Ranging device
A ranging device is configured to emit a transmitted wave and detect a reflected wave from an object illuminated by the transmitted wave, thereby measuring a distance to the object. At least one of the transmitted wave and the reflected wave is transmitted through a transmission window. A heater is configured to heat the transmission window. A controller is configured to control energization of the heater in response to an outside temperature that is a temperature outside the ranging device and a speed of the vehicle.
1. A ranging device for a vehicle, configured to emit a transmitted wave and detect a reflected wave from an object illuminated by the transmitted wave, thereby measuring a distance to the object, the ranging device comprising:
a transmission window through which the transmitted wave and the reflected wave are transmitted;
a heater configured to heat the transmission window, the heater comprising a transparent conductive film disposed on the transmission window, the transparent conductive film generating heat that heats the transmission window from a supply of power that is electrically connected to the transparent conductive film; and
a controller configured to vary the supply of power to the transparent conductive film based on (i) an outside temperature that is a temperature outside the ranging device and (ii) a speed of the vehicle, wherein
the transparent conductive film comprises a film capable of transmitting the transmitted wave and the reflected wave for object detection while the supply of power to the transparent conductive film varies,
the supply of power to the transparent conductive film increases with increasing speed of the vehicle, and
increasing the supply of power to the transparent conductive film increases heat generated by the transparent conductive film that heats the transmission window.
2. The ranging device according to claim 1 , wherein
the controller is configured to control energization of the heater based on a function of the outside temperature and the speed of the vehicle as parameters.
3. The ranging device according to claim 2 , wherein
the ranging device comprises a case including, as a portion, the transmission window, and the function is set up based on a heat-transfer coefficient calculated using a Nusselt number assuming on-plate forced-convection which affects a top surface or a bottom surface of the case with the ranging device mounted on the vehicle, and a characteristic length that is a length along a travel direction of the vehicle, of at least a portion of the case on the top surface or the bottom surface of the case.
4. The ranging device according to claim 1 , wherein
the controller is configured to control energization of the heater based on a table in which an energization condition for the heater is predefined in response to the outside temperature and the speed of the vehicle.
5. The ranging device according to claim 1 , wherein
the controller is configured to control energization of the heater further in response to a detected battery voltage of a battery mounted to the vehicle.
6. The ranging device according to claim 1 , wherein
the controller is configured to determine at least a snowfall condition around the vehicle and control energization of the heater further in response to the snowfall condition.
7. The ranging device according to claim 1 , wherein
the transparent conductive film comprises an indium tin oxide (ITO) film.
8. A ranging device for a vehicle configured to emit a transmitted wave and detect a reflected wave from an object illuminated by the transmitted wave, thereby measuring a distance to the object, the ranging device comprising:
a transmission window through which the transmitted wave and the reflected wave are transmitted;
a heater configured to heat the transmission window, the heater comprising a transparent conductive film disposed on the transmission window, the transparent conductive film generating heat that heats the transmission window from a supply of power that is electrically connected to the transparent conductive film; and
a controller configured to vary the supply of power to the transparent conductive film, wherein
the transparent conductive film comprises a film capable of transmitting the transmitted wave and the reflected wave for object detection while the supply of power to the transparent conductive film varies.