Pixel circuit, active matrix apparatus and display apparatus

• US 20070103419A1
• Filed: 12/22/2006
• Published: 05/10/2007
• Est. Priority Date: 06/02/2004
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Yamamoto, Tetsuro, Uchino, Katsuhide, Yamashita, Junichi
• Granted Patent: US 8,441,417 B2
• Time in Patent Office: Days
• US Class Current: 345/92
• CPC Class Codes: G02B 6/4214 the intermediate optical element having redirecting reflective means, e.g. mirrors, prisms for deflecting the radiation from horizontal to down- or upward direction toward a device G02B6/4246 takes precedence
• CPC Class Codes: G02B 6/4268 Cooling of semiconductor devices H01L23/24; of electric apparatus H05K7/20; of instruments G12B15/00
• CPC Class Codes: G02B 6/4272 with mounting substrates of high thermal conductivity
• CPC Class Codes: G09G 2300/0417 Special arrangements specific to the use of low carrier mobility technology
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2310/0216 Interleaved control phases for different scan lines in the same sub-field, e.g. initialization, addressing and sustaining in plasma displays that are not simultaneous for all scan lines
• CPC Class Codes: G09G 2310/0256 with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
• CPC Class Codes: G09G 2310/0267 Details of drivers for scan electrodes, other than drivers for liquid crystal, plasma or OLED displays
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/045 Compensation of drifts in the characteristics of light emitting or modulating elements
• 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 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/30 using electroluminescent panels
• CPC Class Codes: G09G 3/3233 : with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3258 : with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: G09G 3/3266 : Details of drivers for scan electrodes
• CPC Class Codes: G09G 3/3291 : in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: H01L 2224/16225 : the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2924/15192 : Resurf arrangement of the internal vias
• CPC Class Codes: H01L 2924/15311 : being a ball array, e.g. BGA
• CPC Class Codes: H04B 10/501 : Structural aspects

Abstract

A pixel circuit having a function of compensating for characteristic variation of an electro-optical element and threshold voltage variation of a transistor is formed from a reduced number of component elements. The pixel circuit includes an electro-optical element, a holding capacitor, a sampling transistor, a drive transistor, a switching transistor, and first and second detection transistors. The sampling transistor samples and supplies an input signal from a signal line so as to be held into the holding capacitor. The driving transistor drives the electro-optical element with current in response to the held signal potential. The first and second detection transistors supply a threshold voltage of the drive transistor into the holding capacitor in order to cancel an influence of the threshold voltage in advance.

Claims

1. A pixel circuit disposed at intersection of a scanning line and a signal line comprising:

an electro-optical element;

a holding capacitor;

a sampling transistor;

a drive transistor;

a switching transistor;

a first detection transistor; and

a second detection transistor,

wherein said sampling transistor samples an input signal from said signal line into said holding capacitor;

said drive transistor applies current to said electro-optical element depending on the input signal held by said holding capacitor which holds a voltage between a source and a gate of said driving transistor;

said switching transistor supplies current from a power supply potential to said drive transistor; and

said first and second detection transistors operating to supply a threshold voltage of said drive transistor into said holding capacitor prior to said sampling transistor sampling said input signal into said holding capacitor.

2. An active matrix apparatus, comprising:

a plurality of scanning lines;

a plurality of signal lines disposed perpendicularly to said scanning lines; and

a plurality of pixels respectively disposed at intersections of said scanning lines and said signal lines, individual ones of said plurality of pixels further comprising;

an electro-optical element;

a holding capacitor;

a sampling transistor;

a drive transistor;

a switching transistor;

a first detection transistor; and

a second detection transistor,

wherein said sampling transistor samples an input signal from said signal line into said holding capacitor;

said drive transistor applies current to said electro-optical element depending on the input signal held by said holding capacitor which holds a voltage between a source and a gate of said driving transistor;

said switching transistor supplies current from a power supply potential to said drive transistor; and

said first and second detection transistors operate to supply a threshold voltage of said drive transistor into said holding capacitor prior to said sampling transistor sampling said input signal into said holding capacitor.

3. A display apparatus, comprising:

a plurality of scanning lines;

a plurality of signal lines disposed perpendicularly to said scanning lines; and

a plurality of pixels respectively disposed at intersections of said scanning lines and said signal lines, individual ones of said plurality of pixels further comprising;

an electro-optical element;

a holding capacitor;

a sampling transistor;

a drive transistor;

a switching transistor;

a first detection transistor; and

a second detection transistor,

wherein said sampling transistor samples an input signal from said signal line into said holding capacitor;

said drive transistor applies current to said electro-optical element depending on the input signal held by said holding capacitor which holds a voltage between a source and a gate of said driving transistor;

said switching transistor supplies current from a power supply potential to said drive transistor; and

said first and second detection transistor operate to supply a threshold voltage of said drive transistor into said holding capacitor prior to said sampling transistor sampling said input signal into said holding capacitor.

4. A pixel circuit disposed at intersection of a scanning line and a signal line, the pixel circuit comprising:

an electro-optical element;

a holding capacitor;

a sampling transistor;

a drive transistor;

a switching transistor;

a first detection transistor and

a second detection transistor,

wherein said sampling transistor samples an input signal from said signal line into said holding capacitor;

said drive transistor applies current to said electro-optical element depending on the input signal held by said holding capacitor;

said switching transistor supplies voltage of one of two electrodes of said holding capacitor to a gate of said driving transistor at on state; and

said first and second detection transistors operate to supply a threshold voltage of said drive transistor into said holding capacitor prior to said sampling transistor sampling said input signal into said holding capacitor.

5. An active matrix apparatus, comprising:

a plurality of scanning lines;

a plurality of signal lines disposed perpendicularly to said scanning lines; and

a plurality of pixels respectively disposed at intersections of said scanning lines and said signal lines, individual ones of said plurality of pixels further comprising;

an electro-optical element;

a holding capacitor;

a sampling transistor;

a drive transistor;

a switching transistor;

a first detection transistor and

a second detection transistor;

wherein said sampling transistor samples an input signal from said signal line into said holding capacitor;

said drive transistor applies current to said electro-optical element depending on the input signal held by said holding capacitor;

said switching transistor supplies voltage of one of two electrodes of said holding capacitors to a gate of said driving transistor at on state; and

said first and second detection transistors operate to supply a threshold voltage of said drive transistor into said holding capacitor prior to said sampling transistor sampling said input signal into said holding capacitor.

6. A display apparatus, comprising:

a plurality of scanning lines;

a plurality of signal lines disposed perpendicularly to said scanning lines;

and a plurality of pixels respectively disposed at intersections of said scanning lines and said signal lines, individual ones of said plurality of pixels further comprising;

an electro-optical element;

a holding capacitor;

a sampling transistor;

a drive transistor;

a switching transistor;

a first detection transistor; and

a second detection transistor,

wherein said sampling transistor samples an input signal from said signal line into said holding capacitor;

said drive transistor applies current to said electro-optical element depending on the input signal held by said holding capacitor;

said switching transistor supplies voltage of one of two electrodes of said holding capacitors to a gate of said driving transistor at on state; and

said first and second detection transistors operate to supply a threshold voltage of said drive transistor into said holding capacitor prior to said sampling transistor sampling said input signal into said holding capacitor.