Controllable pixel border for a negative mode passive matrix display device
First Claim
1. A display unit comprising:
- a frame buffer memory operable to store image information;
a first plurality of row drivers and column drivers which depend on said frame buffer memory;
a passive matrix of independently controllable pixels comprising rows and columns of discrete pixels, said passive matrix operable to generate an image in response to electrical signals driven from said first plurality of row drivers and column drivers solely coupled to pixels of said passive matrix, wherein said image is representative of said image information of said frame buffer memory;
a second plurality of row drivers and column drivers which operate independent of said frame buffer memory; and
a border surrounding said passive matrix and comprising a fixed number of pixels arranged in rows and columns, wherein said border includes a fixed width surrounding said passive matrix, wherein each pixel of said border is uniformly controllable between an on state and an off state by a threshold signal applied to each pixel of said border, wherein said threshold signal is based on voltages driven by said second plurality of row drivers and column drivers solely coupled to said pixels of said border.
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Abstract
A display device having a display matrix including a pixel border of width x and located around the edge locations of the matrix for improved viewability. In particular, the border can be several pixels wide, e.g., 1<x<5. In one embodiment, the border region is two pixels wide and surrounds a display region in which images are generated from a frame buffer memory. Both the border region and the display region are implemented using a negative mode passive display matrix using liquid crystal display (LCD) technology. The pixels of the border are controllable between an on state and an off state and have an adjustable threshold voltage level. In one embodiment, the display screen is a negative mode display in which the pixels are normally black when off. The pixel border is useful in providing contrast in display modes having a white background with black characters displayed therein.
46 Citations
25 Claims
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1. A display unit comprising:
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a frame buffer memory operable to store image information; a first plurality of row drivers and column drivers which depend on said frame buffer memory; a passive matrix of independently controllable pixels comprising rows and columns of discrete pixels, said passive matrix operable to generate an image in response to electrical signals driven from said first plurality of row drivers and column drivers solely coupled to pixels of said passive matrix, wherein said image is representative of said image information of said frame buffer memory; a second plurality of row drivers and column drivers which operate independent of said frame buffer memory; and a border surrounding said passive matrix and comprising a fixed number of pixels arranged in rows and columns, wherein said border includes a fixed width surrounding said passive matrix, wherein each pixel of said border is uniformly controllable between an on state and an off state by a threshold signal applied to each pixel of said border, wherein said threshold signal is based on voltages driven by said second plurality of row drivers and column drivers solely coupled to said pixels of said border. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A display unit comprising:
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a frame buffer memory operable to store image information; a first plurality of row drivers and column drivers which depend on said frame buffer memory; a passive matrix of independently controllable pixels comprising rows and columns of discrete pixels, said passive matrix operable to generate an image in response to electrical signals driven from said first plurality of row drivers and column drivers solely coupled to pixels of said passive matrix, wherein said image is representative of said image information of said frame buffer memory; a second plurality of row drivers and column drivers which operate independent of said frame buffer memory; a border surrounding said passive matrix and comprising a fixed number of pixels arranged in rows and columns, wherein said border includes a fixed width surrounding said passive matrix, wherein each pixel of said border is uniformly controllable between an on state and an off state by a threshold signal applied to each pixel of said border, wherein said threshold signal is based on voltages driven by said second plurality of row drivers and column drivers solely coupled to said pixels of said border; and a contrast adjustment circuit for adjusting voltage levels supplied to said first plurality of row drivers and column drivers to adjust a contrast of said image of said passive matrix, wherein said contrast adjustment circuit is also operable to adjust said threshold signal to match a contrast of said border with said contrast of said passive matrix. - View Dependent Claims (13, 14, 15, 16)
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17. A portable electronic device comprising:
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a processor couple to a bus; a memory unit coupled to said bus; a user input device coupled to said bus; and a display unit coupled to said bus and comprising; a frame buffer memory operable to store image information; a first plurality of row drivers and column drivers which depend on said frame buffer memory; a passive matrix of independently controllable pixels comprising rows and columns of discrete pixels, said passive matrix operable to generate an image in response to electrical signals driven from said first plurality of row drivers and column drivers solely coupled to pixels of said passive matrix, wherein said image is representative of said image information of said frame buffer memory; a second plurality of row drivers and column drivers which operate independent of said frame buffer memory; a border surrounding said passive matrix and comprising a fixed number of pixels arranged in rows and columns, wherein said border includes a fixed width surrounding said passive matrix, wherein each pixel of said border is uniformly controllable between an on state and an off state by a threshold signal applied to each pixel of said border, wherein said threshold signal is based on voltages driven by said second plurality of row drivers and column drivers solely coupled to said pixels of said border. - View Dependent Claims (18, 19, 20, 21, 22)
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23. A display unit comprising:
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a frame buffer memory operable to store image information; a first plurality of row drivers and column drivers which depend on said frame buffer memory; a passive matrix of independently controllable pixels comprising rows and columns of discrete pixels, said passive matrix operable to generate an image in response to electrical signals driven from said first plurality of row drivers and column drivers solely coupled to pixels of said passive matrix, wherein said image is representative of said image information of said frame buffer memory; a second plurality of row drivers and column drivers which operate independent of said frame buffer memory; a first threshold voltage driver coupled to and operable to provide a first constant voltage to said second plurality of row drivers; a second threshold voltage driver coupled to and operable to provide a second constant voltage to said second plurality of column drivers; and a border surrounding said passive matrix and comprising a plurality of pixels arranged in rows and columns, wherein said border includes a fixed width surrounding said passive matrix, wherein each pixel of said border is uniformly controllable between an on state and an off state by a threshold signal applied to each pixel of said border, wherein said threshold signal is based on said first and second constant voltages driven by said second plurality of row drivers and column drivers solely coupled to said pixels of said border. - View Dependent Claims (24, 25)
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Specification