensor 3.

[0033] Thermistor 4 is a component whose electrical resistance varies according to temperature, this thermistor being of the CTN type (the acronym CTN being for “negative temperature coefficient” or NTC in English).

[0034] The invention proposes to use a discrete and passive component, here the thermistor 4, of small size and less expensive than a digital sensor, in particular a digital sensor which uses an I2C type bus. The fact of using the same wired connection for both the video data from the camera and for carrying out the temperature measurement makes it possible to simplify the temperature measurement system 1.

[0035] The invention makes it possible to avoid having an additional wire dedicated to temperature measurement. The invention makes it possible to share the transmission of video data and the temperature measurement of the camera on the same link. The wired connection, of the data bus type, for the transfer of video data (for example at 2 gigahertz) is pre-existing.

[0036] The wired connection 7 is of the high-speed type, allowing video data from the camera 3 to be passed.

[0037] The wired connection 7 is a coaxial cable, for example with an impedance of 50 ohms.

[0038] The camera module 2 comprises a housing 9 and the electronic control module 6 comprises a housing 10, and the wired connection 7, here the coaxial cable, is configured to make the electrical connection between these two housings 9 and 10 using electrical connectors 11.

[0039] The optical sensor 3 is configured to capture the video images in the infrared, and a serializer 12 is provided connected to the optical sensor 3 to convert the parallel video data into serial data for transmission over the coaxial cable 7.

[0040] The electronic control module 6 comprises a deserializer 14 configured to receive the data from the wired link 7, and deserialize this data.

[0041] The coaxial cable 7 ensures communication between the serializer 12 of the camera module 2 and the deserializer 14 of the electronic control module 6.

[0042] The electronic control module 6 comprises an analog-digital converter 15 configured to carry out a voltage measurement on the wired connection 7 so as to be able to determine the Team temperature of the camera 3.

[0043] Arrow 17 shows this voltage measurement on the wire connection 7.

[0044] The voltage Vb is determined according to the divider bridge formula: Vb= Rntc / (Rup +Rntc)*Vref with Rntc being the resistance value of thermistor 4, and Rup being the resistance value of resistor 18 of the divider bridge. The resistance value Rntc varies depending on the temperature in camera module 2.

[0045] Knowing Vb and therefore Rntc, it is then possible to access the temperature Team of the thermistor by a law of dependence between the resistance of the thermistor and its temperature.

[0046] A microprocessor 19 in the electronic control module 6 is configured to provide a temperature value Team from the voltage measured Vb by the analog-digital converter 15.

[0047] The microprocessor 19 is configured to control the analog-digital converter 15 depending on whether or not it is necessary to take the temperature measurement.

[0048] The microprocessor 19 is configured to close a switch 20 when it is necessary to make a temperature measurement, and to open the switch in the absence of a temperature measurement.

[0049] In the drawing, the switch 20 is shown in series with the resistor Rup.

[0050] Capacities 21 are present on the wired link 7.

[0051] This is useful because a thermistor (which fulfills the function of a temperature sensor) is polarized, and because the thermistor varies the DC voltage of the data bus, it is necessary to get rid of this DC voltage. The two capacitors 21 are used to isolate the high-speed part from the DC voltage of the bus to keep only the high-frequency component.

[0052] The camera and an infrared camera with an infrared source, for example an LED 25, to illuminate the target.

[0053] The infrared source 25 is controlled by a driver 26.

[0054] The camera module 2 comprises an integrated power management circuit 27 (or PMIC in English) connected to optical sensor 3 and serializer 12.

[0055] The ground of the coaxial cable 7 is isolated from the power ground on the camera 3, this makes it possible to avoid a ground offset and therefore ensure the necessary precision of the analog voltage measurement carried out.

[0056] The temperature measurement system 1 is configured to be installed on a motor vehicle.

Claims

Claims

1. Temperature measurement system (1) of a camera, the measurement system comprising: - a camera module (2) comprising a camera (3) and a temperature sensor (4), in particular a thermistor, sensitive to the temperature of the camera; - an electronic control module (6); - a wired link (7) configured to connect the camera module (2) to the electronic control module (6), this wired link (7) being capable of both transporting data from the camera (3) and enabling communication with the temperature sensor (4).

2. System according to the preceding claim, in which the temperature sensor (4) is a thermistor.

3. System according to one of the preceding claims, in which the wired connection (7) is of the high-speed type, allowing the transmission of video data from the camera (3), being in particular a coaxial cable.

4. System according to one of the preceding claims, in which the camera module (2) comprises a housing (9) and the electronic control module (6) comprises a housing (10), and the wired connection (7), in particular a coaxial cable, is configured to make the electrical connection between these two housings.

5. System according to one of the preceding claims, in which the camera module (2) comprises an optical sensor for capturing the video images in the infrared, and a serializer (12) connected to the optical sensor for converting the parallel video data into serial data for transmission over the wired link (7), in particular a coaxial cable, and the electronic control module (6) comprises a deserializer (14) configured to receive the data from the wired link (7) and deserialize this data.

6. System according to one of the preceding claims, in which the electronic control module (6) comprises an analog-digital converter (15) configured to carry out a measurement, in particular a voltage measurement, on the wired connection (7) so as to be able to determine the temperature of the camera.

7. System according to the preceding claim, in which a microprocessor (19) in the electronic control module (6) is configured to provide a temperature value from the voltage measured by the analog-digital converter, and the microprocessor is configured to close a switch (20) when it is necessary to make a temperature measurement, and to open the switch in the absence of a temperature measurement.

8. System according to one of the preceding claims, in which capacities (21) are present on the wired link (7).

9. System according to one of the preceding claims, wherein the camera (3) is an infrared camera with an infrared source for illuminating the target.

10. Method for measuring the temperature of a camera (3), the method comprising the following steps: - providing a camera module (2) comprising a camera and a temperature sensor (4), in particular a thermistor, sensitive to the temperature of the camera; - providing a wired connection (7) configured to connect the camera module (2) to an electronic control module (6), this wired connection (7) being capable of both transporting data from the camera and enabling communication with the temperature sensor (4); - measuring a voltage on the wired connection (7) to determine the temperature (Team) of the camera.

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