Display device, portable electronic device and method of controlling display device

• US 6,867,757 B1
• Filed: 01/19/2000
• Issued: 03/15/2005
• Est. Priority Date: 01/20/1999
• Status: Expired due to Term

• Current Assignee: Lenovo Innovations Ltd Hong Kong (Lenovo Group Ltd.)
• Original Assignee: NEC Corporation
• Inventors: Nakamura, Taisuke
• Primary Examiner(s): Tran, Henry N.
• Application Number:
  US09/487,330
• Time in Patent Office: 1,882 Days
• Field of Search: 345/3, 345 87- 90, 345211-214, 345/690, 345/102, 345/52, 345 82- 84, 345/98, 345/604, 345/694, 345/696, 315/291, 349/70, 349/71, 349/77, 455/566, 455/572, 455/574, 455/575
• US Class Current: 345/83
• CPC Class Codes: G09G 2310/0272 Details of drivers for data electrodes, the drivers communicating data to the pixels by means of a current
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: H05B 45/24 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/37 Converter circuits
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

Current flowing through a plurality of light emission diodes is individually controlled, thereby an image with a desired color is displayed according to color lights emitted from the light emission diodes. A sum of current flowing through the light emission diodes is maintained at a predetermined current, thereby brightness of the image is maintained at a predetermined brightness.

Claims

1. A display device, comprising:

a plurality of light emitters, each of said light emitters emitting a light different in color from other of said light emitters;

a power source for supplying power to said light emitters;

a controller for controlling a current flowing through at least one of said light emitters such that a sum of currents flowing through said light emitters is maintained at a predetermined value, further comprising;

a plurality of resistors, wherein said resistors are respectively disposed between said power source and said light emitters, and a resistance value of said resistors affects the current flowing through said light emitters;

wherein the resistance values of said resistors are set to be substantially equal to each other whereby the sum of currents flowing through said light emitters is maintained at the predetermined value.

2. A display device, comprising:

a plurality of light emitters, each of said light emitters emitting a light different in color from other of said light emitters,

power source for supplying power to said light emitters; and

a controller for controlling a current flowing through at least one of said light emitters such that a sum of currents flowing through said light emitters is maintained at a predetermined value;

wherein said controller controls the current flowing through said at least one of said light emitters, whereby the currents do not simultaneously flow through the plurality of said light emitters.

3. A display device, comprising:

a plurality of light emitters, each of said light emitters emitting a light different in color from other of said light emitters;

a power source for supplying power to said light emitters;

a controller for controlling a current flowing through at least one of said light emitters such that a sum of currents flowing through said light emitters is maintained at a predetermined value, wherein said controller includes;

a plurality of switches respectively connected to said light emitters, for individually controlling whether or not the currents are flowing through said light emitters connected thereto; and

a plurality of control signal generators for respectively generating a control signal to said switches.

4. The display device as claimed in claim 3, wherein one of said switches includes a field effect transistor.

5. The display device as claimed in claim 3, wherein said controller assigns duty values to said control signal generators.

6. The display device as claimed in claim 5, wherein said control signal generators generate the control signals having pulse widths which are based on the duty values assigned by said controller.

7. The display device as claimed in claim 5, wherein a sum of the duty values assigned to said control signal generators is a constant.

8. A display device, comprising:

a plurality of light emitters, each of said light emitters emitting a light different in color from other of said light emitters;

a power source for supplying power to said light emitters;

a controller for controlling a current flowing through at least one of said light emitters such that a sum of currents flowing through said light emitters is maintained at a predetermined value, further comprising;

a converter for adjusting the power supplied to said light emitters from said power source.

9. The display device as claimed in claim 8, wherein said converter increases the power supplied from said power source to increase a brightness of the light emitted from said light emitters.

10. The display device as claimed in claim 8, wherein said converter decreases the power supplied from said power source to decrease a brightness of the light emitted from said light emitters.