JP2005236597A - Portable terminal equipment having power-saving function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide portable terminal equipment having power-saving function, which can save working power in line with the utilization mode. <P>SOLUTION: The portable terminal equipment comprises a communication section for receiving information data; a display unit for displaying the information data received from the communication section; an imaging unit for capturing the face of an operator as image data; an angle detection unit for detecting the angle of the face of the operator, with respect to the display screen of the display device from the image data to discriminate whether the detected angle is equal to or greater than the specified angle; and a luminance adjustment unit for reducing the display luminance of the display device, when it is discriminated that the angle of the facial surface of the operator is equal to or greater than the specified angle. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a mobile terminal device, and more particularly to a mobile terminal device having a power saving function.

  In recent years, with the widespread use of mobile terminal devices such as mobile phones, the display area has become larger. As a result, a display device such as a liquid crystal display mounted on the portable terminal device is also increased in size and consumes more power. In addition, hardware such as cameras and GPS (Global Positioning System) mounted on mobile terminal devices is increasing. On the other hand, a mobile phone or the like uses a rechargeable battery as a power source, and the battery is consumed quickly due to an increase in installed hardware. Furthermore, recently, a large amount of power is consumed not only for voice communication processing but also for moving image compression / decompression processing due to the installation of a TV tuner and a TV phone function.

  Usually, in a mobile phone, power consumption by a display device is originally large, and high processing performance is required for a processor by adding and enhancing a new function as described above. In order to improve the processing performance, the processing speed is increased by raising the clock of the processor (CPU), and depending on the mounting method, parallel processing by a plurality of processors is performed, resulting in a further increase in power consumption.

Conventionally, power saving control for reducing power consumption of a display device has been studied (see Patent Documents 1 and 2). For power saving control of mobile phones, for example, a method of automatically reducing the brightness of the display, which is the hardware with the largest power consumption of mobile phones, after a certain period of time has elapsed since the previous key input occurred. (For example, refer to Patent Document 1). However, since recent mobile phones are used not only for voice calls but also for accessing e-mails and websites, there are many operations while viewing the display during communication. Even in such a case, the function to automatically reduce the brightness of the display after a certain period of time has elapsed in order to reduce power consumption, but when the e-mail or website is accessed, the brightness reduction function is activated. In many cases, the next key input operation is performed, and the frequency of the luminance reduction (power saving) function is low. Also, when making a videophone call, since there are few key input operations, the display brightness is frequently reduced during a conversation and the screen becomes dark. In order to avoid such power saving operation, it is necessary to press any key periodically, which is inconvenient. On the other hand, when you look at something other than video while looking at the display while making a videophone call, even though it is not necessary to increase the brightness of the display, wasteful power is consumed. There was a case.
JP 2000-253141 A (page 4, FIG. 2) JP 2001-350549 A (page 3, FIG. 1)

  As described above, the conventional technology does not provide a power saving function in accordance with the usage mode of the mobile phone, such that the power saving operation works unnecessarily, or the power saving operation does not function when necessary. There was a problem.

  This invention is made | formed in view of this point, and it aims at providing the portable terminal device provided with the power saving function according to the usage condition.

  A mobile terminal device according to the present invention includes a communication unit that receives information data, a display that displays the information data received by the communication unit, an imager that captures image data obtained by imaging the face of the operator, An angle detector that detects an angle of the operator's face with respect to the display surface of the display device from the image data to determine whether or not the angle is equal to or greater than a predetermined angle, and an angle of the operator's face is equal to or greater than a predetermined angle And a brightness adjuster that reduces the display brightness of the display device.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments described below, equivalent components are denoted by the same reference numerals.

  FIG. 1 is a block diagram schematically illustrating a configuration of a mobile terminal device 10 that is Embodiment 1 of the present invention, and FIG. 2 is a diagram schematically illustrating an appearance of the mobile terminal device 10. In the following, a case where the mobile terminal device 10 is a camera-equipped mobile phone will be described, but a device having a similar function such as a mobile TV phone or a portable information terminal device (PDA) may be used.

  The mobile terminal device 10 includes a camera 11, an input device 12, a display device 13, a communication device (or communication unit) 14, and a processor (CPU) 15. Under the control of the CPU 15, the camera 11 has a function of acquiring time-series continuous still images or moving images. The input device 12 is a device for a user of the mobile terminal device 10 to perform a key input operation. As shown in FIG. 2, various operation keys 12 </ b> B are provided on the operation panel 12 </ b> A of the mobile terminal device 10. That is, these operation keys 12B have the function of the input device 12 as a whole.

  The display device 13 displays the processing result of the CPU 15 and data from the communication device 14. Note that the communication device 14 includes a wireless communication circuit that performs wireless communication, and may have a TV phone function for making a TV phone call. The display device 13 is configured as a liquid crystal display, for example. The display device 13 may be provided with a display controller 17. The display controller 17 has a function of displaying the data supplied from the CPU 15 on the display device 13 or displaying or hiding the data on the display device 13 or controlling the brightness of the entire screen in accordance with the control of the CPU 15. ing. The display controller 17 may be provided inside the CPU 15 instead of being alone.

  The mobile terminal device 10 is provided with a memory 18. The memory 18 is provided as a memory area capable of dynamically changing and storing an image acquired from the camera 11.

  The mobile terminal device 10 is provided with a program storage unit 20, and software used for the operation of the mobile terminal device 10 is loaded from the program storage unit 20 to the CPU 15. Note that the memory 18 and the program storage unit 20 may be provided inside the CPU 15.

  Further, the mobile terminal device 10 is provided with a microphone 21 for a user to make a call.

  The above-described devices are connected via the data bus 19 and are controlled by the CPU 15.

  Below, operation | movement of the portable terminal device 10 is demonstrated. FIG. 3 is a flowchart showing an operation procedure for controlling the luminance of the display device 13 of the mobile terminal device 10. The case where the user makes a videophone call will be described as an example.

  First, the CPU 15 determines whether or not a videophone call is in progress (step S11). If it is determined in step S11 that the call is in progress, an image external to the portable terminal device 10 is captured by the camera 11 under the control of the CPU 15 (step S12).

  As shown in FIG. 4A and FIG. 4B, the CPU 15 causes the user (operator) who is making a call to display the display device 13 of the mobile terminal device 10 from the image data captured by the camera 11. It is determined whether the user is looking (a) or not viewing the display device 13 (b).

  More specifically, the CPU 15 performs analysis using a program loaded from the program storage unit 20. First, feature points representing the face of the user (operator) making a call are detected (step S13).

  FIG. 5 shows a case where the feature point of the user (operator) face is at the reference position. That is, FIG. 5 shows, for example, feature points P1, P2, and P3 at the reference position. In the following, for convenience of explanation, the positions of the feature points P1, P2, and P3 are also indicated using the same reference numerals. That is, description will be made assuming that the reference positions of the feature points are also P1, P2, and P3.

  More specifically, the feature point P1 is a feature point related to the user's mouth, and this figure shows a case where four feature points related to the mouth are set. The feature point P2 is a feature point related to the user's eyes, and this figure shows a case where two feature points related to the eyes are set. The feature point P3 is a feature point related to the user's eyebrow, and this figure shows a case where four feature points related to the eyebrow are set. In short, as the feature points of the user's face, feature points representing the entire face are selected so that the face of the user (the face including the face) can be determined. The CPU 15 includes an angle detector 15A that calculates an angle formed by the user's face with respect to the display surface based on the feature points. The CPU 15 adjusts the display luminance of the display device 13 by controlling the display controller 17 according to the detection result. Further, as will be described in detail later, the CPU 15 may have a determination unit 15B or a determination function for determining whether or not a face including the user's face can be determined. It should be noted that the reference of feature points to be set (eyebrows, eyes, nose, mouth, etc.) and the number of feature points are calculated according to the calculation accuracy of the feature point position of the user's face, the processing time required for the calculation, the detection of the feature point and the position It can be determined as appropriate in consideration of the memory capacity required for the calculation.

  A reference position of a feature point including an angle of the user's face with respect to the display device 13 is determined in advance and stored in the mobile terminal device 10. The angle detector 15A in the CPU 15 detects the feature point of the user's face and calculates the angle (orientation) of the user's face with respect to the display device 13 by comparing with the stored reference position of the feature point (step S14). ). For example, as shown in FIG. 6, when it is detected that the position of the feature point is P1 ′, P2 ′, P3 ′, the detection position (P1 ′, P2 ′, P3 ′) is used as the reference position (P1, P2). , P3), the angle of the user's face relative to the display surface of the display device 13 is calculated. For example, when the user's face is completely facing the display surface of the display device 13, the user's face and the display surface are parallel, and the angle formed by the user's face is 0 degree.

  That is, the feature points of the face are determined so that the face including the face of the user (operator) can be determined. Then, an angle formed by the operator's face and the display surface of the display device 13 (an angle formed between the surfaces) is calculated.

  Next, the CPU 15 and the angle detector 15A determine whether or not the calculated angle is equal to or greater than a predetermined angle (step S15). If the calculated angle is equal to or greater than a predetermined angle (for example, 20 degrees), the CPU 15 determines that the user is not looking at the display and sends an instruction signal to the display controller 17 to reduce the brightness of the display device 13. The level is controlled to be level (step S16). That is, when the brightness of the display device 13 is high, the brightness is reduced to a predetermined level, and when it is low, the brightness is controlled to be maintained. With this control, the angle or orientation of the user's face is detected from the video obtained from the camera 11 during a videophone call. For example, the user's face is tilted from the front (display surface) by a certain angle or more. Therefore, it is determined that the display device 13 is not viewed and the brightness of the display device 13 is automatically reduced to darken (that is, the power saving mode is set).

  On the other hand, if the calculated angle is less than the predetermined angle in step S15, the CPU 15 determines that the user is looking at the display, sends an instruction signal to the display controller 17, and the brightness of the display device 13 is at a high level. (Step S17). That is, when the luminance of the display device 13 is low, the luminance is increased to a predetermined level, and when it is high, the luminance is maintained. By such control, even when the brightness of the display device 13 is lowered and the screen is dark, the orientation of the user's face is always detected from the video obtained from the camera 11, and it is determined that the user is facing the front within a certain angle. In such a case, a function of automatically increasing the brightness of the display device 13 to return to an easy-to-view screen (that is, setting to the return mode) is realized.

  Note that the angle of the face of the user who shifts to the return mode may be different from the angle when shift to the power saving mode. For example, when the angle of the user's face (first predetermined angle) when shifting to the power saving mode is 20 degrees, the angle of the user's face (second predetermined angle) shifting to the return mode exceeds 20 degrees. It may be set to a value. With this setting, when the user views the display device 13 again, the original brightness can be quickly restored prior to the movement of the user's face. On the other hand, the face angle (second predetermined angle) of the user transitioning to the return mode is set to a value smaller than the angle (first predetermined angle) of the user face when shifting to the power saving mode. Also good. With this setting, the power saving effect can be further enhanced.

  If it is determined in step S11 that the call is in progress, the above procedure is repeated, and the brightness control is continuously executed. Note that the image capture in step S12 is performed for each frame of the image. On the other hand, if it is determined in step S11 that the call is not in progress, that is, it is determined that the call has ended, the luminance control operation described above is ended.

  Although the case where the image capturing and the angle detection in step S12 are performed for each frame has been described, the image capturing may be performed at an appropriate interval. For example, images may be captured at intervals that take into account power consumption, user-friendliness, and the like. Alternatively, for example, the control may be performed so that the luminance is changed (from a high level to a low level or vice versa) every predetermined number of frames (for example, 0.1 seconds).

  FIG. 7 is a flowchart illustrating an operation procedure of the mobile terminal device 10 according to the second embodiment of the present invention.

  It is determined whether a telephone call is in progress (step S11), the operator's face is imaged (step S12), and feature points representing the face of the operator who is making a call are detected (step S13). This procedure is the same as in the above-described embodiment.

  Next, it is determined whether or not the user's face can be determined (step S21). For example, when a predetermined feature point is not detected among preset feature points, it is determined that the user's face cannot be determined. Alternatively, when the number of feature points detected among the preset feature points is smaller than the reference number, it is determined that the user's face cannot be determined. Alternatively, this determination can be appropriately determined so that the user's face can be determined.

  If it is determined in step S21 that the user's face can be determined, the process proceeds to step S14, and steps S14 to S17 are executed in the same manner as in the first embodiment.

  If it is determined in step S21 that the user's face cannot be determined, the process proceeds to step S16, and the display device 13 is controlled so that the luminance is low (step S16). That is, when the brightness of the display device 13 is high, the brightness is reduced to a predetermined level, and when it is low, the brightness is controlled to be maintained. With this control, when the user's face cannot be detected from the video obtained from the camera 11 during a call, the display device 13 is automatically reduced in brightness and darkened (that is, in the power saving mode). Realized.

  As described above, it is possible to provide a mobile terminal device having a power saving function in accordance with the usage mode of the mobile terminal device.

It is a block diagram which shows typically the structure of the portable terminal device which is Example 1 of this invention. It is a figure which shows typically the external appearance of the portable terminal device of FIG. It is a flowchart which shows the procedure of the operation | movement which controls the brightness | luminance of the display apparatus of a portable terminal device. It is a figure which shows (a) when the user (operator) who is carrying out a call is looking at the display of a portable terminal device, and (b) when not looking at the display. It is a figure which shows the case where the feature point of a user (operator) face exists in a reference | standard position. It is a figure which shows the case where the angle of a user's face is inclined from the display surface of a display. It is a flowchart which shows the operation | movement procedure of the portable terminal device which is Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Portable terminal device 11 Camera 12 Input device 13 Display device 14 Communication device 15 Processor (CPU)
15A Angle detector 15B Discriminator 17 Display controller 18, 20 Memory

Claims (8)

A portable terminal device,
A communication unit for receiving information data;
A display for displaying information data received by the communication unit;
An imager that captures image data obtained by imaging the operator's face;
An angle detector that detects an angle of the operator's face with respect to the display surface of the display device from the image data and determines whether or not a predetermined angle or more;
A mobile terminal device comprising: a brightness adjuster that reduces the display brightness of the display when it is determined that the angle of the face of the operator is equal to or greater than a predetermined angle.   The brightness adjuster reduces the display brightness of the display unit and reduces the display brightness of the display unit when it is determined that the angle of the operator's face with respect to the display surface is greater than or equal to a first predetermined angle. 2. The portable terminal device according to claim 1, wherein when the angle of the face is determined to be less than a second predetermined angle, the display luminance of the display is returned to the luminance before reduction. .   The mobile terminal device according to claim 1, wherein the second predetermined angle is different from the first predetermined angle.   The angle detector detects a plurality of feature points on the face for determining a face including the face of the operator, and determines an angle of the face of the operator with respect to the display surface based on the detected feature points. The mobile terminal device according to claim 1, wherein the mobile terminal device is detected.   The angle detector has a discriminator for discriminating whether or not the surface including the operator's face can be determined based on the detected feature point, and determines that the surface including the operator's face cannot be determined. The mobile terminal device according to claim 4, wherein the brightness adjuster reduces display brightness of the display when the display is performed.   The mobile terminal device according to claim 1, wherein the angle detector detects an angle of the operator's face for each frame of the image data and determines whether or not the angle is equal to or greater than a predetermined angle.   The mobile terminal device according to claim 1, wherein the communication unit includes a telephone communication circuit that forms a mobile phone.   The mobile terminal apparatus according to claim 1, wherein the communication unit includes a wireless communication circuit that makes a videophone, and the angle detector detects an angle of the face of the operator who is executing the videophone.

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