Multilevel image display method and system

• US 5,172,108 A
• Filed: 02/24/1992
• Issued: 12/15/1992
• Est. Priority Date: 02/15/1988
• Status: Expired due to Term

• Current Assignee: Netcomsec Co., Ltd.
• Original Assignee: NEC Corporation
• Inventors: Hada, Hiroshi, Wakabayashi, Toshiro
• Primary Examiner(s): Oberley, Alvin E.
• Assistant Examiner(s): NGUYEN, CHANH DUY
• Application Number:
  US07/840,583
• Time in Patent Office: 295 Days
• Field of Search: 340/793, 340/703, 340/723, 340/802, 340/803, 340/804, 340/805, 340/811, 340/767, 340/771, 340/760, 340/765, 340/713, 340/784, 358/165, 315/169.4, 328/129.1
• US Class Current: 345/691
• 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 2310/0275 Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/297 using opposed discharge type panels

Abstract

A method for displaying an image with multilevel brightness by using an image display device in which an image is displayed by sequentially activating scan lines one by one, and one complete display image is formed by at least a plurality of continuous frames or fields. A brightness of the whole of the display screen is changed in units of one frame or field, so that each display pixel can have brightness levels which are respectively defined by combinations of brightness levels given by an input display data and brightness levels of the whole of the display screen.

Claims

1. A method for displaying an image having more than two different brightness levels in a line sequential scanning type of a binary image display device in which an image is displayed by sequentially activating scan lines one by one, and in which one complete display image is formed by at least a plurality of continuous frames or fields, said display device having an orthogonal array of column and row electrodes, pixels being formed at intersections in said orthogonal array, each of said electrodes having an individually associated driver, said method comprising the steps of:

(a) changing a brightness of the whole display screen in units of one frame or field during each one period corresponding to one frame or field, and

(b) logically multiplying all column drive video signals which are to be applied to a series of column drivers with a selected one of a plurality of brightness level signals, said logical multiplication being with the same selected one of the plurality of brightness level signals;

(c) applying said signals which are logically multiplied in step (b) through a series of column drivers to corresponding column electrodes of the display device, respectively; and

(d) applying said signals which are logically multiplied in step (b) through a series of row drivers to each of all row so that the respective logically multiplied row drive video signals are applied through the series of row drivers to corresponding row electrodes of the display device, respectively, whereby each display pixel can have a brightness level which is respectively defined by combinations of brightness levels given by an input display data and the selected one of said plurality of brightness levels of the whole of the display screen.

2. A method claimed in claim 1, wherein said plurality of brightness level signals are composed of at least two blanking signals having different inactive periods.

3. A method in claim 1 wherein said plurality of brightness level signals are composed of at least two toggle pulses having frequencies which are different from each other.

4. A circuit for displaying an image having more than two different brightness levels in a line sequential scanning type of binary image display device in which an image is displayed by sequentially activating scan lines one by one, one complete display image being formed by at least first and second continuous alternating frames or fields of display data, the image display device having a plurality of row electrodes and a plurality of column electrodes intersecting with one another in a two-dimensional plane so that each intersecting point between the row electrodes and the column electrodes forms one pixel, said circuit comprising a data selector connected to receive first and second continuous alternating frames or fields of display data, respectively, a counter connected to receive a vertical synchronism signal for counting received vertical synchronizing signals and for generating a switching signal at each vertical synchronizing signal, the switching signal being supplied to the data selector so that the data selector responds to the switching signal to alternately select either the first or the second continuous frames or field of display data, the selection being made responsive to an occurrence of each frame or field, a shift register connected to serially receive the display data outputted from the data selector in synchronism with a clock pulse so as to accumulate one frame or field of display data, a latch circuit having a plurality of parallel outputs and being coupled to receive in parallel the one frame or field of display data held in the shift register and to hold the received frame or field of display data during each horizontal scan period, a plurality of column drivers each having an input connected through an AND gate circuit to a corresponding one of said parallel outputs of the latch circuit and also having an output connected to a corresponding column electrode of the display device, a row signal generator connected to receive a horizontal synchronizing signal and having a plurality of parallel outputs, a plurality of row drivers each having an input connected through an AND gate to a corresponding one of said parallel outputs of said row signal generator and having an output connected to a corresponding row of electrode of the display device, the row generator responding to the horizontal synchronizing signal so as to selectively activate only one of the parallel outputs for each one horizontal scan, and a controller connected to receive a count value of the counter for controlling the opening and closing of the AND gate circuits connected to said column driver and said row driver during each horizontal scan period in a manner such that in at least each two continuous frames or fields an open period of the AND gate circuits connected to said column driver and said row driver for one of the two continuous frames or fields is different from an open period of the gate circuits connected to said column driver and said row driver for the other of the two continuous frames or fields, the controller being composed of a blanking signal generator for alternately generating a first blanking signal for the first frame or field of display data and a second blanking signal for the second frame or field of display data, the first and second blanking signals having active periods which are different from each other, and each first and second blanking signals being generated in synchronism with the horizontal scan signal and for every horizontal scan period.

5. A circuit for displaying an image having more than two different brightness levels in a line sequential scanning type of binary image display device in which an image is displayed by sequentially activating scan lines one by one, one complete display image being formed by at least first and second continuous alternating frames or fields of display data, the image display device having a plurality of row electrodes and a plurality of column electrodes intersecting with one another in a two-dimensional plane so that each intersecting point between the row electrodes and the column electrodes forms one pixel, said circuit comprising a data selector connected to receive first and second continuous alternating frames or fields of display data, respectively, a counter connected to receive a vertical synchronism signal for counting received vertical synchronizing signals and for generating a switching signal at each vertical synchronizing signal, the switching signal being supplied to the data selector so that the data selector responds to the switching signal to alternately select either the first or the second continuous frames or field of display data, the selection being made responsive to an occurrence of each frame or field, a shift register connected to serially receive the display data outputted from the data selector in synchronism with a clock pulse so as to accumulate one frame or field of display data, a latch circuit having a plurality of parallel outputs and being coupled to receive in parallel the one frame or field of display data held in the shift register and to hold the received frame or field of display data during each horizontal scan period, a plurality of column drivers each having an input connected through an AND gate circuit to a corresponding one of said parallel outputs of the latch circuit and also having an output connected to a corresponding column electrode of the display device, a row signal generator connected to receive a horizontal synchronizing signal and having a plurality of parallel outputs, a plurality of row drivers each having an input connected through an AND gate to a corresponding one of said parallel outputs of said row signal generator and having an output connected to a corresponding row electrode of the display device, the row generator responding to the horizontal synchronizing signal so as to selectively activate only one of the parallel outputs for each one horizontal scan, and a controller connected to receive a count value of the counter for controlling the opening and closing of the AND gate circuits connected to said column driver and said row driver during each horizontal scan period in a manner such that in at least each two continuous frames or fields an open period of the AND gate circuits for one of the two continuous frames or fields is different from an open period of the AND gate circuits connected to said column driver and said row driver for the other of the two continuous frames or fields, the controller being composed of a toggle pulse generator for alternately generating a first toggle pulse for the first frame or field of display data and a second toggle pulse for the second frame or field of display data, the first and second toggle pulses having frequencies which are different from each other, and each first and second toggle pulses being generated in synchronism with the horizontal scan signal and for every horizontal scan period.