Classifications

• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
  • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes 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
  • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes 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 by control of light from an independent source
  • G09G3/3433—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes 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 by control of light from an independent source using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices
  • G09G3/344—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes 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 by control of light from an independent source using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices based on particles moving in a fluid or in a gas, e.g. electrophoretic devices
  • G09G3/3446—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes 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 by control of light from an independent source using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices based on particles moving in a fluid or in a gas, e.g. electrophoretic devices with more than two electrodes controlling the modulating element
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2300/00—Aspects of the constitution of display devices
  • G09G2300/06—Passive matrix structure, i.e. with direct application of both column and row voltages to the light emitting or modulating elements, other than LCD or OLED
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2310/00—Command of the display device
  • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
  • G09G2310/0202—Addressing of scan or signal lines
  • G09G2310/0205—Simultaneous scanning of several lines in flat panels
  • G09G2310/021—Double addressing, i.e. scanning two or more lines, e.g. lines 2 and 3; 4 and 5, at a time in a first field, followed by scanning two or more lines in another combination, e.g. lines 1 and 2; 3 and 4, in a second field
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2320/00—Control of display operating conditions
  • G09G2320/06—Adjustment of display parameters

Definitions

• the present invention relates to a method for operating an electrophoretic display panel apparatus and, more particularly, to a method which increases the speed with which information can be written to an electrophoretic display panel.
• Electrophoretic displays are now well known. A variety of display types and features are taught in several patents issued in the names of Frank J. DiSanto and Denis A. Krusos and assigned to the assignee herein, Copytele, Inc. of Huntington Station, New York. For example, U.S Patent Nos. 4,655,897 and 4,732,830, each entitled ELECTROPHORETIC DISPLAY PANELS AND ASSOCIATED METHODS describe the basic operation and construction of an electrophoretic display. U.S. Patent No. 4,742,345, entitled ELECTROPHORETIC DISPLAY PANELS AND METHODS THEREFOR, describes a display having improved alignment and contrast. U.S. Patent No.
• the electrophoretic display apparatus taught in the foregoing U.S. Patents are "triode-type" displays having a plurality of independent, parallel, cathode row conductor elements or "lines” deposited in the horizontal on one surface of a glass viewing screen.
• a glass cap member forms a fluid-tight seal with the viewing window along the cap's peripheral edge for containing the fluid suspension and also acts as a substrate for an anode plate deposited on the interior flat surface of the cap. When the cap is in place, the anode surface is in spaced parallel relation to both the cathode elements and the grid elements.
• the cathode element voltage, the anode voltage, and the grid element voltage can then be ascertained such that when a particular voltage is applied to the cathode and another voltage is applied to the grid, the area proximate their intersection will assume a net charge sufficient to attract or repel pigment particles in suspension in the dielectric fluid. Since numerous cathode and grid lines are employed, there are numerous discrete intersection points which can be controlled by varying the voltage on the cathode and grid elements to cause localized visible regions of pigment concentration and rarefaction.
• the operating voltages on both cathode and grid must be able to assume at least two states corresponding to a logical one and a logical zero.
• Logical one for the cathode may either correspond to attraction or repulsion of pigment.
• the cathode and grid voltages are selected such that only when both are a logical one at a particular intersection point, will a sufficient electrostatic field be present at the intersection relative to the anode to cause the writing of a visual bit of information on the display through migration of pigment particles.
• the bit may be erased, e.g., upon a reversal of polarity and a logical zero-zero state occurring at the intersection coordinated with an erase voltage gradient between anode and cathode.
• the local anode lines are in addition to the "remote" anode, which is the layer deposited upon the anode faceplate or cap as in triode displays.
• the dual anode structure aforesaid provides enhanced - operation by eliminating unwanted variations in display brightness between frames, increasing the speed of the display and decreasing the anode voltage required during Write and Hold cycles, all as explained in Application No. 07/345,825.
• a commonly sought objective for EPIDS of both triode and tetrode types, and for digital display equipment and computer and digital apparatus in general, is increased speed of operation. With respect to displays, it is desirable for the display to be able to write, erase and edit the displayed image as quickly as possible in response to operator input and computer processing.
• a computer with a visual output device for displaying character information such as a CRT
• a visual output device for displaying character information such as a CRT
• the computer memory and processing unit can operate at speeds far exceeding the capacity of a human user, if the input and output devices through which the computer communicates with the user are slow, the computer and the user must wait for the output devices.
• a word processor user is paging through a document at high speed
• a slow visual output device may well slow the speed of paging below that at which the user and/or the computer could potentially perform.
• one factor which contributes to the speed with which the display can operate is the speed with which the pigment particles can travel through the electrophoretic fluid under the influence of a particular voltage gradient.
• Pigment particle migration speed depends, inter alia, upon particle size and electrophoretic fluid viscosity.
• particle speed there is also the factor of spatial distribution within the EPID envelope, i.e., because the particles are in suspension they are distributed, prior to being exposed to voltage gradients, relatively evenly within the fluid envelope. Accordingly, there is a range of particle proximity to the "target" element, the target element being that element to which the particles are sought to be directed to perform an operation, such as write or erase.
• pixel intensity i.e., the greater the number of particles, the greater the intensity.
• pixel intensity is discernable at both sides of the typical EPID so that an intense accumulation of e.g., light colored particles, on one face of the EPID is accompanied by a correspondingly intense lack of light particles on the other face, which, in all probability, will appear dark due the selection of a dark solution or background for the light colored particles.
• writing a character on one faceplate of an EPID results in its reverse image being written on the other plate.
• the writing of a blank character may be termed selective character erasure.
• the problems and disadvantages associated with conventional methods of operating electrophoretic displays are overcome by the present inventive method for decreasing the time to write a frame of display data composed of a plurality of lines of displayable pixels on an electrophoretic display requiring a minimum time period for a line to be fully written.
• a set of at least two adjacent lines is written in a shortened period shorter in duration than the minimum period.
• the elements of the line set are then shifted such that the set contains at least one new line and at least one old line.
• the shifted line set is then written in a subsequent shortened period following the step of shifting.
• the set is repeatedly shifted and written in the foregoing fashion until the frame is completely written.
• FIG. 1 is a cross-sectional view of a typical triode-type EPID showing the essential electrical components thereof.
• FIG. 2 is a simplified schematic diagram illustrating an addressable display matrix comprised of horizontal and vertical elements, such as, a plurality of cathode lines and a plurality of grid lines, driven by display drivers, as would be used in known EPID devices like that shown in FIG. 1.
• FIG. 3 is a simplified schematic diagram illustrating circuitry for controlling the x and y display drivers illustrated in FIG. 2.
• FIG. 4 shows a character which could be displayed upon an x-y matrix using the circuitry and apparatus as illustrated in FIGS. 1-3, as controlled and operated in accordance with the method of the present invention.
• FIG. 5 is a flowchart showing a method for EPID writing in accordance with the present invention. Best Mode for Carrying Out The Invention
• FIG. 1 which is taken from U.S. Patent No. 4,732,830, shows an electrophoretic display 10 as is now known in the art.
• the display 10 has an anode faceplate 12 and a cathode faceplate 14 which are sealably affixed on either side of an interstitial spacer (not shown) to form a fluid-tight envelope for containing a dielectric/pigment particle suspension or electrophoretic fluid.
• the faceplates 12 and 14 are typically flat glass plates upon which are deposited conductor elements to comprise the situs of electrostatic charge for inducing motion of the pigment particles 16 in the electrophoretic fluid.
• the techniques, materials and dimensions used to form the conductor elements upon the faceplates and the methods for making and using EPIDS, in general, are shown in U.S.
• EPIDS as depicted in FIG. 1, for example, have a plurality of independent, electrically conductive cathode lines 18, shown here as horizontal rows, deposited upon the cathode faceplate 14 using conventional deposition and etching techniques.
• the orientation of the cathode lines 18 depends upon the orientation of the screen, which, if rotated 90 degrees, would position the cathode lines vertically.
• the cathode lines are arbitrarily defined as horizontal or in the x-axis.
• the cathode elements 18 be composed of Indium Tin Oxide (ITO) as set forth in U.S.
• ITO Indium Tin Oxide
• a plurality of independent grid conductor lines 20 are superposed in the vertical (parallel with the y-axis) over the cathode elements 18, i.e., at right angles thereto, and are insulated therefrom by an interstitial photoresist layer 22.
• the grid elements 20 may be formed by coating the photoresist layer 22 with a metal, such as nickel or chrome, using sputtering techniques or the like, and then selectively masking and etching to yield the intersecting but insulated configuration shown in FIG. 1.
• Each cathode and grid element 18, 20 terminates at one end in a contact pad, or is otherwise adapted to permit connection to display driver circuitry.
• An anode 26 is formed on an interior surface of the anode faceplate 12 by plating with a thin layer of conductor material, such as, chrome.
• FIG. 2 also taken from U.S. Patent No.
• each horizontal 18 and vertical 20 line has an associated amplifier/driver 24R and 24C, respectively, for impressing either a logical "1" or "0" thereon, such that when both are "1" at an intersection, that intersection is written.
• the horizontal lines have been labelled Rl...R2200 to signify that 2200 display lines 18 or rows would typically be present.
• 1700 vertical lines 20 or columns are common, as depicted by the labels C1...C1700.
• FIG. 3, taken from Patent No. 4,742,345, shows exemplary circuitry for supplying input data to the x and y drivers, 24R and 24C.
• a large capacity, composite, serial-to- parallel register 26 may be used as a buffer for collecting a large number of bits of display data, e.g., 850 bits. After sequentially clocking data into the register 26 and filling it to capacity, the data is latched in parallel into a latch array 28 having an equal capacity. The data is then strobed into the display driver amplifiers 24 through a plurality of AND gates 30. Data may be accumulated in the serial register while the transfer from latch array 28 to drivers 24 occurs.
• FIG. 4 shows exemplary circuitry for supplying input data to the x and y drivers, 24R and 24C.
• the output of the AND gates are labelled with odd number columns 1 through 1699.
• the data for even number columns would be supplied, in this case, by a twin circuit disposed on the cathode faceplate opposite to that for the odd columns. This configuration prevents overcrowding of electrical connections to the grid lines as explained in Patent No. 4,742,345.
• FIGS. 1 and 2 The proportions of the grid 20 and cathode 18 lines as shown in FIGS. 1 and 2 have been greatly enlarged for the purposes of illustration.
• the grid 20 and cathode 18 lines are very thin and elongated.
• a workable panel would have a large number of intersections, e.g., 2,200 X 1,700 or a total of 3,740,000 separately addressable intersection points in a panel approximately 8" X 11".
• cathode lines 18, and grid lines 20 are depicted. Additional illustrations of electrophoretic displays, their components and electrical circuitry can be seen by referring to U.S. Patents Nos. 4,742,345 and 4 ,772,820, each being awarded to the inventors herein and which are incorporated by reference herein.
• FIG. 4 illustrates a character, i.e., the letter "T" written on a EPID as described above in reference to FIGS. 1-3 by utilizing the algorithm flow-charted in FIG. 5.
• the writing time of the EPID can be reduced by simultaneously writing more than one line at a time. That is, in the above-described previously known EPIDS, an entire set of column data for a particular row is impressed upon the columns, e.g., the grid lines. A single row is then enabled with a logical "1" and thereby written. The next set of column data is loaded onto the grid lines and the next row is enabled or written. This goes on sequentially until the entire screen is written.
• each row in past operation had to be held in the logical "1" state for the required writing period or writing cycle time.
• a set of rows greater than one row e.g., two rows
• the two rows will both be dimly written with the same display information in one half the cycle time. For instance, if column data for row 1 is loaded and rows 1 and 2 are written, both row l and row 2 will be dimly written with row 1 display information.
• a 70 line X 25 line matrix with 1750 pixels may be used as the area for expressing a single character.
• the pattern of pixels comprising the common characters is very repetitive.
• Fig. 4 illustrates this principle using a matrix of only 22 X 22 lines, i.e., those lines centrally located within the entire 29 X 31 line matrix depicted.
• the top of the "T” begins at (r5,c5) and ends at (r9,c26). The significance of the X's on row 5 will be explained below.
• the stem of the "T” starts at (rl0,cl3) and ends at (r26,cl7) .
• the top of the "T” is composed of 5 identical rows of pixels and the stem of the "T” is composed of 17 identical rows of pixels.
• the "T” depicted in FIG. 4 is an example of applying the present inventive method in writing in two row sets at one half the normal write cycle time (twice the writing speed) . Specifically, one would execute the following steps in order to display the "T” shown in FIG. 4.: Load cl-c29 with data for rl
• r5 has been selected as the first line that has "Is” or written pixels in it and it should be the first line of the "top" of the "T". Due to the fact, however, that r5 is a transition line, i.e., a transition from non-written to written pixels, it will not be completely written and instead will only be dimly written or half written. This is so because each write cycle, since it is at twice the speed as a normal cycle, only "half writes” the information. The next cycle is necessary to fully write the information, but only if the next cycle uses the same data. In the case of a transition line, succeeding rows have different data. Since there are so many lines of pixels in operable displays, the loss of small numbers of transition lines and/or pixels does not cause a significant loss in readability..
• Load grid with r5 data (0,0,0,0,1,1,1,1,1,1,1,1...1,0,0,0) Write r5,r6 Load grid with r6 data (same as r5 data) Write r6, r7 (since r6 was previously "half" written with r5 data in the prior cycle and since the r5 data was the same as the r6 data, r6 is written completely on the subsequent cycle.)
• Load r7 data Write r7,r8 Load r8 Write r8,r9 Load r9
• FIG. 5 is a generalized flowchart of the steps of the present inventive method for operating an EPID in a multi-line write mode. It would be expected -that operator selection of display writing speed would be offered so that the operator can choose the speed and clarity. This sort of selection is presently offered to operators upon printing on dot- matrix printers, i.e., enhanced printing has greater pixel density but takes longer to print. Accordingly, the operator first enters the number of lines to be written in each write cycle 32. From this input the write cycle time (writing speed) is adjusted 34. The greater the number of lines simultaneously written in each write cycle, the faster the writing speed.
• the operator input could be expressed as a selection of writing speed, wherein the operator would select from a range of speeds corresponding to the number of lines simultaneously written.
• the flowchart shown in FIG. 5 pertains to the display of a single complete image (frame) on the EPID. This algorithm would be utilized over and over under the control of programming at the next higher level. The operator would not be queried as to the operating speed on each frame displayed. Information of that type would be initially set by query or default then changed by interrupt if desired. Having determined the line set size for writing, the writing is begun at the first row 36. (Of course, it would be equally feasible to load rows with data and write columns.) The processor then enters a loop wherein data for the current row is loaded onto the column lines (here grid lines) 38.
• the data is simultaneously written on the current row and the next x-1 rows by enabling those rows with a logical "1" 40, x being the number of rows in the write set selected.
• row 1 and the next (4-1) or 3 rows, i.e. ' , rows 2, 3 and 4 are written.
• the "1" state may correspond to a variety of voltages depending upon the EPID in question, e.g., whether the EPID is a triode or tetrode. A voltage of 0 volts has been used to enable writing in triodes and, in those instances represents a logical "1" or enable state.
• the row set is written for a write cycle time that has been adjusted by the size of the row set (divided by) . This is continued until all rows are written 42,44, whereupon control is returned to the next higher level in the program.
• line writing sequences could be employed using a multi-line write strategy, for example, vertical lines can be written from left to right or right to left, horizontal lines could be written from bottom to top or from the middle to the outer periphery, etc.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• General Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Control Of Indicators Other Than Cathode Ray Tubes (AREA)

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• 1991
  • 1991-09-17 CA CA 2119247 patent/CA2119247C/en not_active Expired - Fee Related
  • 1991-09-17 WO PCT/US1991/006601 patent/WO1993006585A1/en active IP Right Grant
  • 1991-09-17 EP EP92904723A patent/EP0604423B1/de not_active Expired - Lifetime
  • 1991-09-17 DE DE69123605T patent/DE69123605T2/de not_active Expired - Fee Related

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