Display unit and backlight unit
View Patent ↗The disclosure includes various embodiments including, for example: (i) a color liquid crystal display unit has a color display panel of transmissive type and a backlight unit placed behind the color display panel; (ii) a backlight unit has a plurality of LEDs connected in series and a drive unit to drive the LEDs; (iii) a temperature sensor to detect the temperature of LEDs; (iv) groups of LEDs are arranged in regions where the display unit has the same temperature; and (v) a drive unit controls current to be supplied to LEDs in response to temperature detected by the temperature sensor so that the LEDs retain the constant brightness even when the LEDs fluctuate in temperature.
1. A backlight unit installed in the back of a display unit, comprising:
lighting units, each lighting unit comprising:
a light emitting diode, and
a temperature detecting unit to detect the temperature of the lighting unit, and
a drive unit to control current supplied to the light emitting diode according to the temperature of the lighting unit, so that each lighting unit keeps a uniform brightness even though each lighting unit changes in temperature, to adjust current to be supplied to the light emitting diode by means of pulse width modulation, so as to keep at least the brightness of light emitted from each lighting unit uniform, to control the peak value of the current to be supplied to the light emitting diode, so that the resolution of pulse width is the same, and to adjust the peak value of current to be supplied to the light emitting diode in response to the detected temperature.
2. The backlight unit as defined in claim 1 , wherein the drive unit controls current supplied to the light emitting diode, so that each lighting unit keeps a uniform brightness as well as a uniform chromaticity even though each lighting unit changes in temperature.
3. The backlight unit as defined in claim 1 , wherein the temperature detecting unit detects the temperature of one of the lighting units having a malfunctioning temperature sensor according to information from a memory which previously stored the temperature of the lighting unit having the malfunctioning temperature sensor in response to the temperature of one of the lighting units at the position where a temperature sensor is installed.
4. The backlight unit as defined in claim 1 , further comprising a light detecting sensor to detect the brightness of light emitted from the light emitting diode in each lighting unit, wherein the drive unit adjusts current supplied to the light emitting diodes so as to keep at least the brightness of light emitted from each lighting unit uniform.
5. A display unit comprising:
a non-luminous screen of transmissive-type,
lighting units, placed behind the screen, each lighting unit comprising:
a light emitting diode, and
a temperature detecting unit to detect the temperature of the lighting unit, and
a drive unit to control current supplied to the light emitting diode according to the temperature of the lighting unit, so that each lighting unit keeps a uniform brightness even though each lighting unit changes in temperature, to adjust current to be supplied to the light emitting diode by means of pulse width modulation, so as to keep at least the brightness of light emitted from each lighting unit uniform, to control the peak value of the current to be supplied to the light emitting diode, so that the resolution of pulse width is the same, and to adjust the peak value of current to be supplied to the light emitting diode in response to the detected temperature.
6. The display unit as defined in claim 5 , wherein the drive unit controls current supplied to the light emitting diode, so that each lighting unit keeps a uniform brightness as well as a uniform chromaticity even though each lighting unit changes in temperature.
7. The display unit as defined in claim 5 , wherein the temperature detecting unit detects the temperature of one of the lighting units having a malfunctioning temperature sensor according to information from a memory which previously stored the temperature of the lighting unit having the malfunctioning temperature sensor in response to the temperature of one of the lighting units at the position where temperature sensor is installed.
8. The display unit as defined in claim 5 , further comprising a light detecting sensor to detect at least the brightness of light emitted from the light emitting diode in each lighting unit, wherein the drive unit adjusts current to be supplied to the light emitting diode so as to keep at least the brightness of light emitted from each lighting unit uniform.
9. The display unit as defined in claim 5 , which further comprises an optical system that uniformly mixes the colors of light emitted from each light emitting diode in each lighting unit, and wherein the drive unit acquires as a representative value the brightness or chromaticity detected by the light detecting sensor and adjusts current to be supplied to each light emitting diode in each lighting unit so that the lighting unit changes uniformly as a whole and the light emitted from each lighting unit remains constant in brightness or chromaticity.