KR101620061B1 - method for driving electronic paper display with improved low temperature characteristics - Google Patents

Abstract

A driving technique of an electronic paper display suitable for low-temperature operation is disclosed. All black driving is performed, and the background electrodes except the segments of the data portion to be displayed thereafter are driven to display 'white'. As another example, after the black drive is performed, the data electrodes of the data portion to be displayed may be driven to display 'white'. At this time, the 'white' display driving of the background electrode or the data electrodes can be maintained longer than the black driving step. In addition, a full-back driving stage may be added before the black driving stage.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a driving method of an electronic paper display,

An electronic paper display, in particular, a driving technique thereof, is proposed.

An electronic information label (ESL) is known which replaces paper labels and displays information about products displayed on the shelves of stores. Electronic information labels, powered by batteries, use electronic paper displays to reduce power consumption. As in the case of food adhered to the freezer, the electronic information label installed at a low temperature has a problem that the display performance of the electronic paper display is deteriorated and the display data becomes blurred or the reading becomes difficult.

A technique has been proposed in which an afterimage of display data is effectively removed at a low temperature in an electronic paper display to sharpen the display and improve the display speed.

According to one aspect, a new method of driving an electronic paper display is disclosed. All black driving is performed, and the background electrodes except the segments of the data portion to be displayed thereafter are driven to display 'white'.

According to another aspect, after the black driving is performed to improve the low-temperature characteristic, the data electrodes of the data portion to be displayed are driven in the 'white' display.

According to another aspect, the 'white' display driving of the background electrode or the data electrodes can be maintained longer than the black driving step.

According to another aspect, a full-fledged driving stage can be added before the black driving stage.

According to another aspect, the full-back driving stage and the light driving stage may be repeated two or more times.

According to another aspect, when updating the display data, the update display steps may be repeated two or more times as a whole.

It is possible to effectively remove the afterimage generated at the edge of the display data at a low temperature, thereby enabling clear display. Furthermore, the whiteness of the white background is improved, and the display data becomes clear. Furthermore, the display speed, which is the time taken for information to be displayed visually, is improved. .

1 schematically shows the configuration of an electronic paper display according to one embodiment.
FIG. 2 is a flowchart showing a configuration of a driving method of an electronic paper display according to an embodiment.
Fig. 3 is a flowchart showing a configuration of a driving method of an electronic paper display according to still another embodiment.
FIG. 4 is a graph showing the results of measuring the display speed characteristics of a product called E Ink Carta (TM) among black and white electronic paper displays of E Ink Holdings, Inc. according to temperature.

The foregoing and further aspects are embodied through the embodiments described with reference to the accompanying drawings. It is to be understood that the components of each embodiment are capable of various combinations within an embodiment as long as no other mention or mutual contradiction exists.

Electronic paper displays are increasingly used as display devices for information devices. Negatively charged white pigment particles and negatively charged white paper particles filled with positively charged white dye particles were coated with a common transparent electrode on the front surface and a black and white electron Paper displays are known. For example, E Ink Holdings, Inc.'s black and white electronic paper display achieves bistable and reflective characteristics, maintains the display state with no drive voltage applied, and displays the displayed information without backlight Readable and suitable for low power applications.

Typically, the electronic paper display reaches a reference luminance within a range of 100 to 300 ms at a temperature range of 0 to 50 ° C. The L luminance value (L *) is expressed by dividing the brightness into 100 values from the darkest 0 to the brightest 100 values. The display speed of the display can be expressed as the time required for a change from a state of L * value of 25 to a state of 65 or vice versa.

In a typical application, the electronic paper display has no difficulty in displaying the stationary information. However, in an application such as an electronic information label installed in a refrigerator for storing frozen food, the temperature drops below minus 20 ° C, so that the display speed of the electronic paper display is seriously slowed down and the display state becomes unrecognizable.

FIG. 4 is a graph showing the results of measuring the display speed characteristics of a product called E Ink Carta (TM) among black and white electronic paper displays of E Ink Holdings, Inc. according to temperature. The display speed of black -> back is shown in the above graph, and the display speed of back -> black is shown in the following graph. From the two measurement results, it can be seen that the characteristics of black-> white conversion and white-> black conversion are not significantly different from each other at room temperature, but they are significantly different from low temperatures. At minus 25 ℃, it takes about 1 second to switch from black to white, while it takes about 5 seconds to switch back to black.

1 schematically shows the configuration of an electronic paper display according to one embodiment. The inside of the electronic paper film 170 is sealed with charged dye particles. A common transparent electrode 130 is formed on the front surface of the electronic paper film 170, and segment electrodes 151 and 153 are formed on the back surface of the electronic paper film 170 for driving. The segment electrode includes, for example, a data electrode 151 corresponding to a display type of '1' and a background electrode 153 as a background thereof, if the illustrated example indicates '1'. There may be only one background electrode 153 on the display, but it may be divided into several in consideration of the driving load.

The power supply device 190 is a circuit that generates a driving voltage, for example, a two-level voltage of 15 V, with a charge pump. The driving unit 110 may be a circuit for selectively supplying the driving voltage to the common transparent electrode 130, the data electrode 151, and the background electrode 153 through switching.

In the electronic paper display according to an exemplary embodiment, when 15 V is applied to the common transparent electrode and 0 V is applied to the segment electrode, the negatively charged black dye moves toward the common transparent electrode and the display surface becomes black. On the other hand, when 0 V is applied to the common transparent electrode and 15 V is applied to the segment electrode, the positively charged white dye moves toward the common transparent electrode, and the display surface becomes white. However, the level of such a driving voltage may vary depending on the selection of charged particles, and the proposed invention is intended to cover all of them. In general, in the electronic paper display, 0 V is applied to the common transparent electrode, and 15 V is applied to both the data electrode and the segment electrode including the background electrode to perform all-white driving to make all the display surfaces white, 15V is applied to the transparent electrode, 0V is applied to the data electrode of the segment electrode, and 15V is directly applied to the background electrode to drive the information display to be black.

The inventor observed that there was a residual image of the previously displayed information on a white background at low temperature, or the wrong information was displayed or the display contents were not recognized or very difficult. Through the above-described analysis, the inventor found that the cause of such a problem is that the electronic paper film is driven without considering the asymmetry of the display speed of black-and-white conversion and white-black conversion. That is, since the general driving timing is designed within the operating temperature range, since the black-and-white conversion takes a longer time than the black-white conversion, the full-back driving is completed before all the display surfaces are converted to white in the full- The display of the new information is attempted while the residual image remains.

In addition, the electronic paper display has the characteristic of changing the color when the former and the potential are changed, and keeping the former color at the same potential. In the two-level driving method, one of the background segment and the character segment is always driven at the same voltage level as the common transparent electrode, so that one of the two types of segments in one display step must maintain the same voltage level as the transparent electrode, which is the common transparent electrode Therefore, the display data maintains the existing display state but can not be further improved in sharpness. Since it takes time for each display unit to be driven in the electronic paper display, a reasonable selection of one of the background and display data is required. This selection has a decisive influence on the clarity of the display, since the delay in the display is more severe in low-temperature driving.

In the existing method, in which the segment displaying the character is changed to black in the entire white state, the white color of the background color is changed to black while maintaining the previous state. All visible afterimages can be defined as the gray areas, such as gray, that should be marked as white. That is, the magnitude of black brightness has no effect on visual afterimage, and the brightness of White represents all afterimages. At room temperature, there is no problem with afterimage due to the nature of E-paper even with this waveform method. However, when operated in a low temperature, especially in a freezing state, such an operation method causes a great problem.

FIG. 2 is a flowchart showing a configuration of a driving method of an electronic paper display according to an embodiment. According to one aspect, the electronic paper display displays the common transparent electrode at the first level and the segment electrodes including the data electrode and the background electrode at the second level during the first time period. (Step 233), driving the common transparent electrode to the second level and the background electrodes to the first level 'white' during the second duration (step 251). First, the entire display area is driven in black, and then only the background is driven in white. Since white transition is much faster, previous information in the background is effectively erased, and the display area is switched to bright black in a short time. Then, the background electrodes are driven to the first level and the data electrodes are driven to the second level so that the background is switched to white only. Accordingly, the data areas are maintained in the black display state because the same voltage is applied to the front and rear surfaces, and the background areas are switched to white. In one embodiment, the first level is 15V and the second level is 0V.

According to one aspect, the second duration is set to be longer than the first duration. Specifically, the second duration may be set to be four times longer than the first duration. In one embodiment, since the time required for the black-and-white conversion is 5 seconds and the time required for the black-and-white conversion is 1.2 seconds, the first duration is set to 1.5 seconds and the second duration is set to 6 seconds . The black data area is displayed in a clear state even if the second duration, which is the drive time of the background area, is long, so that the user can identify the display information within two seconds before the six seconds expire. The upper limit of the second duration may be determined in consideration of power consumption depending on driving. For example, driving for 30 seconds or more is disadvantageous in terms of power consumption.

According to another aspect of the present invention, a method of driving an electronic paper display includes a step of driving a common transparent electrode to a second level and a segment electrode including a data electrode and a background electrode to a first level, ) 'Display driving all the white driving steps (step 213). A part of the previous display data is erased and the movement of the charged particles is accelerated through the whiteness driving process which has been performed beforehand, so that the performance of the black driving can be further improved.

According to another aspect, the full-back driving stage and the light driving stage may be repeated two or more times (steps 211 to 233). As a result, a part of the display data is erased and the movement of the charged particles is promoted, so that the performance of the driving can be further improved.

According to another aspect, the display drive steps may be repeated two or more times when updating the display data (steps 233 to 253). When the display driving steps are repeated, the duration of the intermediate data display driving step 251 is shortened, and only the final data display driving step 253 can be given a sufficient time.

1, the data display unit 113 of the driving unit 110 drives the common transparent electrode to the first level and the segment electrodes to the second level in the 'black' And then drives the common transparent electrode to the second level and the background electrodes to the first level in a 'white' display during the second duration. As described above, the film initialization unit 111 drives the entire segment electrodes as the 'white' display before the dark field drive, that is, before the operation of the data display unit 113.

Fig. 3 is a flowchart showing a configuration of a driving method of an electronic paper display according to still another embodiment. According to one aspect, the electronic paper display drives a common transparent electrode to a first level and a segment electrode including a data electrode and a background electrode both at a second level for 'black' display during a first duration ( Step 333) drives the common transparent electrode to the second level and the data electrodes to the first level 'white' during the second duration (step 351). First, the entire display area is driven in black, and then only the data is driven in white. Therefore, information is displayed in white on a black background. Since white transition is much faster, previous information in the background is effectively erased, and the display area is switched to bright black in a short time. The background electrodes are driven to the second level and the data electrodes are driven to the first level so that only the letters are switched to white. Accordingly, since the same voltage is applied to the front and rear surfaces of the background area, the black display state is maintained and the data areas are changed to white. In one embodiment, the first level is 15V and the second level is 0V. The user can immediately identify the display information even if the switching of the data area is slow in a state in which the black of the background is clear.

According to one aspect, the second duration is set to be longer than the first duration. Specifically, the second duration may be set to be four times longer than the first duration. In one embodiment, since the time required for black-and-white conversion is 5 seconds at a temperature of -25 ° C and the time required for black-and-white conversion is about 1.2 seconds, the first duration is set to 1.5 seconds and the second duration is set to 6 seconds . The black data area is displayed in a clear state even if the second duration, which is the drive time of the background area, is long, so that the user can identify the display information within two seconds before the six seconds expire. The upper limit of the second duration may be determined in consideration of power consumption depending on driving. For example, driving for 30 seconds or more is disadvantageous in terms of power consumption.

According to another aspect of the present invention, a method of driving an electronic paper display includes a step of driving a common transparent electrode to a second level and a segment electrode including a data electrode and a background electrode to a first level, ) 'Display driving all the white (step 313). A part of the previous display data is erased and the movement of the charged particles is accelerated through the whiteness driving process which has been performed beforehand, so that the performance of the black driving can be further improved.

According to another aspect, the full-back driving stage and the light driving stage may be repeated two or more times (steps 311 to 333). As a result, a part of the display data is erased and the movement of the charged particles is promoted, so that the performance of the driving can be further improved.

According to another aspect, the display drive steps (steps 333 and 351) can be repeated two or more times when updating the display data (steps 333 to 353). When the display driving steps are repeated, the duration of the intermediate data display driving step 351 is shortened, and only the final data display driving step 353 can be given a sufficient time.

1, the data display unit 113 of the driving unit 110 drives the common transparent electrode to the first level and the segment electrodes to the second level in the 'black' And then drives the common transparent electrode to the first level and the data electrodes to the " white " display for the second time period. As described above, the film initialization unit 111 drives the entire segment electrodes as the 'white' display before the dark field drive, that is, before the operation of the data display unit 113.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and similarities that may occur to those skilled in the art. The claims are intended to cover such modifications.

Claims (18)

A method of driving an electronic paper display,
An all black driving step for driving the common transparent electrode to the first level and the segment electrodes including the data electrode and the background electrode to 'black' display at the second level during the first time period;
Driving the common transparent electrode to a second level and the background electrodes to 'white' display to a first level during a second duration after the black driving stage;
And a driving circuit for driving the electronic paper display.
The method of claim 1, wherein the second duration is longer than the first duration.
The method of claim 1, wherein the method further comprises:
An all white driving step of driving the common transparent electrode to a second level and driving the segment electrodes including the data electrode and the background electrode to 'white' display at a first level;
Further comprising the steps of:
The driving method of an electronic paper display according to claim 3, wherein the full-back driving step and the light driving step are repeated two or more times.
A method of driving a voltage of an electronic paper display in which display driving steps according to claim 1 are repeated two or more times when updating display data.
Electronic paper film; A common transparent electrode formed on one surface of the electronic paper film; A segment electrode including a data electrode and a background electrode formed to display data in a background on the other side of the electronic paper film; And a driving unit for driving the electrodes to a two-level voltage, wherein the driving unit comprises:
After driving the common transparent electrode to the first level and the segment electrodes to the second level during the first duration, the common transparent electrode is driven to the second level for the second duration, An electronic paper display including a data display portion for driving a 'white' display to a first level.
7. The electronic paper display of claim 6, wherein the second duration is longer than the first duration.
7. The electronic paper display of claim 6, wherein the driver further comprises a film initialization unit for driving all segment electrodes to a 'back' indication.
A method of driving an electronic paper display,
An all black driving step for driving the common transparent electrode to the first level and the segment electrodes including the data electrode and the background electrode to 'black' display at the second level during the first time period;
A data display driving step of driving the common transparent electrode to a second level and the data electrodes to a first level 'white' display for a second duration after the black driving stage;
And a driving circuit for driving the electronic paper display.
10. The method of claim 9, wherein the second duration is longer than the first duration.
11. The method of claim 10, wherein the second duration is at least 4 seconds.
10. The method of claim 9, wherein the method further comprises:
An all white driving step of driving the common transparent electrode to a second level and driving the segment electrodes including the data electrode and the background electrode to 'white' display at a first level;
Further comprising the steps of:
The driving method of an electronic paper display according to claim 12, wherein the full-back driving step and the light driving step are repeated two or more times.
And the display driving step according to claim 9 is repeated two or more times when the display data is updated.
Electronic paper film; A common transparent electrode formed on one surface of the electronic paper film; A segment electrode including a data electrode and a background electrode formed to display data in a background on the other side of the electronic paper film; And a driving unit for driving the electrodes to a two-level voltage, wherein the driving unit comprises:
After driving the common transparent electrode to the first level and the segment electrodes to the second level during the first duration, the common transparent electrode is driven to the second level during the second sustain period, An electronic paper display including a data display portion for driving a 'white' display to a first level.
16. The electronic paper display of claim 15, wherein the second duration is longer than the first duration.
17. The electronic paper display of claim 16, wherein the second duration is greater than or equal to 4 seconds.
16. The electronic paper display of claim 15, wherein the driving unit further comprises a film initialization unit driving all segment electrodes to a 'black' indication and then driving all segment electrodes to a 'back' indication.

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