JP2854065B2 - Driving device for electrophoretic display panel - Google Patents

Description

The present invention generally relates to a driving device for an electrophoretic display panel, and more particularly to a driving device for an electrophoretic display panel, in which one electrode is common and the other electrode is divided into a plurality of segment electrodes. And a driving device for an electrophoretic display panel including a plurality of elements.

(Prior Art) FIG. 6 is a sectional view showing a basic configuration of the above-described electrophoretic display panel. The outline of the electrophoretic display panel shown in FIG. 6 is as follows. A plate glass 1 on which a flat transparent electrode 2 is mounted and fixed and a substrate 5 on which a plurality of divided electrodes 4 are mounted and fixed are interposed via a spacer 3. Each of the electrodes 2,
4. The electrodes 2 and 4 and the spacers 3 form a closed space portion by assembling and fixing the electrodes so that they face each other. The electrophoretic display dispersion system 6 is accommodated in the closed space. As the electrophoretic display dispersion system 6, for example, a dispersion system including a liquid dispersion medium 7 colored black and white pigment particles 8 dispersed in the black liquid dispersion medium 7 is employed. . It is assumed that the white pigment particles 8 are positively charged in the black liquid dispersion medium 7.

In FIG. 6, the plurality of divided electrodes 4 and the transparent electrodes 2
When a voltage is applied such that the direction of the electric field applied to the electrophoretic display dispersion system 6 accommodated in the closed space is reversed, the positively charged white pigment particles 8 move toward the cathode due to Coulomb force. Electrophoresis results in a particle distribution as shown in FIG. When the electrophoretic display dispersion system 6 in such a state is observed through the transparent electrode 2, the portion on the left side of FIG. 6 of the transparent electrode 2 is formed by the layer of the positively charged white pigment particles 8 attached to the transparent electrode 2. On the other hand, the portion of the transparent electrode 2 on the right side in FIG. 6 appears black because the layer of the positively charged white pigment particles 8 is hidden behind the black liquid dispersion medium 7.

When the polarity of the applied voltage is reversed, the color of the transparent electrode 2 on the left side of FIG. 6 and the color of the transparent electrode 2 on the right side of FIG. 6 are reversed, but the application of the voltage is stopped. Then, the layer of the positively charged white pigment particles 8 attached to the transparent electrode 2 maintains the attached state mainly due to the van der Waals attractive force generated between the transparent electrode 2 and the transparent electrode 2. Little change occurs.

FIG. 7 is a diagram showing a seven-segment numeric display panel as an example of the above-described electrophoretic display panel.
In FIG. 7, parts corresponding to the display panel shown in FIG. 6 are denoted by the same reference numerals.

The configuration of the numeric display panel 20 shown in FIG. 7 is substantially the same as the basic configuration of the electrophoretic display panel shown in FIG. However, in the numeral display panel 20 shown in FIG. 7, the black mask 10 is provided on the transparent electrode 2 on the glass sheet 1 except for the character portion 11, and the seven elements a, b , c,..., g, which are different in that they have segment electrodes 4a, 4b, 4c, 4d, 4e, 4f, and 4g, respectively. Here, using a numerical display panel 20 illustrated in Figure 7, full erasure state (i.e., black display state) from, to display the number 2 at time t ₀ shown in Figure 8, Next, in order to update the display from the numeral 2 to the numeral 3 at the time t ₁ shown in FIG. 8, the respective electrodes provided on the numeral display panel 20 need to be updated as shown in the timing chart of FIG. It can be seen that an appropriate voltage may be applied.

(Problems to be Solved by the Invention) By the way, the numeric display panel 20 having the configuration as described above is used.
(Ie, the electrophoretic display panel shown in FIG. 6)
As described above, even if the application of the voltage to the electrophoretic display dispersion system 6 housed in the closed space is stopped, the positively charged white pigment particles 8 adhered to the transparent electrode 2 by the van der Waals attractive force. This layer maintains the attached state, so that the numeric display panel 20 has a memory function. That is, in the numeric display panel 20 described above,
Since the pattern realized on the numeric display panel 20 is held by the voltage applied immediately before to the electrophoretic display dispersion system 6, the pattern is realized by once applying a voltage to the electrophoretic display dispersion system 6. It is not necessary to newly apply a voltage similar to the applied voltage in order to hold the pattern thus set.

However, in reality, the positively-charged white pigment particles 8 diffuse in the black liquid dispersion medium 7 with the passage of time. 10 when the application of
After a lapse of time, the display quality deteriorates, that is, the memory function of the numeral display panel 20 includes:
There will be a time limit. Therefore, as a means for eliminating such a defect, a dispersion system 6 for electrophoretic display is used.
Then, a method of continuously applying a voltage signal (ie, a DC voltage signal) similar to that applied for realizing the pattern was considered.

However, when the DC voltage is actually continuously applied to the electrophoretic display dispersion system 6 by employing the above method, the electrophoretic display dispersion system 6 is electrolyzed and deteriorated by the integrated current value of the applied DC. The problem arises. In addition, there has been a problem that the positively charged white pigment particles 8 once adhered to the transparent electrode 2 and the plurality of divided electrodes 4 are difficult to peel off from the transparent electrode 2 and the plurality of divided electrodes 4.

Accordingly, the present invention has been made in order to solve the above-mentioned problems of the prior art, and has as its object to solve the problem that the electrophoretic display dispersion system is electrolyzed and deteriorated, as well as the transparent electrode and a plurality of divided electrodes. It is possible to eliminate the problem that the pigment particles and the like attached to the electrodes are difficult to peel off from the transparent electrode and the plurality of divided electrodes, and without deteriorating the display quality.
An object of the present invention is to provide a driving device for an electrophoretic display panel capable of maintaining a display.

[Configuration of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention comprises a liquid phase dispersion medium and particles in a space defined by a pair of transparent electrodes, at least one of which is opposed to each other. An electrophoretic display panel in which an electrophoretic display dispersion system is housed, one of the electrodes is a common electrode, and the other of the electrodes is an electrode that is divided into a plurality of segment electrodes and is composed of a plurality of elements. In a driving device for driving, display signal applying means for applying a display signal to a segment electrode of an element for changing a display state determined based on an externally applied control signal for a preset time, The display signals applied to the segment electrodes maintain the pattern formed by the particles adhering on each of the electrodes, so that the same Refresh signal applying means for applying a polarity signal to each of the segment electrodes for each refresh cycle set shorter than the display quality deterioration time of the electrophoretic display panel.

(Operation) In the above configuration, the display signal applying unit applies the display signal to the segment electrode of the element that changes the display state determined based on the control signal given from the outside for a preset time. A refresh signal applying means for electrophoretic display of a signal having the same polarity as the display signal in order to hold a pattern formed by the charged particles adhering to each electrode according to the display signal applied to the segment electrode. Since the voltage is applied to each of the segment electrodes at each refresh cycle set shorter than the display quality deterioration time of the panel, the electrophoretic display dispersion system is electrolyzed and deteriorates, Eliminates the problem that charged particles and the like adhering to an electrode or a plurality of divided electrodes are difficult to peel off from these transparent electrodes or the plurality of divided electrodes And without deteriorating the display quality,
The display can be maintained.

(Embodiment) Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.

As is clear from the contents already described, the driving device for the electrophoretic display panel according to the present invention is shown in FIG. 6 (that is, showing the basic configuration of the electrophoretic display panel) and FIG. The configuration of the numeric panel shown in Fig. 7 is substantially the same as the basic configuration of the electrophoretic display panel shown in Fig. 6.) It drives the electrophoretic display panel (numerical panel). Therefore, description of the configuration of the electrophoretic display panel (numeric panel) to which the driving device according to the present invention is applied is omitted. The display panel shown in FIG. 1 described below has substantially the same configuration as the numeric display panel 20 shown in FIG. 7, and thus the display panel has the numeric display panel. The same reference numerals are given and the description is omitted.

FIG. 1 is a block diagram showing an overall configuration of a driving device for an electrophoretic display panel according to one embodiment of the present invention. As shown in FIG. 1, an outline of a driving device for an electrophoretic display panel according to an embodiment of the present invention includes a display panel 20, an applied signal switching unit 103, a pulse width control signal generating unit 105, and a memory. The configuration includes a unit 107, a control unit 109, and a refresh clock generation unit 111. In the above-described configuration, at least the applied signal switching unit 103 includes a display application signal W for each of the segment electrodes 4a, 4b, 4c, 4d, 4e, 4f, and 4g provided on the display panel 20. And the same refresh signal R as the display application signal W can be applied. The above configuration is described in more detail below.

That is, the application signal switching unit 103 is placed under the control of the control unit 109, and the pulse width control signal generation unit 10
Also under control of 5. Applied signal switching unit 103
When the rewrite signal is output from the control unit 109, the display panel has a pulse width determined by the pulse width control signal output from the pulse width control signal generation unit 105.
A switching operation is performed to output a display application signal to the display device 20. Signal generator for pulse width control
105, as described above, in order to control the pulse width of the display application signal output from the application signal switching unit 103 to the display panel 20 to drive the display panel 20 to a predetermined value, the application signal switching unit 103 In response, a pulse width control signal is output.

The refresh clock generation unit 111 is set in advance so that the same signal as the display application signal is output from the application signal switching unit 103 to each of the segment electrodes 4a to 4g configuring the display panel 20. A predetermined clock signal is generated for each period and output to the control unit 109. Here, the period at which the refresh clock generation unit 111 generates and outputs a predetermined clock signal is determined by the display application signal output from the application signal switching unit 103 to each of the segment electrodes 4a to 4g of the display panel 20. In order to maintain the display pattern formed on the display panel 20 by the positively charged white pigment particles 8 adhering to the transparent electrode 2 and the plurality of divided electrodes 4, the same signal as the display application signal is applied to each segment. This is a cycle applied to the electrodes 4a to 4g. Hereinafter, the above cycle is referred to as a refresh cycle. In the present embodiment, the refresh cycle at which the refresh clock generator 111 outputs a predetermined clock signal to the controller 109 is determined by the refresh cycle setting information transmitting means (not shown). It is determined based on the refresh cycle setting information transmitted.
The mode of setting the refresh cycle is a specific example according to an embodiment of the present invention, and does not mean that the present invention is limited only to the above mode. That is, the refresh clock generator 111 itself can be configured so that the refresh cycle can be freely set.

The storage unit 107 stores various necessary data under the control of the control unit 109. As the data that the storage unit 107 stores under the control of the control unit 109, for example, the control unit 109 outputs a rewrite signal to the application signal switching unit 103 so that the display application signal is output to any segment electrode. Starting with the writing information of the latest display pattern to the display panel 20 indicating which segment electrode the display application signal was not output to, the same signal as the latest display application signal is applied as a refresh signal. There are information for identifying the segment electrodes output from the signal switching unit 103 and the segment electrodes not output, various control information related to the control unit 109, and the like.

As is clear from the content already described, the control unit 109 converts the clock signal output from the refresh clock generation unit 111 and display data given from outside indicating a display pattern to be realized on the display panel 20. receive,
A signal output to each of the segment electrodes 4a to 4g of the display panel 20 through the applied signal switching unit 103 is controlled. The control unit 109 also receives the clock signal and the display data, stores the necessary data in the storage unit 107 in the above-described manner, and reads out the data stored in the storage unit 107 as necessary. . To further describe the above, the control unit 109 is based on display data supplied from the outside and a clock signal output from the refresh clock generation unit 111, and for each segment electrode configuring the display panel 20, It is determined whether to rewrite the display. Based on the result of the determination, the write signal generated based on the clock signal and the display data is applied to the segment electrode determined to require rewriting based on the applied signal switching unit 103.
, The applied signal switching unit 103
Output a display application signal. On the other hand, the display signal is not output from the application signal switching unit 103 by not outputting the above-described write signal to the application signal switching unit 103 for the segment electrode that is determined not to need rewriting. The control unit 109 further stores the display pattern before rewriting displayed on the display panel 20 in the storage unit 107, and outputs display data supplied from the outside and the refresh clock generation unit 111. When a new display pattern is rewritten by the clock signal, the display pattern stored in the storage unit 107 is compared with the display pattern after the rewriting. The control unit 109 further determines whether there is a segment electrode whose time from the output time of the latest rewrite signal to the time when the same signal as the refresh signal is output as the refresh signal is shorter than the refresh cycle. Check.

Next, the control operation of the above configuration will be described with reference to the timing chart shown in FIG. The timing chart of FIG. 2 shows that all the segment electrodes 4 a to 4
With respect to 4g, a refresh signal is applied simultaneously in each refresh cycle described above. Here, an applied signal switching unit is applied to each of the segment electrodes 4a to 4g.
The refresh signal applied from the control unit 109 through 103 is the same signal as the latest display application signal applied to each segment electrode. That is, the display panel at time t ₁
In order to display “2” on 20, the segment electrodes 4a, 4b, 4
A positive display application signal W (that is, a write signal) having a pulse width T is output for d, 4e, and 4g, while the display application signal is not output to the segment electrodes 4c, 4f. Next, in order to change the display on the display panel 20 from “2” to “5” at time t _2, the segment electrodes 4 c and 4 f that did not output the positive display application signal W at time t ₁ were applied. On the other hand, a positive display application signal W is output, while a negative display application signal W is output to the segment electrodes 4b and 4e. Then time
When the refresh cycle described above from t ₁ (about 10 minutes to 10 several hours) has reached the time t ₃ when passed, the segment electrodes
For 4a, 4c, 4d, 4f and 4g, the positive display application signal W
Is output as a refresh signal R, while the same signal as the negative display application signal W is output as a refresh signal R to the segment electrodes 4b and 4e. Then, upon reaching the time t ₄ when the refresh period has elapsed from the time t _3, the same signal as that output to the segment electrodes at time t _3, and outputs a refresh signal R. Reaches from the time t ₄ to time t _5, time t ₅
In order to change the display on the display panel 20 from "5" to "3", a positive display application signal W is output to the segment electrode 4b, and a positive display application signal W is output to the segment electrode 4f. , And outputs a negative display application signal W. Then, upon reaching the time t ₄ to time t ₆ in which the refresh period has elapsed, the segment electrodes 4a, 4c, 4d, relative to the 4e and 4g, respectively at time t
_{In step 4} , the same signal as the refresh signal R output separately is output as the refresh signal R. On the other hand, for the segment electrodes 4b and 4f, and outputs the same signal as the display application signal W outputted at each time t ₅ as the refresh signal R.

As described above, if the same signal as the latest display application signal W is always output as the refresh signal R for each segment electrode at a predetermined refresh cycle, deterioration of the memory function of the display panel 20 can be prevented. It is possible to prevent. That is, it is possible to solve the problem that the display pattern formed by the positively charged white pigment particles 8 and the black liquid dispersion medium 7 on the display panel 20 disappears or the display pattern disappears and the display quality deteriorates. The refresh cycle determined by the refresh clock generator 111 may be set shorter than the memory function deterioration time of the display panel 20 to be used according to the memory function of each display panel 20. For example, when the display panel 20 having the memory function deterioration time of one hour is used, the above-described refresh cycle is preferably set to about 40 to 50 minutes. Further, if the control operation based on the timing chart shown in FIG. 2 is adopted, signal control at the time of refreshing becomes unnecessary, and the configuration and control procedure of the driving device shown in FIG. 1 can be simplified. it can. Further, a refresh cycle close to the memory function deterioration time of the display panel 20 can be set, and the life of the display panel 20 can be extended.

Next, a control operation of the driving device for the electrophoretic display panel shown in FIG. 1 will be described with reference to a timing chart shown in FIG. The timing chart in FIG. 3 is different from the timing chart shown in FIG. 2 as apparent with reference to FIG. 2, and in each segment electrode, the point in time when the display is rewritten and the refresh signal R is output. When there is a segment electrode shorter than the set refresh period, the application of the refresh signal R to the segment electrode is stopped only once. That is, the timing chart shown in FIG. 3 and the timing chart shown in FIG. 2 are the same as the basic control mode, but in the control mode according to the timing chart shown in FIG. As for the segment electrodes 4b, 4c, 4e, and 4f, the display application signal W (that is, the rewrite signal) is input during one refresh cycle, so that the refresh cycle is shortened for these segment electrodes. As described above, when the refresh cycle is shortened, in an extreme case, the display application signal W immediately before the next refresh cycle is entered.
When a rewrite signal is input, the pulse width of the write signal may be doubled (see FIG. 4, segment electrodes 4b and 4f). Thus, when the pulse width of the write signal is 2
If the number is doubled, there is a possibility that a problem that the life of the display panel 20 is shortened may occur. Therefore, it has been considered that a control mode based on the timing chart shown in FIG. 3 is implemented.

That is, in order to display “2” on the display panel 20 at time t _1, a positive display application signal W having a pulse width T with respect to the segment electrodes 4 a, 4 b, 4 d, 4 e, and 4 g (that is, Write signal)
Is output, while the display application signal is not output to the segment electrodes 4c and 4f. Next, the display panel at time t ₂
The segment electrode which did not output the positive display application signal W at time t ₁ to change the display on 20 from “2” to “5”
A positive display application signal W is output for 4c and 4f, while
A negative display application signal W is applied to the segment electrodes 4b and 4e.
Is output. Then, when the refresh cycle described above from time t ₁ (about 10 minutes to 10 several hours) has reached the time t ₃ when passed, the segment electrodes 4a, for the 4d and 4g, the positive display application signal Refresh signal R
Output as On the other hand, the segment electrodes 4b, 4c, 4e and 4f
For, because doing the writing at the time t ₂ as described above, is applied to each write signal W same refresh signal R and at time t _3, shorter than the refresh cycle is the set Each of the segment electrodes is refreshed in a refresh cycle. Thus, at time t _3, the segment electrodes 4b, 4c, 4e and 4f
Does not output the refresh signal R (see FIG. 3,
See the * mark at time t _3). Then, upon reaching the time t ₃ to time t ₄ when the refresh period has elapsed, the segment electrodes 4a, 4d and against 4g, refresh signal the same signal as that applied at each time point t ₃ R output as while the segment electrodes 4b, 4c, against 4e and 4f, and outputs the same signal as the write signal W which is applied at each time t ₂ as the refresh signal R. That is, at time t _4, since the set refresh cycle for all segment electrodes 4a~4g has passed, it is necessary to perform the refresh in the manner described above for all of the segment electrodes 4a~4g Because. Reaches from the time t ₄ to time t _5, the display on the display panel 20 at time t _{5 "5"} from "3"
To the segment electrode 4b, a positive display application signal W is output, and to the segment electrode 4f, a negative display application signal W is output. Then, upon reaching the time t ₆ to the refresh period has elapsed from the time t _4, the segment electrodes 4a, 4c, 4d, relative to the 4e and 4g, the refresh signal R outputted by each time t ₄ in each different
Is output as a refresh signal R. On the other hand, for the segment electrodes 4b and 4f, because doing the writing at the time t _5, as described above, at time t ₆ is applied to each write signal W same refresh signal R and, the setting Each of the segment electrodes is refreshed at a refresh cycle shorter than the refresh cycle that has been set. Thus, at time t _6, with respect to the segment electrodes 4b and 4f does not output a refresh signal R (FIG. 3, reference mark * at time t ₆₎ In the control operation based on the timing chart of FIG. 3 described above In some cases, application of the refresh signal R is not performed once depending on the timing of application of the write signal W to each segment electrode. Therefore, the refresh cycle is one time of the display quality deterioration time of the display panel 20 used. Must be set to / 2 or less. That is, for example, when the display quality deterioration time of the used display panel 20 is one hour, it is preferable to set the refresh cycle to about 20 to 25 minutes. Further, if the control operation based on the timing chart shown in FIG. 3 is adopted, depending on the application timing of the write signal W, the display application signal W and the refresh signal R are continuously applied. In addition, it is possible to prevent a problem that the pulse width of the write signal W is substantially doubled, so that the write signal W is likely to be deteriorated due to an increase in the pulse width. This is particularly effective when the display panel 20 that is easily affected by the display panel is adopted.

Next, a control operation of the driving device for the electrophoretic display panel shown in FIG. 1 will be described with reference to a timing chart shown in FIG. As is clear from FIG. 5, the timing chart of FIG. 5 is set in advance for each of the segment electrodes 4a to 4g with the time point at which the latest display application signal W is output as a reference time point. When the refresh period has elapsed, a refresh signal R, which is the same signal as the display application signal W, is output independently for each of the segment electrodes 4a to 4g. That is, the second
In the control mode according to the figure and the control mode according to FIG. 3,
When a preset refresh cycle is reached, a refresh signal R is simultaneously output to all the segment electrodes 4a to 4g, so that a display pattern rewriting completely asynchronous with the refresh signal R is performed. When the display application signal W is applied, various problems occur as described above in controlling the output timing of these two types of signals. Therefore, it has been considered that a control mode based on the timing chart shown in FIG. 5 is implemented.

That is, in order to display “2” on the display panel 20 at time t _1, a positive display application signal W having a pulse width T with respect to the segment electrodes 4 a, 4 b, 4 d, 4 e, and 4 g (that is, Write signal)
Is output, while the display application signal is not output to the segment electrodes 4c and 4f. Next, the display panel at time t ₂
The segment electrode which did not output the positive display application signal W at time t ₁ to change the display on 20 from “2” to “5”
A positive display application signal W is output for 4c and 4f, while
A negative display application signal W is applied to the segment electrodes 4b and 4e.
Is output. Then, when the refresh cycle described above from time t ₁ (about 10 minutes to 10 several hours) has reached the time t ₃ when passed, the segment electrodes 4a, for the 4d and 4g, the positive display application signal Refresh signal R
Output as, whereas, for the segment electrodes 4b, 4c, 4e and 4f, in order to have performed write at time t ₂ as described above, at time t ₃ of the same respective write signal W Refresh When the signal R is applied, the segment electrodes 4b, 4c, 4e and 4f are refreshed at a refresh cycle shorter than the set refresh cycle. Thus, at time t _3, the segment electrodes 4
No refresh signal R is applied to b, 4c, 4e and 4f. Then, when the refresh period on the basis point of time t ₃ from time t ₃ has reached the time t ₄ is a time that has elapsed, the segment electrodes 4b, 4c, against 4e and 4f, respectively time t ₂ Then, the same signal as the display application signal W applied is output as the refresh signal R. Meanwhile, the segment electrode
4a, for the 4d and 4g, in order to have outputs respectively refresh signal R at time t ₃ as described above, the time t ₄
When the same refresh signal R as the refresh signal R applied is applied to each of the segment electrodes 4a, 4d, and 4g, the segment electrodes 4a, 4d, and 4g are refreshed at a refresh cycle shorter than the set refresh cycle. Thus at time t _4, the segment electrodes 4a, 4d
And 4g, the refresh signal R is not applied. Time t ₄
It reaches the time t ₅ from the display on the display panel 20 at time t ₅ to change to "3" to "5", for the segment electrodes 4b, and outputs a positive display application signal W Also, a negative display application signal W is output to the segment electrode 4f. At the same time, the segment electrodes 4a, for the 4d and 4g, since the time t ₃ is the refresh period on the basis the time has elapsed, the applying the same refresh signal R as that applied at each time point t ₃ . Note that the segment electrodes 4b and 4f are applied timing of the display application signal W for those other segment electrodes 4a, so synchronized with the refresh cycle of the 4d and 4g, newly counted refresh cycle from time t ₅ Shall be.

With the above-described control mode, the timing of applying the refresh signal can be variably adjusted in relation to the display application signal W applied to each segment electrode. Timing control can be realized. The configuration for realizing the control operation based on the timing chart shown in FIG. 5 is substantially the same as the configuration shown in FIG.
The storage unit 107 needs to newly store refresh cycle count data for each of the segment electrodes 4a to 4g in order to realize the timing chart, and the refresh clock generation unit 111 is set in advance. It is necessary that each of the segment electrodes 4a to 4g be configured to output a separate clock signal to the control unit 109 based on the refresh cycle.

In addition, separately from the above-described configuration, for example, a semiconductor switching element or an open / close circuit is provided between the applied signal switching unit 103 illustrated in FIG. 1 and the transparent electrode (common electrode) 2 provided on the display panel 20. The display signal W is applied to the transparent electrode 2 from the application signal switching unit 103 by being connected through a contact that can be closed. At the same time, when the semiconductor switching element or the like is closed and a certain electric signal is applied to the transparent electrode 2, the applied signal switching unit 103 is connected to the segment electrode of the element that does not change the display state. In addition, the same electric signal as the electric signal may be applied so that the potential difference between the transparent electrode 2 and the transparent electrode 2 becomes zero.

In this embodiment, the liquid dispersion medium 7 colored black and the liquid dispersion medium 7 dispersed in the black liquid dispersion medium 6 are dispersed in the electrophoretic display dispersion system 6 sealed in the display panel 20. Although a description has been given of the use of the particles composed of the white pigment particles 8, it is a matter of course that the electrophoretic display dispersion system is not limited to the above in the present invention.

Further, in the present embodiment, the description has been made assuming that the display application signal W and the refresh signal R have the same magnitude and width, but they may be different as long as the display quality is not deteriorated. Absent.

〔The invention's effect〕

As described above, according to the present invention, the display signal applying unit performs the display for a preset time for the segment electrode of the element that changes the display state determined based on the control signal given from the outside. A signal is applied, and the refresh signal applying means applies a signal having the same polarity as the display signal in order to hold a pattern formed by particles adhering to each electrode by the display signal applied to the segment electrode. Since the voltage is applied to each of the segment electrodes at each refresh cycle set shorter than the display quality deterioration time of the electrophoretic display panel, the electrophoretic display dispersion system is electrolyzed and deteriorates. In addition, it is difficult for charged particles and the like adhered to the transparent electrode and the plurality of divided electrodes to be easily separated from the transparent electrode and the plurality of divided electrodes. Consumption can, it is possible to provide a driving device of the electrophoretic display panel capable of and the time required by the electrophoretic display panel is securely retain the memory function comprising.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a driving apparatus for an electrophoretic display panel according to an embodiment of the present invention.
FIGS. 3, 3, 4 and 5 are timing charts showing the control operation of the driving device for the electrophoretic display panel shown in FIG. 1, respectively, and FIG. FIG. 7 is a cross-sectional view showing the configuration of the electrophoretic display panel.
FIG. 8 shows the structure of a conventional numeric display panel using a dispersion system for electrophoretic display, and FIG.
6 is a timing chart for explaining the operation of the numeric display panel shown in the figure. 2 ... Transparent electrode, 4 ... Split electrode, 4a-4g ... Segment electrode, 6 ... Dispersion system for electrophoretic display, 7 ... Black liquid dispersion medium,
8: positively charged white pigment particles, 20: display panel, 103: applied signal switching section, 105: pulse width control signal generation section, 107: storage section, 109: control section, 111: refresh clock generation section.

Claims (5)

(57) [Claims] An electrophoretic display dispersion system comprising a liquid phase dispersion medium and particles is housed in a space defined by a pair of transparent electrodes, at least one of which is opposed to each other, and one of the electrodes is A driving device for driving an electrophoretic display panel, which is a common electrode, and the other of the electrodes is an electrode composed of a plurality of elements divided into a plurality of segment electrodes, based on a control signal given from outside. For the segment electrode of the element that changes the display state determined by
Display signal applying means for applying a display signal for a preset time; and a display signal for holding a pattern formed by particles adhering to the respective electrodes by the display signal applied to the segment electrodes. Refresh signal applying means for applying a signal having the same polarity as the signal to each of the segment electrodes for each refresh cycle set shorter than the display quality deterioration time of the electrophoretic display panel. Driving device for electrophoretic display panel. 2. The driving device for an electrophoretic display panel according to claim 1, wherein said refresh signal applying means is configured to apply a refresh signal simultaneously to the electrodes of all the segments in said refresh cycle. A driving device for an electrophoretic display panel. 3. The driving apparatus for an electrophoretic display panel according to claim 1, wherein said refresh signal applying means refreshes from a time when said display signal applying means applies a display signal to said segment electrode. When there is a time period before the signal applying means applies a signal having the same polarity as the display signal, the signal having the same polarity as the display signal from the refresh signal applying means to the segment electrode is provided when there is a signal whose time is shorter than the refresh cycle. A driving device for an electrophoretic display panel, wherein the driving device is configured to present application of at least one time. 4. A driving apparatus for an electrophoretic display panel according to claim 1, wherein said refresh signal applying means has the same polarity as a display signal applied to each segment electrode from said display signal applying means. A driving apparatus for an electrophoretic display panel, wherein a signal is applied to each segment electrode at each refresh cycle. 5. The driving device for an electrophoretic display panel according to claim 1, wherein the switching means connects the common electrode and the display signal applying means to apply the display signal. Means for applying an electric signal to the common electrode from the means, and the display signal applying means, when the switching means is closed and the electric signal is applied to the common electrode, all the segment electrodes An electrophoretic display panel configured to apply an electric signal such that a potential difference between the common electrode and the segment electrode of an element that does not change a display state in the element is zero. Drive.