JP2007148064A - Portable electronic device and control method thereof - Google Patents

Abstract

A portable electronic device capable of reducing power consumption more reliably and easily and a control method thereof.
An EL display unit 20 in which a large number of pixels composed of a plurality of organic EL elements are arranged, and display information for storing data of all or part of a region in a display image displayed on the EL display unit 20 A storage unit 11, a luminance information calculation unit 12 that calculates luminance information for all the pixels in this region from data in the region stored in the display information storage unit 11, and luminance information and threshold values calculated by the luminance information calculation unit 12 And a control unit for controlling the luminance of the pixels in the region based on the comparison with.
[Selection] Figure 1

Description

  The present invention relates to a portable electronic device including a self-luminous element type display such as an organic EL display and a control method thereof.

  In recent years, organic EL displays have attracted attention in mobile phone devices. This organic EL display is a display using an organic EL element which is a self-luminous element, and has features such as high brightness, wide viewing angle, ultra-thinness, and power saving. Some organic EL elements emit light in a single color such as green, blue, and red, and a multicolor display can be created by combining them. In addition, since a backlight is not required, it is possible to reduce the thickness of highly demanded devices in the market.

  However, the organic EL display consumes power as the emission luminance of the pixel on which the display is performed is higher, and the power consumption increases as the proportion of pixels having a higher luminance value in all the pixels is higher. In addition, in the case of a device based on text information such as e-mail or web browsing, such as a portable electronic device, the character color is distinguished from the background color in order to make the character easier to see, and one of the devices has high brightness. In many cases, the other is low-luminance color information.

When an organic EL display is used in a mobile phone device or the like, the power consumption can be reduced by correcting the display so that the background is black and the characters are white in order to reduce the power consumption. (See Patent Document 1). In other words, in the organic EL display, when the black display is performed, since the current supply to the organic EL element is cut off to stop the light emission, the current is not consumed in the pixel performing the black display. The power consumption is reduced by displaying most of the pixels in black.
Japanese Patent Laid-Open No. 2002-199078

  However, in the above prior art, it is necessary to distinguish between character information and background information, and a natural image taken by a camera such as that used in current mobile phone devices is set as a background image by the user. If the background is filled with characters, appropriate power consumption cannot be reduced. Furthermore, since it is necessary to control each luminance information by distinguishing character information and background information, complicated control is required.

  In view of such problems, an object of the present invention is to provide a portable electronic device and a control method thereof that can reduce power consumption more reliably and easily.

  In order to achieve the above object, a display unit configured by arranging a large number of pixels composed of a plurality of self-luminous elements, and a display unit for storing data of all or a part of a region in a display image displayed on the display unit An information storage unit; a luminance information calculation unit for calculating luminance information for all the pixels in the region from the data in the region stored in the display information storage unit; and the luminance information calculated by the luminance information calculation unit And a control unit that controls the luminance of the pixel in the region based on the comparison between the threshold value and the threshold value.

The present invention is characterized in that the luminance information calculation unit calculates an average luminance per pixel as the luminance information.
In the present invention, the power required for displaying a predetermined image can be estimated by calculating the average luminance per pixel as the luminance information. For example, when the average luminance exceeds a threshold value, power consumption can be reduced by controlling the luminance of each pixel to be low.

In the present invention, the control unit includes a plurality of the threshold values, and controls the luminance of the pixels in the region in a stepwise manner based on a calculation result of the luminance information calculation unit and the plurality of threshold values. Features.
According to the present invention, a plurality of threshold values are provided, and the luminance of the pixels in the area stored in the display information storage unit is controlled stepwise based on the calculation result of the luminance information calculation unit and the plurality of threshold values. It is possible to provide a display image without giving a sense of incongruity to the user at the time of luminance switching while achieving power saving.

The present invention includes a battery remaining amount detection unit, and the control unit controls the luminance of the pixels in the region in accordance with a remaining battery level.
In the present invention, when the remaining battery level is low by controlling the data of the area stored in the display information storage unit according to the remaining battery level so as to change the luminance of the pixels in this area, the display unit The luminance of the pixels can be greatly reduced. Therefore, when the remaining battery level is low, it is possible to extend the time when the battery runs out by reducing power consumption.

The present invention includes an optical sensor, and the control unit controls the luminance of the pixels in the region according to the brightness of ambient light.
In the present invention, the control unit controls the data of the area stored in the display information storage unit according to the brightness of the ambient light so as to change the luminance of the pixels in the area, thereby allowing the image of the display unit to be changed. Can be reduced while reducing power consumption. When the surroundings are bright, the pixels are allowed to emit light with high brightness. On the other hand, when the surroundings are dark, the user can see even if the brightness of the pixels is low. The time when the battery runs out can be extended by lowering the power.

The present invention calculates luminance information for all the pixels in the region from data of all or a part of the region in a display image displayed on a display unit formed by arranging a large number of pixels composed of a plurality of self-luminous elements. The brightness of the pixel in the area is controlled based on a comparison between the calculated brightness information and a threshold value.
In the present invention, the luminance information for all the pixels in this region is calculated from the data of all or part of the region in the display image displayed on the display unit formed by arranging a large number of pixels composed of a plurality of self-luminous elements, Based on the comparison between the calculated luminance information and the threshold value, the luminance of the pixels in the area is controlled, so that no complicated control is required regardless of the image set by the user as the background. It becomes possible to reduce the power consumption of the display unit. Further, the power consumption of the display unit can be reduced without degrading the image quality in any screen configuration. This makes it possible to reduce power consumption reliably and easily.

  In the present invention, the power consumption of the display unit can be reduced without degrading the image quality in any screen configuration. Thereby, power consumption can be reduced reliably and easily.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Here, a mobile phone will be described as an example of the portable electronic device of the present embodiment. FIG. 1 is a block diagram showing the configuration of the present embodiment.
In FIG. 1, reference numeral 10 denotes a control unit that performs overall control of processing operations of the mobile phone 1, and includes a display information storage unit 11, a luminance information calculation unit 12, and a luminance control unit 13. Reference numeral 20 denotes an EL display unit that displays a battery remaining amount mark, a radio wave reception state mark, a time display, an arbitrary image, and the like based on a signal output from the control unit 10, and is configured by an organic EL display. It can be displayed. Reference numeral 21 denotes an EL display driving circuit for driving the EL display unit 20.

  The control unit 10 displays all or a predetermined partial area of the display image displayed on the EL display unit 20 in which a large number of pixels composed of organic EL elements that are self-light-emitting elements are arranged vertically and horizontally. On the other hand, the luminance information calculation unit 12 adds and averages the luminance values Y of all the pixels that display the data of the area stored in the display information storage unit 11, and averages it per pixel. A luminance value is calculated. Then, the luminance control unit 13 controls the luminance value Y of all the pixels that display the data of the area stored in the display information storage unit 11 based on the calculated average luminance value. The data converted by the luminance control unit 13 is displayed on the EL display unit 20 via the EL display drive circuit 21.

  Reference numeral 30 denotes an operation unit that outputs a signal corresponding to the operation content by the user to the control unit 10. Reference numeral 31 denotes a ROM in which a program for operating the mobile phone 1 is stored in advance. Reference numeral 32 denotes a RAM that stores a program or the like for displaying an image or the like on the EL display unit 20 as needed. Reference numeral 33 denotes a remaining battery level detection unit that detects the remaining battery level (power supply amount) of the mobile phone 1, and outputs the measured value detected here to the control unit 10. Further, a display corresponding to the remaining battery level is displayed on the EL display unit 20 as a remaining battery level mark, and the user uses the mobile phone 1 while checking the remaining battery level by displaying the remaining battery level mark. Charging is performed when the battery level is low. Reference numeral 34 denotes a microphone that collects the voice of the speaker, converts the voice uttered by the user into a voice signal, and outputs the voice signal to the control unit 10. Reference numeral 35 denotes a speaker that emits the voice of the other party, and produces a sound by converting a voice signal into a voice. Reference numeral 36 denotes an antenna that receives a radio wave from the base station and transmits the radio wave toward the base station. Reference numeral 37 denotes a transmission / reception unit that establishes wireless communication between the antenna 36 and the base station and realizes a telephone function and information communication. Reference numeral 38 denotes an optical sensor unit that measures the brightness around the mobile phone 1 during use, and outputs the measured value to the control unit 10. The control unit 10 controls the luminance of the EL display unit 20 according to the measurement value of the optical sensor unit 38.

  The electric circuit provided in the mobile phone 1 includes the control unit 10, the EL display unit 20, the EL display drive circuit 21, the operation unit 30, the ROM 31, the RAM 32, the remaining battery level detection unit 33, the microphone 34, the speaker 35, and the antenna. 36, a transmission / reception unit 37 and an optical sensor unit 38.

  Next, the EL display unit 20 will be described. The EL display unit 20 has a large number of pixels composed of organic EL elements, which are self-luminous elements, arranged vertically and horizontally, and here, has a size of 240 × 320 pixels. Each of these pixels is caused to emit light, and a large number of pixels emit light continuously to form an arbitrary image. One pixel is composed of three organic EL elements of red, green, and blue (that is, RGB). By adjusting the light emission intensity of each of these organic EL elements, a light emission color as a whole pixel is formed. Yes.

  As described above, the pixel can produce various colors depending on the emission intensity of each of the red, green, and blue organic EL elements. Each RGB value (light intensity) of each organic EL element is defined to vary between 0 and 255. For example, according to the laws of the three primary colors of light, not only can yellow and purple be produced, but all three organic EL elements emit strong light, and all RGB values are “255”, “white”, and conversely If the RGB values are all “0” without emitting light, the background color of the display, that is, “black” can be expressed. Thus, the light emission color of the pixel can be instructed by the combination (pattern) of the signal instructing the light emission intensity for each of the three organic EL elements for each pixel, and an image is displayed on the EL display unit 20. . That is, by performing a pattern instruction on the RGB values of the pixels for a plurality of pixels, the color display for each pixel in the EL display unit 20 is changed, and the display object such as characters, symbols, icons, and the background color thereof are changed. Can be displayed. Since the organic EL element itself emits light, no special backlight is provided.

  However, white display, that is, high-luminance light emission is directly reflected in power consumption, and power consumption is higher in a display image based on white than in a display image based on black. Therefore, in order to reduce power consumption, it is necessary to reduce the luminance without changing the hue of the pixel.

The luminance value Y (luminance information) and the color difference (difference from the reference color) U and V can be obtained from the three primary colors of RGB.
These Y, U, and V are obtained by the following formulas, for example.
Y = 0.299R + 0.587G + 0.114B (1)
U = −0.169R−0.331G + 0.500B (2)
V = 0.500R-0.419G-0.081B (3)

  U is a difference from blue, V is a difference from red, and sometimes U = Cb, V = Cr. For example, when the value of U is small, the color is green, and when the value of U is large, blue is displayed. Further, when the value of V is small, the color is green, and when the value of V is large, the color is red. Thus, Y represents the luminance per pixel, that is, the brightness, and U and V can represent the color. From the above, it is possible to control only the luminance value Y without changing the color of the pixel. Therefore, the power consumption can be reduced by controlling the luminance of the pixels to be displayed without changing the display image.

In addition, the RGB value of the pixel after changing the luminance value Y is calculated | required by the following formula | equation, for example.
R = 1.000Y + 1.402V (4)
G = 1.000Y-0.344U-0.714V (5)
B = 1.000Y + 1.772U (6)
Here, since only the luminance of the pixel is controlled and the display color remains as it is, U and V do not need to be changed, and the value when the luminance value Y is obtained is used as it is.

Next, the operation of the mobile phone 1 having the above configuration, that is, the control method of the mobile electronic device according to the present embodiment will be described.
FIG. 2 is a flowchart showing a first embodiment of the control method of the mobile phone 1. This flowchart shows a process from acquiring an image to be displayed to controlling the luminance of a pixel indicating data of a predetermined area in the image and displaying it on the EL display unit 20. This operation is performed as needed until the power is turned off, such as when the power is turned on, when a predetermined operation is performed by the user, or when an operation is waited.

  In the control method of the first embodiment, the data of the entire display image to be displayed on the EL display unit 20 or a predetermined part of the data is stored in the display information storage unit 11 (step S1). The luminance value Y and the color differences U and V for all the pixels displaying data are calculated by the above formulas (1) to (3), and the calculated luminance value Y of each pixel is added and averaged by the luminance information calculation unit 12. Then, an average luminance value per pixel is obtained (step S2). Then, the average luminance value obtained in step S2 is compared with a preset threshold value (a predetermined value between 0 and 255) to determine whether the average luminance value exceeds the threshold value (step S3). When the determination result is “Yes”, the luminance control unit 13 sets the luminance value Y of each pixel without changing the hue of all the pixels displaying the data of the area stored in step S1, for example. Control is performed so as to decrease to about 50% from the predetermined value, and control is performed by the above-described equations (4) to (6) using the luminance value Y after control and the color difference U and V values similar to those before control. The later RGB values are calculated and displayed on the EL display unit 20 with the processed data (steps S4 and S5). On the other hand, if the determination result in step S3 is “No”, the process is terminated without controlling the luminance value Y, and the data is displayed on the EL display unit 20 as it is (step S5).

  As described above, in the flowchart shown in FIG. 2, the average luminance value of all the pixels belonging to the designated screen area is compared with the threshold value, and the average luminance value exceeds the threshold value, that is, the pixel with the high luminance value is selected. In the case of an image including many, the display image that should have been displayed as shown in FIG. 3 on the EL display unit 20 is controlled by controlling the luminance to be lowered without changing the hue of the display image. As shown in a), the brightness of the entire display screen is controlled to be low. In FIG. 4 (a), the brightness of the remaining battery level mark, the mail reception mark, the time and the operation display mark is controlled to decrease, but only the brightness of the background image is controlled as shown in FIG. 4 (b). The brightness of the remaining battery level mark, mail reception mark, time, and operation display mark may be controlled so as not to change. In any case, it is possible to effectively reduce the power consumption by reducing the luminance of the pixels of the entire display image or a part of the display image.

  Note that the setting of the image area stored in the display information storage unit 11 may be appropriately changed by the user. Further, the calculation of the average luminance value in step S2 may be performed every time for all the pixels in the data stored in the display information storage unit 11, or the luminance value of each pixel in the previously stored data is saved. In addition, only the changed pixels may be controlled. In the above description, the calculation result of the display information storage unit 11 is the average luminance value. However, other values, for example, the total luminance value of all the pixels may be used. Further, the threshold value and the brightness level may be appropriately changed by the user. Further, the present invention can be similarly applied to the following embodiments (second embodiment to fourth embodiment).

FIG. 5 is a flowchart showing a second embodiment of the control method of the mobile phone 1.
In this flowchart, the luminance levels of all the pixels that display the data of the area stored in the display information storage unit 11 are selected based on the luminance level table shown in FIG. This pattern table is used to determine the luminance level according to the average luminance value per pixel calculated by the luminance information calculation unit 12, and a plurality of specific threshold values set between 0 and 255, specifically three threshold values. The brightness levels are set stepwise in association with each other.

  In the control method of the second embodiment, for example, the data of the entire display image to be displayed on the EL display unit 20 or a predetermined part of the data is stored in the display information storage unit 11 (step S1). The luminance information calculation unit 12 adds and averages the luminance values Y for all the pixels displaying the data in the area to obtain an average luminance value per pixel (step S2). The brightness level corresponding to the average brightness value obtained in step S2 is obtained from the table shown in FIG. 6, and the brightness control unit 13 emits light corresponding to the corresponding brightness level in the area stored in step S1. The luminance value Y is controlled without changing the hue of all the pixels displaying data (step Sa1), and the display is performed on the EL display unit 20 with the processed data (step S5).

  As described above, in the luminance level table shown in FIG. 6, the luminance level of each pixel is set in a stepwise manner according to the average luminance value of all the pixels belonging to the designated screen area as the calculation result. For example, when the average luminance value is in the range of 0 to less than 63, the luminance level of each pixel is set to 90%, and the luminance value based on the data stored in step S1 is controlled to be 10% lower. When the average luminance value is within the range of 63 to less than 127, the luminance level is 80%. When the average luminance value is within the range of 127 to less than 191, the luminance level is 70%, and the average luminance value is within the range of 191 to 255. In the above case, the luminance level is lowered so that the luminance level becomes 60%, and the light emission of each pixel is suppressed. In this way, by reducing the luminance level significantly for an image with many pixels having a high luminance value, the power consumption can be reduced more effectively.

FIG. 7 is a flowchart showing a third embodiment of the control method of the mobile phone 1.
In this flowchart, the luminance levels of all the pixels displaying the data in the area stored in the display information storage unit 11 are selected based on the luminance table for each remaining battery level shown in FIG. This pattern table determines the luminance level according to the average luminance value per pixel calculated by the luminance information calculation unit 12 and the remaining battery level detected by the remaining battery level detection unit 33. The brightness level is set in a stepwise manner in association with the three threshold values set in between and the remaining battery level set in three steps.

  In the control method of the third embodiment, the data of the entire display image to be displayed on the EL display unit 20 or a predetermined part of the data is stored in the display information storage unit 11 (step S1). The luminance information calculation unit 12 adds and averages the luminance information for all the pixels displaying data to obtain an average luminance value per pixel (step S2). Further, the remaining battery level of the mobile phone 1 is acquired from the remaining battery level detection unit 33 (step Sb1), and the average luminance value obtained in step S2 and the luminance level corresponding to the remaining battery level obtained in step Sb1 are stored in the battery. Obtained from the remaining power level luminance table (step Sb2), the luminance control unit 13 changes the hue of all the pixels that display the data of the area stored in step S1 so as to emit light according to the corresponding luminance level. Without controlling the brightness value, the data after processing is displayed on the EL display unit 20 (step S5). In some cases, display is performed on the EL display unit 20 without control (step S5).

  That is, in the luminance table for each remaining battery level shown in FIG. 8, the luminance level of each pixel is set according to the average luminance value per pixel and the remaining battery level in all the pixels belonging to the designated screen area. The remaining battery level is normally set to a threshold value for dividing into three levels from full to empty, and full is set to “3”, and the remaining battery level until reaching empty is set to “1”. Further, although three threshold values are provided and the luminance level is set to four levels, the present invention is not limited to this, and any number of levels may be set. Here, for example, if the average luminance value is a low luminance value in the range of 0 to less than 63 and the battery remaining amount is “3”, the luminance value is not changed and stored in step S1. A display image is displayed with a luminance value based on the data. On the other hand, when the average luminance value is a high luminance value in the range of 191 to 255 and the remaining battery level is “1”, the luminance value is reduced to half of the luminance value based on the data stored in step S1. To be controlled. Also, even if the average brightness value is the same, when the remaining battery level is low (battery level “1”), the brightness level of each pixel is lower than when the battery level is high (battery level “3”). By doing so, it is possible to reduce power consumption and further extend the time of battery exhaustion. As described above, the power consumption can be effectively reduced by changing the decrease rate of the luminance value of each pixel in accordance with the remaining battery level.

FIG. 9 is a flowchart showing a fourth embodiment of the control method of the mobile phone 1.
In this flowchart, the luminance levels of all the pixels displaying the data of the area stored in the display information storage unit 11 are selected based on the luminance table for each ambient light shown in FIG. This pattern table is used to determine the luminance level according to the average luminance value per pixel calculated by the luminance information calculation unit 12, the remaining battery level, and the intensity of ambient light of the mobile phone 1. In association with the three threshold values set in between and the remaining battery level set in three stages, the ambient light detected by the optical sensor unit is “dark” (FIG. 10A), “normal” (FIG. 10 ( b)), the brightness level to be determined in three stages of light conditions of “bright” (FIG. 10C) is set stepwise.

  Here, as the intensity of the ambient light, for example, a situation where the situation when the mobile phone 1 is used is “bright” is assumed to be “normal”, assuming that it is used outdoors under strong sunlight. Is assumed to be used under indoor lighting such as a fluorescent lamp, and “dark” is assumed to be used at night, when there is no light such as lighting.

  In the control method of the fourth embodiment, the data of the entire display image displayed on the EL display unit 20 or a predetermined part of the data is stored in the display information storage unit 11 (step S1). The luminance information calculation unit 12 adds and averages the luminance information for all the pixels displaying data to obtain an average luminance value per pixel (step S2). Further, the optical sensor unit 38 acquires the intensity of ambient light of the mobile phone 1 and also acquires the remaining battery level from the remaining battery level detection unit 33 (step Sc1), and the ambient light of the mobile phone 1 obtained in step Sc1. A pattern table corresponding to the strength and the remaining battery level is selected, and a luminance level corresponding to the average luminance value obtained in step S2 is obtained from the selected pattern table (step Sc2). The luminance value is controlled without changing the hue of all the pixels that display the data of the area stored in step S1 so that the light emission according to the level is displayed, and display is performed on the EL display unit 20 with the processed data. (Step S5). In some cases, display is performed on the EL display unit 20 without control (step S5).

  That is, in the brightness table for each ambient light shown in FIG. 10, the pattern table is selected according to the ambient light in addition to the remaining battery level when the mobile phone 1 is used, and the data stored in the display information storage unit 11 is displayed. The luminance level of each pixel is set according to the average luminance value per pixel and the remaining battery level in all pixels. As described above, the threshold for determining the remaining battery level is set in three stages from full to empty, full is set to “3”, and empty is set to “1”. Further, the threshold value of the average luminance value is set in four stages. For example, as shown in FIG. 10C, when the ambient light is detected as “bright”, the average luminance value is in the range of 0 to less than 63, and the remaining battery level is “3”, the luminance The value is not changed, and the display image is displayed with the luminance value based on the data stored in step S1. On the other hand, as shown in FIG. 10A, when the ambient light is detected as “dark”, the average luminance value is in the range of 191 to 255 and the remaining battery level is “1”, Control is performed so that the luminance value is reduced to half or less (40% luminance level) based on the data stored in step S1. In addition, referring to FIGS. 10A and 10C, the ambient light is used when the ambient light is determined to be “dark” even if the average brightness value and the remaining battery level are the same. Lowers the luminance level of each pixel than when “is bright”.

  In other words, when the cellular phone 1 is used under a dark environment, the cellular phone 1 can be visually recognized even when the luminance level of the EL display unit 20 is low. By reducing the luminance level as compared with the case where 1 is used, the time of running out of the battery can be extended.

  In the above description, three threshold values are provided and the luminance level is set to four levels. By setting more threshold values and changing the luminance level to be changed in stages, the luminance change of the display image viewed from the user can be reduced. Further, the threshold setting may be freely changed.

  From the above, according to the present embodiment, all or a part of the data in the display image to be displayed on the EL display unit 20 is stored in the display information storage unit 11, and all the data in this region is stored from this region data. Luminance information for the pixel is calculated by the luminance information calculation unit 12, and based on the comparison between the luminance information and the threshold value, the luminance control unit 13 converts the data of the region stored in the display information storage unit 11 into By controlling to change the luminance of the pixels, it is possible to reduce the power consumption of the EL display unit 20 without requiring complicated control, regardless of the image set by the user as the background. become. In addition, the power consumption of the EL display unit 20 can be reduced without degrading the image quality in any screen configuration. This makes it possible to reduce power consumption reliably and easily.

  Further, by calculating the average luminance per pixel as the luminance information, it is possible to estimate the power required for displaying a predetermined image. That is, when the average luminance exceeds a preset threshold value, power consumption can be reduced by controlling the luminance of each pixel to be low.

  In addition, while having a plurality of thresholds and controlling the data of the area stored in the display information storage unit 11 stepwise based on the calculation result of the luminance information calculation unit 12, A good display image can be provided without causing the user to feel uncomfortable when switching the luminance.

  Further, by controlling the data of the area stored in the display information storage unit 11 according to the remaining battery level so as to change the luminance of the pixels in the area, the EL display unit 20 can be used when the remaining battery level is low. The brightness can be significantly reduced. Therefore, when the remaining battery level is low, it is possible to extend the time when the battery runs out by reducing power consumption.

  In addition, since the mobile phone 1 includes the optical sensor unit 38, the luminance of the pixels in this region is changed in the data stored in the display information storage unit 11 according to the brightness of the ambient light. By controlling to, low power consumption can be achieved while displaying the image of the EL display unit 20 satisfactorily. That is, when the surroundings of the mobile phone 1 are bright, the pixels are allowed to emit light with high luminance. On the other hand, when the surroundings are dark, the user can see even if the luminance of the pixels is low. Lowering the brightness can reduce the power consumption and extend the time when the battery runs out.

In the present embodiment, the luminance value to be changed is indicated by a reduction rate with respect to the default luminance. Then, the display data is processed based on this reduction rate. In addition to this processing, the current, voltage, light emission time (duty ratio), and the like related to the display unit are controlled. You may implement | achieve by the control reduced based on the luminance value which changes the brightness | luminance of a screen.
The present invention has been described with reference to the embodiment. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit and intention of the present invention.

It is a block diagram which shows roughly the structure of the mobile telephone of one Embodiment in this invention. It is a flowchart which shows the control method of 1st Example in this invention. It is a display image by the data before control in the present invention. (A) is a display image based on data controlled by the control method of the first embodiment of the present invention, and (b) is a display image based on data controlled by another control method of the first embodiment. It is a flowchart which shows the control method of the mobile telephone of 2nd Example in this invention. It is a table which shows the luminance level used for the control method of 2nd Example in this invention. It is a flowchart which shows the control method of 3rd Example in this invention. It is explanatory drawing which shows the battery residual amount table of the mobile telephone in this invention. It is a flowchart which shows the control method of 4th Example in this invention. It is explanatory drawing which shows the brightness | luminance level table of the mobile telephone in this invention, Comprising: (a) is ambient light "dark", (b) is ambient light "normal", (c) is ambient light " This is the case of “bright”.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cellular phone 10 Control part 11 Display information storage part 12 Luminance information calculation part 13 Brightness control part 20 EL display part (display part)
21 EL display driving circuit 30 Operation unit 31 ROM
32 RAM
33 Battery level detector 34 Microphone 35 Speaker 36 Antenna 37 Transmitter / receiver 38 Optical sensor (optical sensor)

Claims (6)

A display unit comprising a large number of pixels composed of a plurality of self-luminous elements,
A display information storage unit for storing data of all or part of a region in a display image to be displayed on the display unit;
A luminance information calculation unit that calculates luminance information for all the pixels in the region from the data of the region stored in the display information storage unit;
A portable electronic device comprising: a control unit that controls the luminance of the pixel in the region based on a comparison between the luminance information calculated by the luminance information calculation unit and a threshold value.    The portable electronic device according to claim 1, wherein the luminance information calculation unit calculates an average luminance per pixel as the luminance information.    The control unit includes a plurality of the threshold values, and controls the luminance of the pixels in the region in a stepwise manner based on a calculation result of the luminance information calculation unit and the plurality of threshold values. Item 3. The portable electronic device according to item 1 or 2.    4. The apparatus according to claim 1, further comprising: a battery remaining amount detection unit, wherein the control unit controls the luminance of the pixels in the region in accordance with the remaining amount of the battery. Portable electronic device.    5. The portable device according to claim 1, further comprising: an optical sensor, wherein the control unit controls the luminance of the pixel in the region according to brightness of ambient light. Electronics. Calculating luminance information for all of the pixels in the region from data of all or part of the region in the display image displayed on the display unit formed by arranging a plurality of pixels composed of a plurality of self-luminous elements;
A method for controlling a portable electronic device, wherein the luminance of the pixel in the region is controlled based on a comparison between the calculated luminance information and a threshold value.

Images