Cooling of electronic displays

1 . An electronic display comprising:

a housing;

a display panel within the housing and having a display surface that is visible through the housing;

a heat exchanger that provides: (a) a first path through which internal air is circulated to cool the display panel; (b) a second path through which external air passes without mixing with said internal air; and (c) heat exchange between said internal air and external air;

an inlet to allow external air into the heat exchanger;

an outlet to allow external air out of the heat exchanger;

a closable vent at said inlet or outlet;

a temperature sensor; and

a controller arranged to control opening and closing of said closable vent in response to an output of said temperature sensor, thereby to conserve heat generated within the display in cooler ambient conditions.

2 . The electronic display of claim 1 , wherein said inlet and outlet are at a top and a bottom of the electronic display.

3 . The electronic display of claim 1 , further comprising:

at least one first fan for circulating internal air through said first path; and

at least one second fan for passing air through said second path, from said inlet to said outlet;

wherein the controller is arranged to switch off said second fan when said closable vent is closed.

4 . The electronic display of claim 1 , wherein the controller is arranged to control and adjust the closable vent to intermediate positions between fully open and fully closed.

5 . The electronic display of claim 1 , comprising a plurality of said inlets and outlets and a plurality of said closable vents, each closable vent being provided at a respective said inlet or outlet.

6 . The electronic display of claim 1 , further comprising a heater arranged to heat the internal air and/or external air within the electronic display.