Electronic paper and image display method

Abstract

To provide an electronic paper and an image display method that can display information on the remaining amount of a battery without obstructing the original content of display.SOLUTION: An electronic paper 100 comprises: a battery 5 that supplies power; a display panel 10 including color particles that move and rotate upon application of voltage; a control unit 21 that controls a rewriting operation of applying rewriting voltage to the color particles on the basis of image data to rewrite an image on the display panel 10; a remaining amount detection unit 22 that detects the remaining amount of the battery 5; and an image conversion unit 23 that performs image conversion having a visual effect on at least part of the image data on the basis of the detected remaining amount.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to electronic paper and an image display method. [Background technology]

[0002] Conventionally, electronic paper has been known as a display device that can be rewritten many times and has low power consumption (see, for example, Patent Document 1). Patent Document 1 describes that information on the remaining battery level (an image showing the remaining battery level) is displayed on the display unit of the display based on the remaining battery level of the electronic paper. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2011 / 001671 Summary of the Invention [Problem to be solved by the invention]

[0004] Like personal computers and mobile phones, mobile devices using electronic paper have built-in batteries. The remaining battery level is displayed by an icon or other display, allowing the user to keep track of it. When the battery level gets low, the user charges the battery as needed. However, the situation with electronic paper devices for business use is different from that of consumer devices. For example, when an electronic paper device is displaying an advertisement, it is not desirable to display the remaining battery level or a message urging the user to charge the battery on the screen that is unrelated to the advertisement content.

[0005] In addition, electronic paper has the advantage of being in standby mode except when the display screen is being rewritten, which reduces power consumption, but on the other hand, when used to display advertisements, it may be left unused for long periods of time, and for this reason, there is concern that electronic paper products with built-in batteries may deteriorate due to over-discharge (becoming unable to charge, leaking, etc.).

[0006] An object of the present disclosure is to provide an electronic paper and an image display method that are capable of displaying information about the remaining battery power without interfering with the intended display content. [Means for solving the problem]

[0007] The electronic paper of the present disclosure comprises a battery that supplies power, a display panel including color particles that move when a voltage is applied to it, a control unit that controls a rewrite operation that rewrites the image on the display panel by applying a rewrite voltage to the color particles based on image data, a remaining charge detection unit that detects the remaining charge of the battery, and an image conversion unit that performs image conversion having a visual effect on at least a portion of the image data based on the detected remaining charge.

[0008] The image display method of the present disclosure includes a control process for controlling a rewrite operation of rewriting an image on a display panel including color particles based on image data by applying a rewrite voltage to color particles that move when a voltage is applied to the color particles, a remaining charge detection process for detecting the remaining charge of a battery, and an image conversion process for performing a visible image conversion on at least a portion of the image data based on the detected remaining charge. Effect of the Invention

[0009] According to the present disclosure, information regarding the remaining battery charge can be displayed without interfering with the intended display content. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view illustrating a schematic structure of electronic paper 100 according to a first embodiment of the present disclosure. [Diagram 2] 2 is an enlarged view showing a schematic structure of the microcapsules of electronic paper 100 and the surrounding area. FIG. [Diagram 3] 1 is a block diagram showing a functional configuration of electronic paper 100. FIG. [Figure 4] 1 is a flowchart illustrating an image display method of the electronic paper 100. [Diagram 5]1 is a graph showing an example of the transition of the remaining charge of a battery 5 over time, assuming that the remaining charge of the battery 5 will run out in about six months. [Figure 6A] FIG. 13 is a diagram showing an example of a display image when the remaining charge of the battery 5 is 100%. [Figure 6B] FIG. 13 is a diagram showing an example of a display image when the remaining charge of the battery 5 is about 60%. [Figure 6C] FIG. 13 is a diagram showing an example of a display image when the remaining charge of the battery 5 is almost 0%. [Figure 7] 10 is a graph illustrating the transition over time of the remaining charge of a battery 5 of an electronic paper 100A according to a second embodiment of the present disclosure. [Figure 8A] 11 is a diagram showing an example of a display image on electronic paper 100A when the remaining charge of battery 5 is 100 to 40%. FIG. [Figure 8B] FIG. 13 is a diagram showing an example of a display image when the remaining charge of the battery 5 is about 30%. [Figure 8C] FIG. 13 is a diagram showing an example of a display image when the remaining charge of the battery 5 is about 20%. [Figure 8D] FIG. 13 is a diagram showing an example of a display image when the remaining charge of the battery 5 is 10%. [Figure 9A] FIG. 13 is a diagram illustrating an example of a display image when the remaining charge of the battery 5 is 30% in the electronic paper 100B according to a modified example of the second embodiment of the present disclosure. [Figure 9B] FIG. 13 is a diagram showing an example of a display image when the remaining charge of the battery 5 is 20%. [Figure 9C] FIG. 13 is a diagram showing an example of a display image when the remaining charge of the battery 5 is 10%. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present disclosure will now be described with reference to the accompanying drawings, in which the same or corresponding parts are designated by the same reference characters and will not be described repeatedly.

[0012] First Embodiment 1.1 Structure of e-paper 100 Electronic paper 100 according to a first embodiment of the present disclosure will be described with reference to Figures 1 to 6. Figure 1 is a cross-sectional view that illustrates a schematic structure of electronic paper 100 according to the first embodiment of the present disclosure.

[0013] As shown in Fig. 1, electronic paper 100 functions as a display device that displays images. Electronic paper 100 is used, for example, as an electronic shelf label, an electronic advertisement, an electronic book terminal, or an electronic notebook, but here it is assumed that it is a commercial device that displays advertisements. However, electronic paper 100 may be used as devices other than electronic shelf labels, electronic advertisements, electronic book terminals, and electronic notebooks.

[0014] The electronic paper 100 includes a housing 1, a display panel 10, and a control device 20 (described later with reference to FIG. 3). The housing 1 houses the display panel 10. The housing 1 has an opening 1a on the front side. The control device 20 controls various operations of the electronic paper 100. As a result, the electronic paper 100 displays a predetermined image.

[0015] The display panel 10 displays an image. The display panel 10 is formed to be larger than the opening 1a of the housing 1, and is disposed so as to cover the opening 1a. The area of ​​the display panel 10 that corresponds to the opening 1a is a display area in which an image is visually recognized by a user.

[0016] The display panel 10 also includes a first substrate 11, a second substrate 12 disposed opposite the first substrate 11, a plurality of microcapsules 13, a first electrode 14, and a second electrode 15.

[0017] The first substrate 11 is formed of a transparent plate member or sheet member such as glass or resin. An anti-reflection film may be formed on the outer surface (opposite side to the second substrate 12) of the first substrate 11, and a water-repellent treatment may be applied. The second substrate 12 is formed of a plate member or sheet member such as glass or resin.

[0018] The microcapsules 13 are disposed between the first substrate 11 and the second substrate 12. The microcapsules 13 are spread, for example, in one layer between the first substrate 11 and the second substrate 12. The microcapsules 13 have a substantially spherical shape. The microcapsules 13 have a diameter, for example, of several tens of μm or more and several hundreds of μm or less.

[0019] Fig. 2 is an enlarged view showing a schematic structure of the microcapsule 13 and its surroundings of the electronic paper 100. As shown in Fig. 2, the microcapsule 13 has a film 131, a plurality of color particles 132, and a dispersion liquid 133. The film 131 is, for example, transparent. The film 131 is, for example, a film made of a transparent resin. The material of the film 131 is not particularly limited, but is, for example, a urethane resin, a melamine resin, or rubber.

[0020] The color particles 132 are pigments. The color particles 132 form part of an image displayed on the display panel 10. The color particles 132 move when a voltage is applied. In this embodiment, "moving" includes moving and rotating. In this embodiment, the color particles 132 are electrophoretic particles. Specifically, the color particles 132 move within the dispersion liquid 133 in response to a voltage applied between the first electrode 14 and the second electrode 15. As a result, a predetermined image is displayed on the display panel 10.

[0021] The color particles 132 are, for example, organic or inorganic particles. In this embodiment, the color particles 132 have, for example, black particles 132a as a black pigment and white particles 132b as a white pigment. The black particles 132a as a black pigment are not particularly limited, but include, for example, carbon black or titanium black. The white particles 132b as a white pigment are not particularly limited, but include, for example, titanium dioxide or antimony trioxide. The black particles 132a and the white particles 132b are examples of "color particles" in the present disclosure.

[0022] The black particles 132a are, for example, negatively charged. On the other hand, the white particles 132b are, for example, positively charged. That is, the black particles 132a and the white particles 132b are different in color and charged with different polarities. Note that the black particles 132a may be positively charged and the white particles 132b may be negatively charged.

[0023] In this embodiment, as described above, the color particles 132 include a black pigment and a white pigment. However, the color particles 132 may include a pigment of another color instead of the black pigment and the white pigment. Furthermore, the color particles 132 may include a pigment of another color in addition to the black pigment and the white pigment. As the pigment of another color, for example, a yellow pigment, a red pigment, a blue pigment, a white pigment, and / or a green pigment can be used.

[0024] The dispersion liquid 133 is, for example, transparent. The dispersion liquid 133 is an insulating liquid. The dispersion liquid 133 is not particularly limited, and may include, for example, water, an alcohol-based solvent, esters, ketones, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, or oils. In this embodiment, the dispersion liquid 133 includes, for example, an aliphatic hydrocarbon.

[0025] The first electrode 14 and the second electrode 15 are disposed opposite to each other so as to sandwich the microcapsule 13 therebetween.

[0026] The first electrode 14 is disposed, for example, on the outer side (first substrate 11 side) of the microcapsules 13. The first electrode 14 may be formed, for example, on the first substrate 11. In this embodiment, the first electrode 14 is formed on the first substrate 11.

[0027] The first electrode 14 is formed of a conductive material having light-transmitting properties. The first electrode 14 is not particularly limited, but is formed of, for example, ITO. In this embodiment, the first electrode 14 is a common electrode. For example, one first electrode 14 is provided for a plurality of pixels (here, all pixels). The first electrode 14 is, for example, grounded and has a ground potential.

[0028] The second electrode 15 is disposed, for example, on the inner side (the second substrate 12 side) of the microcapsules 13. The second electrode 15 may be formed, for example, on the second substrate 12. In this embodiment, the second electrode 15 is formed on the second substrate 12.

[0029] The second electrode 15 is formed of, for example, a metal material such as copper, although it is not particularly limited thereto. In this embodiment, the second electrode 15 is a pixel electrode. The second electrode 15 is formed in a substantially rectangular shape in a plan view, and a plurality of second electrodes 15 are provided. The plurality of second electrodes 15 are disposed adjacent to each other with a predetermined gap therebetween.

[0030] For example, when a positive potential is applied to the second electrode 15a, the black particles 132a between the second electrode 15a and the first electrode 14 are attracted to the second electrode 15a. Also, the white particles 132b between the second electrode 15a and the first electrode 14 are attracted to the first electrode 14.

[0031] On the other hand, for example, when a negative potential is applied to the second electrode 15b, the black particles 132a between the second electrode 15b and the first electrode 14 are attracted to the first electrode 14. Also, the white particles 132b between the second electrode 15b and the first electrode 14 are attracted to the second electrode 15b.

[0032] 1.2 Functional configuration of electronic paper 100 Next, the functional configuration of the electronic paper 100 will be described with reference to Fig. 3. Fig. 3 is a block diagram showing the functional configuration of the electronic paper 100.

[0033] 3, the electronic paper 100 includes a communication unit 3 and a battery 5 that supplies power, in addition to the display panel 10 and control device 20 described above. The electronic paper 100 may further include an operation button that accepts an input operation by a user. The electronic paper 100 may also include a touch panel on the surface of the display panel 10 that accepts an input operation by a user.

[0034] The communication unit 3 is, for example, an interface device for wireless communication. The communication unit 3 is, for example, a network interface controller. The communication unit 3 communicates with a personal computer or the like via a communication network such as the Internet and a public telephone network. The communication unit 3 is capable of receiving an instruction signal from an instruction terminal (not shown) such as a personal computer. The communication unit 3 may be capable of transmitting and receiving a signal to and from the instruction terminal (not shown). The communication unit 3 may also be, for example, an interface device for wired communication.

[0035] The control device 20 includes a control unit 21, a remaining amount detection unit 22, an image conversion unit 23, and a storage unit 24. The control unit 21 has a processor. The control unit 21 has, for example, a central processing unit (CPU). Alternatively, the control unit 21 may have a general-purpose computer.

[0036] The storage unit 24 stores data and computer programs. The data includes, for example, image data related to a display image to be displayed on the display panel 10.

[0037] The storage unit 24 includes a main storage device and an auxiliary storage device. The main storage device is, for example, a semiconductor memory. The auxiliary storage device is, for example, a semiconductor memory and / or a hard disk drive. The storage unit 24 may include a removable medium. The control unit 21 executes a computer program stored in the storage unit 24 to perform a rewrite operation, which will be described later.

[0038] Next, a detailed description will be given of the control unit 21. The control unit 21 is capable of executing a rewriting operation. The rewriting operation is an operation for rewriting the image on the display panel 10.

[0039] The control unit 21 executes a rewriting operation based on image data. The control unit 21 executes the rewriting operation by applying a rewriting voltage to the color particles 132. Specifically, the control unit 21 executes the rewriting operation by applying a rewriting voltage between the first electrode 14 and the second electrode 15.

[0040] The rewrite voltage is a voltage corresponding to the display gradation of the rewritten image. For example, in a dynamic range of 16 gray levels of black and white, if the display gradation of a pixel in the rewritten display image is, for example, "5", a voltage corresponding to the display gradation "5" is applied to that pixel. In the rewrite operation, a voltage corresponding to the display gradation of each pixel in the rewritten display image is applied to each pixel. Note that, if the display gradation of a pixel in the rewritten display image is, for example, "15 (white)", a positive maximum voltage (a voltage corresponding to the display gradation "15") is applied to that pixel. Also, if the display gradation of a pixel in the rewritten display image is, for example, "0 (black)", a negative maximum voltage (a voltage corresponding to the display gradation "0") is applied to that pixel.

[0041] The remaining charge detection unit 22 detects the remaining charge of the battery 5. The remaining charge of the battery 5 can be detected, for example, based on the detection result of the voltage of the battery 5 at a predetermined current consumption. However, if the current consumption during voltage detection is too small, the voltage may temporarily appear higher than normal even if the remaining charge of the battery 5 is low, so care must be taken. For example, the relationship between the detection result of the voltage of the battery 5 and the remaining charge may be obtained in advance by experiment or the like, and the data may be stored in the memory unit 24. In this case, the remaining charge detection unit 22 can detect the remaining charge of the battery 5 using the detection result of the voltage of the battery 5 and the data stored in the memory unit 24.

[0042] As a method for detecting the voltage of the battery 5, for example, if the control device 20 has an A / D conversion (Analog / Digital Conversion) function, that function can be used. Specifically, by connecting the positive electrode side of the battery 5 to an A / D input port of the control device 20, the control device 20 can detect the voltage of the battery 5. However, the method for detecting the voltage of the battery 5 is not limited to this.

[0043] If most of the power consumption of electronic paper 100 is due to operations such as rewriting the display content of display panel 10 and calculations including image conversion immediately before the rewriting, it is possible to estimate the remaining charge of battery 5 based on the number of rewriting operations performed. Therefore, the storage unit 24 may be configured to store the cumulative number of rewriting operations performed on display panel 10 after charging of battery 5 is complete and data relating to the cumulative number of rewriting operations performed on battery 5 and the remaining charge of battery 5. In this case, remaining charge detection unit 22 can detect the remaining charge of battery 5 based on the cumulative number of rewriting operations performed, etc.

[0044] Furthermore, even if the current consumption itself in the standby state of the display panel 10 is small, it may become non-negligible as power consumption after a long time has passed. Therefore, data on the relationship between the time elapsed since charging of the battery 5 is completed and the remaining amount of the battery 5, and the date and time of charging completion may be stored in the storage unit 24. In this case, the remaining amount detection unit 22 can detect the remaining amount of the battery 5 based on the time elapsed since charging of the battery 5 is completed, etc.

[0045] Furthermore, the remaining charge detection unit 22 may detect the remaining charge of the battery 5 by combining at least two of the above-mentioned methods, that is, the detection result of the voltage of the battery 5, the cumulative number of rewriting operations of the display panel 10, and the elapsed time after the completion of charging of the battery 5. However, the method of detecting the remaining charge of the battery 5 is not limited to the method exemplified here.

[0046] If the battery 5 is a smart battery, the remaining charge detection unit 22 can read information about the remaining charge from the battery 5. This allows the remaining charge detection unit 22 to detect the accurate remaining charge of the battery 5.

[0047] The image conversion unit 23 performs image conversion having a visual effect on at least a part of the image data based on the detected remaining charge. Therefore, the electronic paper 100 can perform a rewriting operation after performing image conversion having a visual effect on at least a part of the image data based on the remaining charge of the battery 5. As a result, information regarding the remaining charge of the battery 5 can be displayed without interfering with the original display content to be displayed on the display panel 10.

[0048] Note that "on at least a portion of the image data" means that image transformation is not always performed on the entire image data, but may be performed on only a portion of the image data. "Image transformation having a visual effect" means that it has a direct and intentional visual effect. In other words, image transformation that does not have a direct and intentional visual effect, such as file format conversion (JPEG, GIF, PNG, etc.), is not included in principle.

[0049] Image conversion unit 23 may perform image conversion on a portion of the image data based on the remaining charge of battery 5. Therefore, electronic paper 100 can perform a rewriting operation after performing image conversion having a visual effect on only a portion of the image data based on the remaining charge of battery 5. As a result, it becomes possible to display information related to the remaining charge of battery 5 on a portion of display panel 10 while maintaining the original display content as is on most of display panel 10.

[0050] The image conversion unit 23 may perform image conversion when the remaining charge of the battery 5 is equal to or less than a predetermined reference value. Therefore, the electronic paper 100 does not perform image conversion while the remaining charge of the battery 5 exceeds the predetermined reference value. As a result, the original display content is maintained as is while the remaining charge of the battery 5 is sufficient, and information regarding the remaining charge can be displayed only when the remaining charge of the battery 5 becomes low. The "reference value" is, for example, 40%. In other words, the image conversion unit 23 may perform image conversion when the remaining charge of the battery 5 is 40% or less.

[0051] The image conversion unit 23 may increase the degree of image conversion as the remaining charge of the battery 5 decreases. Thus, when the remaining charge of the battery 5 is sufficient, the electronic paper 100 performs a weaker image conversion, and increases the degree of image conversion as the remaining charge decreases. As a result, the appearance of the display content is not changed much while the remaining charge of the battery 5 is sufficient, and the appearance of the display content is gradually changed significantly when the remaining charge of the battery 5 becomes low, so that information regarding the remaining charge can be displayed in an easily understandable manner. For example, when the remaining charge of the battery 5 is 50%, the image conversion unit 23 corrects the gradation of the image to be slightly brighter, and when the remaining charge of the battery 5 becomes 25%, the image conversion unit 23 corrects the gradation of the image to be significantly brighter.

[0052] 1.3 Example of image conversion (1) Tone correction The image conversion unit 23 may perform image conversion to convert the input gradation value so that the output gradation value is higher (an example of the "first gradation conversion" of the present disclosure). Alternatively, the image conversion unit 23 may perform image conversion to convert the input gradation value so that the output gradation value is lower (an example of the "second gradation conversion" of the present disclosure). Thus, the gradation of the image is corrected to be brighter (closer to white) or darker (closer to black) than an image faithful to the original image data. As a result, an image that is visually different from an image faithful to the original image data is displayed, so that the effect of the image conversion can be easily visually recognized.

[0053] (2) Gradation Compression The image conversion unit 23 may perform gradation compression to reduce the number of gradations of the output gradation value relative to the input gradation value as the remaining charge of the battery 5 decreases. Therefore, as the remaining charge of the battery 5 decreases, the number of gradations of the image data decreases, and the previously smooth gradation changes become rougher. As a result, an image that is visually different from an image faithful to the original image data is displayed, so the effect of the image conversion can be easily visually recognized.

[0054] (3) Spatial filtering The image conversion unit 23 may perform spatial filtering on each pixel of the image, and may increase the number of surrounding pixels used in the spatial filtering as the remaining charge of the battery 5 decreases. Therefore, as the remaining charge of the battery 5 decreases, the number of surrounding pixels used in the spatial filtering increases, and the effect of the spatial filtering becomes stronger. As a result, an image that is visually different from an image faithful to the original image data is displayed, and the effect of the image conversion can be easily visually recognized.

[0055] An example of spatial filtering is smoothing. Therefore, as the remaining charge of the battery 5 decreases, the number of surrounding pixels used in smoothing increases, and the blurring of the edges of the image becomes stronger. As a result, an image that is visually different from an image faithful to the original image data is displayed, so that the effect of the image conversion can be easily recognized. However, the spatial filtering is not limited to smoothing, and may be, for example, mosaic processing.

[0056] (4) Color Tone Conversion The image conversion unit 23 may perform color tone conversion on each pixel of the image. Therefore, the color tone of the image faithful to the original image data gradually changes. As a result, an image that is visually different from the image faithful to the original image data is displayed, so that the effect of the image conversion can be easily recognized. Examples of color tone conversion include, but are not limited to, making the color lighter (making a color image closer to a monochrome image) or changing the whole image to a sepia tone.

[0057] 1.4 Image display method of electronic paper 100 Next, an image display method of the electronic paper 100 of this embodiment will be described with reference to Fig. 4. Fig. 4 is a flowchart for explaining the image display method of the electronic paper 100. The image display method of the electronic paper 100 includes steps S1 to S4.

[0058] Hereinafter, a method of displaying an image after electronic paper 100 receives an instruction to rewrite an image from a user or an instruction terminal will be described with reference to Fig. 4. Note that a rewrite instruction by a user is issued, for example, by the user operating electronic paper 100. Also, a rewrite instruction by an instruction terminal is issued, for example, by transmitting a rewrite signal from the instruction terminal to electronic paper 100 at a predetermined time.

[0059] In addition, in explaining the image display method of electronic paper 100, for ease of understanding, the first voltage will be described as a voltage corresponding to display gradation 0 (here, -5V), and the second voltage will be described as a voltage corresponding to display gradation 15 (here, +5V).

[0060] 4, in step S1, the control unit 21 acquires image data related to the rewritten display image. Specifically, the control unit 21 acquires the image data related to the rewritten display image from the storage unit 24. Note that the image data may be stored in the storage unit 24 in advance, or may be transmitted from the instruction terminal to the electronic paper 100.

[0061] Next, in step S2, the remaining charge detection unit 22 detects the remaining charge of the battery 5. Note that step S2 is an example of the "remaining charge detection step" of the present disclosure.

[0062] Next, in step S3, the image conversion unit 23 performs image conversion having a visual effect on at least a part of the image data based on the detected remaining amount. Note that step S3 is an example of the "image conversion step" of the present disclosure.

[0063] Next, in step S4, the control unit 21 executes a rewriting operation based on the image data. Specifically, the control unit 21 applies a rewriting voltage between the first electrode 14 and the second electrode 15. At this time, the control unit 21 applies a voltage corresponding to the display gradation of each pixel of the display image after rewriting to each pixel. Then, the control unit 21 stops applying the rewriting voltage after applying the voltage for a predetermined time (e.g., 0.2 sec x 6 times). Note that in the electronic paper 100, the display image is maintained on the display panel 10 even after the application of the voltage is stopped. Also, step S4 is an example of a "control process" of the present disclosure.

[0064] In this manner, rewriting of the display image on the electronic paper 100 is completed.

[0065] 1.5 Example of image display using electronic paper 100 Fig. 5 is a graph illustrating the transition of the remaining charge of the battery 5 over time, assuming that the remaining charge of the battery 5 will run out in about six months. Fig. 6A is a diagram illustrating an example of a display image when the remaining charge of the battery 5 is 100%. Fig. 6B is a diagram illustrating an example of a display image when the remaining charge of the battery 5 is about 60%. Fig. 6C is a diagram illustrating an example of a display image when the remaining charge of the battery 5 is close to 0%.

[0066] In electronic paper 100, image conversion unit 23 corrects the gradation of the displayed image so that the image becomes brighter as the remaining charge of battery 5 decreases. For example, when battery 5 has just been charged and the remaining charge is 100% (P51 in FIG. 5), image conversion unit 23 does not correct the gradation of the image, as shown in FIG. 6A.

[0067] After about three months have passed and the remaining charge of battery 5 is about 60% (P52 in FIG. 5), image conversion unit 23 corrects the gradation of the image to be slightly brighter as shown in FIG. 6B. After another three months (about six months in total) have passed and the remaining charge of battery 5 is close to 0% (P53 in FIG. 5), image conversion unit 23 corrects the gradation of the image to be slightly brighter as shown in FIG. 6C.

[0068] As a result, a visual effect that is easily noticeable to installers and managers of electronic paper 100A is achieved without significantly compromising the design of the displayed advertisement.

[0069] <Second embodiment> The electronic paper 100 according to the first embodiment described above gradually strengthens the degree of tone correction of an image according to the remaining charge of the battery 5. In contrast, the electronic paper 100A according to the second embodiment differs in that image conversion is performed only when the remaining charge of the battery 5 is equal to or less than a predetermined reference value.

[0070] Fig. 7 is a graph illustrating the time transition of the remaining charge of the battery 5 of the electronic paper 100A according to the second embodiment of the present disclosure. Fig. 8A is a diagram illustrating an example of a display image when the remaining charge of the battery 5 is 100 to 40% in the electronic paper 100A. Fig. 8B is a diagram illustrating an example of a display image when the remaining charge of the battery 5 is about 30%. Fig. 8C is a diagram illustrating an example of a display image when the remaining charge of the battery 5 is about 20%. Fig. 8D is a diagram illustrating an example of a display image when the remaining charge of the battery 5 is close to 0%.

[0071] In electronic paper 100A, image conversion unit 23 does not perform image conversion while the remaining charge of battery 5 exceeds 40%. For example, when battery 5 has just been charged and the remaining charge is 100% (P71 in FIG. 7), image conversion unit 23 does not correct the gradation of the image, as shown in FIG. 8A. Even after about four months have passed and the remaining charge of battery 5 is about 40% (P72 in FIG. 7), image conversion unit 23 still does not correct the gradation of the image.

[0072] However, after about five months, when the remaining charge of the battery 5 is about 30% (P73 in FIG. 7), the image conversion unit 23 corrects the gradation of the image to be slightly brighter, as shown in FIG 8B. After about half a month has passed, when the remaining charge of the battery 5 is about 20% (P74 in FIG. 7), the image conversion unit 23 corrects the gradation of the image to be even brighter, as shown in FIG 8C. Then, when the remaining charge of the battery 5 is close to 0% (P75 in FIG. 7), the image conversion unit 23 corrects the gradation of the image to be much brighter, as shown in FIG 8D.

[0073] As a result, the original display content is maintained as is for a period when the battery 5 has sufficient remaining power (approximately four months), and the design of the displayed advertisement is not impaired in any way. On the other hand, when the remaining power of the battery 5 becomes low, a visual effect that is easy for the installer or manager of the electronic paper 100A to notice is provided while maintaining the basic design of the displayed advertisement. Furthermore, the rate at which the visual effect of the display content changes in response to the decrease in the remaining power of the battery 5 becomes greater compared to the first embodiment. This makes it easier for the installer or manager of the electronic paper 100A to notice.

[0074] <Modification of the second embodiment> In the electronic paper 100A according to the second embodiment described above, image conversion is always performed on the entire image data. In contrast, in the electronic paper 100B according to a modified example of the second embodiment described below, image conversion is performed on only a part of the image data (specifically, a thin strip area on the right side).

[0075] Fig. 9A is a diagram illustrating an example of a display image when the remaining charge of the battery 5 is 30% in electronic paper 100B according to a modified example of the second embodiment of the present disclosure. Fig. 9B is a diagram illustrating an example of a display image when the remaining charge of the battery 5 is 20%. Fig. 9C is a diagram illustrating an example of a display image when the remaining charge of the battery 5 is 10%.

[0076] In electronic paper 100B, image conversion unit 23 does not perform image conversion while the remaining charge of battery 5 exceeds 40%. Therefore, the image displayed on display panel 10 is exactly the same as the image displayed by electronic paper 100A according to the second embodiment. That is, for example, the image shown in FIG. 8A is displayed when battery 5 has just been charged and the remaining charge is 100% (P71 in FIG. 7) and when the remaining charge is about 40% (P72 in FIG. 7).

[0077] On the other hand, after about five months, when the remaining charge of the battery 5 is about 30% (P73 in FIG. 7), the image conversion unit 23 corrects the gradation of the thin strip region 10a on the right side of the image to be slightly brighter, as shown in FIG 9A. After about half a month has passed and the remaining charge of the battery 5 is about 20% (P74 in FIG. 7), the image conversion unit 23 corrects the gradation of the thin strip region 10a on the right side of the image to be even brighter, as shown in FIG 9B. Then, when the remaining charge of the battery 5 is close to 0% (P75 in FIG. 7), the image conversion unit 23 corrects the gradation of the thin strip region 10a on the right side of the image to be significantly brighter, as shown in FIG 9C.

[0078] As a result, even if the remaining charge of the battery 5 becomes low, the basic design of the displayed advertisement is maintained over most of the screen, while providing a visual effect that is easily noticeable to installers and managers of the electronic paper 100A.

[0079] <Other embodiments> For example, in the above embodiment, an example has been described in which the present disclosure is applied to the microcapsule-type electronic paper 100 having the microcapsules 13, but the present disclosure is not limited thereto. For example, the present disclosure may be applied to electronic paper having color particles 132 without the microcapsules 13. In addition, the present disclosure may be applied to a twist ball-type electronic paper in which the surface of the color particles 132 is painted in two colors for each hemisphere, and the displayed image is rewritten by rotating the color particles 132.

[0080] The present invention can be embodied in various other forms without departing from its spirit or main features. Therefore, the above-described embodiments are merely illustrative in all respects and should not be interpreted as being limiting. The scope of the present invention is defined by the claims and is not limited to the text of the specification. Furthermore, all modifications and changes within the scope of the claims are within the scope of the present invention. [Industrial Applicability]

[0081] The present disclosure can be used for electronic paper and the like. [Explanation of symbols]

[0082] 100, 100A, 100B Electronic Paper 1 Case 3. Communications Department 5 batteries 10 Display Panel 20 Control device 21 Control section 22 Remaining amount detection unit 23 Image conversion section 24 Memory section

Claims

1. A battery for supplying power; A display panel including color particles that move when a voltage is applied to the color particles; a control unit that controls a rewriting operation for rewriting an image on the display panel by applying a rewriting voltage to the color particles based on image data; a remaining charge detection unit for detecting a remaining charge of the battery; an image conversion unit that performs image conversion having a visual effect on at least a part of the image data based on the detected remaining amount; Equipped with electronic paper.

2. The electronic paper according to claim 1 , wherein the image conversion unit performs the image conversion on a portion of the image data based on the remaining amount.

3. The electronic paper according to claim 1 , wherein the image conversion unit performs the image conversion when the remaining amount is equal to or less than a predetermined reference value.

4. The electronic paper according to claim 1 , wherein the image conversion unit increases a degree of the image conversion as the remaining amount decreases.

5. The electronic paper according to claim 1 or claim 2, wherein the image conversion unit performs either a first gradation conversion that converts an input gradation value so that an output gradation value is higher, or a second gradation conversion that converts the input gradation value so that the output gradation value is lower.

6. The electronic paper according to claim 1 or 2, wherein the image conversion section performs gradation compression that reduces the number of gradations of an output gradation value relative to an input gradation value as the remaining amount decreases.

7. The electronic paper according to claim 1 , wherein the image conversion unit performs spatial filtering on each pixel of the image, and increases a number of surrounding pixels used in the spatial filtering as the remaining amount decreases.

8. The electronic paper of claim 7 , wherein the spatial filtering comprises smoothing.

9. The electronic paper according to claim 1 , wherein the image conversion unit performs color tone conversion on each pixel of the image.

10. a control step of controlling a rewriting operation for rewriting an image on a display panel including color particles based on image data by applying a rewriting voltage to the color particles which are moved by applying a voltage; a remaining charge detection step of detecting a remaining charge of a battery; an image conversion step of converting at least a part of the image data into a visible image based on the detected remaining amount; 23. A method for displaying an image, comprising:

Images