Camera temperature measurement system

Abstract

Title: Camera Temperature Measurement System The invention relates to a camera temperature measurement system (1), the measurement system comprising: a camera module (2) including a camera (3) and a temperature sensor (4), in particular a thermistor, sensitive to the camera's temperature; an electronic control module (6); a wired connection (7) configured to link the camera module (2) to the electronic control module (6), this wired connection (7) being capable of both carrying data from the camera (3) and communicating with the temperature sensor (4). Figure for the abstract: Fig. 1

Description

Title of the invention: Temperature measurement system for a camera

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

[0002] Cameras (particularly infrared cameras) are currently in use, and it is necessary to know their temperature because if the temperature rises excessively, certain camera functions must be interrupted. A digital temperature sensor is used to determine the camera's temperature. Such a digital temperature sensor is a component that can be bulky and is generally relatively expensive.

[0003] The present invention aims in particular to provide a camera temperature measurement solution that remedies the above drawbacks.

[0004] The invention thus relates to a temperature measurement system for a camera, the measurement system comprising: - a camera module comprising a camera and a temperature sensor, including a thermistor, sensitive to the camera's temperature; - an electronic control module (or ECU); - a wired connection configured to link the camera module to the module electronic control unit (or ECU), this connection being capable of both carrying data from the camera and communicating with the temperature sensor

[0005] The invention proposes using a discrete and passive component, in particular a thermistor, which is compact and less expensive than a digital sensor, especially a digital sensor that uses an I2C bus. Using the same wired connection for both the camera's video data and for temperature measurement simplifies 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 eliminates the need for an additional wire dedicated to temperature measurement. The invention allows for the combined transmission of video data and the measurement of the camera's temperature over a single connection. The wired connection, of the data bus type, for the video data transfer (for example, at 2 gigahertz) is pre-existing.

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

[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 link, 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 parallel video data into serial data for transmission over a 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 includes a deserializer configured to receive data from the wired link, in particular a coaxial cable, and deserialize this data.

[0013] Thus the wired link, 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 includes an analog-to-digital converter configured to perform a measurement, in particular a voltage measurement, on the wired link so as to be able to determine the temperature of the camera.

[0015] We measure the voltage on the wired link (which includes the coaxial cable), 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 voltage divider formula: Vb = Rntc / (Rup + Rntc) * Vref, where Rntc is the resistance of the thermistor, and Rup is the resistance. The resistance Rntc varies with 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 drive the analog-to-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 take a temperature measurement, and to open the switch in the absence of a temperature measurement.

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

[0021] This is useful because a thermistor (which acts as a temperature sensor) is polarized, and since the thermistor causes the DC voltage of the data bus to vary, it is necessary to isolate this DC voltage. The two capacitors serve to isolate the high-speed portion from the DC bus voltage, thus retaining 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) to illuminate the target.

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

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

[0025] According to one aspect of the invention, the coaxial cable mass is isolated from the power mass on the camera, this avoids a mass offset and thus ensures the necessary accuracy of the analog voltage measurement performed.

[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, including a thermistor, sensitive to the camera's temperature; - provide a wired connection configured to link the camera module to an electronic control module, this wired connection being capable of both carrying data from the camera and allowing communication with the temperature sensor; - measure a voltage on the wired connection to determine the camera temperature.

[0028] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and several illustrative and non-limiting examples of embodiments given with reference to the accompanying schematic drawings on the other hand, in which:

[0029] [Fig.1] Fig.1 is a schematic representation of the temperature measurement system according to an example of implementation of the invention.

[0030] The features, variations, and different embodiments of the invention can be combined with one another in various ways, provided they are not incompatible or mutually exclusive. In particular, variations of the invention may be imagined that do not include that 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] Figure 1 shows a temperature measurement system 1 of a camera, the measurement 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 connection 7 configured to connect the camera module 2 to the module control electronics 6, this wired link 7 being capable of both carrying data from the camera 3 and allowing communication with the temperature sensor 4 in order to access the temperature data through the thermistor 4.

[0032] In the present invention, the camera 3 refers to the optical part, namely the optical sensor 3.

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

[0034] The invention proposes using a discrete and passive component, here the thermistor 4, which is compact and less expensive than a digital sensor, particularly a digital sensor that uses an I2C bus. Using the same wired connection for both the camera's video data and the temperature measurement simplifies the temperature measurement system 1.

[0035] The invention eliminates the need for an additional wire dedicated to temperature measurement. The invention allows for the combined transmission of video data and the measurement of the camera's temperature over a single connection. The wired connection, of the data bus type, for the video data transfer (for example, at 2 gigahertz) is pre-existing.

[0036] The wired link 7 is of the high-speed type, allowing the transmission of video data from the camera 3.

[0037] The wired link 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 includes a box 10, and the wired link 7, here the coaxial cable, is configured to make the electrical connection between these two boxes 9 and 10 by means of electrical connectors 11.

[0039] The optical sensor 3 is configured to capture 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 includes a deserializer 14 configured to receive data from the wired link 7, and deserialize this data.

[0041] The coaxial cable 7 provides 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 includes an analog-to-digital converter 15 configured to perform a voltage measurement on the wired link 7 so as to be able to determine the temperature Team of the camera 3.

[0043] Arrow 17 schematically represents this voltage measurement on the wired connection 7.

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

[0045] Knowing Vb and therefore Rntc, it is then possible to access the Team temperature 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-to-digital converter 15.

[0047] The microprocessor 19 is configured to control the analog-to-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 take 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 resistance Rup.

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

[0051] This is useful because a thermistor (which performs the function of a temperature sensor) is polarized, and since the thermistor causes the DC voltage of the data bus to vary, it is necessary to eliminate this DC voltage. The two capacitors 21 serve to isolate the high-speed portion from the DC voltage of the bus, thus retaining 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 or Driver in English.

[0054] The camera module 2 includes a power management integrated 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 avoids a ground offset and thus ensures the necessary accuracy of the analog voltage measurement performed.

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

Claims

Demands

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 carrying data from the camera (3) and allowing communication with the temperature sensor (4), the electronic control module (6) comprising an analog-to-digital converter (15) configured to perform a measurement, in particular a voltage measurement, on the wired link (7) so as to be able to determine the temperature of the camera, the electronic control module (6) also comprising a microprocessor (19) which is configured to provide a temperature value from the voltage measured by the analog-to-digital converter, and 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.;

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

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

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

5. A system according to any one of the preceding claims, wherein 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 to convert parallel video data into serial data for transmission over the wired link (7), including a coaxial cable, and the electronic control module (6) includes a deserializer (14) configured to receive data from the wired link (7) and deserialize this data.

6. System according to any one of the preceding claims, wherein capacities (21) are present on the wired link (7).

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