JPH096277A - Migration time measuring method and electrophoresis display device - Google Patents

Abstract

PURPOSE: To provide an electrophoresis display device and migration time measuring method capable of preventing deterioration caused by electrode reaction or electrolysis as much as possible without drop in contrast. CONSTITUTION: Time required to movement of pigment 13b in an electrophoresis display element 2 is measured as the brightness saturation time. A voltage applying time control device in which driving voltage applying time is set in the brightness saturation time is arranged in the electrophoresis display device. Or, a voltage applying control means in which a sensor capable of detecting the brightness of the electrophoresis display element 2 is installed, and when the output of the sensor 2 has reached the sensor output corresponding to the saturated value of the brightness previously measured, apply of driving voltage is stopped is arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophoretic display device which utilizes the movement of a charged pigment in a medium upon application of a voltage, and a method for measuring its migration time.

[0002]

2. Description of the Related Art Conventionally, an electrophoretic display device as shown in FIG. 13 has been known. This electrophoretic display element includes two glass substrates 10 of which at least one is transparent.
Are opposed to each other at a predetermined interval through the partition wall 11,
The glass substrate 10 and the partition wall 11 form a closed space. A pair of planar transparent electrodes 12 made of ITO or the like are fixed to the inner surfaces of the glass substrates 10 facing each other. The closed space contains the electrophoretic display dispersion liquid 13. The electrophoretic display dispersion liquid 13 is contained in the closed space.
Includes a colored dispersion medium 13a colored black, for example, and a charged white pigment 13b dispersed in the dispersion medium 13a.

Such an electrophoretic display element is colored by applying a positive voltage to the upper electrode and a negative voltage to the lower electrode with respect to the pair of electrodes 12 as shown in FIG. 14A, for example. The negatively charged white pigment 13b dispersed in the dispersion medium 13a is electrophoresed toward the anode by Coulomb force, and the white pigment 13b is attached to the upper anode electrode. FIG. 14 shows an electrophoretic display device in such a state.
When observed from the eye position as shown in (A), the portion where the white pigment 13b is adhered to form a layer looks white through the transparent electrode 12 and the glass substrate 10. On the other hand, if the polarity of the applied voltage is reversed, as shown in FIG. 14 (B), the white pigment 13b adheres to the facing electrode 12 to form a layer, and when observed from the position shown in the figure, it is white. Since the pigment layer 13b is hidden behind the black dispersion medium 13a, the electrophoretic display panel looks black. When the voltage application is stopped, the white pigment layer 13b attached to the electrode 12
Maintains its adhered state, so that once the white pigment layer 13
After b is attached to the electrode 12, it is not necessary to apply a voltage except for applying a voltage for maintaining the attached state.

In the electrophoretic display device having such a principle, the driving voltage needs to be continuously applied while the white pigment 13b moves. If the application time is short, the white pigment 13b cannot reach the electrode 12, resulting in a decrease in display contrast. Therefore, conventionally, the application time has been set to be long with a considerable margin.

[0005]

However, if the application time is made longer than necessary, an electrode reaction, electrolysis of the dispersion liquid, and the like occur, and as a result, the life of the electrophoretic display device is shortened. By the way, in the electrophoretic display device, the applied voltage and the applied time vary depending on the dispersion medium of the electrophoretic display element, the distance between the electrodes, etc., and an appropriate applied voltage for a certain electrophoretic display element and an appropriate applied time for the same are obtained. Things have never been easier.

Further, the electrophoretic display device has instability factors peculiar to the device for applying a voltage to the liquid, such as alteration of the dispersion liquid and alteration of additives such as surfactants in the dispersion liquid, and thus it is appropriate over time. There is also the problem that the voltage and application time vary. Therefore, there is a demand for an electrophoretic display device in which the voltage application time is optimized and the life is long.

The present invention has been made in view of the above demands, and a migration time measuring method capable of easily obtaining an appropriate applied voltage and an appropriate application time for the applied voltage, and an appropriate voltage application time to lower the contrast. It is an object of the present invention to provide an electrophoretic display device capable of preventing deterioration due to electrode reaction and electrolysis as much as possible without inviting.

[0008]

In order to achieve the above object, the present invention provides a liquid phase dispersion medium in a closed space having a pair of electrodes, which are opposed to each other and at least one of which is transparent, as a peripheral wall constituent element. The electrode in the electrophoretic display element containing the electrophoretic display dispersion liquid containing a pigment, and the pigment in the dispersion liquid migrates to the electrode after the application of a predetermined drive voltage by the drive power source. Is a method of measuring the time until the end as an appropriate application time, the brightness of the electrophoretic display element is detected by a sensor, and the pair of electrodes of the electrophoretic display element is changed by the driving power supply at each predetermined time. The procedure for obtaining the time from when the drive voltage is applied until the brightness value of the sensor reaches almost saturation and the relationship between the drive voltage and the time when the brightness value of the sensor almost reaches the saturation value are obtained. And a procedure of obtaining a proper application time for a given drive voltage of the electrophoretic display device from this relationship.

Further, according to the present invention, there is provided a dispersion liquid for electrophoretic display, which comprises a liquid phase dispersion medium and a pigment in a closed space having a pair of electrodes, which are opposed to each other and at least one of which is transparent, as a peripheral wall constituent element. In the electrode of the accommodated electrophoretic display element,
A method of measuring the time from the start of application of a predetermined drive voltage by a drive power source until the pigment in the dispersion liquid reaches the electrode and the end of migration as an appropriate application time. The current value flowing in the electrophoretic display element is detected, and a predetermined drive voltage that is different each time by the drive power supply is applied to the pair of electrodes of the electrophoretic display element until the detected current value reaches almost saturation. A procedure for obtaining each time and a procedure for obtaining the relationship between the drive voltage and the time when the detected current value reaches a substantially saturated value, and the procedure for obtaining an appropriate application time for the predetermined drive voltage of the electrophoretic display element from this relationship are provided. Have.

Further, the electrophoretic display device of the present invention is an electrophoretic device containing a liquid phase dispersion medium and a pigment in a closed space having a pair of electrodes, which are opposed to each other and at least one of which is transparent, as a peripheral wall component. An electrophoretic display element containing a display dispersion liquid, a driving power supply for applying a voltage to a pair of electrodes of the electrophoretic display element to drive the electrophoretic display element, and the electrophoretic display element by the driving power supply. A drive voltage application time of the drive power supply to the electrophoretic display element is determined based on a saturation time data value obtained by previously measuring the time from the start of voltage application until the brightness of the electrophoretic display element reaches a substantially saturated value. And a voltage application time control device for setting.

Further, the electrophoretic display device of the present invention is an electrophoretic device containing a liquid phase dispersion medium and a pigment in a closed space having a pair of electrodes, which are opposed to each other and at least one of which is transparent, as a peripheral wall component. An electrophoretic display element containing a display dispersion liquid, a driving power supply for applying a voltage to a pair of electrodes of the electrophoretic display element to drive the electrophoretic display element, and a luminance of the electrophoretic display element are detected. When the sensor and the output of the sensor reach the output value of the sensor when the brightness of the electrophoretic display element measured in advance reaches almost saturation, a drive voltage is applied to the electrophoretic display element of the drive power source. And a voltage application control means for stopping.

Further, the electrophoretic display device of the present invention is an electrophoretic device containing a liquid phase dispersion medium and a pigment in a closed space having a pair of electrodes, which are opposed to each other and at least one of which is transparent, as a peripheral wall component. The electrophoretic display element containing the display dispersion liquid, a driving power supply for applying a voltage to a pair of electrodes of the electrophoretic display element to drive the electrophoretic display element, and a current value flowing in the electrophoretic display element are described. When the current detection means for detecting and the output of the current detection means reach the output value of the current detection means when the current flowing in the electrophoretic display element measured in advance reaches the saturation, the drive power source And voltage application control means for stopping the application of the drive voltage to the electrophoretic display element.

[0013]

According to the migration time measuring method of the present invention, paying attention to the change in the brightness or current value of the electrophoretic display element depending on the voltage application time, the time when the brightness or current value almost reaches saturation is determined in the dispersion liquid. It is considered that it is the time when the pigment reaches the electrode and almost completely migrates, and the luminance or current value of the electrophoretic display element is almost saturated after the application of a predetermined voltage to the electrophoretic display element is started. The application time until the value is reached is measured. Then, the time to reach the saturation of the brightness or the current value at the predetermined voltage is the proper application time at that voltage, and the proper voltage and the proper application time are obtained by repeating this measurement at various voltages.

According to the electrophoretic display device of the present invention,
An appropriate application time corresponding to the drive voltage is set based on the method described above, and the voltage application time control device stops the voltage application of the drive power supply at this appropriate application time. in this way,
By providing the voltage application time control device in the electrophoretic display device, it is possible to optimize the application time to a necessary minimum, and prevent deterioration due to electrode reaction or electrolysis as much as possible without lowering the contrast. Further, a sensor capable of detecting the brightness of the electrophoretic display element or a current detecting means for detecting the current value is provided, and the output of the sensor or the current detecting means corresponds to the brightness or the saturation value of the current value measured in advance. When the output of the detection means is reached, the application of drive voltage is stopped by the voltage application control means.

[0015]

EXAMPLES Examples of the present invention will be described in detail below, but the present invention is not limited to the following examples.

[First Embodiment] FIG. 1 is a block diagram of an apparatus used in the migration time measuring method of the present invention. The electrophoretic display element 2 is included in the present device.

In this electrophoretic display element 2, at least one of the two translucent glass substrates 10, for example, is a partition wall 1.
1, a pair of flat plate-shaped transparent electrodes 12 are fixed to the inner surfaces of the glass substrates 10 facing each other at a predetermined interval.
The electrode 12 and the partition wall 11 form a closed space.
The electrode 12 itself may form the substrate, and in this case, the glass substrate 10 can be omitted. It is also possible to provide some such closed spaces and combine each closed space. As the transparent electrode 12, for example, indium tin oxide (ITO) formed in a desired pattern can be exemplified. The thickness of the partition wall 11 (distance between electrodes) is usually about 20 μm to 1 mm.

In the closed space, the electrophoretic display dispersion liquid 1
3 is contained in the electrophoretic display dispersion liquid 13.
Includes a colored dispersion medium 13a and a charged pigment 13b dispersed in the dispersion medium.

A predetermined voltage is applied to the electrodes 12 of the electrophoretic display element 2 by the driving power supply 3. Also,
A luminance meter (sensor) 2 is provided on the front surface of the electrophoretic display element 2.
1 is installed. As the luminance meter 21, for example, an optical sensor such as a photomultiplier tube can be used. The electrophoretic display element 2 is driven by the driving power supply 3 at a predetermined voltage, and the display (luminance) change of the electrophoretic display element 2 is measured by the luminance meter 2
1 is measured, and the data value is processed by the processing means 22. The applied voltage of the driving power source 3 is changed and the same measurement is performed. With this procedure, it is possible to obtain appropriate application times for various voltages.

FIG. 2 shows an example of changes in luminance with respect to the voltage application time. From Fig. 2, the time when the pigment finishes the migration is
It was found that it can be detected as saturation of brightness, and this time is taken as the saturation time data value. In the example of FIG. 2, the saturation time data value of the electrophoretic display element 2 is 60 milliseconds (ms). Therefore, with the voltage applied at this time, by setting the application time to 60 ms, deterioration can be minimized without causing a decrease in contrast. The brightness is
One of the photometric quantities related to an area light source, which is a point on the surface of the area light source, and a light beam traveling in a given direction is an orthographic projection area in a given direction of a minute area including the point and a minute projection in that direction. It is the value obtained by multiplying the solid angles.

A method of automatically measuring the change in the brightness with respect to the various applied voltages described above will be described with reference to FIGS.
FIG. 3 shows a range in which the minimum application time T _L and the maximum application time T _U and the minimum application voltage V _L and the maximum application voltage V _U are set in advance, and these are tabulated and stored in the processing means 22 of the measuring apparatus. Show.

The processing procedure of the processing means 22 will be described with reference to the flowchart of FIG. First, the applied voltage V is set to the minimum applied voltage V _L in step S1, and the applied time T is set in step S2.
Is set to the minimum application time T _L. Next, step S3
At the set applied voltage V, the device (electrophoretic display element) is driven for the set applied time T, and the brightness of the electrophoretic display element 2 is detected by the sensor 21 in step S4. Brightness, applied voltage V,
The application time T is stored. Then, in step S6, it is determined whether or not the application time exceeds the maximum application time T _U, and if it does not exceed (N), a predetermined time (ΔT) is added to the application time, and the application time (T + ΔT), The electrophoretic display element 2 is continuously driven with the applied voltage V, and the luminance is measured with the applied voltage V set up to the maximum application time T _U. When the application time exceeds the maximum application time T _U , it is determined in the next step S8 whether the applied voltage exceeds the maximum application voltage V _U.
If it does not exceed (N), the applied voltage is the specified voltage (ΔV).
After adding the voltage, the process returns to step S2 and the applied voltage (V +
The electrophoretic display element is driven for a minimum application time T _{L at} ΔV), and the application time and the brightness at the applied voltage (V + ΔV) are measured. With such a procedure, the procedure of applying a voltage and driving until the maximum applied voltage V _U is repeated is repeated, and the relationship between the change in the brightness at each ΔV interval and the application time is changed from the lowest applied voltage V _L to the highest applied voltage V _U. You can ask. If the applied time exceeds the maximum applied voltage V _U , the measurement is completed, and the result is printed and displayed in the next step S10. Further, in step S11, the optimum applied voltage,
Determine the optimum application time.

According to such an electrophoretic time measuring method, an appropriate application time for each electrophoretic display element can be easily and reliably obtained even if there are variations in manufacturing, deterioration with time, etc. If the electrophoretic display element is driven in time, deterioration due to electrode reaction or electrolysis can be prevented as much as possible without lowering the contrast.

[Second Embodiment] FIG. 5 is a schematic view showing an embodiment of the constitution of the electrophoretic display device of the present invention. This electrophoretic display device includes an electrophoretic display element 2, a driving power supply 3a for driving the electrophoretic display element 2, and a driving power supply 3a.
And a voltage application time control device 4 for controlling the voltage application time for the electrophoretic display element 2. Of these, the electrophoretic display element 2 has already been described, and thus the same reference numerals are given and the description thereof is omitted.

Voltage application time control device 4 which is a feature of this example
Has a function of controlling the application time of the electrophoretic display element 2 by the driving power supply 3a. The voltage application time control device 4 is
For example, a pulse width setting mechanism using a variable resistor can be used, but the invention is not limited to this. In the present invention, this pulse width is set in advance. Such a pulse width setting method can be obtained by the migration time measuring method described in the first embodiment. For example, in the example of FIG. 2, the saturation time data value is 60 ms. Therefore, the drive voltage application time (pulse width) of the pulse width setting mechanism is set to 60 ms. Note that, for example, the time when the brightness reaches 95% of the saturation value may be used as a reference,
Various other setting standards can be changed.

According to this embodiment, the voltage application can be stopped at the time when the pigment of the electrophoretic display element 2 has finished migrating, so that the deterioration due to the electrode reaction or electrolysis can be prevented without lowering the contrast. Can be prevented as much as possible.

[Third Embodiment] FIG. 6 is a block diagram showing the arrangement of an electrophoretic display device according to the third embodiment of the present invention.
This electrophoretic display device drives the electrophoretic display element 2 by applying the drive voltage of the drive power supply 3a to the electrophoretic display element 2 via the switching unit 23.
Further, a sensor 21 that can detect the brightness of the electrophoretic display element 2 is provided, and the signal of this sensor 21 is output to the sensor output determination means 22a. The sensor output determination means 22a and the switching section 23 constitute a voltage application control means.

The processing procedure of the sensor output judging means 22a will be described with reference to the flowchart shown in FIG. 7. The saturated sensor output value THL corresponding to the saturated brightness (for example, the brightness of 60 ms in FIG. 2) is previously obtained and set, The saturation sensor output value THL is compared with the sensor output L, and when the sensor output L exceeds the saturation sensor output value THL, the switching unit 23 outputs a signal for stopping the voltage application, and the switching unit 23 outputs the signal. In response to this, the drive voltage from the drive power supply 3a is stopped.

As a result, the driving of the electrophoretic display element can be surely stopped at the time when the pigment has finished moving,
It is possible to reliably prevent deterioration of the electrophoretic display element due to electrode reaction or electrolysis.

It should be noted that the electrophoretic display element for detecting the brightness by the sensor may be built as a built-in type separately from the panel which actually performs the display function for the monitor. Moreover, the same sensor as in Example 1 can be used. In the case of the built-in type, since the detection light can have a high intensity, a sensor with low sensitivity can also be used.

[Fourth Embodiment] FIG. 8 is a block diagram of an apparatus used in another migration time measuring method of the present invention. Book 4
The method according to the embodiment differs from the method using the apparatus shown in FIG. 1 in the following points. That is, according to the method using the device of FIG. 1, the display (luminance) change of the electrophoretic display element 2 is measured by the luminance meter 2.
1, the data value is processed by the processing means 22, the applied voltage of the driving power source 3 is changed, and the same measurement is performed to obtain the proper application time for various voltages. In the method according to the fourth embodiment, when a drive voltage is applied, the current value flowing in the electrophoretic display element 2 is measured by a current detector 24 equipped with, for example, a monitor, and the data value is processed by a processing means 25 to drive the data. The difference is that the appropriate application time for various voltages is obtained by changing the applied voltage of the power source 3 and performing the same measurement.

The present method is applied to the electrophoretic display device 2,
When the drive voltage is applied, the value of the current flowing changes during the movement (migration) of the particles (pigment 13b) and when it reaches the surface of the electrode 12, that is, the current is large while the charged pigment migrates. , When the electrode surface is reached, the movement stops and the current decreases. Based on this principle, the present method detects the moment when the pigment has completely moved to the other electrode by measuring the current when the driving voltage is applied, thereby minimizing the driving voltage application time. It makes it possible.

Electrophoretic display element 2 with respect to voltage application time
FIG. 9 shows an example of the change in the current flowing through. This example shows an example of current data when a driving voltage is applied for 400 msec (ms). It can be seen from FIG. 9 that the time when the pigment has finished the migration can be detected as the saturation of the current, and this time is taken as the saturation time data value. In the example of FIG. 9, the saturation time data value of the electrophoretic display element 2 is 300 ms. Therefore, with the voltage applied at this time, the application time is 300 m
By setting to s, deterioration can be minimized without lowering the contrast.

A method for automatically measuring the change in brightness with respect to the various applied voltages described above will be described with reference to FIGS. 3 and 10 referred to in the description of the above-described embodiment. Note that, as described above, in FIG. 3, the minimum application time T _L , the maximum application time T _{U, the} minimum application voltage V _L and the maximum application voltage V _U are set in advance, and these are made into a table to process the processing means 25 of the measuring device. Indicates the range to be stored in.

The processing procedure of the processing means 25 will be described with reference to the flowchart of FIG. First, the applied voltage V is set to the minimum applied voltage _VL in step ST1, and the application time T is set to the minimum applied time _TL in step ST2. Next, in step ST3, the device (electrophoretic display element) is driven at the set applied voltage V for the set application time T, and in step ST4, the current value flowing in the electrophoretic display element 2 is detected. Detected by the device 24, step ST5
The current value, the applied voltage V, and the applied time T detected in step S1 are stored. Then, in step ST6, it is determined whether or not the application time exceeds the maximum application time T _U, and if not (N),
A predetermined time (ΔT) is added to the application time, the electrophoretic display element is further driven at the application time (T + ΔT) and the application voltage V, and the current value is measured at the application voltage V set up to the maximum application time T _U. I do. When the application time exceeds the maximum application time T _U , it is determined in the next step ST8 whether the applied voltage exceeds the maximum application voltage V _U. If it does not exceed (N), after applying a predetermined voltage (ΔV) to the applied voltage,
Returning to step ST2, the electrophoretic display element 2 is driven by the applied voltage (V + ΔV) for the minimum application time T _L , and the application time and the brightness at the applied voltage (V + ΔV) are measured.
By such a procedure, the procedure of applying a voltage and driving until the maximum applied voltage V _U is reached is repeated until the minimum applied voltage V _{L is reached.}
To the maximum applied voltage V _U , the relationship between the change in luminance and the application time at each ΔV interval can be obtained. When the applied time exceeds the maximum applied voltage V _U , the measurement is completed,
In the next step ST10, the result is printed and displayed. In step ST11, the optimum applied voltage and the optimum application time are determined based on the result.

As described above, according to the migration time measuring method of the fourth embodiment, as in the migration time measuring method of the first embodiment, there are variations in manufacturing, deterioration with time, and the like. Can easily and surely determine the appropriate application time for each electrophoretic display element, and if the electrophoretic display element is driven at the obtained appropriate application time, it is possible to reduce the contrast without causing the electrode reaction or electrolysis. Deterioration can be prevented as much as possible.

[Fifth Embodiment] FIG. 11 is a schematic view showing the arrangement of an electrophoretic display device according to the fifth embodiment of the present invention. This electrophoretic display device includes an electrophoretic display element 2, a drive power source 3a for driving the electrophoretic display element 2, and a voltage application time control device 4a for controlling a voltage application time of the drive power source 3a to the electrophoretic display element 2. And. Of these, the electrophoretic display element 2 has already been described, and thus the same reference numerals are given and the description thereof is omitted.

Voltage application time control device 4 which is a feature of this example
“A” has a function of controlling the application time of the electrophoretic display element 2 by the driving power supply 3a. Voltage application time control device 4a
Can be configured by, for example, a pulse width setting mechanism using a variable resistor, but is not limited to this.
Also in the fifth embodiment, the drive pulse width is set in advance, as in the case of the second embodiment described above. The method of setting the pulse width by the voltage application time control device 4a can be obtained by the migration time measurement method described in the fourth embodiment. For example, in the example of FIG. 9, the saturation time data value is 3
It is 00 ms. Therefore, the drive voltage application time (pulse width) of the pulse width setting mechanism is set to 300 ms. In this case as well, for example, the time when the current value reaches 95% of the saturation value may be used as a reference, and the reference for other settings may be variously changed.

According to the fifth embodiment, like the second embodiment described above, the voltage application can be stopped at the time when the pigment of the electrophoretic display element 2 has finished the migration, so that the contrast is lowered. It is possible to prevent deterioration due to electrode reaction and electrolysis as much as possible without inducing.

[Sixth Embodiment] FIG. 12 is a schematic view showing the arrangement of an electrophoretic display device according to the sixth embodiment of the present invention. This electrophoretic display device has an electrophoretic display element 2, a drive power source 3a for driving the electrophoretic display element 2, and a predetermined width applied to the electrophoretic display element 2 by receiving a power source voltage of the drive power source 3a. A pulse control circuit 5 for generating a drive pulse signal S5, an ammeter 24a for detecting a current value flowing through the electrophoretic display element 2 when a drive voltage is applied, and a current value measured by the ammeter 24a is, for example, about 200 μA (* Person, please check the value and unit of current)
It is provided with a current saturation detection circuit 25a that outputs to the pulse control circuit 5 a control signal S25 for stopping the pulse output by the pulse control circuit 5 when it reaches the saturated state.
Then, the pulse control circuit 5 and the current saturation detection circuit 25
The voltage application control means is constituted by a.

According to the sixth embodiment, as in the case of the third embodiment described above, the driving of the electrophoretic display element 2 can be surely stopped at the time when the movement of the pigment is completed, and the electrode reaction can be performed. It is possible to reliably prevent deterioration of the electrophoretic display element due to electrolysis or electrolysis.

[0042]

According to the electrophoretic time measuring method of the present invention, the proper voltage and the proper application time for the electrophoretic display device can be easily obtained.

Further, in the case of being based on the brightness detection, various modes such as spot-wise measuring only a part of the display surface or averagely measuring the entire display surface are possible. Further, in the case of being based on current detection, since the analog value is directly measured, fine control is possible.

According to the electrophoretic display device of the present invention, since the voltage is applied in a proper time, it is possible to prevent the deterioration due to the electrode reaction and the electrolysis as much as possible without lowering the contrast. Further, since the electrophoretic display device of the present invention detects the appropriate time and stops the voltage application, it is possible to surely prevent the deterioration due to the electrode reaction and the electrolysis without lowering the contrast.

Further, in the case of the brightness detection, for example, when the brightness is completely changed, that is, when the display is completely changed, the brightness is detected, so that a highly reliable appropriate voltage and an appropriate application time can be easily obtained. You can ask. Further, in the case of being based on current detection, there is an advantage that a large-scale device such as a luminance meter is not required, the circuit configuration is simple, and a so-called feedback loop is easy to configure.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an outline of an apparatus used for a migration time measuring method of the present invention.

FIG. 2 is a graph showing a change in brightness of an electrophoretic display device with respect to a voltage application time.

FIG. 3 is a graph showing preset application time and applied voltage range.

FIG. 4 is a flow chart showing an example of the processing procedure of the migration time measuring method of the present invention.

FIG. 5 is a schematic configuration diagram of an electrophoretic display device according to a second embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of an electrophoretic display device according to a third embodiment of the present invention.

FIG. 7 is a flowchart showing a processing procedure of a sensor output determination means.

FIG. 8 is a schematic configuration diagram showing an outline of an apparatus used for another migration time measuring method of the present invention.

FIG. 9 is a graph showing changes in current with respect to voltage application time of the electrophoretic display device.

FIG. 10 is a flowchart showing a processing procedure of another migration time measuring method of the present invention.

FIG. 11 is a block diagram showing a configuration of an electrophoretic display device according to a fifth embodiment of the present invention.

FIG. 12 is a block diagram showing a configuration of an electrophoretic display device according to a sixth embodiment of the present invention.

FIG. 13 is a cross-sectional view showing a configuration of an electrophoretic display element.

FIG. 14 is an explanatory diagram illustrating an operation of the electrophoretic display element.

[Explanation of symbols]

 2 Electrophoretic display element 3, 3a, 3b Driving power source 4, 4a Voltage application time control device 5 Pulse control circuit 10 Glass substrate 11 Partition wall 12 Electrode 13 Electrophoretic dispersion liquid 13a Colored dispersion medium 13b Pigment 21 Luminance meter (sensor) 22, 25 processing means 24 current detector 24a ammeter 25a current saturation detection circuit

Claims (5)

[Claims] 1. An electrophoretic display dispersion liquid containing a liquid phase dispersion medium and a pigment contained in a closed space having a pair of electrodes, which are opposed to each other and at least one of which is transparent, as a peripheral wall constituent element. A method in which the time from the start of application of a predetermined drive voltage from the drive power supply to the electrodes of the electrophoretic display element until the pigment in the dispersion reaches the electrodes and the migration is completed is measured as an appropriate application time. The sensor detects the brightness of the electrophoretic display element, and the brightness value of the sensor is almost saturated from the time when the driving power source applies different predetermined driving voltages to the pair of electrodes of the electrophoretic display element each time. And a relationship between the drive voltage and the time when the brightness value of the sensor reaches a saturation value, and the relationship between the drive voltage and the predetermined drive voltage of the electrophoretic display element is calculated from this relationship. Migration time measurement method and a procedure of obtaining a proper application time that. 2. Electricity in which a dispersion liquid for electrophoretic display containing a liquid phase dispersion medium and a pigment is contained in a closed space having a pair of electrodes, which are opposed to each other and at least one of which is transparent, as a constituent element of a peripheral wall. A method in which the time from the start of application of a predetermined drive voltage from the drive power supply to the electrodes of the electrophoretic display element until the pigment in the dispersion reaches the electrodes and the migration is completed is measured as an appropriate application time. There, the current value flowing through the electrophoretic display element when a drive voltage is applied is detected, and the detected current from when a different predetermined drive voltage is applied to the pair of electrodes of the electrophoretic display element each time by the drive power supply. The procedure for obtaining the time until the value almost reaches the saturation and the relationship between the driving voltage and the time for the detected current value to reach the substantially saturated value are obtained, and from this relationship, the predetermined value of the electrophoretic display element is determined. Migration time measurement method and a procedure of obtaining a proper application time on the kinematic voltage. 3. An electrophoretic display dispersion liquid containing a liquid phase dispersion medium and a pigment is contained in a closed space having a pair of electrodes, which are opposed to each other and at least one of which is transparent, as a peripheral wall constituent element. An electrophoretic display element; a driving power supply for applying a voltage to a pair of electrodes of the electrophoretic display element to drive the electrophoretic display element; A voltage application time control device for setting a drive voltage application time of the drive power supply to the electrophoretic display element based on a saturation time data value obtained by previously measuring the time until the brightness of the electrophoretic display element reaches a substantially saturated value. An electrophoretic display device having. 4. Electricity in which a dispersion liquid for electrophoretic display containing a liquid phase dispersion medium and a pigment is contained in a closed space having a pair of electrodes, which are opposed to each other and at least one of which is transparent, as a peripheral wall constituent element. An electrophoretic display element, a driving power supply that applies a voltage to a pair of electrodes of the electrophoretic display element to drive the electrophoretic display element, a sensor that detects the brightness of the electrophoretic display element, and an output of the sensor, Voltage application control means for stopping the application of the drive voltage of the drive power source to the electrophoretic display element when the output value of the sensor when the luminance of the electrophoretic display element measured in advance reaches almost saturation is reached. An electrophoretic display device having. 5. Electricity in which a dispersion liquid for electrophoretic display containing a liquid phase dispersion medium and a pigment is contained in a closed space having a pair of electrodes, which are opposed to each other and at least one of which is transparent, as a peripheral wall constituent element. An electrophoretic display element, a driving power supply that applies a voltage to a pair of electrodes of the electrophoretic display element to drive the electrophoretic display element, a current detection unit that detects a current value flowing in the electrophoretic display element, and the current When the output of the detection means reaches the output value of the current detection means when the current flowing in the electrophoretic display element, which is measured in advance, reaches almost saturation, the drive voltage is applied to the electrophoretic display element by the drive power source. And an electrophoretic display device having a voltage application control means for stopping.