JP2007518111A - Ebook with improved image quality - Google Patents

Abstract

By shifting the start column and / or the row in which successive pages are displayed in order, the image quality in an electronic reading device (300, 400) such as an electronic book using an electrophoretic display is improved. For example, the first page (530, 830) is displayed starting from the first position, the second page (630, 930) is displayed starting from the second position, and the third page (730). 1030) can be displayed starting from the third position and so on. By shifting the starting position, eg, columns and / or rows, of each page relative to the previous page, the image retention effect caused by repeated image / text updates is significantly reduced, resulting in higher image quality. It is. The need for periodic erasing or resetting of the display to remove image retention effects is also reduced, thereby reducing power consumption and increasing user convenience.

Description

  The present invention generally relates to electronic reading devices such as electronic books and electronic newspapers, and more particularly to methods and apparatus for improving image quality using such devices by reducing image retention.

  Recent technological advances have provided “user friendly” electronic reading devices such as electronic books, which offer many opportunities. For example, electrophoretic displays are highly promising. Such displays have inherent memory behavior and can hold images for a relatively long time without consuming power. Power is consumed only when the display needs to be refreshed, i.e. updated, with new information. Therefore, the power consumption in such a display is very small, which is suitable for application to portable electronic reading devices such as electronic books and electronic newspapers. Electrophoresis involves the operation of charged particles in an applied electric field. When electrophoresis occurs in a liquid, the particles are velocity determined primarily by the viscous resistance experienced by the particles, the charge of the particles (permanent or induced), the dielectric properties of the liquid, and the magnitude of the applied electric field. It moves with.

  U.S. Pat. No. 6,057,028 published on Apr. 9, 1999 by Eink in Cambridge, Mass., USA and having the name "Full Color Reflective Display With Multichromatic Sub-Pixels" describes such a display device. Patent Document 1 describes an electronic ink display having two substrates. One substrate is transparent and the other substrate is provided with electrodes arranged in a matrix. A display element, or pixel, is associated with the intersection of the column electrode and the row electrode. The display element is coupled to the row electrode using a thin film transistor (TFT) and its gate is coupled to the column electrode. This display element, TFT transistor, and matrix electrode configuration together form an active matrix. Furthermore, the display element has a pixel electrode. A column driver selects a column of display elements, and a row driver supplies a data signal to the selected column of display elements via a row electrode and a TFT transistor. The data signal corresponds to graphic data to be displayed, such as text or figures.

  Electronic ink is applied between the pixel electrode and the common electrode on the transparent substrate. Electronic ink has a number of microcapsules having a diameter of about 10 to 50 microns. In one approach, each microcapsule has positively charged white particles and negatively charged black particles suspended in a liquid carrier medium or fluid. When a positive voltage is applied to the pixel electrode, the white particles move to one side of the microcapsule in the direction of the transparent substrate and the observer will see a white display element. At the same time, the black particles move towards the pixel electrode on the opposite side that is hidden from the microcapsule observer. By applying a negative voltage to the pixel electrode, the black particles move towards the common electrode on one side of the microcapsule in the direction of the transparent substrate, and the display element appears dark to the viewer. At the same time, the white particles move towards the pixel electrode on the opposite side that is hidden from the microcapsule observer. When the voltage is removed, the display device remains in the obtained state and thus exhibits bistable characteristics. In another approach, the particles are provided in a dyed liquid. For example, black particles can be provided in a white liquid. Alternatively, white particles can be provided in the black liquid. Alternatively, other colored particles can be provided in different colored liquids. For example, white particles can be provided in a green liquid.

  Other fluids, such as air, may be used as a medium in which black and white particles charged in an electric field move (eg, Bridgestone SID 2003-Symposium on Information Display, May 18-23, 2003, Summary 20.3). Colored particles can also be used.

  To form an electronic display, electronic ink can be printed on a plastic film sheet that is laminated to a circuit layer. The circuit forms a pattern of pixels that can be controlled by the display driver. Since the microcapsules are suspended in a liquid carrier medium, the microcapsules can be printed on virtually any surface, including glass, plastic, cloth or even paper, using current screen-printing processes. Is possible. In addition, the use of elastic sheets also allows for the design of electronic reading devices that resemble the appearance of a conventional book.

However, one difficulty of such an electronic reading device is that the image quality is degraded by the image holding action. Especially when the next image is displayed due to the strong memory effect of the electronic ink type display, especially when the pixel is repeatedly switched, the previous image may not be sufficiently erased, and the image retention is integrated on the display. Will bring. The memory action of a pixel is mainly localized to each pixel, but sometimes it depends on surrounding pixels. In order to avoid an unacceptable accumulation of image retention over time, the reset is periodically performed, for example, by switching the entire display to a completely black state and a completely white state at least three times. . A reset pulse is used that has a duration of, for example, a maximum of 500 milliseconds which is sufficient to move the particles to an extreme optical state, for example a black or white state. Reset is inconvenient for the user because it usually takes 3 to 5 seconds and is clearly visible. Therefore, it is desirable to reduce the image holding action in order to reduce the frequency with which such a reset is required.
International Publication No. 99/53373

  The present invention addresses such and other problems as described above.

  In one aspect of the present invention, a method is provided for displaying information on an electronic reading device having a display area having pixels arranged in a plurality of columns and rows. Each pixel may have switching electronics such as, for example, a thin film transistor (TFT), a diode, or a metal-insulator-metal (MIM) device. The method includes starting from a first position, such as a column or row of the display area, displaying a first page on the display area, and in response to a next page command, the first position of the display area is Starting at a second position, such as a different column or row, and displaying a second page on the display area instead of the first page. In response to the next next page command, the next page is displayed on the display area, starting at various positions in the display area. Vertical column shifts and horizontal parallel shifts may be used individually or in combination.

  Related electronic reading devices and computer program products are also provided.

  Corresponding parts are designated by the same reference numerals throughout the drawings.

  1 and 2 show an embodiment of a part of a display panel 1 of an electronic reading device having a first substrate 8, a second opposing substrate 9, and a plurality of image elements 2. The image element 2 can be arranged in a two-dimensional structure substantially along a straight line. Although the image elements 2 are shown away from each other for clarity, in practice the image elements 2 are very close to each other to form an uninterrupted image. In addition, only a portion of the entire display screen is shown. Other configurations of the image element, such as a honeycomb configuration, are possible. An electrophoretic medium 5 with charged particles 6 is between the substrates 8 and 9. The first electrode 3 and the second electrode 4 are associated with each image element 2. Electrodes 3 and 4 are capable of receiving a potential difference. In FIG. 2, for each image element 2, the first substrate has the first electrode 3, and the second substrate 9 has the second electrode 4. The charged particles 6 can further occupy positions in the vicinity of the electrodes 3 and 4 or their middle. Each image element 2 has an appearance determined by the position of the charged particles 6 between the electrodes 3 and 4. The electrophoretic medium 5 itself is known from, for example, US Pat. Nos. 5,961,804, 6,120,839, and 6,130,774, and is available from, for example, Eink. is there.

  For example, the electrophoretic medium 5 can include negatively charged black particles 6 in a white liquid. When the charged particles 6 are in the vicinity of the first electrode 3 due to, for example, a potential difference of +15 volts, the appearance of the image element 2 is white. When the charged particles 6 are in the vicinity of the second electrode 4 due to a potential difference of the opposite polarity, for example, −15 volts, the appearance of the image element 2 is black. When the charged particles 6 are between the electrodes 3 and 4, the image element has an intermediate appearance, such as a gray level between black and white. The drive control unit 100 controls the potential difference of each image element 2 so as to create a desired image or text on the entire display screen. The entire display screen is formed from a number of image elements corresponding to the pixels in the display.

  FIG. 3 schematically shows an overall view of the electronic reading apparatus. The electronic reading device 300 includes a control unit 100 having an addressing circuit 105. The control unit 100 controls one or more display screens 310 such as an electrophoretic screen to display a desired text or image. For example, the control unit 100 may supply voltage waveforms to various pixels on the display screen 310. The addressing circuit provides information for addressing specific pixels, eg, a matrix, to display the desired image or text. As will be described below, the control unit 100 displays a continuous image starting from various columns and / or rows. Image or text data may be stored in the memory 120. One example is the Philips Electronics Small Form Factor Optical (SFFO) disk system. The controller 100 may respond to software or hardware buttons 320 that are activated by a user to activate a user command, such as a next page command or a previous page command.

  The controller 100 can be part of a computer that executes any type of computer code device such as software, firmware, microcode, etc. to implement the functions described herein. Accordingly, a computer program product including such a computer code device may be provided in a manner that will be apparent to those skilled in the art. For example, after the x pages are displayed, the control unit 100 may be configured such that the electronic reading apparatus is first turned on every y minutes, for example, 10 minutes, and / or the luminance deviation is reflected by 3%. There may be logic that periodically provides a forced reset of the display area of the electronic book when it exceeds the value. For automatic reset, the acceptable frequency can be determined empirically based on the lowest frequency that results in acceptable image quality. In addition, the reset can be manually initiated by the user via a function button or other interface device, for example, when the user begins reading the electronic reading device or when the image quality has dropped to an unacceptable level. is there. In the present invention, the required reset frequency is reduced by, for example, 80% or more.

  The present invention may be used with any type of electronic reading device. FIG. 4 shows one possible example of an electronic reading device 400 having two separate display screens. In particular, the first display area 442 is provided on the first screen 440, and the second display area 452 is provided on the second screen 450. Screens 440 and 450 may be connected by a coupling 445 that allows the screens to be folded flat against each other and opened to lay flat on a surface. This configuration is preferred because it closely reproduces the experience of reading a conventional book.

  Various user interface devices may be provided to allow the user to activate page forward commands, page return commands, and the like. For example, the first area 442 is activated using a mouse or other pointing device, touch activation, PDA pen, or other well-known technique to enable turning on-screen buttons 424. Can be included. In addition to the page forward command and the page return command, a function of scrolling up or down the same page may be provided. A hardware button 422 may alternatively or additionally be provided that allows the user to provide page forward and page back commands. Second region 452 may also have on-screen buttons 414 and / or hardware buttons 412. Note that the frames 405 around the first display area 442 and the second display area 452 are not necessary because the display area may be frameless. Other interfaces such as a voice command interface may be used. Note that buttons 412, 414 and 422, 424 are not required for both display areas. That is, one set of page forward button and page return button may be provided. Alternatively, other devices such as a single button or rocker switch can be activated to provide both page forward and page back commands. Function buttons or other interface devices can also be provided to allow the user to manually initiate a reset.

  In another possible design, the electronic book has a single display screen with a single display area that displays one page at a time. Alternatively, a single display screen may be divided into two or more display areas arranged, for example, horizontally or vertically. In any case, the present invention can be used with each display area to reduce memory retention.

  Further, if multiple display areas are used, successive pages can be displayed in any desired order. For example, in FIG. 4, a first page can be displayed on the display area 442, while a second page is displayed on the display area 452. When the user requests to see the next page, the third page is displayed in the first display area 442 instead of the first page, while the second page is in the second display area 452. May remain displayed within. Similarly, the fourth page is displayed in the second display area 452 and so on. In another approach, when the user requests to see the next page, both display areas are updated so that the third page is displayed in the first display area 442 instead of the first page. The fourth page is displayed in the second display area 452 instead of the second page. If a single display area is used, the first page may be displayed, then when the user enters a next page command, the second page overwrites the first page, and so on. This process works in reverse for the page return command. Furthermore, this process is equally applicable to languages where text is read from right to left, such as Hebrew, and languages where text is read line by line rather than column by word, such as Chinese.

  Furthermore, the entire page need not be displayed on the display area. A portion of the page is displayed and a scroll function is provided that allows the user to scroll up, down, or scroll left and right to read other portions of the page. Enlarging and reducing functions can also be provided to allow the user to change the size of the text or image. This may be suitable for users with low vision, for example.

  FIG. 5 schematically shows a display screen having columns used to display the first page. A display screen with a number of pixels 2 arranged in a matrix, ie a region 520, is shown. For example, only a few pixels of 12 pixels in width and 16 pixels in height are shown. Thus, region 520 may be considered to form only a complete image or part of a page. In practice, thousands or millions of pixels are used to provide uninterrupted high quality images. As described above, the desired image / text can be displayed on the display area 520 by controlling each pixel according to its particular column and row address. In particular, a column driver 510 and a row driver (source driver) 500 provide signals to each pixel to display a desired image, for example, a page of text read by a user. In the present invention, when a new page is to be displayed in the display area 520, the new page is displayed starting from a different location than the previous page, eg, a different column. For example, in FIG. 5, the first page is displayed with hatched pixels 530 forming a subset of all pixels in display area 520. In particular, the first page is displayed starting from the first column of the display area 520 and extends to the fourteenth column. The fifteenth and sixteenth columns are not used to display the first page.

  FIG. 6 shows a second page displayed on the second through fifteenth columns of the display area 520 as indicated by the hatched pixels 630. Here, the display of the second page starts from the second column of the display area 520. FIG. 7 shows a third page displayed on the third through sixteenth columns of the display area 520. Therefore, the column in which the display of each page starts varies from page to page. In one approach, the column from which the page display begins is determined in response to a changing offset from the reference column in the display area. For example, the reference column can be the first column in the display area, or any other designated column. Further, the offset amount can vary between a minimum value and a maximum value. For example, for the first page in FIG. 5, the offset amount from the first column is a minimum value of zero. This is because there is no offset amount. For the second page in FIG. 6, the offset amount from the first column is one column, and for the third page in FIG. 7, the offset amount from the first column is two columns. If the bottom column is selected as the reference column, the offsets for the first, second, and third pages are 15, 14, and 13, respectively.

  Many different variations on this idea are possible. For example, the start column can be changed for each displayed page, every other page, every third page, or the like. However, changing the start row for each page is considered to give the greatest reduction in image retention. Each page can be considered to be on the display screen no matter what image / text is displayed. Furthermore, the start column can be changed in one or more columns for each page. Furthermore, there is no need to increase the start column by the same amount for each page. Further, the offset amount from the reference column can be varied, for example, so as to increase from the minimum value until reaching the maximum value at which the offset amount is reset to the minimum value in one cycle. This can be performed using, for example, continuous offset amounts of 0 column, 1 column, 2 columns, 3 columns, 0 column, 1 column, 2 columns, 3 columns,. In another approach, the offset amount is varied from the minimum value to increase until the maximum value is reached, and the offset amount is decreased from the maximum value to the minimum value. This can be performed using, for example, continuous offset amounts of 0 column, 1 column, 2 columns, 3 columns, 2 columns, 1 column, 0 columns, 1 column, 2 columns, 3 columns,. The maximum offset amount can be any number of columns. For example, when a page of text is displayed, the maximum amount of offset can be based on the height of the space between lines of text. This uses a blank space between lines that is not used unless it is based on height to actually display the text, thereby avoiding the accumulation of image retention effects at specific locations on the display. The maximum amount of offset should not be so great that the shifted pages are inconvenient or frustrating for the user. For example, the maximum offset amount may be limited to the height of one line of text that is added to the height of the space between the lines of text.

  In addition to the column shift techniques described above, similar row shift techniques may be used by themselves or in combination with column shifts. For example, FIG. 8 schematically illustrates a display screen 520 that displays a first page using row shift. Here, the first page is displayed using hatched pixels 830 that form a subset of all the pixels in display area 520. The first page is displayed starting from the position of the first row in the display area 520 and extending to the tenth row. The eleventh and twelfth rows are not used to display the first page.

  FIG. 9 shows a second page displayed on the second through eleventh rows of the display area 520 as indicated by the hatched pixels 930. Here, the display of the second page is started from the position of the second row in the display area 520. FIG. 10 shows a third page displayed on the third through twelfth rows of the display area 520 as indicated by the hatched pixels 1030. Therefore, the line where the display of each page starts varies from page to page. In one approach, the line at which the display of the page begins is determined according to the amount of offset that changes from the reference line in the display area. For example, the reference line can be the first line in the display area, or any other designated line. Furthermore, the offset amount can vary between a minimum value and a maximum value in a manner similar to the column shift technique described above.

  In another variation, the starting line can be changed for each displayed page, every other page, every third page, or the like. However, changing the starting line for each page is believed to give the greatest reduction in image retention. Furthermore, the starting line can be changed in one or more lines per page. Furthermore, there is no need to increase the starting line by the same amount for each page. Also, the offset amount from the reference row can be varied, for example, so as to increase from the minimum value until reaching the maximum value at which the offset amount is reset to the minimum value in one cycle. In another approach, the offset amount is varied from the minimum value to increase until the maximum value is reached, and the offset amount is decreased from the maximum value to the minimum value. The maximum offset amount can be any number of rows. The maximum amount of offset should not be so great that the shifted pages are inconvenient or frustrating for the user. For example, the maximum offset amount can be limited to the width of one character of text.

  Column shifts and row shifts may be used in combination. FIGS. 11, 12, and 13 schematically illustrate display screens that display first, second, and third pages, respectively, using column and row shifts. The first page is displayed using hatched pixels 1130, while the second page is displayed using hatched pixels 1230, and the third page is hatched. The displayed pixel 1330 is used for display. For each successive page, column and row shifts are used. Note that the variations described above for column and row shifts are also applicable to this technique. Further variations are possible, such as shifting in a clockwise or counterclockwise circular pattern. For example, in a clockwise pattern, the image is shifted from left to right for each page, then shifted from top to bottom, then shifted from right to left, and finally shifted from bottom to top, starting first Return to position. This can be done, for example, by referring to FIG. 11, and the upper left pixel has coordinates (0, 0) where, for example, row = 0 and column = 0, and its right pixel is, for example, a row = 1 and column = 0 have coordinates (1, 0), and the pixel below it has coordinates (0, 1) where row = 0 and column = 1, for example. Thus, by identifying the pixels used to display the page by the upper left pixel coordinates, the clockwise circular pattern is a series of (0,0), (1,0), (2,0), ( 2, 1), (2, 2), (1, 2), (0, 2), (0, 1), (0, 0). Similar counterclockwise patterns are a series of (0,0), (0,1), (0,2), (1,2), (2,2), (2,1), (2, 0), (1, 0), (0, 0).

  In addition, row based shifts may be used from left to right of display screen 520 for a given column position. The column position can then be increased and a shift based on a further series of rows can be performed. For the next column, the row position can be reset, or a zigzag pattern may be used by working in the opposite row order. For example, a pattern with row reset is a series of (0,0), (1,0), (2,0), (0,1), (1,1), (2,1), (0, 2), (1,2), (2,2). The zigzag pattern consists of a series of (0,0), (1,0), (2,0), (2,1), (1,1), (0,1), (0,2), (1 , 2), (2, 2). A similar right-to-left pattern may be used. For example, when the position is reached at the end, position (2, 2), the pattern can follow the reverse order or start again from the first starting position. Similarly, column-based shifts may be used from top to bottom of the display screen 520 for a given row position using a column reset or zigzag pattern. For example, a pattern with column reset is a series of (0,0), (0,1), (0,2), (1,0), (1,1), (1,2), (2, 0), (2, 1), (2, 2). The zigzag pattern is a series of (0,0), (0,1), (0,2), (1,2), (1,1), (1,0), (2,0), (2 , 1), (2, 2). A similar right-to-left pattern may be used. In another approach, for example, a series of (0,0), (1,0), (2,0), (2,1), (2,2), (1,2), (0,2) , (0,1), (1,1), a spiral pattern is used. Various other patterns can also be used. Furthermore, substantially random vertical and / or horizontal offset amounts can also be selected for column and / or row shift, for example by providing a random number generator that outputs an integer between the minimum and maximum offset values. Can be done. The term “random” is meant to encompass “pseudorandom”.

  By shifting the starting column and / or row of each page relative to the previous page, image retention effects and subsequent incomplete erasures or resets caused by repeated image / text updates are significantly reduced, As a result, higher image quality is provided. In the example described above, an active matrix electronic ink display is used as the screen of the electronic book. The display has both a source driver that supplies data to be displayed and a gate driver that switches lines. In column shift, for example, during image update, image data is sent from the source driver, and each column is switched using the column driver and scanned from the top column to the bottom column in the display area. Is done. The nth page is updated starting from the first column of the display, while the (n + 1) th page has a vertical shift starting from the second column of the display, for example. Updated. The (n + 2) th page may start from the third column. Or, when a maximum shift is reached, for example up to 2 columns, the third page starts at the first column and the pattern continues. In this way, the probability that the same pixel is repeatedly switched, for example to black text, is significantly reduced, which avoids the integration of image retention on the pixel. Experiments have observed that the frequency of forced reset of the entire display can be significantly reduced, thereby reducing power consumption and improving user convenience.

  While what has been considered as the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various modifications and changes in form or detail may readily be made without departing from the spirit of the invention. is there. Accordingly, the invention is not intended to be limited to the precise form described and illustrated, but is to be construed as including all modifications that fall within the scope of the claims.

It is a front view which shows the one Example of the display screen of an electronic reading apparatus. It is sectional drawing about the line 2-2 in FIG. It is a figure which shows the whole image of an electronic reading apparatus. FIG. 2 shows two display screens with each display area. FIG. 6 shows a display screen that displays a first page using column shift. FIG. 6 shows a display screen that displays a second page using column shift. FIG. 6 shows a display screen that displays a third page using column shift. FIG. 6 shows a display screen that displays a first page using row shift. FIG. 6 shows a display screen that displays a second page using row shift. FIG. 10 illustrates a display screen that displays a third page using row shift. FIG. 6 shows a display screen displaying a first page using column and row shifts. FIG. 6 shows a display screen displaying a second page using column and row shifts. FIG. 6 shows a display screen displaying a third page using column and row shifts.

Claims (18)

A method for displaying information on an electronic reading device having a display area having pixels arranged in a plurality of columns and rows, comprising:
Displaying a first page on the display area starting from a first position of the display area;
Responsive to a next page command to display a second page on the display area instead of the first page starting from a second position different from the first position of the display area; ,
Having a method.   The method of claim 1, further comprising the step of sequentially displaying subsequent pages on the display area starting from various positions in the display area in response to subsequent next page commands.   The method according to claim 2, wherein the various positions at which the display of the next page starts are determined according to respective offset amounts that change from a reference position of the display area.   4. The method of claim 3, wherein each varying offset amount is in a range between a minimum value and a maximum value.   5. The method of claim 4, wherein each changing offset amount increases with each display of successive pages until the maximum value is reached, at which the offset amount is reset to the minimum value.   5. The method of claim 4, wherein each changing offset amount decreases with each display of successive pages until the minimum value is reached, at which the offset amount is reset to the maximum value.   Each changing offset amount increases with each display of successive pages until the maximum value is reached, and from the maximum value, the offset amount is displayed for further successive pages until the minimum value is reached. The method of claim 4, wherein the method decreases with time.   Each changing offset amount decreases with each display of successive pages until the minimum value is reached, and from the minimum value, the offset amount is displayed for further successive pages until the maximum value is reached. The method of claim 4, wherein the method increases with time.   The method of claim 4, wherein each of the varying offset amounts varies randomly between the minimum value and the maximum value.   The method of claim 1, further comprising controlling a column electrode associated with the column and a row electrode associated with the row to provide an indication of the first page and the second page on the display area. Method. The first position has a first row;
The method of claim 1, wherein the second location comprises a second column. The first position has a first row;
The method of claim 1, wherein the second location comprises a second row. A display area having pixels arranged in a plurality of columns and rows;
A controller that controls the display area to display a first page on the display area starting from a first position of the display area;
Have
In response to a next page command, the controller starts a second page on the display area instead of the first page, starting from a second position different from the first position in the display area. An electronic reading device that controls the display area to display on the screen.   The electronic reading apparatus according to claim 13, wherein the display area includes an electrophoretic display.   The control unit controls the display region to display the first page and the second page by controlling a column electrode associated with the column and a row electrode associated with the row. 13. The electronic reading device according to 13. The first position has a first row;
The electronic reading device of claim 13, wherein the second position has a second column. The first position has a first row;
The electronic reading device of claim 13, wherein the second location has a second row. A computer program product for displaying information on an electronic reading device having a display area with pixels arranged in a plurality of columns and rows,
Causing the computer to display a first page on the display area starting from the first position of the display area, and different from the first position of the display area in response to a next page command A computer program product comprising a computer code device configured to display a second page on the display area instead of the first page starting from a second location.

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