Image display apparatus

• US 20050237277A1
• Filed: 06/24/2005
• Published: 10/27/2005
• Est. Priority Date: 04/12/1999
• Status: Active Grant

• Current Assignee: Isao Kawahara
• Original Assignee: Isao Kawahara
• Inventors: Kawahara, Isao
• Granted Patent: US 7,474,280 B2
• Time in Patent Office: Days
• US Class Current: 345/63
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/0266 Reduction of sub-frame artefacts
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2048 with addition of random noise to an image signal or to a gradation threshold
• CPC Class Codes: G09G 3/288 using AC panels
• CPC Class Codes: H04N 5/202 Gamma control circuits for controlling camera response irrespective of the scene brightness H04N23/82
• CPC Class Codes: H04N 5/70 Circuit details for electroluminescent devices

Abstract

An image display apparatus using a display panel such as a plasma display panel having two illumination states aims to widen a dynamic range by increasing a ratio of maximum to minimum luminance reproducible on the same screen. In the image display apparatus, one TV field period is divided into a plurality of sub-fields which respectively have luminance weights and are arranged in order of time, and a gray-scale image is displayed by selecting a combination of sub-fields for each pixel and sustaining a light emission state of each pixel during the selected sub-fields, wherein when arranged in ascending order of luminance weight, the plurality of sub-fields include at least one sub-field whose luminance weight is one-half of a luminance weight of the next sub-field.

Claims

1-32. -32. (canceled)

33. An image display apparatus, in which a current TV field period is divided into a plurality of sub-fields that are respectively given luminance weights and are arranged in order of time, and a gray-scale image for the current TV field period is displayed by coding input pixel image signals using different coding modes that are switched in accordance with an amount of movement from an image of a past TV field period to the image of the current TV field period, wherein a combination of sub-fields is selected for each pixel depending on the amount of movement, and a light emission state is sustained in each pixel during the selected sub-fields, characterized in that

a signal used for switching between the different coding modes is arbitrarily space-modulated so that the different coding modes are interspersedly applied to input pixel image signals that correspond to an image area where the switching between the different coding modes is needed and that show a predetermined characteristic.

34. An image display apparatus, in which a current TV field period is divided into a plurality of sub-fields that are respectively given luminance weights and are arranged in order of time, and a gray-scale image for the current TV field period is displayed by coding input pixel image signals using different coding modes that are switched in accordance with an amount of movement from an image of a past TV field period to the image of the current TV field period, wherein a combination of sub-fields is selected for each pixel depending on the amount of movement, and a light emission state is sustained in each pixel during the selected sub-fields, characterized in that

a signal used for switching between the different coding modes is regularly space-modulated so that the different coding modes are interspersedly applied to input pixel image signals that correspond to an image area where the switching between the different coding modes is needed and that show a predetermined characteristic.

35. An image display apparatus, in which a current TV field period is divided into a plurality of sub-fields that are respectively given luminance weights and are arranged in order of time, and a gray-scale image for the current TV field period is displayed by coding input pixel image signals using different coding modes which are switched in accordance with an amount of movement from an image of a past TV field period to the image of the current TV field period, wherein a combination of sub-fields is selected for each pixel depending on the amount of movement, and a light emission state is sustained in each pixel during the selected sub-fields, characterized in that

a signal used for switching between the different coding modes, when expressed pixel by pixel as a virtual image of a matrix form in a plane, assumes a shape that contains a zigzag as a main component which turns no more than once in a pixel, so that the different coding modes are interspersedly applied to input pixel image signals that correspond to an image area where the switching between the different coding modes is needed and that show a predetermined characteristic.

36. The image display apparatus of claim 35,

wherein the shape that contains the zigzag as the main component has a pattern in which adjacent pixels alternate between two states.

37. The image display apparatus of claim 35,

wherein the shape that contains the zigzag as the main component is a shape that randomly combines zigzags each of which turns no more than once in a pixel.

38. The image display apparatus of claim 35,

wherein the input pixel image signals that show the predetermined characteristic correspond to a non-edge image area.

39. An image display apparatus, in which a current TV field period is divided into a plurality of sub-fields that are respectively given luminance weights and are arranged in order of time, and a gray-scale image for the current TV field period is displayed by coding input pixel image signals using different coding modes which are switched in accordance with an amount of movement from an image of a past TV field period to the image of the current TV field period, wherein a combination of sub-fields is selected for each pixel depending on the amount of movement, and a light emission state is sustained in each pixel during the selected sub-fields, characterized in that

a modulation signal having periodicity corresponding to no smaller than a pixel interval is applied to input pixel image signals that correspond to an image area where switching between the different coding modes is needed.

40. An image display apparatus, in which a current TV field period is divided into a plurality of sub-fields that are respectively given luminance weights and are arranged in order of time, and a gray-scale image for the current TV field period is displayed by coding input pixel image signals using different coding modes which are switched in accordance with an amount of movement from an image of a past TV field period to the image of the current TV field period, wherein a combination of sub-fields is selected for each pixel depending on the amount of movement, and a light emission state is sustained in each pixel during the selected sub-fields, characterized in that

input pixel image signals corresponding to an image area where switching between the different coding modes is needed are modulated to shift a display position of the image area.