Display device and display panel device

1. A plasma display device, comprising:

a plasma display panel having a screen including a plurality of cells;

a drive voltage output circuit outputting to the plasma display panel a drive voltage pulse train that generates display discharges plural times corresponding to a gradation;

a controller that controls a frequency of the drive voltage pulse train in accordance with a display ratio;

a sheet glued on a front surface of the plasma display panel and having an optical filter function to light emitted from the screen; and

the sheet having a thickness of not more than 2 mm and a thermal conductivity ratio within a range of 0.1 W·m −1 ·K −1 to 0.4 W·m −1 ·K −1 and less than that of a plate forming the front surface portion of the plasma display panel and more than that of outside air.

2. The plasma display device according to claim 1 , wherein:

in the event that the display ratio is a first value, the controller sets the frequency of the drive voltage pulse train so as to be a first frequency and, in the event that the display ratio of the screen is a second value, higher than the first value, the controller sets the frequency of the drive voltage pulse train so as to be a second frequency, lower than the first frequency.

3. The plasma display device according to claim 2 , wherein:

the controller controls the frequency of the drive voltage pulse train such that the higher the display ratio is, the lower the frequency is.

4. The plasma display device according to claim 2 , wherein:

the controller controls the frequency of the drive voltage pulse train so that a power consumption per unit area within the screen is not more than a set value.

5. The plasma display device according to claim 2 , wherein:

the controller controls the frequency of the drive voltage pulse train so that power consumption by display discharges in a unit area in a light emission region within the screen is not more than a set value.

6. The plasma display device according to claim 1 , wherein:

the controller controls the frequency of the drive voltage pulse train in accordance with a ratio of the number of cells to be energized to a total number of the plurality of cells.

7. The plasma display device according to claim 2 , wherein

in an operation under an environment of not more than 40° C., a temperature on a front surface of the sheet is kept not higher than 70° C. and a temperature on the front surface of the plasma display panel is kept not more than 80° C.

8. The plasma display device according to claim 2 , wherein the sheet has a unit weight within a range of 0.2-3 kg/m 2 .

9. The plasma display device according to claim 4 , wherein the set value is 2500 W/m 2 .

10. The plasma display device according to claim 4 , wherein an instantaneous peak luminance of light emission of the screen on a front surface of the sheet is not less than 200 cd/m 2 , and a stationary peak luminance of light emission of the screen on the front surface of the functional sheet is not less than 100 cd/m 2 .

11. The plasma display device according to claim 2 , wherein

the sheet is a layered film including a first layer containing a coloring matter that absorbs light in a specific wavelength range and a second layer that does not contain the coloring matter,

the second layer is disposed more closely than the first layer, to the plasma display panel, and

the second layer is glued on the plasma display panel.

12. The plasma display device according to claim 11 , wherein:

the second layer has a thickness of not less than 0.1 mm, and the second layer is thicker than the first layer.

13. The plasma display device according to claim 11 , wherein:

the second layer is a resin layer having a visible light transmittance at a normal temperature of not less than 80%, is made of a resin having a variation in transmittance that is less than 5% over the entire visible light wavelength range after being exposed to an environment at 80° C. for 500 hrs.

14. The plasma display device according to claim 11 , wherein:

the second layer is a resin layer having a visible light transmittance at the normal temperature of not less than 80%, which is made of a resin having a variation in the transmittance that is less than 5% over the entire visible light wavelength range after being exposed to an environment at a temperature of 60° C. and a relative humidity of 90% for 500 hrs.