Exemplary embodiments of the invention will be described in detail with reference to the following figures, wherein:
The exemplary embodiments of the present invention will now be described in detail with reference to the drawings.
The colored layer 22 is a layer colored to a color different from the black particles 30 and the white particles 32, and is assumed as being colored red in the present exemplary embodiment.
The image display medium 10 shown in
As shown in
The gap member includes plural scanning electrodes 14 and plural data electrodes 20, and is formed into a grid configuration so as to form plural cells 34. In
In
In the present exemplary embodiment, a configuration of arranging the scanning electrodes 14 on the display substrate side and the data electrodes 20 on the back surface substrate side is provided, but the data electrodes 20 may be arranged on the display substrate side and the scanning electrodes 14 on the back surface substrate side.
The scanning electrodes 14 and the data electrodes 20 may be formed not on the surfaces of the sides at which the display substrate 18 and the back surface substrate 28 face each other, but on the surfaces on the opposite sides, or may be separately and independently arranged on the outer sides of the display substrate 18 and the back surface substrate 28. When arranging the electrodes separately and independently from the image display medium, an electric field is created between the substrates by configuring the substrate with a member having dielectric property.
In the present exemplary embodiment, the black particles 30 have positive chargeability and the white particles 32 have negative chargeability, but the black particles 30 may have negative chargeability and the white particles 32 may have positive chargeability. Each particle may be an insulating particle, an electrically conductive particle or the like.
Each member configuring the image display medium 10 may be those disclosed in, for example, Japanese Patent Application Laid-Open (JP-A) No. 2001-312225.
In such image display medium 10, when a predetermined voltage (e.g., ±140 V), which is a voltage necessary to generate a potential difference between the substrates for at least being able to move the particles and which is a voltage that ensures the required density, is applied between the electrodes of the scanning electrode 14 and the data electrode 20, the black particles 30 and the white particles 32 at the relevant position move between the substrates. For example, when a predetermined voltage (e.g., +140 V), at which the potential of the scanning electrode 14 becomes positive with respect to the data electrode 20, is applied between the electrodes, the black particles 30 having positive chargeability on the display substrate 18 side move to the back surface substrate 28 side, and the white particles 32 having negative chargeability on the back surface substrate 28 side move to the display substrate 18 side, thereby “white” being displayed.
When a predetermined voltage (e.g. −140 V), at which the potential of the scanning electrode 14 becomes negative with respect to the data electrode 20, is applied between the electrodes, the white particles 32 having negative chargeability on the display substrate 18 side move to the back surface substrate 28 side and the black particles 30 having positive chargeability on the back surface substrate 28 side move to the display substrate 18 side, thereby “black” being displayed.
Therefore, when a predetermined positive or negative voltage is applied between the data electrode 20 and the scanning electrode 14 of the position corresponding to the pixel to which the particles are be moved, the particles move according to the image, and the image is displayed. The black particles 30 or the white particles 32 remain adhered to the display substrate 18 or the back surface substrate 28 by van der Waals' force or image force even after the application of the voltage is stopped, thereby maintaining the image-display.
In the present exemplary embodiment, a case in which the density property of the image display medium 10 is the property shown in
The ON voltage and the OFF voltage for black display to be applied to the scanning electrode 14 and the data electrode 20, that is, the value of the voltage to be applied to each electrode when moving the black particles 30 to the display substrate 18 side may be set to various values, where the first scanning electrode ON voltage to be applied to the scanning electrode 14 is set to −70 V, the first data electrode ON voltage to be applied to the data electrode 20 is set to +70 V, and the OFF voltage to be applied to the scanning electrode 14 and the data electrode 20 is set to 0 V in the present exemplary embodiment, as shown in
Similarly, the ON voltage and the OFF voltage for white display to be applied to the scanning electrode 14 and the data electrode 20, that is, the value of the voltage to be applied to each electrode when moving the white particles 32 to the display substrate 18 side may be set to various values, where the second scanning electrode ON voltage to be applied to the scanning electrode 14 is set to +70 V with opposite polarity from the first scanning electrode ON voltage, the second data electrode ON voltage to be applied to the data electrode 20 is set to −70 V with opposite polarity from the first data electrode ON voltage, and the OFF voltage is set to 0 V, similar to the OFF voltage for black display, in the present exemplary embodiment.
When the ON voltage and the OFF voltage for black display are set as mentioned above, if the ON voltage for black display is applied to both the scanning electrode 14 and data electrode 20, as shown in
In the present exemplary embodiment, the number of pulses for black display voltage to be applied between the substrates is in plurals to enhance the black and white display contrast, Further, the present exemplary embodiment, in order to shorten the display switching time, the pulse width of the pulse voltage to be applied at a first time is set to a pulse width longer than the normal pulse width, that is, set to a pulse width (first pulse width) that can sufficiently cause the particles in a stationary state to start moving, and the pulse width of the pulse voltage to be subsequently applied is set to a pulse width (second pulse width) that can sufficiently drive the particles that have started moving, which pulse width is shorter than the pulse width of the pulse voltage that is applied at the first time. The details will be hereinafter described, when displaying the red color of the back surface substrate, the pulse voltage of the first pulse width is applied at a first time, and thereafter, the pulse voltage of the second pulse width is applied, similar to the black display.
Specifically, the first scanning electrode ON voltage of the first pulse width is applied first, and thereafter, the second scanning electrode ON voltage of the second pulse width and the first scanning electrode ON voltage of the second pulse width are alternately applied for a few pulses to the scanning electrode 14 to be scanned, as shown in
To the data electrode 20 corresponding to the pixel to be displayed black, the first data electrode ON voltage of the first pulse width is first applied, and thereafter, the second data electrode ON voltage of the second pulse width and the first data electrode ON voltage of the second pulse width are alternately applied for a few pulses, as shown in
In other words, the pulse voltages which phase differs by 180 degrees are applied to the scanning electrode 14 and the data electrode 20. As shown in
Therefore, the pulse width of the voltage applied first is the pulse width that can sufficiently cause the particles in a stationary state to start moving, and the pulse width of the subsequently applied voltage is shorter than the pulse width of the voltage applied first, whereby the particles are sufficiently driven in a short period of time, the black and white display contrast becomes satisfactory, and the display switching time becomes shorter compared to the prior art.
In
When the first scanning electrode ON voltage is applied to the scanning electrode 14 and the OFF voltage is applied to the data electrode 20, the application voltage to the scanning electrode 14 with respect to the data electrode 20 becomes −70 V, and the particles of the relevant pixel (non-image part) do not move. Similarly, when the OFF voltage is applied to the scanning electrode 14 and the first data electrode ON voltage is applied to the data electrode 20, the application voltage to the scanning electrode 14 with respect to the data electrode 20 becomes −70 V, and the particles of the relevant pixel do not move, and when the OFF voltage is applied to the scanning electrode 14 and the OFF voltage is applied to the data electrode 20, the application voltage to the scanning electrode 14 with respect to the data electrode 20 becomes 0 V, and the particles of the relevant pixel do not move. The case for the white display is similar to the case for the black display except for the polarity being inverted.
When performing an initialization drive for equalizing the arrangement of the particles within the cell 34, that is, the particle density, and eventually obtaining the white display, an alternating voltage serving as the initialization drive voltage is applied between the scanning electrode 14 and the data electrode 20. For example, assuming the first scanning electrode initialization voltage is 140 V and the second scanning electrode initialization voltage is 0 V, such initialization voltages are alternately applied to the scanning electrode 14 at a predetermined pulse width, and in synchronization therewith, assuming the first data electrode initialization voltage is 0 V and the second data electrode initialization voltage is 140 V, such initialization voltages are alternately applied to the data electrode 20 at the predetermined pulse width. The alternating voltage is thereby applied between the scanning electrode 14 and the data electrode 20.
The above applications are executed for a predetermined number of pulses, and the first scanning electrode initialization voltage is applied to the scanning electrode 14 and the first data electrode initialization voltage is applied to the data electrode 20 to eventually obtain a white display. Preferably, application is executed at the pulse width longer than the predetermined pulse width to perform the white display of a more stable density. The predetermined number of pulse is set to a number that can sufficiently equalize the arrangement of the particles.
When displaying the color other than the particles, that is, the color of the colored layer 22 at a predetermined pixel in the cell, the first scanning electrode ON voltage of long pulse width that can sufficiently cause the particles in a stationary state to start moving is applied first, and thereafter, the second scanning electrode ON voltage of short pulse width that can sufficiently drive the particles that have started moving and the first scanning electrode ON voltage of the short pulse width are alternately applied for a few tens of the pulses to the scanning electrode 14 to be scanned, similar to the black display, as shown in
The first data electrode ON voltage of long pulse width is first applied, and thereafter, the second data electrode ON voltage of short pulse width and the first data electrode ON voltage of short pulse width are alternately applied for a few pulses to the data electrode 20 corresponding to the pixel to be displayed red, similar to the black display, as shown in
Therefore, with respect to the data electrode 20, the voltage (−140 V) which is twice the first scanning electrode ON voltage is first applied at a long pulse width and thereafter, the voltage (−140 V) which is twice the first scanning electrode ON voltage and the voltage (+140 V) which is twice the second scanning electrode ON voltage are alternately applied at a short pulse width for a few pulses to the scanning electrode 14, as the display drive voltage, as shown in
The OFF voltage is applied to the scanning electrodes 14 and the data electrodes 20 corresponding to the pixels other than the predetermined pixel.
Thus, particles in the region of the predetermined pixel move to the region in another pixel in the cell by the edge electric field (electric field in a direction parallel to the substrate surface) generated between the adjacent data electrode while reciprocating between the substrates, so that the colored layer 22 is exposed and the red color is displayed at the predetermined pixel.
The pulse width of the voltage applied first is the pulse width that can sufficiently cause the particles in a stationary state to start moving, and the pulse width of the subsequently applied voltage is shorter than the pulse width of the voltage applied first, so that the particles are sufficiently driven compared to the conventional art, and the dot defect in the red display is prevented.
The driving device 40 is configured including a scanning electrode drive circuit 42, a data electrode drive circuit 44, power supply circuits 46 and 48, and a control device 50.
The scanning electrode drive circuit 42 is connected to each scanning electrode 14, and applies various voltages supplied from the power supply circuit 46, that is, the first scanning electrode initialization voltage and the second scanning electrode initialization voltage, the first scanning electrode ON voltage and the second scanning electrode ON voltage, the OFF voltage and the like to each scanning electrode 14 according to the instruction of the control device 50.
The data electrode drive circuit 44 is connected to each data electrode 20, and applies various voltages supplied from the power supply circuit 48, that is, the first data electrode initialization voltage and the second data electrode initialization voltage, the first data electrode ON voltage and the second data electrode ON voltage, the OFF voltage and the like to each data electrode 20 according to the instruction of the control device 50.
The scanning electrode drive circuit 42 is connected to each scanning electrode 14, and applies various voltages supplied from the power supply circuit 46 to each scanning electrode 14 according to the instruction from the control device 50.
The data electrode driving circuit 44 is connected to each data electrode 20, and applies various voltages supplied from the power supply circuit 48 to each data electrode 20 according to the instruction from the control device 50.
The image data corresponding to the image to be displayed on the image display medium 10 is input to the control device 50. The control device 50 outputs, based on the input image data, a row number specifying signal for specifying the row number of the scanning electrode 14 to be scanned and a scanning electrode voltage specifying signal for specifying the type of application voltage, to the scanning electrode driving circuit 42, and also outputs a column number specifying signal for specifying the column number of the data electrode 20 to be applied with a predetermined voltage and a data electrode voltage specifying signal for specifying the type of predetermined voltage, based on the line image corresponding to the scanning electrode 14 specified by the row number specifying signal, to the data electrode driving circuit 44.
The scanning electrode drive circuit 42 applies the voltage of the type specified by the scanning electrode voltage specifying signal to the scanning electrode 14 of the row specified by the row number specifying signal from the control device 50, and applies the OFF voltage to the scanning electrodes 14 other than the scanning electrode 14 specified by the row number specifying signal.
The data electrode drive circuit 44 applies the voltage of the type specified by the data electrode voltage specifying signal to the data electrode 20 of the column specified by the column number specifying signal from the control device 50, and applies the OFF voltage to the data electrodes 20 other than the data electrode 20 specified by the column number specifying signal.
The voltage application sequence of the image display drive executed in the control device 50 will now be described.
The control device 50 first initializes the image display medium 10. In other words, the control device 50 instructs the scanning electrode drive circuit 42 and the data electrode drive circuit 44 so that the pulse voltages of a predetermined number of pulses having phases that differ by 180 degrees are applied to all the scanning electrodes 14 and the data electrodes 20, and furthermore, so that eventually the first scanning electrode initialization voltage is applied to the scanning electrodes 14 and the first data electrode initialization voltage is applied to the data electrodes 20, in order to equalize the particles and to obtain an entirely white display. The particles between the substrates are thereby equalized, and ultimately, all the white particles 32 move to the display substrate side 18 and all the black particles 30 move to the back surface substrate 28 side, thereby obtaining an entirely white display.
The control device 50 then outputs a row number specifying signal for specifying the scanning electrode 14 in the first row and a scanning electrode voltage specifying signal for specifying the scanning electrode pulse voltage as shown in
The voltage having a long pulse width is first applied, and thereafter, the alternating voltage having a short pulse width, such as shown in
The black and white line image is thereby displayed on the first row. The OFF voltage is applied to the other electrodes.
The black and white line images are sequentially displayed by repeating the processes similar to the above for the second and subsequent rows, thereby displaying a black and white image.
The control device 50 then outputs a row number specifying signal for specifying the scanning electrode 14 in the first row and a scanning electrode voltage specifying signal for specifying the scanning electrode pulse voltage as shown in
The alternating voltage for removing particles as shown in
The particles between the scanning electrode 14 and the data electrode 20 corresponding to the pixel to be displayed red move to the region of other pixel, that is, the region of the pixel to be displayed white or the region of the pixel to be displayed black, while reciprocating between the substrates. The colored layer 22 is thereby exposed, and the red color is displayed.
The line image is sequentially displayed by repeating the processes similar to the above for the second row as well, and the color image of red, white and black is displayed.
In the present exemplary embodiment, in black display, a case of first applying the voltage of long pulse width once, and thereafter, applying the voltage of shorter pulse width has been explained, but the voltage of long pulse may be applied over plural times, that is, the alternating voltage of long pulse width may be applied, and thereafter, the alternating voltage of short pulse width may be applied, as shown in
Furthermore, instead of having a long pulse width for the voltage to be applied first, the pulse width may all be the same, and the voltage of high voltage value may first be applied, that is, the voltage that can sufficiently cause the particles in the stationary state to start moving may be applied once, and then the voltage lower than the voltage applied first, that is, the voltage that can sufficiently drive the particles that have started moving may be applied, as shown in
The high voltage of long pulse width may be applied first, and thereafter, the voltage of shorter pulse width and lower than those of the voltage applied first may be applied.
The voltage of long pulse width or the high voltage is not limited to being applied first and the voltage of long pulse width or the high voltage may be applied in the middle.
The frequency of the voltage to be applied may gradually shift from low frequency to high frequency.
A sequence in which an entirely white display is obtained, then the black display is obtained with respect to each row and then the red display is obtained is described in the present exemplary embodiment, but may be a sequence of obtaining the black display after the red display.
The present invention is applied to the black display and the red display in the present exemplary embodiment, but is not limited thereto, and the invention may be applied to the initialization drive.
In the present exemplary embodiment, a case of displaying the image on the image display medium in which the arrangement of the electrodes is a simple matrix configuration has been described, but the invention is also applicable to the image display medium in which the arrangement of the electrodes is an active matrix configuration.
Number | Date | Country | Kind |
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2006-104491 | Apr 2006 | JP | national |