Liquid crystal display method and apparatus capable of making multi-level tone display

• US 5,583,530 A
• Filed: 02/10/1993
• Issued: 12/10/1996
• Est. Priority Date: 10/09/1989
• Status: Expired due to Term

• Current Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Original Assignee: Hitachi, Ltd., Hitachi Video Engineering Incorporated
• Inventors: Tsunekawa, Satoru, Fujisawa, Kazuhiro, Mano, Hiroyuki, Futami, Toshio, Inuzuka, Tatsuhiro, Konuma, Satoshi
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): NGUYEN, CHANH DUY
• Application Number:
  US08/015,896
• Time in Patent Office: 1,399 Days
• Field of Search: 340/793, 340/784, 340/767, 340/805, 340/701, 340/703, 345/87, 345/88, 345/89, 345/147, 345/148, 345/94, 359/54, 359/56, 359/59
• US Class Current: 345/89
• CPC Class Codes: G09G 2310/0297 Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/2025 the sub-frames having all the same time duration
• CPC Class Codes: G09G 3/2051 with use of a spatial dither pattern
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: H04N 3/127 using liquid crystals

Abstract

A liquid crystal display system capable of making a display of 2^i+j (i, j: positive integers) kinds of tones display includes a frame rate control device for selecting one out of frame rate control data of 2^j kinds in accordance with j-bit display data included in (i+j)-bit display data, i and j being positive integers, a multi-level tone pulse generator for generating display pulses of 2ⁱ +1 kinds including at least activation for display, inactivation for display, and intermediate display corresponding to an intermediate level, and a selection drive device for selecting a display pulse of one kind out of display pulses of 2ⁱ +1 kinds in accordance with the frame rate control data supplied from the frame rate control device and i-bit display data and applying the selected display pulse to a liquid crystal panel, the i-bit being different from the j-bit.

Claims

1. A multi-level tone display method of display data for a dot matrix display panel comprising the steps of:

generating three kinds of pulses including an OFF pulse, an ON pulse and a 1/2 display ON pulse during one horizontal interval, said 1/2 display ON pulse including a first 1/2 display ON pulse which is ON in a first half of the one horizontal interval and a second 1/2 display ON pulse which is ON in a second half of the one horizontal interval;

generating a frame rate control signal for controlling one of the multi-level tones by controlling a ratio among a plurality of frames in response to the display data, said frame rate control signal being generated so that said three kinds of pulses are continuous in a vertical direction of the frames; and

controlling supply of one of a pair of the pulses to a display dot of the dot matrix display panel at each frame by the frame rate control signal so as to display the display dot of the dot matrix display panel at one of the multi-level tones, said 1/2 display ON pulse being provided so that the first 1/2 display ON pulse and the second 1/2 display ON pulse are alternately supplied to vertically adjacent display dots.

2. A multi-level tone display method according to claim 1, wherein said frame rate control signal is generated so that said first 1/2 pulse display ON and said second 1/2 display ON pulse are alternatively supplied to each dot of a row of the dot matrix display panel.