JP2011013467A - Electrophoretic display device and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophoretic display device and electronic equipment, preventing occurrence of burn-in of an image in use in a high temperature environment.SOLUTION: This electrophoretic display device 100 is equipped with: an electrophoretic display section gripping an electrophoretic element between a pair of substrates; a temperature sensor 65; and a controller 63 for controlling the electrophoretic display section and the temperature sensor 65. The controller 63 operates the electrophoretic display section in display limiting mode of fixing at least some region to single gradation display in the period when the environmental temperature detected by the temperature sensor 65 is a preset reference temperature or higher.

Description

  The present invention relates to an electrophoretic display device and an electronic apparatus.

  2. Description of the Related Art As an electrophoretic display device, a type in which an electrophoretic element composed of charged particles (electrophoretic particles) and a dispersion medium is sandwiched in a space provided between a pair of substrates is known. Patent Document 1 describes an image rewriting system in which electronic paper, which is a kind of electrophoretic display device, is applied to a watch.

JP 2008-39697 A

As a characteristic of electronic paper, in particular, in a high temperature zone (above 40 ° C. or more), there is a property that current flows more easily than a normal temperature zone (around 25 ° C.), and there is a tendency that overwriting occurs when switching the display. For this reason, if the drive display in a high-temperature environment or an arbitrary image is left for a long time while being displayed, there will be a problem (burn-in) that the image at that time will remain thin even after the display is updated. End up.
According to the technique described in the above document, an increase in power consumption can be suppressed by displaying and holding an image without energization, but there is no mention of the temperature of the use environment, and depending on the environment temperature, the image There is a risk of seizing.

  The present invention has been made in view of the above-mentioned problems of the prior art, and is an electrophoretic display device capable of suppressing power consumption and preventing image burn-in even when used in a high-temperature environment. One of the purposes is to provide electronic devices.

  In order to solve the above problems, an electrophoretic display device of the present invention includes an electrophoretic display unit in which an electrophoretic element is sandwiched between a pair of substrates, a temperature measuring unit, and the electrophoretic display unit and the temperature measuring unit. An electrophoretic display device comprising: a control unit that controls the electrophoretic display unit during a period in which an environmental temperature detected by the temperature measuring unit is equal to or higher than a preset reference temperature. Is operated in a display restriction mode in which at least a part of the region is fixed to single gradation display.

  According to the present invention, the display restriction mode for fixing at least a part of the region of the electrophoretic display unit to a single gradation display during a period in which the environmental temperature detected by the temperature measurement unit is equal to or higher than a preset reference temperature. Therefore, it is possible to effectively prevent burn-in by performing display using electrophoretic particles of a specific color that is difficult to adhere.

In the display restriction mode, the control unit preferably fixes the entire surface of the electrophoretic display unit to single gradation display.
According to the present invention, since the entire surface of the electrophoretic display unit is fixed to single gradation display, all of the display image can be erased, and burn-in of the display image can be more effectively and reliably prevented. .

An operation input unit that outputs a control signal to the control unit based on an operation input from the outside is provided. In the display restriction mode, the control unit performs the electrophoresis only during a period in which the control signal is input. It is preferable to display an image on the display unit.
According to the present invention, since the image is displayed on the electrophoretic display unit only during the period when the control signal from the operation input unit is input, the image can be displayed at any time when the user wants to confirm, It is possible to prevent burn-in without causing the user to feel stress.

In addition, an operation input unit that outputs a control signal to the control unit based on an operation input from the outside is provided. In the display restriction mode, the control unit performs a predetermined period after the control signal is input. It is preferable to display an image on the electrophoretic display unit only.
According to the present invention, since the image is displayed on the electrophoretic display unit only during a predetermined time after the control signal from the operation input unit is input, the image can be displayed at any time when the user wants to confirm. It is possible to prevent burn-in without causing the user to feel stress. In addition, since the operation time is short, the user's behavior is not limited.

In the display restriction mode, the control unit preferably moves the display position of the image component displayed on the electrophoretic display unit intermittently or continuously.
According to the present invention, it is possible to prevent image burn-in without erasing all images by intermittently or continuously moving the display position of the image component displayed on the electrophoretic display unit. This can prevent burn-in without causing the user to feel stress.

Further, it is preferable that the control unit executes a mode change notification operation for notifying that the electrophoretic display unit is to be shifted to the display restriction mode before the electrophoretic display part is to be shifted to the display restriction mode.
According to the present invention, by notifying the user in advance that the display restriction mode is to be shifted, the user can be surely recognized that the display restriction mode is in effect. Thereby, it is possible to prevent the user from misunderstanding that the device has failed due to a difference from the normal display.

The mode change notification operation is preferably an operation for displaying an image indicating or suggesting the mode change on the display unit of the electrophoretic display unit.
According to the present invention, as the mode change notification operation, the operation of displaying or suggesting an image indicating the mode change is displayed on the display unit of the electrophoretic display unit, thereby surely recognizing to the user that the mode is shifted to the display restriction mode. Can be made. Thereby, it is possible to prevent the user from misunderstanding that the device has failed due to a difference from the normal display.

In addition, it is preferable that a sound source device for generating sound is further provided, and the mode change notification operation is an operation for generating a notification sound for notifying mode change from the sound source device.
According to the present invention, the mode change notification operation is performed by generating an alarm sound for notifying the mode change from the sound source device, so that even if the user cannot check the electrophoretic display unit, the display is performed. The user can be surely recognized that the mode is shifted to the restriction mode.

An electronic apparatus according to the present invention includes the electrophoretic display device described above.
ADVANTAGE OF THE INVENTION According to this invention, the electronic device provided with the display means which can prevent the burning of the image in a high temperature environment can be provided.

  In addition, the driving method of the electrophoretic display device of the present invention is a driving method of an electrophoretic display device including an electrophoretic display unit in which an electrophoretic element is sandwiched between a pair of substrates, and a temperature measuring unit. Detecting the environmental temperature by the temperature measuring unit; and switching the operation mode of the electrophoretic display unit based on the detected environmental temperature, and the detected environmental temperature is preset. The electrophoretic display unit is operated in a display restriction mode in which at least a part of the region is fixed to a single gradation display during a period that is equal to or higher than a reference temperature.

In addition, in the driving method of the electrophoretic display device described above, the following driving method is also preferable.
In the display restriction mode, it is also preferable to fix the entire surface of the electrophoretic display unit to single gradation display.

  In addition, an operation input unit that outputs a control signal to the control unit based on an operation input from the outside is provided. In the display restriction mode, the electrophoretic display unit is provided only during a period in which the control signal is input. It is also preferable to display an image.

  In addition, an operation input unit that outputs a control signal to the control unit based on an operation input from the outside is provided. In the display restriction mode, the electrophoretic display is performed only during a predetermined period after the control signal is input. It is also preferable to display an image on the part.

  In the display restriction mode, it is also preferable to move the display position of the image component displayed on the electrophoretic display unit intermittently or continuously.

  In addition, it is preferable to have a mode change notification step for notifying that the electrophoretic display unit is to be shifted to the display restriction mode prior to the transition to the display restriction mode.

  Further, the mode change notification step is preferably a step of causing the electrophoretic display unit to display an image indicating or suggesting the mode change.

  Further, it is preferable that a sound source device for generating sound is further provided, and the mode change notifying step is a step of generating a notification sound for notifying mode change from the sound source device.

  The mode change notification step preferably includes a step of stopping updating of display of at least a part of the electrophoretic display unit.

1 is a schematic configuration diagram of an electrophoretic display device according to an embodiment. The figure which showed the electrical structure with the cross-sectional structure of the electrophoretic display apparatus. FIG. 6 is an operation explanatory diagram of the electrophoretic display device. The functional block diagram of an electrophoretic display device. The flowchart which shows the drive method of this invention. Explanatory drawing of the drive method of this invention. A graph showing image contrast (density / reflectance) for each temperature range. The graph which showed the image contrast (black-and-white) according to temperature range. FIG. 14 illustrates an example of an electronic device. FIG. 14 illustrates an example of an electronic device. FIG. 14 illustrates an example of an electronic device.

Hereinafter, an electrophoretic display device and a driving method thereof according to the present invention will be described with reference to the drawings.
Note that this embodiment shows one aspect of the present invention, and does not limit the present invention, and can be arbitrarily changed within the scope of the technical idea of the present invention. Moreover, in the following drawings, in order to make each configuration easy to understand, the actual structure is different from the scale and number of each structure.

FIG. 1 is a schematic configuration diagram of an electrophoretic display device 100 according to an embodiment of the present invention. FIG. 2A is a diagram showing an electrical configuration together with a cross-sectional structure of the electrophoretic display device 100.
The electrophoretic display device 100 includes a display unit 5 in which a plurality of pixels (segments) 40 are arranged, a controller (control unit) 63, and a pixel electrode drive circuit 60 connected to the controller 63. The pixel electrode drive circuit 60 is connected to each pixel 40 via a pixel electrode wiring 61. Further, the display unit 5 is provided with a common electrode 37 (see FIG. 2) common to the respective pixels 40. In FIG. 1, the common electrode 37 is shown as a wiring for convenience.

  The electrophoretic display device 100 is a segment drive type electrophoretic display device that transfers image data from the controller 63 to the pixel electrode drive circuit 60 and directly inputs a potential based on the image data to each pixel 40.

  As shown in FIG. 2A, the display unit 5 of the electrophoretic display device 100 has a configuration in which an electrophoretic element 32 is sandwiched between a first substrate 30 and a second substrate 31. A plurality of pixel electrodes (segment electrodes; first electrodes) 35 are formed on the electrophoretic element 32 side of the first substrate 30, and a common electrode (second electrode) 37 is formed on the electrophoretic element 32 side of the second substrate 31. Has been. The electrophoretic element 32 has a configuration in which a plurality of microcapsules 20 enclosing electrophoretic particles are arranged in a plane. The electrophoretic display device 100 displays an image formed by the electrophoretic element 32 on the common electrode 37 side.

The first substrate 30 is a substrate made of glass, plastic, or the like and is not required to be transparent because it is disposed on the side opposite to the image display surface. The pixel electrode 35 is formed using a laminate of nickel plating and gold plating in this order on a Cu (copper) foil, Al (aluminum), ITO (indium tin oxide), or the like.
On the other hand, the second substrate 31 is a substrate made of glass, plastic, or the like, and is a transparent substrate because it is disposed on the image display side. The common electrode 37 is a transparent electrode formed using MgAg (magnesium silver), ITO, IZO (registered trademark; indium / zinc oxide), or the like.

  A pixel electrode drive circuit 60 is connected to each pixel electrode 35 via a pixel electrode wiring 61. The pixel electrode driving circuit 60 is provided with switching elements 60s corresponding to the respective pixel electrode wirings 61. The operation of the switching element 60s performs input of electric potential to the pixel electrode 35 and electrical disconnection (high impedance). .

  On the other hand, a common electrode drive circuit 64 is connected to the common electrode 37 via a common electrode wiring 62. The common electrode driving circuit 64 is provided with a switching element 64 s connected to the common electrode wiring 62, and a potential input to the common electrode 37 and electrical disconnection (high impedance) are performed by the operation of the switching element 64 s.

  In general, the electrophoretic element 32 is formed in advance on the second substrate 31 side and is handled as an electrophoretic sheet including the adhesive layer 33. In the manufacturing process, the electrophoretic sheet is handled in a state where a protective release sheet is attached to the surface of the adhesive layer 33. And the display part 5 is formed by sticking the said electrophoresis sheet which peeled off the peeling sheet with respect to the 1st board | substrate 30 (pixel electrode 35 grade | etc., Formed separately) manufactured separately. For this reason, the adhesive layer 33 exists only on the pixel electrode 35 side.

  FIG. 2B is a schematic cross-sectional view of the microcapsule 20. The microcapsule 20 has a particle size of, for example, about 30 to 50 μm, and contains therein a dispersion medium 21, a plurality of white particles (electrophoretic particles) 27, and a plurality of black particles (electrophoretic particles) 26. An encapsulated spherical body. As shown in FIG. 2, the microcapsule 20 is sandwiched between the common electrode 37 and the pixel electrode 35, and one or a plurality of microcapsules 20 are arranged in one pixel 40.

The outer shell portion (wall film) of the microcapsule 20 is formed using a translucent polymer resin such as an acrylic resin such as polymethyl methacrylate or polyethyl methacrylate, a urea resin, or gum arabic.
The dispersion medium 21 is a liquid that disperses the white particles 27 and the black particles 26 in the microcapsules 20. Examples of the dispersion medium 21 include water, alcohol solvents (methanol, ethanol, isopropanol, butanol, octanol, methyl cellosolve, etc.), esters (ethyl acetate, butyl acetate, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). ), Aliphatic hydrocarbons (pentane, hexane, octane, etc.), alicyclic hydrocarbons (cyclohexane, methylcyclohexane, etc.), aromatic hydrocarbons (benzene, toluene, benzenes having a long-chain alkyl group ( Xylene, hexylbenzene, hebutylbenzene, octylbenzene, nonylbenzene, decylbenzene, undecylbenzene, dodecylbenzene, tridecylbenzene, tetradecylbenzene)), halogenated hydrocarbons (methylene chloride, chloroform, tetrachloride) Element, and 1,2-dichloroethane), can be exemplified a carboxylate, it may be other oils. These substances can be used alone or as a mixture, and a surfactant or the like may be further blended.

The white particles 27 are particles (polymer or colloid) made of a white pigment such as titanium dioxide, zinc white, and antimony trioxide, and are used, for example, by being negatively charged. The black particles 26 are particles (polymer or colloid) made of a black pigment such as aniline black or carbon black, and are used by being charged positively, for example.
These pigments include electrolytes, surfactants, metal soaps, resins, rubbers, oils, varnishes, compound charge control agents, titanium-based coupling agents, aluminum-based coupling agents, silanes as necessary. A dispersant such as a system coupling agent, a lubricant, a stabilizer, and the like can be added.
Further, instead of the black particles 26 and the white particles 27, for example, pigments such as red, green, and blue may be used. According to such a configuration, red, green, blue, or the like can be displayed on the display unit 5.

FIG. 3 is an operation explanatory diagram of the electrophoretic element. 3A shows a case where the pixel 40 displays white, and FIG. 3B shows a case where the pixel 40 displays black.
In the case of white display shown in FIG. 3A, the common electrode 37 is held at a relatively high potential and the pixel electrode 35 is held at a relatively low potential. As a result, the negatively charged white particles 27 are attracted to the common electrode 37, while the positively charged black particles 26 are attracted to the pixel electrode 35. As a result, when this pixel is viewed from the common electrode 37 side which is the display surface side, white (W) is recognized.
In the case of black display shown in FIG. 3B, the common electrode 37 is held at a relatively low potential, and the pixel electrode 35 is held at a relatively high potential. As a result, the positively charged black particles 26 are attracted to the common electrode 37, while the negatively charged white particles 27 are attracted to the pixel electrode 35. As a result, when this pixel is viewed from the common electrode 37 side, black (B) is recognized.

FIG. 4 is a functional block diagram of the electrophoretic display device 100.
As shown in FIG. 4, the electrophoretic display device 100 includes a controller 63, a temperature sensor 65, an operation input unit 66, an interface 67, a power source 68, a drive circuit 69, and a sound source device 74. Yes. The drive circuit 69 includes the pixel electrode drive circuit 60 and the common electrode drive circuit 64 shown in FIGS. 1 and 2, and is connected to the display unit 5.

The controller 63 includes a control circuit 70, a memory 71, a timer 72, and a display rewriting circuit 73.
The control circuit 70 is a CPU (Central Processing Unit) in the electrophoretic display device 100 and comprehensively controls the operation of each part of the electrophoretic display device 100. The control circuit 70 is connected to the memory 71, the timer 72, and the display rewriting circuit 73 inside the controller 63. Further, a temperature sensor 65 (temperature measurement unit), an operation input unit 66, an interface 67, and a power source 68 provided outside the controller 63 are connected to the control circuit 70.

  The memory 71 may be a volatile memory or a nonvolatile memory. As the volatile memory, for example, an SRAM (Static Random Access Memory) or a DRAM (Dynamic Random Access Memory) can be used. As the nonvolatile memory, for example, a mask ROM (Read Only Memory), a flash memory, an FeRAM (Ferroelectric Random Access Memory), or the like can be used.

  The memory 71 drives and controls predetermined image data that defines a display image pattern when the power is turned on and off, an LUT (Look up Table) that defines the correspondence between temperature information and an operation mode, and the display unit 5. Programs are stored. Also, it functions as a working memory that holds temperature information, operating time information, and the like acquired using the temperature sensor 65.

  The timer 72 performs a desired time measurement independently or under the control of the control circuit 70. The configuration of the timer 72 is not particularly limited, and may be mounted as an independent device in the same manner as the temperature sensor 65 in addition to a form that can be built in the controller 63.

  The display rewriting circuit 73 converts the image data input from the control circuit 70 via the interface 67 and transmitted from the control circuit 70 into image data that can be displayed on the pixels 40 of the display unit 5. The image data converted by the display rewriting circuit 73 includes display color information corresponding to each pixel 40. The image data generated by the display rewriting circuit 73 is transmitted to the drive circuit 69 (pixel electrode drive circuit 60, common electrode drive circuit 64).

  The temperature sensor 65 is a sensor in which the amount of electricity such as a resistance value or a capacitance value changes according to the temperature, and transmits the detected temperature to the control circuit 70. As the temperature sensor 65, for example, a thermistor or a thermocouple can be used. Since the signal input from the temperature sensor 65 to the control circuit 70 is an analog detection signal, the controller 63 or the control circuit 70 incorporates an AD converter that AD converts the analog detection signal into encoded data as temperature information. It is preferable.

One or a plurality of temperature sensors 65 are provided in the electrophoretic display device 100, and are provided at positions where the temperature of the display unit 5 shown in FIGS. 1 and 2 can be measured.
For example, the temperature sensor 65 can be attached to the back surface of the first substrate 30 shown in FIG. Further, when the flat area of the display unit 5 is large, the temperature sensors 65 may be attached at two or more locations near the center of the display unit 5 and the peripheral part. The temperature information acquired by the control circuit 70 when a plurality of temperature sensors 65 are attached may be a simple average value or a weighted average value of a plurality of temperatures measured by the plurality of temperature sensors 65, or a plurality of temperatures. May be the highest value.

  The sound source device 74 includes a speaker or the like, and generates a notification sound for notifying that the display unit 5 is shifted to the display restriction mode according to the temperature detected by the temperature sensor 65. The type of timbre used for notification may be one or may notify the user of a change in detected temperature by using a plurality of types. For example, another notification sound may be generated when returning to the normal mode.

The operation input unit 66 is a user interface of the electrophoretic display device 100 to which an operation instruction by a user is input.
The interface 67 is a connection device between the electrophoretic display device 100 and an external device (not shown). The interface 67 transfers image data and commands input from the external device to the control circuit 70, and a response output from the control circuit 70. Transfer signals to external devices.
The power source 68 is a battery that supplies power to the electrophoretic display device 100 or a power circuit connected to an external power source.
The drive circuit 69 inputs an image signal to each pixel 40 based on the image data input from the display rewriting circuit 73. Thereby, the electrophoretic element 32 of each pixel 40 is driven, and an image defined in the image data is displayed on the display unit 5.

[Driving method]
Next, a driving method of the electrophoretic display device having the above configuration will be described.
FIG. 5 is a flowchart showing the driving method of this embodiment. FIG. 6 is an explanatory diagram illustrating state transition of the display unit 5 in the driving method of the present embodiment.

  As shown in FIG. 5, the driving method of the present embodiment includes a temperature detection step ST10, a detection temperature determination step ST11, a mode conversion notification step ST12, a display restriction mode transition step ST13, and a normal mode transition step ST14. including.

  A first area A1 shown in FIG. 6 corresponds to an area where a black-displayed character image is displayed, and a second area A2 corresponds to an area where a white-displayed background image is displayed. The third area 3A corresponds to an area where black notification content is displayed.

The control circuit 70 displays an arbitrary image in the first area A1 and the second area A2 of the display unit 5 as shown in FIG. For example, the black display time “12:00” is displayed in the first area A1, and the white background image is displayed in the second area.
At this time, the control circuit 70 transfers the image data corresponding to the time “12:00” to the display rewriting circuit 73. The display rewriting circuit 73 sequentially transfers the control signal and the converted image data to the driving circuit 69. Then, a potential corresponding to the image data is input to the pixel electrode 35 of each pixel 40 by the drive circuit 69.

  Next, in the temperature detection step ST10, the control circuit 70 acquires temperature information from the output from the temperature sensor 65, holds it as the current environmental temperature (the temperature of the display unit 5), and the environment provided in the memory 71. The temperature is stored in a temperature storage area (not shown). Thereafter, the process proceeds to the detected temperature determination step ST11.

Next, in the detected temperature determination step ST11, the control circuit 70 compares the temperature detected by the temperature sensor 65 with a preset reference temperature (about 50 ° C.). As will be described in detail later, in the present embodiment, it is more preferable to set the reference temperature to at least 50 ° C. and to 40 ° C. The set reference temperature value is a temperature that serves as a reference for determining whether or not notification display for leaving the transition to the display restriction mode in the mode conversion notification step ST12 is allowed.
As a result of comparison, if the environmental temperature is equal to or higher than the reference temperature (50 ° C.), the mode conversion notification step ST12 is selected. If the environmental temperature is equal to or lower than the reference temperature (50 ° C.), the process proceeds to the normal mode transition step ST14. And the environmental temperature monitoring operation is continued.

FIG. 7 is a graph showing image density / reflectance for each temperature zone when the same drive and the same pulse (pulse potential) are used, and FIG. 8 is a graph showing image contrast (black and white) for each temperature zone. It is.
In the electrophoretic display device 100 configured as described above, the higher the environmental temperature, the greater the degree of image sticking, and the shorter the time until image sticking occurs.
In general, the density of white display is higher as the reflectance is higher, and the density of black display is higher as the reflectance is lower. Therefore, the contrast is high and the visibility is good. As the ambient temperature increases, the particles move more easily, so the contrast improves. However, as shown in FIG. 7 and Table 1 below, when the ambient temperature exceeds 40 ° C., the reflectance (density) of white display decreases and the reflectance (density) of black display increases, and the contrast of the entire image is increased. Has decreased (FIG. 8). From this, it is estimated that image sticking occurred when the environmental temperature became 40 ° C. or higher. Such a tendency is particularly remarkable when the environmental temperature exceeds 50 ° C.
Therefore, in this embodiment, the reference temperature is 50 ° C. In addition, since the fall of contrast is observed when environmental temperature exceeds 40 degreeC, you may set reference temperature to 40 degreeC.

  In the mode conversion notification step ST12, the control circuit 70 executes a mode conversion notification operation for notifying the user that the display restriction mode is to be shifted. The mode change notification operation is an operation for displaying an image indicating or indicating the mode change on the display unit 5 or generating a notification sound from the sound source device 74.

When performing the notification display, as shown in FIG. 6, the control circuit 70 displays, for example, “TOO HOT!” As a notification display for notifying that the mode is changed to the third area A <b> 3 of the display unit 5. Display a message. The display content is not limited to this. Further, the tone color and volume of the notification sound are preferably those that draw the user's attention.
And after performing such alerting | reporting operation for predetermined time, it transfers to display restriction | limiting mode transfer step ST13.
In this step, both the notification display and the notification sound are performed. However, only one of the notification display and the notification sound may be performed.

  In the display restriction mode transition step ST13, the display mode is shifted from the normal mode to the display restriction mode. When the display restriction mode is entered, one of the first to third display settings shown in Table 2 is executed.

In the case of the first display setting, the control circuit 70 erases all the display images displayed on the display unit 5 including the notification display and time (FIG. 6). That is, the first area A1 displaying the time and the third area A3 displaying the notification display are changed to white display, and the entire screen is fixed to single gradation display. The white electrophoretic particles contained in the electrophoretic element are harder to fix than the black electrophoretic particles, and the image sticking is not noticeable, so that the entire display area is fixed to the white display.
When a signal input from the operation input unit 66 is detected during the display restriction mode, an operation for displaying the erased time on the display unit 5 is executed only during the period in which the signal is input. Then, when there is no signal input from the operation input unit 6, the time display is deleted.

In the case of the second display setting, the control circuit 70 erases all the display images displayed on the display unit 5 as described above. When a signal input from the operation input unit 66 is detected, a display operation at a time that is a part of the display image that has been erased is executed.
For example, when the display selection button is operated in the operation input unit 66 and a signal related to image display is input from the operation input unit 66, only the time is displayed on the display unit 5, and the display time is measured by the timer 72. Start.
And when predetermined time passes after an input signal is detected, the measurement by the timer 72 is complete | finished and a time display is erase | eliminated. As described above, the display operation at the erased time is performed only after the signal input from the operation input unit 66 is detected until the predetermined time elapses.

In the case of the third display setting, the control circuit 70 deletes the background image that is a part of the display image displayed on the display unit 5 and changes the display position of the character image (time). That is, the display position of the time which is the image component displayed on the display unit 5 is moved intermittently or continuously.
For example, the display time of a preset time may be measured by the timer 72, and the display position of the time may be changed every predetermined time, or the display position may be moved gradually by changing the display position continuously. You may let them. Thus, in the display restriction mode, the first area A1 is changed according to time.

After such a display operation, steps ST10 to ST13 are repeated, and the display restriction mode is executed in a period in which the environmental temperature detected by the temperature sensor 65 is equal to or higher than a preset reference temperature. That is, the display restriction mode is executed until the environmental temperature detected by the temperature sensor 65 is equal to or lower than the reference temperature (40 ° C. or lower).
Here, the mode conversion notification operation may be executed only at the first stage of transition from the normal mode to the display restriction mode, or may be executed periodically during the display restriction mode. When it is detected that the environmental temperature is 40 ° C. or less, the normal display operation is resumed by shifting to the normal mode.

In the electrophoretic display device 100 of the present embodiment described above, the display mode is switched according to the environmental temperature detected by the temperature sensor 65. In other words, when the environmental temperature detected by the temperature sensor 65 exceeds the reference temperature (about 50 ° C.), the mode is changed from the normal mode to the display restriction mode and is displayed only when requested by the user. The display limit of the image displayed on the part 5 is added.
That is, by changing the display time and the display position, all or part of the electrophoretic particles (black particles 26 and white particles 27) attracted to the wall film of the microcapsule 20 in the image display are changed. Can be pulled away from.
Therefore, when the same image is displayed in the same region for a long time, it is possible to prevent the electrophoretic particles from adhering to the wall film of the microcapsule 20, and to effectively prevent the occurrence of burn-in. be able to.

  In the present embodiment, in the detected temperature determination step ST11, it is determined whether or not to shift to the display restriction mode by comparing the detected temperature (environment temperature) detected in the temperature detection step ST10 with the reference temperature. . Accordingly, it is possible to smoothly execute from the mode conversion notification step ST12 to the display restriction mode transition step ST13 at an appropriate timing, and it is possible to prevent burn-in of the display image while suppressing power consumption.

  The seizure that occurs when the electrophoretic particles adhere to the wall film of the microcapsule 20 tends to be accelerated by the environmental temperature. That is, seizure hardly occurs at a relatively low temperature, and seizure tends to occur at a high temperature. For this reason, in the display restriction mode transition step ST13, when the environmental temperature exceeds the reference temperature and becomes high, all display images are fixed by fixing the entire area of the display unit 5 to single gradation display (white display). After that, an arbitrary image such as a time is displayed only when the user gives an instruction.

  Or if the display position of an image is changed, it is not necessary to delete all the images. Thereby, since the burn-in is prevented by changing the display position without erasing the display image, the display image is not lost and can be suitably used for the purpose of continuously displaying the same image. .

  Further, in the present embodiment, before the transition to the display restriction mode, in the mode conversion notification step ST12, a notification operation for notifying that the transition to the display restriction mode is performed is performed. Thereby, even if it is different from the display method in the normal mode, it is possible to prevent the user from misunderstanding that the device has failed.

  Further, in the notification operation, not only the notification display but also the notification sound is generated at the same time, so that even in a situation where the user cannot confirm the display unit 5, the user can be surely notified of the mode conversion. .

In this embodiment, monitoring of the environmental temperature is continued in both the normal mode and the display restriction mode. As a result, the mode can be changed appropriately and image burn-in can be prevented reliably and for a long time.
Further, in the display restriction mode, not only the entire area of the display unit 5 is fixed to the single gradation display but also the at least a part of the area is fixed to the single gradation display to obtain the burn-in prevention effect. Can do.

  In this embodiment, the segment type electrophoretic display device has been described as an example. However, the driving method according to the present invention can be suitably used for an active matrix type electrophoretic display device. That is, the electrophoretic display device according to the present invention can be an SRAM (Static Random Access Memory) type electrophoretic display device in which a latch circuit is provided for each pixel, and includes a selection transistor and a capacitor for each pixel. A dynamic random access memory (DRAM) type electrophoretic display device can also be used.

(Electronics)
Next, a case where the electrophoretic display device 100 of the above embodiment is applied to an electronic device will be described.
FIG. 9 is a front view of the wrist watch 1000. The wrist watch 1000 includes a watch case 1002 and a pair of bands 1003 connected to the watch case 1002.
On the front surface of the watch case 1002, a display unit 1005 including the electrophoretic display device 100 of each of the above embodiments, a second hand 1021, a minute hand 1022, and an hour hand 1023 are provided.
On the side surface of the watch case 1002, a crown 1010 and an operation button 1011 are provided as operation elements. The crown 1010 is connected to a winding stem (not shown) provided inside the case, and is integrally provided with the winding stem so that it can be pushed and pulled in multiple stages (for example, two stages) and can be rotated. . The display unit 1005 can display a background image, a character string such as date and time, or a second hand, a minute hand, and an hour hand.

  FIG. 10 is a perspective view illustrating a configuration of the electronic paper 1100. An electronic paper 1100 includes the electrophoretic display device 100 of the above embodiment in a display area 1101. The electronic paper 1100 is flexible and includes a main body 1102 made of a rewritable sheet having the same texture and flexibility as conventional paper.

FIG. 11 is a perspective view showing the configuration of the electronic notebook 1200. An electronic notebook 1200 is obtained by bundling a plurality of the electronic papers 1100 and sandwiching them between covers 1201.
The cover 1201 includes display data input means (not shown) for inputting display data sent from an external device, for example. Thereby, according to the display data, the display content can be changed or updated while the electronic paper is bundled.

  According to the wristwatch 1000, the electronic paper 1100, and the electronic notebook 1200 described above, since the electrophoretic display device 100 according to the present invention is employed, a display with excellent reliability that can maintain display quality over a long period of time. It becomes an electronic device provided with a section.

  In addition, said electronic device is an example of the electronic device which concerns on this invention, Comprising: The technical scope of this invention is not limited. For example, the electrophoretic display device according to the present invention can be suitably used for a display unit of an electronic device such as a mobile phone or a portable audio device.

DESCRIPTION OF SYMBOLS 100 ... Electrophoretic display apparatus, 5 ... Display part (electrophoretic display part), 30 ... 1st board | substrate, 31 ... 2nd board | substrate, 32 ... Electrophoretic element, 63 ... Controller (control part), 65 ... Temperature sensor (temperature) Measurement unit), 66 ... Operation input unit, 74 ... Sound source device

Claims (9)

An electrophoretic display device comprising an electrophoretic display unit having an electrophoretic element sandwiched between a pair of substrates, a temperature measuring unit, and a control unit for controlling the electrophoretic display unit and the temperature measuring unit,
The control unit is configured to fix the electrophoretic display unit to a single gradation display in a period in which the environmental temperature detected by the temperature measurement unit is equal to or higher than a preset reference temperature. An electrophoretic display device that is operated in a restricted mode. In the display restriction mode,
The electrophoretic display device according to claim 1, wherein the control unit fixes the entire surface of the electrophoretic display unit to a single gradation display. An operation input unit that outputs a control signal to the control unit based on an operation input from the outside;
In the display restriction mode,
The electrophoretic display device according to claim 1, wherein the control unit displays an image on the electrophoretic display unit only during a period in which the control signal is input. An operation input unit that outputs a control signal to the control unit based on an operation input from the outside;
In the display restriction mode,
The electrophoretic display device according to claim 1, wherein the control unit causes the electrophoretic display unit to display an image only during a predetermined period after the control signal is input. In the display restriction mode,
The electrophoretic display device according to claim 1, wherein the control unit moves the display position of the image component displayed on the electrophoretic display unit intermittently or continuously.   The control unit executes a mode change notification operation for notifying that the electrophoretic display unit is to be shifted to the display restriction mode before the electrophoretic display unit is to be shifted to the display restriction mode. The electrophoretic display device according to any one of the above.   The electrophoretic display device according to claim 6, wherein the mode change notification operation is an operation for displaying an image indicating or suggesting a mode change on a display unit of the electrophoretic display unit. A sound source device that generates sound;
The electrophoretic display device according to claim 6, wherein the mode change notification operation is an operation for generating a notification sound for notifying mode change from the sound source device.   An electronic apparatus comprising the electrophoretic display device according to claim 1.

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