Display device, display device control method and program

Abstract

To reduce the power consumption for rewriting a screen.SOLUTION: A display device for performing rewriting processing of a screen for each predetermined period of time includes: a contact detector for detecting a handwriting input to the screen; and a display controller for performing the rewriting processing at each set time which is longer than the predetermined period of time when the contact detector detects a handwriting input.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a display device. 、 Display device control method and programs Regarding. [Background technology]

[0002] In recent years, electrophoretic display devices have become known that consume power only when rewriting the screen display and do not consume power to maintain the display. As an example of an electrophoretic display device, for example, an electrophoretic display device that reduces power consumption in a low-temperature environment has been disclosed (Patent Documents 1 and 2). Summary of the Invention [Problem to be solved by the invention]

[0003] In the conventional electrophoretic display devices described above, for example, when the screen display is switched, the image that was displayed on the screen before the switch may remain as an afterimage. For this reason, conventional electrophoretic display devices erase the afterimage by periodically rewriting the screen, but the more frequently the screen is rewritten, the greater the power consumption.

[0004] The disclosed technology aims to reduce power consumption due to screen rewriting. [Means for solving the problem]

[0005] According to one aspect of the disclosed technique, there is provided a display device that performs a screen rewriting process at predetermined intervals, the display device including: a contact detection unit that detects handwritten input on the screen; and a setting unit that, when the contact detection unit detects the handwritten input, executes the rewriting process at predetermined intervals that are longer than the predetermined intervals. The number of times the handwritten input is detected during a predetermined period is counted, and the set time is changed in accordance with the counted number of times. A display control unit. [Effects of the Invention]

[0006] According to the disclosed technology, it is possible to reduce power consumption due to screen rewriting. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a hardware configuration of a display device according to a first embodiment. [Figure 2] FIG. 1 is a schematic diagram illustrating an example of a functional configuration of a display device according to a first embodiment. [Figure 3] FIG. 2 is a diagram illustrating a screen of electronic paper according to the first embodiment. [Figure 4] 5 is a flowchart showing processing of the display device of the first embodiment. [Figure 5] 10 is a flowchart showing the processing of the display device of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] (First embodiment) Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description may be omitted.

[0009] FIG. 1 is a schematic diagram showing an example of a hardware configuration of a display device according to a first embodiment.

[0010] The display device 100 shown in FIG. 1 includes a CPU (Central Processing Unit) 110, which is a central processing unit, and electronic paper 120 including an electrophoretic display (EPD). The electronic paper 120 is an example of a display unit. The display device 100 includes an EPD controller 121, a battery 130, and a direct current-direct current (DCDC) converter 131 including a DC voltage converter. The battery 130 may be, for example, a lithium ion battery. The display device 100 includes a volatile random access memory (RAM) 140, a nonvolatile flash memory 150, and a temperature sensor 170.

[0011] 1 includes an acceleration sensor 161, a contact sensor 162, and a wireless module 180 for wireless communication with a local area network (LAN). The display device 100 also includes an operation member 190 including various switches and light-emitting diodes (LEDs).

[0012] The electronic paper 120 requires power when performing writing and erasing processes. Once an image is displayed, the electronic paper 120 maintains it without power supply. In other words, the electronic paper 120 consumes power only when rewriting the display, and does not consume power to maintain the display. Note that the electronic paper 120 may be realized using various methods other than EPD, such as liquid crystal or electronic liquid powder.

[0013] The CPU 110 uses the RAM 140, which is the main memory, as a work area, and reads and executes programs stored in the flash memory 150. The contact sensor 162 is a sensor that detects contact of a pen or a user's hand with the electronic paper 120. The temperature sensor 170 is a sensor that measures the temperature of the electronic paper 120. The temperature sensor 170 is provided for adjusting the contrast of the electronic paper 120. The contrast of the electronic paper 120 may need to be adjusted because the viscosity and characteristics of the EPD change with temperature. Note that contrast is the difference in brightness between bright and dark areas of an image.

[0014] FIG. 2 is a schematic diagram illustrating an example of a functional configuration of the display device according to the first embodiment.

[0015] The display device 100 of this embodiment includes a display control unit 221, a power control unit 231, and a data storage unit 240. The display device 100 further includes an installation orientation detection unit 261, a contact detection unit 262, a temperature monitoring unit 270, and a network communication unit 280.

[0016] The display control unit 221 controls the electronic paper 120 via the EPD controller 121. The power supply control unit 231 controls the battery 130 via the DCDC converter 131. The data storage unit 240 is realized by, for example, the RAM 140, and stores data to be displayed on the electronic paper 120. The installation orientation detection unit 261 detects the orientation in which the display device 100 is installed via the acceleration sensor 161.

[0017] The contact detection unit 262, which is an input reception unit, detects the reception of handwritten input via the contact sensor 162. Handwritten input includes, for example, operations such as writing and erasing on the electronic paper 120. The temperature monitoring unit 270 monitors the temperature of the electronic paper 120 via the temperature sensor 170. The network communication unit 280 communicates with the network via the wireless module 180.

[0018] 2 are realized by the CPU 110 reading and executing a program stored in the flash memory 150 or the like.

[0019] 3 is a diagram illustrating the screen of the electronic paper according to the first embodiment. The screen 300 of the electronic paper 120 shown in FIG. 3 has a handwriting input area 310, a menu button display area 320, a zoom pan window display area 330, a page number display area 340, a page navigation display area 350, and an information display area 360.

[0020] The handwriting input area 310 is an area where handwriting input using a pen etc. is possible. The menu button display area 320 is an area where a plurality of icons for changing the pen type and color are displayed.

[0021] The menu button display area 320 is an area that displays the undo and redo icons. Undo is a process that cancels the immediately previous operation or process and returns to the original state. Redo is a process that re-executes the operation or process that was canceled by undo. The menu button display area 320 is also an area that displays an icon for switching screens and a delete icon.

[0022] The zoom pan window display area 330 is an area that displays icons for enlarging or reducing the screen. The page number display area 340 is an area that displays the page number of the currently displayed screen and the total number of pages. The page navigation display area 350 is an area that displays navigation for pages. The information display area 360 has a date display area 361 that displays the date, and a time display area 362 that displays the time.

[0023] In this embodiment, for example, when the screen 300 is rewritten, an afterimage remaining on the screen 300 is erased. Note that the afterimage occurs when the screen 300 is rewritten because the white reflectance of a pixel that is rewritten from white to white differs from the white reflectance of a pixel that is rewritten from black to white.

[0024] Specifically, the display device 100 performs a black-and-white inversion process that inverts white and black at predetermined intervals using the display control unit 221, thereby rewriting the display on the screen 300. In other words, the rewriting process on the screen 300 is a process in which all pixels of the image displayed on the screen 300 are temporarily rewritten to either white or black. As an example, the display control unit 221 may perform the rewriting process with the predetermined interval set to one minute.

[0025] Furthermore, in this embodiment, when the state of the display device 100 satisfies a predetermined condition, the rewriting process of the screen 300 is stopped. Also, in this embodiment, when the state of the display device 100 satisfies the predetermined condition and handwritten input is detected, the rewriting process of the screen 300 is executed at set time intervals longer than a predetermined period.

[0026] In this embodiment, this reduces the frequency of executing the rewriting process. Specifically, for example, the display device 100 performs the rewriting process at set time intervals longer than a predetermined period only when the temperature detected by the temperature sensor 170 is equal to or lower than a predetermined temperature and when handwritten input is performed, thereby reducing the frequency of executing the rewriting process.

[0027] In this case, the predetermined condition is a state in which the temperature detected by the temperature sensor 170 of the display device 100 is equal to or lower than a predetermined temperature.

[0028] In this embodiment, the frequency of the rewrite process is reduced, which contributes to reducing power consumption.

[0029] Next, a flow for reducing the frequency of the process of rewriting the screen 300 will be described below with reference to Fig. 4. Fig. 4 is a flowchart showing the process of the display device of the first embodiment.

[0030] The display device 100 is started up when the power is turned on via the operation member 190. Then, the display control unit 221 starts executing the processing shown in the flowchart 400.

[0031] When the display device 100 is started up, the temperature monitoring unit 270 reads the temperature sensor information from the temperature sensor 170 (step S401).

[0032] Next, the display control unit 221 compares the temperature indicated by the temperature sensor information read by the temperature monitoring unit 270 with the set temperature stored in advance in the flash memory 150. Then, the display control unit 221 determines whether the temperature indicated by the temperature sensor information is equal to or lower than the set temperature (step S402).

[0033] In step S402, if the temperature indicated by the temperature sensor information is higher than the set temperature, the display device 100 proceeds to step S408, which will be described later.

[0034] In step S402, if the temperature indicated by the temperature sensor information is equal to or lower than the set temperature, the display control unit 221 stops the rewriting process of the screen 300 that is performed every predetermined period (step S403).

[0035] Next, the display control unit 221 starts measuring time using a timer (step S404). The timer measures the time from when the rewriting process is stopped until when handwritten input is detected, and may be built into the display device 100.

[0036] Next, the display control unit 221 determines whether or not handwriting input has been detected by the contact detection unit 262 (step S405). That is, it determines whether handwriting input has been detected while the rewriting process is stopped. The display control unit 221 repeatedly performs this determination until the contact detection unit 262 detects the acceptance of handwriting input. Therefore, if the contact detection unit 262 does not detect the acceptance of handwriting input, the rewriting process is not executed.

[0037] If handwriting input is detected in step S405, the display control unit 221 reads the first set time from the flash memory 150. Then, the display control unit 221 determines whether the time indicated by the timer is equal to or greater than the first set time (step S406).

[0038] The first set time in this embodiment is the time from when the rewriting process of the screen 300 is stopped to when the next rewriting process of the screen 300 is started. In other words, the first set time is the time during which the rewriting process is suspended. Therefore, the first set time can also be said to be the suspension time of the rewriting process. Note that the first set time is a time longer than a predetermined period. The first set time may be, for example, five minutes.

[0039] In step S406, if the time indicated by the timer is less than the first set time, the process returns to step S405.

[0040] In step S406, if the time indicated by the timer is equal to or greater than the first set time, the display control unit 221 executes a process of rewriting the screen 300 (step S407).

[0041] Here, a modified example of the process of step S406 will be described. In this modified example, if the time indicated by the timer is less than the first set time, the process may wait until the time indicated by the timer reaches the first set time without returning to step S405. In this case, in step S406, the display control unit 221 repeatedly executes step S406 until the time indicated by the timer indicates that the time is equal to or greater than the first set time. Then, when the time indicated by the timer indicates that the time is equal to or greater than the first set time, the process proceeds to the next step S407.

[0042] Following step S407, the display control unit 221 determines whether the power has been turned off (step S408). If the power has been turned off in step S408, the display device 100 ends the processing. If the power has not been turned off in step S408, the display device 100 returns to step S401.

[0043] In this way, the display control unit 221 stops the execution of the rewriting process at predetermined intervals when the temperature indicated by the temperature sensor information is equal to or lower than the predetermined temperature. After that, the display control unit 221 does not execute the screen rewriting process until it detects the acceptance of handwritten input. Then, after detecting the acceptance of handwritten input, the display control unit 221 executes the screen rewriting process. This rewriting process is executed after the first set time or more has elapsed since the rewriting process was stopped.

[0044] Therefore, the display device of the first embodiment can reduce the frequency of rewriting processes in a low-temperature environment where power consumption is high, thereby reducing the power consumption of the display device.

[0045] In the first embodiment, the first set time is described as five minutes, but the first set time may be changed in stages according to the temperature detected by the temperature sensor 170. This is because the remaining capacity of the battery 130 decreases depending on the temperature. Therefore, the first set time may be set by dividing the temperature range below a predetermined temperature into multiple ranges, and setting a separate first set time (interruption time for the rewriting process) for each range. It is preferable that the first set time for each range can be changed as needed according to the temperature characteristics of the battery, etc.

[0046] As an example, if the temperature detected by the temperature sensor 170 is between less than 0 degrees and greater than or equal to -5 degrees, the first set time may be set to 2 minutes, and if the temperature detected by the temperature sensor 170 is between less than -5 degrees and greater than or equal to -10 degrees, the first set time may be set to 3 minutes. Also, if the temperature detected by the temperature sensor 170 is less than or equal to -10 degrees, the first set time may be set to 5 minutes.

[0047] In this embodiment, a table or the like showing the relationship between such a temperature range and the first set time may be created in advance. By storing this table in flash memory 150, display control unit 221 can appropriately change the first set time used in step S406 depending on the temperature. Furthermore, the relationship between the temperature range and the first set time may be defined by a function or the like.

[0048] (Second embodiment) The second embodiment will be described below with reference to Fig. 5. The second embodiment differs from the first embodiment in that the remaining capacity of the battery 130 is added to the predetermined conditions indicating the state of the display device 100. Therefore, in the following description of the second embodiment, differences from the first embodiment will be described, and components having the same functional configuration as the first embodiment will be assigned the same reference numerals as those used in the description of the first embodiment, and descriptions thereof will be omitted.

[0049] FIG. 5 is a flowchart showing the processing of the display device of the second embodiment.

[0050] The processing from step S501 to step S508 in Fig. 5 is the same as the processing from step S401 to step S408 in Fig. 4, except that in step S502, if the temperature indicated by the temperature sensor information is higher than the set temperature, the processing proceeds to step S509, which will be described later. Therefore, a description of the processing from step S501 to step S508 in Fig. 5 will be omitted.

[0051] In step S502, if the temperature indicated by the temperature sensor information is higher than the set temperature, the display control unit 221 determines whether the remaining capacity of the battery 130 is equal to or less than a predetermined capacity via the power control unit 231 (step S509). As an example, the display control unit 221 determines whether the remaining capacity of the battery 130 is equal to or less than 30%, and if it is not equal to or less than 30%, the process proceeds to step S408. If the remaining capacity of the battery is equal to or less than 30%, the process proceeds to the next step.

[0052] In step S509, if the remaining capacity of the battery 130 is equal to or less than the predetermined capacity, the display control unit 221 stops the rewriting process of the screen 300 that is performed every predetermined period (step S510).

[0053] That is, in this embodiment, the predetermined condition is that the temperature detected by the temperature sensor 170 is equal to or lower than a predetermined temperature, and also that the remaining capacity of the battery 130 of the display device 100 is equal to or lower than a predetermined capacity.

[0054] The processing from step S510 to step S514 in Fig. 5 is the same as the processing from step S403 to step S407 in Fig. 4, except that the set time read out in step S512 is the second set time. Therefore, a description of the processing from step S510 to step S514 in Fig. 5 will be omitted.

[0055] Here, the second set time will be explained. Like the first set time, the second set time is the time from when the rewriting process of the screen 300 is stopped to when the next rewriting process of the screen 300 is started. In other words, the second set time is also the time during which the rewriting process is suspended. The second set time is a time longer than a predetermined period. Note that the second set time may be the same as or different from the first set time used in step S406.

[0056] In this way, the second embodiment executes the same flow as the first embodiment when the temperature is below a predetermined temperature. Furthermore, the second embodiment reduces the frequency of screen rewriting processing according to the remaining battery capacity even when the temperature is higher than the predetermined temperature. Therefore, the second embodiment can also reduce power consumption.

[0057] In the second embodiment, as in the first embodiment, a table showing the relationship between the temperature range and the second set time may be created in advance. By storing this table in flash memory 150, the display device can appropriately change the second set time used in step S506 depending on the temperature. Furthermore, the relationship between the temperature range and the second set time may be defined by a function or the like.

[0058] Next, a modified example of step S505 will be described.

[0059] In the first modified example, the display control unit 221 counts the number of times handwritten input is accepted by a pen or the like. The counted number is the number of times handwritten input is accepted that is detected during a predetermined period after the rewriting process of the screen 300 is stopped. The display control unit 221 compares the number of times handwritten input is accepted that is counted during the predetermined period with a predetermined value. The number of times handwritten input is accepted is, in other words, the number of times handwritten input is detected by the contact detection unit 262.

[0060] Then, when the counted number of accepted handwriting inputs reaches a predetermined value, the display control unit 221 resets the first set time to a set time that is shorter than the currently set set time. In other words, the display control unit 221 changes the first set time to a set time that is shorter than the currently set set time. However, the changed first set time is longer than the predetermined period.

[0061] For example, suppose that in step S504 the first set time is set to five minutes, and then in step S505, acceptance of handwriting input is detected a predetermined number of times or more before the first set time has elapsed. In this case, display control unit 221 resets the first set time from five minutes to three minutes. Note that a state in which the number of times handwriting input is accepted before the first set time has elapsed reaches a predetermined value is a state in which there is a possibility that multiple afterimages may have occurred on screen 300.

[0062] In this modification, when the acceptance of handwritten input is detected multiple times within a short period of time, the rewriting process of screen 300 to erase the afterimage can be executed at short intervals. Therefore, it is possible to prevent the afterimage from remaining on screen 300.

[0063] The above-described modified example can also be applied to the first embodiment.

[0064] In the above-described embodiment, the frequency of the rewriting process for the entire screen is changed. However, the frequency of the rewriting process for a part of the screen may be changed as follows.

[0065] This will be described with reference to Fig. 3. For example, the display control unit 221 constantly executes a rewrite process for the time display area 362 at predetermined intervals. That is, regardless of the temperature or remaining battery level, the display control unit 221 always executes a black-and-white inversion process for a portion of the screen at predetermined intervals. At this time, the display control unit 221 executes the process described in the first or second embodiment for the handwriting input area 310.

[0066] In this manner, in this embodiment, information such as time, which changes every moment, can be notified to the user by rewriting a specific area at predetermined intervals. The rewriting process for the handwriting input area 310 is executed only when handwriting input is accepted. As described above, the first and second set times referenced at this time are longer than the predetermined period. Therefore, the frequency of the rewriting process for the handwriting input area 310 can be reduced, thereby reducing power consumption.

[0067] The above-described embodiment is suitable for display devices using electronic paper, which do not generate heat from the backlight like smartphones or notebook PCs, and which generate almost no heat from the CPU due to their low load. Display devices using electronic paper operate at temperatures roughly the same as the outside air because they do not generate heat. Therefore, in low-temperature environments, such as outdoors in winter or in a freezer, the battery capacity decreases. Furthermore, in low-temperature environments, the viscosity of the elements that make up the electronic paper increases, making rewriting take longer, and so the display device tends to consume more power.

[0068] In such a low-temperature environment that is harsh on electronic paper, the display devices of the first and second embodiments change the timing of the screen rewriting process in response to the acceptance of handwritten input. In other words, the display devices of the first and second embodiments do not perform the screen rewriting process when there is no handwritten input. This allows for reduced power consumption.

[0069] Furthermore, when the display device of the first and second embodiments detects the acceptance of handwritten input, it executes a screen rewriting process at first or second set time intervals. Therefore, the display device of the first and second embodiments can reduce the frequency of the screen rewriting process when no handwritten input is being performed, thereby reducing power consumption.

[0070] Furthermore, the display device of the second embodiment can reduce the frequency of screen rewriting processing according to the remaining battery power, thereby reducing power consumption.

[0071] In the above-described embodiments, a lithium ion battery is used as the battery, but the present invention is also suitable for display devices that use rechargeable or non-rechargeable batteries.

[0072] The program for realizing the functions of the display device of each embodiment may be recorded on a computer-readable recording medium such as a CD-ROM and distributed.

[0073] Furthermore, the above-described display device may be applied to an image processing system connected to a computer or another electronic whiteboard via a network.

[0074] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims. [Explanation of symbols]

[0075] 100 display device 110 CPU 120 Electronic Paper 130 Battery 150 flash memory 170 Temperature Sensor 221 Display control unit 300 screens [Prior art documents] [Patent documents]

[0076] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-286602 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-13466

Claims

1. A display device that performs a screen rewriting process at predetermined intervals, a contact detection unit that detects handwritten input on the screen; a display control unit that, when the contact detection unit detects the handwritten input, executes the rewriting process at set time intervals longer than the specified period, counts the number of times the handwritten input is detected within the specified period, and changes the set time in accordance with the counted number of times.

2. The display control unit The display device according to claim 1, wherein the rewriting process is stopped when the state of the display device satisfies a predetermined condition, and when the contact detection unit detects the handwritten input while the rewriting process is stopped, the rewriting process is executed every set time.

3. Further comprising a temperature sensor; The predetermined condition is:

3. The display device according to claim 2, wherein the temperature detected by said temperature sensor is equal to or lower than a predetermined temperature.

4. The display device further comprises a battery; The predetermined condition is:

4. The display device according to claim 2, wherein the remaining charge of the battery is equal to or less than a predetermined capacity.

5. A control method for a display device that performs a screen rewrite process at predetermined intervals, comprising: A control method for a display device, wherein when handwritten input is detected by a contact detection unit that detects handwritten input on the screen, the rewriting process is executed at set time intervals that are longer than the specified period, the number of times the handwritten input is detected within the specified period is counted, and the set time is changed according to the counted number of times.

6. A program for causing a display device to execute a screen rewriting process at predetermined intervals, A process of detecting handwritten input on the screen; a process of executing the rewriting process at set time intervals longer than the predetermined period when the handwritten input is detected; a process of counting the number of times the handwritten input is detected during a predetermined period and changing the set time period in accordance with the number of times the handwritten input is detected; A program that executes the following.

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