Image display apparatus and its method of operation

• US 6,545,652 B1
• Filed: 07/06/2000
• Issued: 04/08/2003
• Est. Priority Date: 07/08/1999
• Status: Expired due to Term

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Tsuji, Ryuhei
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): Nguyen, Jennifer T.
• Application Number:
  US09/610,991
• Time in Patent Office: 1,006 Days
• Field of Search: 345/82, 345/350, 345/76, 345/77, 345/78, 345/204, 345/214, 315/169.3, 315/169.1, 315/169.2
• US Class Current: 345/82
• CPC Class Codes: G09G 2300/06 Passive matrix structure, i.e. with direct application of both column and row voltages to the light emitting or modulating elements, other than LCD or OLED
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2370/04 Exchange of auxiliary data, i.e. other than image data, between monitor and graphics controller
• CPC Class Codes: G09G 3/32 semiconductive, e.g. using light-emitting diodes [LED]
• CPC Class Codes: G09G 3/3216 using a passive matrix
• CPC Class Codes: G09G 3/3275 Details of drivers for data electrodes
• CPC Class Codes: G09G 3/3283 in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements

Abstract

The image display apparatus is provided with a dot matrix of light emitting devices, driver circuitry, and switching circuitry. The dot matrix is a plurality of light emitting devices arranged in an m-line by n-column matrix, and one terminal of each light emitting device in each line is connected to a common source line. Driver circuitry controls light emitting devices active or inactive depending on an input illumination signal. In the active state, switching circuitry floats common source lines, and in the inactive state, discharges all common source lines to ground.

Claims

1. An image display apparatus comprising:

a dot matrix of a plurality of light emitting devices arranged in a matrix with m-lines and n-columns, one terminal of each of the light emitting devices disposed in each column is connected to a respective current line, and the other terminal of each of the light emitting devices disposed in each line is connected to a respective common source line;

driver circuitry operable to control an activation state to be either active or inactive depending on an input illumination control signal and, in the active state, control conduction through one end of each common source line and each current line based on input display data; and

a switching circuit section operable to float the other end of each common source line in the active state, and to ground the other end of each common source line in the inactive state;

wherein said driver circuitry is provided with a current source switching circuit with m-switching circuits corresponding to each common source line and, in the active state, said current source switching circuit is operable to connect the common source line selected by an input address signal to the current source; and

wherein said driver circuitry is provided with a constant current control circuit section having memory circuits operable to store n-sets of pixel level data of the sequentially input display data and, in the active state, said constant current control circuit section is operable to put the related current line in the conducting state for a pixel level width corresponding to the pixel level data stored in each of said memory circuits.

2. An image display apparatus as recited in claim 1, wherein said switching circuit section is a plurality of switches connected between each common source line and ground.

3. An image display apparatus as recited in claim 2, wherein said switching circuit section is controlled by the illumination control signal which controls a state of light emitting device illumination to be on or off, wherein in the illumination on state, said switches of said switching circuit section are turned off to disconnect the common source line from ground, and wherein in the illumination off state, said switches of said switching circuit section are turned on to connect the common source line to ground.

4. An image display apparatus as recited in claim 1, wherein said switching circuit section is controlled by the illumination control signal which controls a state of light emitting device illumination to be on or off, wherein in the illumination on state of the illumination control signal, said switching circuit section is operable to disconnect the common source line from ground, and wherein in the illumination off state, said switching circuit section is operable to connect the common source line to ground.

5. An image display apparatus as recited in claim 1, wherein said switching circuit section is operable to disconnect the common source line from ground for a logic LOW illumination control signal for light emitting device activation, and connect the common source line to ground for a logic HIGH illumination control signal for light emitting device deactivation.

6. An image display apparatus comprising:

a dot matrix of a plurality of light emitting diodes (LEDs) arranged in a matrix with m-lines and n-columns, a cathode of each of the LEDs disposed in each column is connected to a respective current line, and an anode of each of the LEDs disposed in each line is connected to a respective common source line;

driver circuitry operable to control an activation state to be either active or inactive depending on an input illumination control signal and, in the active state, control conduction through one end of each common source line and each current line based on input display data; and

a switching circuit section operable to float the other end of each common source line in the active state, and to ground the other end of each common source line in the inactive state;

wherein said driver circuitry is provided with a current source switching circuit with m-switching circuits corresponding to each common source line and, in the active state, said current source switching circuit is operable to connect the common source line selected by an input address signal to the current source; and

wherein said driver circuitry is provided with a constant current control circuit section having memory circuits operable to store n-sets of pixel level data of the sequentially input display data and, in the active state, said constant current control circuit section is operable to put the related current line in the conducting state for a pixel level width corresponding to the pixel level data stored in each of said memory circuits.

7. An image display apparatus as recited in claim 6, wherein said switching circuit section is a plurality of switches connected between each common source line and ground.

8. An image display apparatus as recited in claim 7, wherein said switching circuit section is controlled by the illumination control signal which controls a state of LED illumination to be on or off, wherein in the illumination on state, said switches of said switching circuit section are turned off to disconnect the common source line from ground, and wherein in the illumination off state, said switches of said switching circuit section are turned on to connect the common source line to ground.

9. An image display apparatus as recited in claim 6, wherein said switching circuit section is controlled by the illumination control signal which controls a state of LED illumination to be on or off, wherein in the illumination on state of the illumination control signal, said switching circuit section is operable to disconnect the common source line from ground, and wherein in the illumination off state, said switching circuit section is operable to connect the common source line to ground.

10. An image display apparatus as recited in claim 6, wherein said switching circuit section is operable to disconnect the common source line from ground for a logic LOW illumination control signal for LED activation, and connect the common source line to ground for a logic HIGH illumination control signal for LED deactivation.

11. An image display method comprising:

providing a dot matrix of a plurality of light emitting devices to be arranged in a matrix with m-lines and n-columns such that one terminal of each of the light emitting devices disposed in each column is connected to a respective current line, and the other terminal of each of the light emitting devices disposed in each line is connected to a respective common source line;

controlling an activation state to be either active or inactive depending on an input illumination control signal and, in the active state, controlling conduction through one end of each common source line and each current line based on input display data; and

floating the other end of each common source line in the active state, and grounding the other end of each common source line in the inactive state;

connecting, in the active state, the common source line selected by an input address signal to the current source; and

storing n-sets of pixel level data of the sequentially input display data and, in the active state, putting the related current line in the conducting state for a pixel level width corresponding to the stored pixel level data.

12. An image display method as recited in claim 11, wherein said floating is achieved by providing a plurality of switches to be connected between each common source line and ground.

13. An image display method as recited in claim 12, wherein the illumination control signal controls a state of the light emitting device illumination to be on or off, wherein in the illumination on state, the switches are turned off to disconnect the common source line from ground, and wherein in the illumination off state, the switches are turned on to connect the common source line to ground.

14. An image display method as recited in claim 11, wherein the illumination control signal controls a state of the light emitting device illumination to be on or off, wherein in the illumination on state of the illumination control signal, the common source line is disconnected from ground, and wherein in the illumination off state, the common source line is connected to ground.

15. An image display method as recited in claim 11, wherein the common source line is disconnected from ground for a logic LOW illumination control signal for light emitting device activation, and the common source line is connected to ground for a logic HIGH illumination control signal for light emitting device deactivation.

16. An image display method comprising:

providing a dot matrix of a plurality of light emitting diodes (LEDs) to be arranged in a matrix with m-lines and n-columns such that a cathode of each of the LEDs disposed in each column is connected to a respective current line, and an anode of each of the LEDs disposed in each line is connected to a respective common source line;

controlling an activation state to be either active or inactive depending on an input illumination control signal and, in the active state, controlling conduction through one end of each common source line and each current line based on input display data; and

floating the other end of each common source line in the active state, and grounding the other end of each common source line in the inactive state;

connecting, in the active state, the common source line selected by an input address signal to the current source; and

storing n-sets of pixel level data of the sequentially input display data and, in the active state, putting the related current line in the conducting state for a pixel level width corresponding to the stored pixel level data.

17. An image display method as recited in claim 16, wherein said floating is achieved by providing a plurality of switches to be connected between each common source line and ground.

18. An image display method as recited in claim 17, wherein the illumination control signal controls a state of LED illumination to be on or off, wherein in the illumination on state, the switches are turned off to disconnect the common source line from ground, and wherein in the illumination off state, the switches are turned on to connect the common source line to ground.

19. An image display method as recited in claim 16, wherein the illumination control signal controls a state of LED illumination to be on or off, wherein in the illumination on state of the illumination control signal, the common source line is disconnected from ground, and wherein in the illumination off state, the common source line is connected to ground.

20. An image display method as recited in claim 16, wherein the common source line is disconnected from ground for a logic LOW illumination control signal for LED activation, and the common source line is connected to ground for a logic HIGH illumination control signal for LED deactivation.