JP5217410B2 - Drive device and image display device - Google Patents

Description

  The present invention relates to a drive device and an image display device.

  In recent years, image display media using colored particles are known as image display devices that can be rewritten repeatedly. Such an image display device is configured to include a pair of substrates including a front substrate and a rear substrate, and colored particles that are sealed between the pair of substrates and move between the pair of substrates by an applied voltage. The color particles are moved by applying a voltage according to the above between the pair of substrates, and an image is displayed by the color of the color particles.

  In Patent Document 1, a microcapsule including a dispersion medium and a plurality of types of particle groups each having different optical characteristics and particle mobility for each type is enclosed between a pair of substrates, and voltage is applied between the pair of substrates. A technique is disclosed in which an arbitrary particle group is moved to the surface substrate side by controlling time to display a color image.

  In order to perform such color image display, a prescribed drive sequence is required, and in order to perform arbitrary color display, it is necessary to form a plurality of types of electric fields between a pair of substrates.

  Currently, the magnitude of the electric field required for particle movement to display a color image with good color developability is the magnitude of the electric field required to remove the history of the displayed color image, and a single color. This is larger than the magnitude of the electric field required for image display.

In general, when an image is displayed by active matrix driving, the device is configured by using a thin film transistor (TFT) as a switch. However, an electric field necessary for moving particles with good color development is formed. In this case, it is necessary to apply a contrast potential exceeding the breakdown voltage of a general TFT gate driver. For this reason, it is assumed that it is necessary to use a custom IC that is a semiconductor chip specially designed and manufactured for a specific application / product.
JP 2006-58901 A

  The present invention relates to an image display device configured by using a general thin film transistor as a switch, a drive device that performs driving for moving particles to display a color image with good color development, and an image including the drive device. An object is to provide a display device.

In order to achieve the above object, according to the first aspect of the present invention, there is provided the driving device according to the first aspect of the present invention, wherein the source of the thin film transistor has at least one first potential in the positive potential group consisting of at least one positive predetermined potential and zero potential. And one of the second potentials in the negative potential group consisting of at least one negative predetermined potential and the zero potential, and the other of the first potential and the second potential. When the thin film transistor is turned on with the source potential applying means applying the first potential, the gate potential of the thin film transistor is set to the gate potential of the thin film transistor. Applying a potential obtained by adding a maximum potential of at least one kind of positive predetermined potential and a minimum potential for turning on the thin film transistor; When the means turns off the thin film transistor with the first potential applied, the source potential applying means applies the maximum potential for turning off the thin film transistor to the gate potential of the thin film transistor. When the thin film transistor is turned on with the second potential applied, a minimum potential for turning on the thin film transistor is applied to the gate potential of the thin film transistor, and the source potential applying means When the thin film transistor is turned off with the second potential applied , the gate potential of the thin film transistor is set to the minimum potential of the at least one negative predetermined potential and the thin film transistor is turned off. Gate potential applying means for applying a potential added with the maximum potential for , It is configured to include a.

  According to a second aspect of the present invention, in the driving device according to the first aspect, the source potential applying means applies the positive predetermined potential and the negative predetermined potential in order from the potential having the largest absolute value. Is.

  According to a third aspect of the present invention, in the driving device according to the first or second aspect, the source potential applying means is configured to use three types of positive predetermined potentials and three types of positive predetermined potentials, the source potentials having different magnitudes. One of the three types of negative potentials having the same potential and absolute value and the zero potential is applied.

According to a fourth aspect of the present invention, an image display device is formed at a plurality of source lines and a plurality of gate lines arranged crossing each other, at an intersection of the source lines and the gate lines, and each source is the source. An active matrix substrate having a plurality of thin film transistors connected to a line and having a gate connected to the gate line, and a plurality of pixel electrodes connected to drains of the plurality of thin film transistors, and a common electrode A counter substrate disposed opposite to the active matrix substrate, and sealed between the active matrix substrate and the counter substrate, and moved according to an electric field formed between the active matrix substrate and the counter substrate. together, the force to leave from either of color and the active matrix substrate and the counter substrate different to An image display medium including several types of particle groups, the driving apparatus according to any one of claims 1 to 3, and a common potential applying unit that applies a common potential to the common electrode. It is configured.

  According to a fifth aspect of the present invention, in the image display device according to the fourth aspect, the potential applied by the source potential applying means is determined according to the color displayed on the image display medium after being driven by the driving device. Is.

  According to a sixth aspect of the present invention, in the image display device according to the fourth or fifth aspect, the source potential applying means applies the potential in frame units according to the gradation of the color displayed on the image display medium. The number of times is adjusted.

  A seventh aspect of the present invention is the image display device according to any one of the fourth to sixth aspects, wherein the first potential and the second potential are predetermined according to characteristics of the plurality of types of particle groups. The source potential applying means applies a potential according to the order of application.

  According to an eighth aspect of the present invention, in the image display device according to any one of the fourth to seventh aspects, the source potential applying means calculates a maximum potential of a positive electrode that can be applied and a minimum potential of a negative electrode that can be applied. By alternately applying, the state of the image display medium is initialized.

  According to the first aspect of the present invention, the contrast of the potential applied to the gate is compared with the case where the potential applied to the gate is not changed between a state in which a positive potential is applied to the source and a state in which a negative potential is applied. Can be suppressed.

  According to the second aspect of the present invention, it is possible to obtain an effect that the driving can be performed with a smaller sequence than in the case where the potentials are not applied in order from the potential having the largest absolute value.

  According to the invention of claim 3, when any of the three types of positive predetermined potentials, the three types of positive predetermined potentials, the three types of negative potentials having the same absolute value, and the zero potential are not applied to the source As compared with the case, it is possible to obtain an effect that the drive can be performed with a small number of sequences.

  According to the fourth aspect of the present invention, compared to the case where the potential applied to the gate is not changed between the state where the positive potential is applied to the source and the state where the negative potential is applied, the active matrix drive using the thin film transistor as a switch. Thus, an effect that an image can be displayed is obtained.

  According to the invention of claim 5, there is an effect that an image can be displayed in a fewer sequence compared to the case where the potential to be applied is not determined according to the color displayed on the image display medium after driving. can get.

  According to the sixth aspect of the present invention, it is possible to obtain an effect that the gradation of the color displayed on the image display medium can be adjusted better than in the case where the number of times of applying the potential in frame units is not adjusted.

  According to the seventh aspect of the present invention, it is possible to display an image better than when the positive electrode potential or the negative electrode potential is to be applied first in accordance with the characteristics of the plurality of types of particle groups. The effect that it can do is acquired.

  According to the eighth aspect of the present invention, the state of the image display medium is improved by alternately applying the maximum potential of the positive electrode and the minimum potential of the negative electrode that can be applied. The effect that an image can be displayed on the screen is obtained.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. In each figure, the scale of each part is appropriately changed and displayed for easy visual recognition.

  As shown in FIG. 1, an image display medium 10 according to an embodiment of the present invention includes a display substrate 12 serving as an image display surface, a back substrate 14 facing the display substrate 12 with a gap therebetween, and a display substrate. A gap member 16 that holds the substrate 12 and the rear substrate 14 at a predetermined interval and partitions the substrate into a plurality of cells is configured.

  The above cell indicates a region surrounded by the display substrate 12, the back substrate 14, and the gap member 16, and a dispersion medium 18 is enclosed in the cell. In the dispersion medium 18, particle groups 20Y, 20M, 20C, and 20W (details will be described later, and hereinafter referred to as the particle group 20 if not distinguished) are dispersed, and the particle group 20 was formed in the cell. It moves between the display substrate 12 and the back substrate 14 according to the strength of the electric field.

  The gap member 16 is provided so as to correspond to each pixel when an image is displayed on the image display medium 10. Thereby, cells are formed so as to correspond to each pixel, and the image display medium 10 is configured so that color display for each pixel is possible.

  Note that the size of the cell corresponding to each pixel is closely related to the resolution of the image display medium 10, and the smaller the cell, the higher the resolution display medium can be manufactured. In this embodiment, it is about 10 μm to 1 mm.

  A common electrode 22 is provided on the display substrate 12. The back substrate 14 is provided with pixel electrodes 24 corresponding to the respective pixels.

  For fixing the display substrate 12 and the back substrate 14, fixing means such as a combination of bolts and nuts, a clamp, a clip, and a frame for fixing the substrate can be used. Moreover, you may use fixing means, such as an adhesive agent, heat melting, and ultrasonic bonding.

  Further, the display substrate 12, the gap member 16, and the common electrode 22 are made of colorless and transparent members.

  Such an image display medium 10 is shared with bulletin boards, circulars, electronic blackboards, advertisements, signboards, flashing signs, electronic newspapers, electronic books, and copiers and printers, as well as electronic paper that can store and rewrite images. It can be used for document sheets that can be used.

  Next, the configuration of the back substrate 14 will be described with reference to FIG.

  In the image display medium 10 according to the present embodiment, the image is rewritten by active matrix driving using a thin film transistor (TFT) in order to increase the display speed.

  Active matrix driving is a method in which a thin film transistor serving as a switch is provided on a substrate for each pixel, and an image is displayed by controlling the thin film transistor. Each pixel of interest can be switched with sharpness.

  The common electrode 22 provided on the display substrate 12 is used in common for the entire image display medium 10.

Further, as shown in FIG. 2A, the back substrate 14 is provided with source lines 28L ₁ , 28L ₂ , 28L ₃ ,..., 28 L _m (hereinafter, distinction) in order to enable active matrix driving. If not, it will be described as a source line 28L by using a code from which the subscript is deleted) and gate lines 30L ₁ , 30L ₂ , 30L ₃ ,..., 30 L _n as gate inputs of the TFT 26 (hereinafter, not distinguished) Is described as a gate line 30L using a code from which the subscript is deleted). In the vicinity of the intersection between the source line 28L and the gate line 30L, pixel electrodes 24 ₁₁ , 24 ₁₂ , 24 ₁₃ ,..., 24 _nm corresponding to the intersection (hereinafter, subscripts are deleted if not distinguished) The pixel electrode 24 is described using a reference numeral. A thin film transistor (TFT) 26 is provided corresponding to each pixel electrode 24, and the source line 28 </ b> L is connected as a source input of the TFT 26, and the gate line 30 </ b> L is connected as a gate input of the TFT 26.

  The drain 26D of each TFT 26 is connected to each pixel electrode 24 corresponding to each pixel including each TFT 26.

  Further, the source 26S of each TFT 26 is connected to the source line driving circuit 28 via the source line 28L. The TFTs 26 of the pixels in the same column are connected to the source line driving circuit 28 through the same source line 28L.

  Further, the gate 26G of each TFT 26 is connected to the gate line driving circuit 30 via the gate line 30L. The TFTs 26 of the pixels in the same row are connected to the gate line driving circuit 30 through the same gate line 30L.

  With this structure, only the pixel region sandwiched between the common electrode 22 and the pixel electrode 24 is affected by the electric field between the electrodes. The TFT 26 is turned on when there is a valid input to both the source 26S and the gate 26G of the TFT 26 corresponding to the pixel. Further, the pixel electrode 24 becomes the potential of the source 26S when the TFT 26 is in the on state, and maintains the on state potential before the off state when the TFT 26 is in the off state.

  The controller 32 includes a CPU, a ROM, a RAM, and the like, and controls the potential corresponding to the image data representing the image displayed by the source line driving circuit 28 to be applied to the source 26S of each TFT 26.

  The source line driver circuit 28 applies a potential corresponding to the image data to the source 26S of each TFT 26 as indicated by an arrow AS in FIG.

  Further, the controller 32 performs control so that a potential corresponding to image data representing an image displayed by the source line driving circuit 28 is applied to the source 26 </ b> S of each TFT 26.

  The gate line driving circuit 30 applies a potential corresponding to the image data to the gate 26G of each TFT 26 as indicated by an arrow AG in FIG.

  The mechanism including the source line driving circuit 28, the gate line driving circuit 30, and the controller 32 functions as a driving device. The mechanism including the driving device and the image display medium 10 is an image display. Functions as a device.

Incidentally, since the lamination and component mounting of the wiring is easy, but in the present embodiment has a configuration for forming a TFT on the rear substrate 14, forming a T FT on the display substrate 12, the common electrode on the rear substrate 14 It is good also as a structure which forms.

  Next, the particle group 20 enclosed between the substrates will be described.

  In the dispersion medium 18 enclosed in the image display medium 10, a plurality of types of particles having different colors and different detaching forces from the display substrate 12 and the back substrate 14 (hereinafter, appropriately referred to as detaching forces). Groups 20Y, 20M, 20C, and 20W are dispersed.

  The detachment force is a value obtained by subtracting, from the electrostatic force of the particle group 20, a force that restrains the particle group 20 on the display substrate 12 side or the back substrate 14 side (hereinafter referred to as a restraining force). This is a force for separating each particle from the substrate 14. This binding force includes magnetic force acting on each particle, flow resistance of particles due to a weak network between each particle, van der Waals force between each particle, and between each particle and the display substrate 12 and the back substrate 14. is there. That is, the separation force of the particle group 20 with respect to the display substrate 12 and the back substrate 14 indicates the difficulty of detaching each particle of the particle group 20 from the display substrate 12 and the back substrate 14.

  In the present embodiment, each particle group 20Y, 20M, 20C, 20W is separated from the state in which each particle is located on either one of the display substrate 12 and the back substrate 14 for each color, and on the other side. Although it moves so that it may be located, the magnitude | size of the electric potential difference which starts this movement is determined so that it may differ.

  The image display medium 10 displays different colors according to the strength of the electric field (potential difference (V / m) per unit distance) formed between the display substrate 12 and the back substrate 14.

  That is, the image display medium 10 moves the particle group 20 in accordance with the electric field formed between the display substrate 12 and the back substrate 14, so that each pixel of the image data is assigned to each pixel corresponding to each pixel. Display the corresponding color.

  Next, the detachment force from the display substrate 12 and the back substrate 14 of each particle group 20 different for each color will be described.

  The potential difference necessary for moving each particle included in each particle group 20 is determined from the potential difference between the substrates for forming the strength of the electric field necessary for each particle constituting each particle group 20 to start moving. The range is up to the maximum potential difference.

  The “potential difference necessary for the start of movement of the particles” indicates a potential difference between the substrates for forming an electric field having the intensity required when the particle group 20 starts to move. When the applied potential difference is continuously changed, the display density is changed from the state in which the display density of the image display medium 10 does not change due to the movement of the particles constituting each color particle group 20 for each color particle group 20. The potential difference when transitioning to the state where the change appears is shown.

  In addition, the “maximum potential difference” refers to the potential difference between the substrates when the display density does not change and the display density saturates even if the potential difference applied between the substrates and the application time are further increased from the start of the movement. Show.

  Next, with reference to FIG. 3, the relationship between the potential difference per unit distance between the display substrate 12 and the back substrate 14 and the change in display density due to the movement of each particle group 20 between the substrates will be specifically described. To do.

  The absolute values of potential differences Vtc, −Vtc, Vdc, −Vdc, Vtm, −Vtm, Vdm, −Vdm, Vtyw, −Vtyw, Vdyw, and −Vdyw described below are expressed as | Vtc | <| Vdc | < | Vtm | <| Vdm | <| Vtyw | <| Vdyw |.

  When a potential difference is gradually increased by applying a potential difference from 0 V between the substrates and the potential difference between the substrates exceeds + Vtc, the display surface of the image display medium 10 changes to a display density by the movement of the cyan particle group 20C. Begins to appear, and the cyan density increases. Further, when the potential difference is increased and the potential difference between the substrates becomes + Vdc, the change in display density due to the movement of the cyan particle group 20C on the display surface of the image display medium 10 stops.

Further increase the potential difference, and the potential difference between the substrate + exceeds Vt m, the display surface of the display medium 10 is started to appear a change in display density due to the movement of the magenta particle group 20M, the magenta color density becomes thinner. When the potential difference is further increased and the potential difference between the substrates becomes + Vdm, the change in display density due to the movement of the magenta color particle group 20M on the display surface of the image display medium 10 stops.

  When the potential difference is further increased and the potential difference between the substrates exceeds + Vtyw, the display surface of the image display medium 10 starts to change in display density due to the movement of the yellow color particle group 20Y and the white color particle group 20W. As the color becomes darker, the white color density becomes lighter. When the potential difference is further increased so that the potential difference between the substrates becomes + Vdyw, the display density of the display surface of the image display medium 10 stops changing due to the movement of the yellow color particle group 20Y and the white color particle group 20W.

On the contrary, when the potential difference from 0V to the minus pole is given between the substrates to gradually increase the absolute value of the potential difference and the potential difference between the substrates exceeds the absolute value of −Vt c , the display surface of the image display medium 10 is cyan. Due to the movement of the particle group 20C between the substrates, the display density starts to change, and the cyan color becomes lighter. Furthermore, increasing the absolute value of the potential difference, and the potential difference between the substrate becomes less -Vd c, the display surface of the display medium 10 stops the change in display density due to the movement of the cyan particle group 20C.

When the absolute value of the potential difference between the substrates is further increased so that the absolute value of the potential difference between the substrates exceeds the absolute value of the voltage value −Vt m , the display surface of the image display medium 10 is between the substrates of the magenta color particle group 20M. Due to the movement, the display density starts to change, and the magenta color becomes darker. Furthermore, increasing the absolute value of the potential difference, and the potential difference between the substrate is less than -Vd m, the display surface of the display medium 10 stops the change in display density due to the movement of the magenta particle group 20M.

  When the absolute value of the potential difference is further increased and the absolute value of the potential difference between the substrates exceeds the absolute value of −Vtyw, the display surface of the image display medium 10 is displayed by the movement of the yellow color particle group 20Y and the white color particle group 20W. A change in density begins to appear, the yellow color becomes lighter and the white color becomes darker. When the absolute value of the potential difference is further increased so that the potential difference between the substrates becomes less than -Vdyw, the display density of the display surface of the image display medium 10 stops changing due to the movement of the yellow color particle group 20Y and the white color particle group 20W.

  That is, in this embodiment, as shown in FIG. 2, when a voltage is applied between the substrates so that the absolute value of the potential difference between the substrates is less than | Vtc | There is no movement of the particles of the particle group 20 to such an extent that the display density changes. When a potential difference equal to or greater than | Vtc | is generated between the substrates, a change occurs in the display density of the display surface of the image display medium 10 for the cyan particle group 20C among the four color particle groups 20. When the particles move to such a degree that the display density per unit voltage starts to change, the absolute value of the potential difference between the substrates exceeds | Vdc |, and the potential difference with the absolute value of the potential difference less than | Vtm | No change occurs in the display density per unit voltage.

  Further, when a potential difference equal to or greater than | Vtm | is generated between the substrates, the movement of particles to the extent that the display density of the display surface of the image display medium 10 is changed in the magenta color particle group 20M starts to occur. When the display density per unit voltage begins to change and the absolute value of the potential difference between the substrates exceeds | Vdm | and the potential difference with the absolute value of the potential difference less than | Vtyw | occurs, the display density per unit voltage changes. Will no longer occur.

  Further, when a potential difference of | Vtyw | or more is generated between the substrates, the display density of the display surface of the image display medium 10 is changed with respect to the yellow color particle group 20Y and the white color particle group 20W. When the movement of particles begins to occur and the display density per unit voltage starts to change, and the absolute value of the potential difference between the substrates exceeds | Vdyw |, the display density per unit voltage does not change.

  In the present embodiment, in order to display an image with good color developability, the charge amount of the particle group 20 is determined so that the threshold value of the potential difference becomes larger for lighter colors (yellow and white).

  In the present embodiment, in order to display an image with good color developability, the particle diameter of the light-colored (yellow and white) particle group 20 is designed to be large, and a dark color (cyan, And the magenta color) particle group 20 is designed to have a small particle diameter.

  In the following, an electric field having an intensity that causes a potential difference between the substrates with an absolute value | Vtyw | that is greater than or equal to absolute value | Vdyw | is less than an absolute value | Vtm | An electric field having an intensity that causes a potential difference between the substrates is referred to as a “medium electric field”, and an electric field having an intensity that is greater than the absolute value | Vtc | and less than the absolute value | Vdc | Call it.

  Further, when a potential higher than that on the rear substrate 14 side is applied to the display substrate 12 side to provide a potential difference between the substrates, the respective electric fields are “+ large electric field”, “+ medium electric field”, and “+ small electric field”. Called. Further, when a potential higher than that on the display substrate 12 side is applied to the back substrate 14 side to provide a potential difference between the substrates, the respective electric fields are “−large electric field”, “−medium electric field”, and “−small electric field”. Called.

  Table 1 below shows specific potential differences capable of moving the particles.

全ての粒子群２０を移動させることが可能な大電界は、コモン電極２２の電位に対する電位の絶対値が｜１７｜Ｖ以上のときに発生する。すなわち、コモン電極２２の電位に対してソース２６Ｓの電位の絶対値を｜１７｜Ｖにすると共に、ＴＦＴ２６をオン状態にしたときに、大電界が発生する。

A large electric field capable of moving all the particle groups 20 is generated when the absolute value of the potential with respect to the potential of the common electrode 22 is | 17 | V or more. That is, when the absolute value of the potential of the source 26S is set to | 17 | V with respect to the potential of the common electrode 22, a large electric field is generated when the TFT 26 is turned on.

  The numbers in parentheses in Table 1 indicate the potential applied to the source 26S when the potential of the common electrode 22 is “22” V.

  The medium electric field capable of moving the cyan particle group 20C and the magenta particle group 20M is when the absolute value of the potential with respect to the potential of the common electrode 22 is | 10 | V or more and less than | 17 | V. Occur. That is, when the absolute value of the potential of the source 26S with respect to the potential of the common electrode 22 is set to | 10 | V and the TFT 26 is turned on, a medium electric field is generated.

  The medium electric field capable of moving only the cyan particle group 20C is generated when the absolute value of the potential with respect to the potential of the common electrode 22 is | 5 | V or more and less than | 10 | V. That is, when the absolute value of the potential of the source 26S is set to | 5 | V with respect to the potential of the common electrode 22, a small electric field is generated when the TFT 26 is turned on.

  By the way, the TFT 26 is turned on when a potential higher by “+15” V or more than the potential applied to the source 26S is applied to the gate 26G, and “−5” V or more than the potential applied to the source 26S. It is turned off when a low potential is applied to the gate 26G.

  Even when a negative potential is applied to the source 26S, in order to turn on the TFT 26, it is necessary to apply a potential of “+15” V or higher to the gate 26G, and a positive potential is applied to the source 26S. Even when it is applied, in order to turn off the TFT 26, it is necessary to apply a potential of "-5" V or less to the gate 26G.

  That is, in the present embodiment in which the potential of the pixel electrode 24 is changed in the range of “−17” V to “17” V, the TFT 26 is turned on when a potential of “+32” V is applied to the gate 26G. When the potential of “−22” V is applied to the gate 26G, the TFT 26 is turned off.

  However, when the potential of “−22” V and the potential of “+32” V are applied, the contrast of the potential of the gate 26G is “54” V, and “˜50” V of the gate 26G. The breakdown voltage is exceeded. That is, when applying a potential of “−22” V and applying a potential of “+32” V, a thin film transistor cannot be used as an active matrix drive switch, and a custom IC must be used.

  Therefore, in this embodiment, the potential applied to the gate 26G is controlled as shown in Table 2 below.

すなわち、ソース２６Ｓにプラスの電位が印加されているときは、ＴＦＴ２６をオン状態とする場合はゲート２６Ｇに「＋３２」Ｖの電位を印加し、ＴＦＴ２６をオフ状態とする場合はゲート２６Ｇに「−５」Ｖの電位を印加する。

That is, when a positive potential is applied to the source 26S, a potential of “+32” V is applied to the gate 26G when the TFT 26 is turned on, and “−” is applied to the gate 26G when the TFT 26 is turned off. A potential of 5 "V is applied.

  When a negative potential is applied to the source 26S, a potential of “+15” V is applied to the gate 26G when the TFT 26 is turned on, and “−” is applied to the gate 26G when the TFT 26 is turned off. A potential of 22 "V is applied.

  Accordingly, the potential contrast of the gate 26G can be set to | 37 | V which is lower than the withstand voltage of the gate 26G, and a thin film transistor can be used as a switch for active matrix driving.

  In this embodiment, the six types of potentials shown in Table 1 are applied in the order of increasing absolute value of the potential difference, as shown in FIG. 4A, and alternately plus and minus. In FIG. 3A, the horizontal axis indicates the passage of time, and the vertical axis indicates the potential.

  V3 is a potential at which the potential difference from the common electrode 22 is “0” V, for example “22” V.

  V6 is a potential for generating a large + electric field, and is, for example, “+17 (39)” V. The values in parentheses indicate a relative potential difference from V3, which is a driving voltage for particle movement.

  V5 is a potential for generating a + medium electric field, and is, for example, “+10 (32)” V.

  V4 is a potential for generating a + small electric field, for example, “+5 (27)” V.

V2 is a potential for generating a small electric field, and is, for example, “ −5 (17) ” V.

V1 is - the potential for generating a medium electric field, for example, "-10 (12)" V.

V0 is a potential for generating a large electric field, and is, for example, “ −17 (5) ” V.

  Note that FIG. 4A shows all the potentials that can be applied. At the time of rewriting, only the necessary potentials are selected depending on the color to be rewritten by driving the source line driver circuit 28 and the gate line driver circuit 30. Apply.

  In FIG. 4A, the potential applied for each frame is switched, but gradation expression is achieved by applying the same potential over a plurality of frames in accordance with the gradation of the image represented by the pixels. Is possible.

  The order of potential application may be reversed between plus and minus.

  FIG. 4B shows a potential applied to the gate 26G when a potential is applied to the source 26S as shown in FIG. In FIG. 5B, the horizontal axis indicates the passage of time, and the vertical axis indicates the potential.

  That is, in a frame in which a positive potential is applied to the source 26S, V8 (+32 (54) V) is applied to the gate 26G when the TFT 26 is turned on, and V2 is applied to the gate 26G when the TFT 26 is turned off. In a frame in which (−5 (17) V) is applied and a negative potential is applied to the source 26S, when the TFT 26 is turned on, V7 (+15 (37) V) is applied to the gate 26G and the TFT 26 When turning off the gate, 0 (−22 (0) V) is applied to the gate 26G.

  FIG. 5 shows potentials applied by driving the source line driving circuit 28 and the gate line driving circuit 30 and colors before and after driving.

  As shown in FIG. 5, the potential to be applied is determined by the color after driving, not by the color before driving.

  Further, there are at least one kind of potential to be applied and at most three kinds.

  Further, the polarity of the applied potential is alternately switched.

  For example, when rewriting from yellow to blue, the potential is applied in the order of + large electric field → −medium electric field → + small electric field.

  FIG. 6A shows the state of the particle group 20 before driving, and the pixel has a yellow color.

  First, by applying a large + electric field, as shown in FIG. 6B, the cyan particle group 20C and the white particle group 20W move toward the display substrate 12, and the magenta particle group 20M. The yellow color particle group 20Y moves to the back substrate 14 side, and the pixel exhibits a cyan color.

  Next, by applying the -medium electric field, as shown in FIG. 6C, the cyan particle group 20C moves to the back substrate 14 side, and the magenta particle group 20M moves to the display substrate 12 side. The pixel moves to a magenta color.

  Finally, by applying a + small electric field, as shown in FIG. 6D, the cyan particle group 20C moves to the display substrate 12 side, and the pixel exhibits a blue color.

  That is, when rewriting to blue, a potential difference is generated between the substrates only in the 1st Frame, 4th Frame, and 5th Frame in FIG. 4A, and no potential difference is generated between the substrates in the 2nd Frame, 3rd Frame, and 6th Frame. Note that a potential difference V3 is not generated as the same potential as the common electrode 22 by applying the potential V3 to the source 26S in the 2ndFrame, 3rdFrame, and 6thFrame.

  In the present embodiment, the magnitude relationship between the color of the particles and the moving electric field is described as an example, but the relationship is not determined but determined by the properties of the particle group.

  Similarly, in FIG. 6, in order to clearly know the difference between the particle color and the driving electric field, a model with a difference in particle size and particle size is described, but this does not necessarily depend on the particle size. .

  Next, a routine for controlling the driving of the source line driving circuit 28 and the gate line driving circuit 30 by the controller 32 will be described with reference to the flowcharts of FIGS.

  In step 100, it is determined whether there is an instruction to rewrite the image. If the determination is affirmative, the process proceeds to step 102. If the determination is negative, the process returns to step 100.

  In step 102, the display history is removed by initializing the state of the image display medium 10 by alternately applying a + large electric field and a -large electric field.

  Note that the initialization process in step 102 is not an essential process and may not be performed. Further, the initialization process in step 102 may be designed to be performed every predetermined number of rewrites.

  In step 104, the polarity is determined. Here, it is determined which of the positive potential and the negative potential is applied first. Which is applied first is determined by the characteristics of the particle group 20 enclosed between the substrates of the image display medium 10, and is determined by the image display medium 10. If it is determined positive in this step, the process proceeds to step 106, and if it is determined negative, the process proceeds to step 118.

  In step 106, the + large electric field generation process shown in the flowchart of FIG. 8A is executed.

  In step 130, it is determined whether or not a large electric field is generated. If the determination is affirmative, the routine proceeds to step 132. If the determination is negative, the routine ends.

  In step 132, the counter “C” is cleared.

  In step 134, it is determined whether or not the counter “C” is less than “N1”. “N1” is the number of frames to which + a large electric field is applied, and is determined by an image to be displayed.

  In step 136, a large electric field of 1 frame is applied.

  In step 138, the counter “C” is incremented by “1”, and the process returns to step 134.

  In step 108, the process for generating a large electric field shown in the flowchart of FIG. 8B is executed.

  In step 140, it is determined whether or not to generate a large electric field. If the determination is affirmative, the routine proceeds to step 142, and if the determination is negative, the routine ends.

  In step 142, the counter “C” is cleared.

In step 144, it is determined whether the counter “C” is less than “N2”. “N2” is the number of frames to which a large electric field is applied. In step 146 determined by the image to be displayed, one frame of the large electric field is applied.

  In step 148, the counter “C” is incremented by “1”, and the process returns to step 144.

  In step 110, a + medium electric field generation process shown in the flowchart of FIG. 8C is executed.

  In step 150, it is determined whether or not a + medium electric field is generated. If the determination is affirmative, the routine proceeds to step 152. If the determination is negative, the routine ends.

  In step 152, the counter “C” is cleared.

In step 154, it is determined whether or not the counter “C” is less than “N3”. “N3” is the number of frames to which the + medium electric field is applied. In step 156 determined by the image to be displayed, one frame of the + medium electric field is applied.

  In step 158, the counter “C” is incremented by “1”, and the process returns to step 154.

  In step 112, the process of generating a medium electric field shown in the flowchart of FIG. 8D is executed.

  In step 160, it is determined whether or not a -medium electric field is generated. If the determination is affirmative, the routine proceeds to step 162. If the determination is negative, the routine ends.

  In step 162, the counter “C” is cleared.

In step 164, it is determined whether the counter “C” is less than “N4”. “N4” is the number of frames to which the medium electric field is applied. In step 166 determined by the image to be displayed, one frame of the medium electric field is applied.

  In step 168, the counter “C” is incremented by “1”, and the process returns to step 164.

  In step 114, the + small electric field generation process shown in the flowchart of FIG. 8E is executed.

  In step 170, it is determined whether or not a + small electric field is generated. If the determination is affirmative, the routine proceeds to step 172. If the determination is negative, the routine ends.

  In step 172, the counter “C” is cleared.

  In step 174, it is determined whether the counter “C” is less than “N5”. “N5” is the number of frames to which a + small electric field is applied, and is determined by an image to be displayed.

  In step 176, one frame of + small electric field is applied.

  In step 178, the counter “C” is incremented by “1”, and the process returns to step 174.

  In step 116, the small electric field generation process shown in the flowchart of FIG. 8F is executed.

  In step 180, it is determined whether to generate a small electric field. If the determination is affirmative, the routine proceeds to step 182. If the determination is negative, the routine ends.

  In step 182, the counter “C” is cleared.

  In step 184, it is determined whether the counter “C” is less than “N6”. “N6” is the number of frames to which a small electric field is applied, and is determined by an image to be displayed.

  In step 186, a small electric field of one frame is applied.

  In step 188, the counter “C” is incremented by “1”, and the process returns to step 184.

  In step 118, the process for generating a large electric field shown in the flowchart of FIG. 8B is executed.

  In step 120, the + large electric field generation process shown in the flowchart of FIG. 8A is executed.

  In step 122, the process of generating a medium electric field shown in the flowchart of FIG. 8D is executed.

  In step 124, the + medium electric field generation process shown in the flowchart of FIG. 8C is executed.

  In step 126, the small electric field generation process shown in the flowchart of FIG. 8F is executed.

  In step 128, the + small electric field generation process shown in the flowchart of FIG. 8E is executed.

  As described above, in this embodiment, the potential applied to the gate of the thin film transistor is switched between the case where a positive potential is applied to the source of the thin film transistor and the case where a negative potential is applied to the source of the thin film transistor. Active matrix driving can be performed using a general thin film transistor as a switch.

  In the present embodiment, the present invention is applied to an image display device that displays an image by electrophoresis. However, the present invention can be applied to a toner display and a mechanism that displays an image by moving particles such as electrochromic. It is.

1 is a schematic configuration diagram of an image display medium according to an embodiment. It is a schematic block diagram of a back substrate and a driving device according to the present embodiment. It is a figure which shows the electrical potential difference required in order to move each particle | grain in the image display apparatus which concerns on this Embodiment. (A) is a figure which shows the electric potential applied to the source | sauce of TFT, (B) is a figure which shows the electric potential applied to the gate of TFT. It is a table | surface which shows the electric potential applied to the source | sauce of TFT for every color after a drive. It is a figure which shows the mode of the movement of the particle | grains when rewriting a display color from yellow color to blue color. It is a flowchart of the routine of the drive control of a drive device. It is a flowchart of the drive control routine of the drive device for each electric field to be generated.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image display medium 12 Front substrate 14 Rear substrate 20Y Yellow particle group 20M Magenta particle group 20C Cyan particle group 20W White particle group 22 Common electrode 24 Pixel electrode 26 Thin film transistor 26G Gate 26S Source 26D Drain 28 Source line drive circuit 28L Source line 30 Gate line drive circuit 30L Gate line 32 Controller

Claims (8)

The source of the thin film transistor has at least one first potential in a positive potential group consisting of at least one positive predetermined potential and zero potential, and at least one negative predetermined potential and negative potential consisting of the zero potential. Source potential applying means for alternately applying one potential of any one of the second potentials in the potential group and the other potential of the first potential and the second potential;
In the case where the thin film transistor is turned on while the source potential applying means applies the first potential, the gate potential of the thin film transistor includes a maximum potential of the at least one kind of positive predetermined potential and the gate potential of the thin film transistor. When applying a potential that is a minimum potential for turning on the thin film transistor and turning off the thin film transistor with the source potential applying means applying the first potential, the thin film transistor When the maximum potential for turning off the thin film transistor is applied to the gate potential of the thin film transistor and the thin film transistor is turned on with the source potential applying means applying the second potential, When applying the minimum potential for turning on the thin film transistor to the gate potential , The minimum potential of said if the source potential applying means is the thin film transistor in an off state while applying said second potential, wherein said at least one negative predetermined potential to the gate potential of the thin film transistor And a gate potential applying means for applying a potential obtained by adding a maximum potential for turning off the thin film transistor;
A driving device including:   2. The driving device according to claim 1, wherein the source potential applying unit applies the positive predetermined potential and the negative predetermined potential in order from a potential having a larger absolute value.   The source potential applying means includes any one of three types of positive predetermined potentials having different magnitudes, the three types of positive predetermined potentials, three types of negative potentials having the same absolute value, and the zero potential. The driving device according to claim 1, wherein the driving device is applied. A plurality of source lines and a plurality of gate lines arranged crossing each other, formed at intersections of the source lines and the gate lines, each source being connected to the source line, and a gate being the gate line A plurality of thin film transistors connected to the active matrix substrate, and a plurality of pixel electrodes connected to each of the drains of the plurality of thin film transistors;
A counter substrate provided with a common electrode and disposed opposite the active matrix substrate;
Enclosed between the active matrix substrate and the counter substrate, and moves in accordance with an electric field formed between the active matrix substrate and the counter substrate, and the color and the active matrix substrate and the counter substrate of each other A plurality of types of particle groups having different forces to be detached from either one of them,
An image display medium including:
The drive device according to any one of claims 1 to 3,
Common potential applying means for applying a common potential to the common electrode;
An image display device.   The image display device according to claim 4, wherein the potential applied by the source potential application unit is determined according to a color displayed on the image display medium after being driven by the drive device.   The image display device according to claim 4, wherein the source potential applying unit adjusts the number of times of applying a potential in frame units according to a gradation of a color displayed on the image display medium.   7. The source potential applying means applies a potential according to the order of application of the first potential and the second potential determined in advance according to characteristics of the plurality of types of particle groups. The image display device described in 1.   8. The source potential applying unit initializes the state of the image display medium by alternately applying a maximum potential of a positive electrode and a minimum potential of a negative electrode that can be applied. Any one of the image display apparatuses.

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