CN102376256A - Driving method of display unit - Google Patents

Abstract

A method for driving a display unit includes the following steps: applying a first voltage difference between a first electrode and a second electrode to move a first particle toward the second electrode; stopping applying the first voltage difference; and applying a second voltage difference between the first electrode and the second electrode to decelerate the first particle toward the second electrode to prevent the first particle from excessively colliding with or adhering to the second electrode.

Description

Driving method of display unit

technical field

The invention mainly discloses a driving method of a display unit, in particular a charged particle driving method capable of protecting the display unit and increasing contrast.

Background technique

The technology in this field is based on the fact that in a closed space composed of two electrodes and compartments, at least one electrode is transparent, and there will be charged particles of at least one color in this space. The magnitude and polarity of the voltage generate an electric field to move the particles. Examples are as follows:

Please refer to FIG. 1 , which is a schematic diagram of a display unit and a driving method of the display unit in the prior art. There may be two slightly different driving methods in the known technology, as shown in the upper and lower parts of Figure 1 respectively. For the convenience of description, this specification first uses the upper part as an example. As shown in the figure, the display unit 1 at least includes a first electrode 11, a second electrode 13, a first particle 15 and a second particle 17, wherein the first electrode 11 and the second electrode 13 maintain an appropriate The space allows the first particles 15 and the second particles 17 to be filled in an accommodating space defined by the first electrode 11 and the second electrode 13 and the device body (not shown). By applying voltages to the first electrode 11 and the second electrode 13 simultaneously or separately, a voltage difference (or electric field) V2 is generated between the first electrode 11 and the second electrode 13, thereby driving the first particle 15 and the second electrode 13. Two particles 17 move, in this example, the first particle 15 moves toward the second electrode 13 , and the second particle 17 moves toward the first electrode 11 .

Please continue to refer to Figure 1. In order to obtain better contrast results, the driving method of the known technology will be driven by PWM, and the ON/OFF time, ratio and number of pulses will be adjusted to achieve the required contrast. It is hoped that during the ON time, the applied electric field can move the particles, and during the OFF time, the voltage at both ends is turned off, so that the particles are no longer affected by the external electric field, and the particle can be obtained within the ON time. energy to keep going until the energy is gone. Similarly, for the driving method described in the lower part of FIG. 1, a voltage difference -V1 opposite to the aforementioned V2 is generated between the first electrode 11 and the second electrode 13, and the first particle 15 is driven from the first electrode 11 to the second electrode 13. The first electrode 11 moves to the second electrode 13 , and the second particle 17 moves from the second electrode 13 to the first electrode 11 . Of course, the driving method described in the lower part of Figure 1 is still driven by PWM, and the ON/OFF time, ratio and number of pulses are adjusted to achieve the required contrast, and the rest of the operating methods will not be described in detail.

As mentioned above, there are at least three ways to make energy disappear: (1) stopping due to the influence of the interaction force between particles; (2) stopping by hitting other particles or electrode partition walls; The interaction force of the medium in the confined space formed by the two electrodes and the compartment stops, and because of the relationship between the characteristics of the particles themselves, the initial position, the uniformity of distribution, the attraction and the mutual repulsion, a single and long driving time is usually applied The Pulse is a way to drive Pulses multiple times to overcome these variables, so that after the drive is over, the particles can stop on the other end of the electrode and distribute evenly. Therefore, the longer the ON time, the greater the energy obtained by the particle. This energy acts on the particle, resulting in three phenomena: (1) The particle is still moving, and the energy obtained during the next ON time will make the particle The particles continue to accelerate; (2) the particles are in a static state and are in contact with the electrodes, and the energy obtained within the next ON time will make the particles continue to squeeze towards the electrodes; and (3) if there are particles of different polarities In the same space, it is possible that particles with different polarities will attract each other after the last driving, and the energy obtained during the next ON time will cancel out the mutual attraction between the particles, so that the particles Separate and go to the corresponding electrode. During the OFF time, the electric field will stop the force on the particles, allowing the particles to continue to move forward with the energy obtained from the ON time or interact with other particles and electrodes to reach a stable state.

However, the above three phenomena all have the following deficiencies: (1) the energy obtained during the ON time is insufficient to allow the particles to overcome the interaction force between particles or electrodes; (2) the particles hit the electrodes at high speed, or It is to hit other particles, causing the position of the particles to shift or rebound, and permanent damage to the particles and electrodes; The structure or charging characteristics of the particle itself change.

2A , 2B and 2C are schematic diagrams of three commonly used driving methods in the known technology, respectively. Please refer to Figure 2A, the known technology (1) using a single Pulse driving method with a longer ON time will allow the particles to hit other particles and electrodes at the highest speed, and continue to squeeze the particles, which may cause particles and electrodes permanent damage.

Please refer to Figure 2B, the known technology (2) uses the drive method of multiple Pusles with shorter ON time, which will fix the ratio of ON/OFF time, so that the particles move forward with lower energy, and let the particles move forward within the OFF time. The interaction between the particles and the electrodes stabilizes them. In this method, the driving time will be longer because a longer OFF time is required.

Please refer to FIG. 2C , the known technique (3) is to adjust the length of the ON time to allow the particles to quickly move to the electrode at the other end, so as to reduce the driving time consumption. However, this method cannot avoid the phenomenon that particles collide with particles and electrodes at high speed.

Contents of the invention

The main purpose of the present invention is to provide a driving method of a display unit. During the driving process, a group of electric fields with opposite polarities to the ON driving time are provided, so that the particles can obtain an anti-phase electric field within the OFF time: (1 ) to reduce the energy of particles colliding with particles and electrodes, reduce loss, and improve the life of particles and electrodes; Particles are more likely to move under the influence of other particles or the force between electrodes, but the particles are not separated from the electrodes. This force can make the particle arrangement time shorter, easier and more orderly. Or, within the ON time, the particles that are squeezed on the electrode can return to their original shape, reducing the contact area with the electrode.

In the driving process, a new set of reverse voltage/electric field with ON is added, combined with the single/multiple Pulses driving method, it can greatly reduce the driving time consumption, reduce particle impact and deformation, improve service life, and particle arrangement More tidy for higher contrast.

Description of drawings

FIG. 1 is a schematic diagram of a display unit and a driving method of the display unit in the known technology;

2A, 2B and 2C are respectively schematic diagrams of three driving methods commonly used in known technologies;

3 is a schematic diagram of a display unit and a driving method of the display unit according to the present invention;

4A and 4B are respectively schematic diagrams of two driving methods of the display unit shown in FIG. 3;

Fig. 5 is a comparison chart of contrast and driving time using the driving method of the present invention relative to the driving method of the known technology; and

Attached Tables 1, 2 and 3 are comparison tables of experimental data such as driving time, contrast and time-consuming when using the driving method of the present invention and the driving method of the known technology.

[Description of main component labels]

Display unit 1, 2 First electrode 11, 21

Second electrode 13, 23 First particle 15, 25

Second Particle 17, 27

Detailed ways

FIG. 3 is a schematic diagram of a display unit and a driving method of the display unit according to the present invention. As shown in the figure, the present invention is mainly applied in the technical field of display units, such as electronic paper or similar devices with charged display particles. The present invention also provides two slightly different driving methods, which are respectively shown in the upper and lower half waveform diagrams of Figure 3 and the corresponding schematic diagrams of the display device. method as an example.

As shown in the upper part of Figure 3. The display unit 2 at least includes a first electrode 21 and a second electrode 23 oppositely disposed and kept at a distance. The closed space defined by the first electrode 21, the second electrode 23 and the body of the display device 2 has two kinds of particles with different electrical properties and colors. In this embodiment, the particles with different electrical properties are, for example, the first Particles 25 and second particles 27, for the sake of illustration, only one of each particle is shown, which is hereby described. Wherein, the first particles 25 are, for example, white and negatively charged, and the second particles 27 are, for example, black and positively charged. At least one side of the display unit 2 is transparent, allowing light to penetrate and reflect back through the surface of particles of different colors, so the distribution and color of the particles close to the penetration surface will make the display unit 2 display different colors. Or grayscale, in this embodiment, the transparent surface is, for example, the surface where the first electrode 21 is located. In the static state before driving, the first particle 25 is, for example, partially attached to the first electrode 21, the second particle 27 is, for example, partially attached to the second electrode 23, and the upper half of FIG. 3 ( and the lower half) are the moving directions and positions of the particles after the drive starts, as described in detail later.

The change of the particle position is determined by adjusting the voltage applied to each electrode, maintaining time and polarity, etc. In this embodiment, for example, when negative electricity is applied to the first electrode 21 and positive electricity is applied to the second electrode 23, a voltage difference (or electric field) V2 will be formed at this time, and the intensity of the voltage difference V2 is greater than that of particles adsorbed on the electrodes. Attraction, and the attraction between particles will make the particles start to move along the electric field. At this time, the second particles 27 that were originally attached to the second electrode 23 will start to approach the first electrode 21 ( On the contrary, the first particles 25 originally attached to the first electrode 21 start to approach (or move) towards the second electrode 23 . At this time, the user sees black from the outside of the transparent surface of the first electrode 21 , and vice versa. Therefore, in order for the particles to start moving, the electric field strength must be at least greater than the attractive force formed by the particles and the electrodes, and the applied voltage must be large enough. After the threshold voltage (Threshold Voltage) is greater than this, the particles will begin to be affected by the electric field and The size of the charge itself forms a kind of thrust to start moving, coupled with the influence of the time of applying the voltage (Fe=qE=ma; v=at), after turning off the applied voltage, the particle itself will continue to fly according to the speed obtained at last , until: (1) it is decelerated to a stop due to the influence of the interaction force with other particles; or (2) it directly hits the electrode and stops.

The above-mentioned first way, because it is the influence of non-contact force, does not have much influence on the characteristics of the particle itself, but this relative repulsion or attraction may cause the particle to change its moving path, causing confusion, and affecting whether the particle can Neatly arranged, and relative position.

The above-mentioned second method directly hits the electrode at a relatively high speed, and the energy will relatively affect the particles and the electrode during the collision, which may cause permanent damage to the physical material of the particle and the electrode itself, and the particle will be damaged when it touches the electrode. A certain degree of electrical neutralization on the contact surface will slightly affect the charging characteristics of the particles, and the direct impact will cause the particles to deform, resulting in a larger contact area with the electrode, and the electrically neutralized area. Larger, the particle charging properties will be more affected. After the particles hit the electrode many times, it will cause permanent damage to the electrode and affect the strength of the electric field. Even this kind of impact will cause vibration on the soft panel material (Flexible type), and the shock wave of the vibration may affect the Particle alignment results in other display areas or produce sounds.

The main reason for these problems is that the known technology uses particle interaction force and direct impact on the electrode to stop the movement of the particles during the movement process. When the electric field strength is not enough, the particle flying distance is not enough, or the energy is not enough, so it cannot Push away other particles on the electrode, and the arrangement will be irregular, resulting in poor contrast. However, using a larger driving electric field will cause problems as mentioned in the introduction. The present invention is mainly used for improving these shortcoming, hereby describe as follows:

Please refer to FIGS. 3 , 4A and 4B at the same time, wherein FIGS. 4A and 4B are schematic diagrams of two driving methods of the display unit shown in FIG. 3 . As shown in the figure, E1/Eb/E2 respectively represent the electric field intensity generated by the different voltages of the two electrodes 21 and 23, and the positive and negative values represent the direction of the electric field or the value of the voltage difference, which is V2/-V1 in this embodiment. Ton/Toff_1/Toff_2/Tbreak represent the electric field application time. Therefore, taking the upper part of Fig. 3 as an example, the driving method provided by the present invention at least includes the following steps:

(1) applying a first voltage difference V2 between the first and second electrodes 21, 23, so that the first particles 25 move toward the second electrode 23;

(2) stop applying the first voltage difference V2; and

(3) Apply a second voltage difference -V1 between the first electrode 21 and the second electrode 23, the polarity of the second voltage difference -V1 is opposite to that of the first voltage difference V2, so the first voltage difference V2 can be driven. The particles 25 decelerate towards the second electrode 23 .

Wherein in above-mentioned steps (1), (2), (3), still can do same drive to second particle 27 simultaneously, and second particle 27 and first particle 25 electric properties are opposite, so in above-mentioned step (1) The motion modes presented in (2), (3) should all correspond to the opposite of the first particle 25 . In addition, when applying the first and second voltage differences V2/-V1, it may include separately applying the potential differences V2/-V1 to the first electrode 21 or the second electrode 23, or applying different voltages to the first electrode 21 or the second electrode 23. The electrode 21 and the second electrode 23 make the sum voltage difference reach the desired polarity and value. Furthermore, if the above-mentioned step (3) is controlled by appropriate voltage difference and time, the first particle 25 can be made to lean against, stop, or partially stick to the second electrode 23 after moving, and the second particle can be made to 27 lightly leans against, stops, or partially attaches to the first electrode 21 after moving, thus achieving the effect of protecting particles and electrodes from collision damage. The various operations mentioned above should be easily thought of by practitioners in the industry, so they will not be described in detail.

Succeeding from the above, the main feature of the present invention is to add a new reverse electric field with the driving electric field within the Ton time, so that the particles 25 and 27 can obtain a group of adjustable non-contact reaction forces: (1 ) deceleration; and (2) reduction of particle-particle or particle-electrode mutual attraction. This set of opposite electric field application time, electric field strength, and application times can be adjusted according to the required reflectivity, the distance between the upper and lower electrodes, particle material characteristics, particle starting position, temperature and other external equipment conditions. And it can cooperate with the drive method of single/multi-pulse output to achieve better display results.

Please refer to FIG. 5 , which is a comparison chart of contrast ratio and driving time between the driving method of the present invention and the driving method of the known technology. The following is the experimental data chart of Figure 5:

(1) Two sets of test conditions are Pulse number = 20, 20 pulses are output continuously, and Ton is 100μs, where μs refers to the microsecond of the time unit.

(2) The upper line in FIG. 5 is the driving method of the present invention, and its Toff_1 is 150 μs, and no reverse voltage is output.

(3) The lower line in FIG. 5 is the driving method of the known technology, where Toff_1 is 0 μs, Tbreak is 50 μs, and Toff_2 is 10 μs.

It can be seen from the chart in Figure 5 that after using the driving method of the present invention, better contrast can be obtained within the same time, and higher contrast can also be obtained by using the present invention, that is to say, the present invention can not only improve the contrast, And it can save a lot of time. In addition, you can also refer to Attached Tables 1, 2 and 3, which are comparison tables of experimental data such as driving time, contrast, and time-consuming when using the driving method of the present invention and the driving method of the known technology. The above statement can also be verified from these appended tables, which fully proves that the driving method provided by the present invention has a better display effect than the known technology.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, this The scope of protection of the invention should be defined by the appended claims.

Claims (13)

1. A driving method of a display unit, the display unit comprising a first electrode and a second electrode arranged oppositely and keeping a distance, and a first particle with polarity, the first particle is dispersed on the first electrode Between the electrode and the second electrode, wherein the driving method includes the following steps: applying a first voltage difference between the first and second electrodes to move the first particles toward the second electrode; ceasing to apply the first voltage difference; and Applying a second voltage difference between the first electrode and the second electrode, the polarity of the second voltage difference is opposite to that of the first voltage difference, so as to drive the first particle to decelerate in the direction of the second electrode. 2. The driving method according to claim 1, wherein the first particle part is attached to the first electrode before the first voltage difference is applied. 3. The driving method according to claim 1, wherein the first particles are driven by the first voltage difference to move toward the second electrode with a constant velocity or acceleration. 4. The driving method according to claim 1, wherein applying the first voltage difference comprises applying the potential difference to the first electrode or the second electrode alone, or applying different voltages to the first electrode and the second electrode. 5. The driving method according to claim 1, wherein applying the second voltage difference comprises applying the potential difference to the first electrode or the second electrode alone, or applying different voltages to the first electrode and the second electrode. 6. The driving method according to claim 1, further comprising stopping and attaching the first particles to the surface of the second electrode. 7. The driving method according to claim 1, wherein the first particles are white and negatively charged. 8. The driving method according to claim 1, further comprising a second particle dispersed between the first electrode and the second electrode, the second particle having a different polarity from the first particle. 9. The driving method according to claim 8, further comprising stopping and attaching the second particles to the surface of the first electrode. 10. The driving method according to claim 8, wherein the second particles are black and positively charged. 11. The driving method according to claim 8, wherein the second particle part is attached to the second electrode before the first voltage difference is applied. 12. The driving method according to claim 11, wherein the first voltage difference is sufficient to overcome the first particle or the second particle being attracted by the first electrode or the second electrode. 13. The driving method according to claim 12, wherein the first voltage difference is greater than a threshold voltage.

Images