Information processing apparatus and radio wave intensity control method

An information processing apparatus has radio communication function. A tilt detection unit detects a tilt of the information processing apparatus. An output changing unit changes an output of radio waves from an antenna for radio communication. Based on a detection result through the tilt detection unit, when a tilt θ of a predetermined external surface of a chassis of the information processing apparatus to a horizontal surface H is a predetermined angle or less, an output controller reduces an output of radio waves from the antenna to a predetermined value or less with respect to the output changing unit.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2011-100395, filed on Apr. 28, 2011, the entire contents of which are incorporated herein by reference.

FIELD

The embodiment discussed herein is related to an information processing apparatus, a radio wave intensity control method, and a program.

BACKGROUND

As a unit for evaluating an influence of radio waves transmitted from a radio device such as a mobile phone, an SAR (Specific Absorption Rate) is used. The SAR indicates the amount of energy absorbed in a unit of time with respect to a tissue per unit mass of a human body exposed to radio waves. In Japan, based on a guideline indicated by WHO (World Health Organization), “a local SAR fails to exceed an allowed value of 2 W/kg” with regard to portable devices is obliged by an Ordinance of the Ministry of Internal Affairs and Communications.

Therefore, some portable information processing devices such as a mobile phone and a notebook PC (Personal Computer) stop an output of radio waves from an antenna, or reduce its output when detecting that their own devices each come close to a human body. For example, based on detection results of a display direction of a screen, when detecting that antennas come close to users, some tablet PCs stop an output of radio waves from the antennas. Some tablet PCs further detect a display direction of a screen by using a tilt sensor.

Incidentally, nations slightly differ from each other in interpretations of a standard of SAR. For example, as an object for restricting the SAR, there are some nations in which knees or thighs are included, and the other nations in which they are not included. In the case where knees or thighs are included as an object for restricting the SAR, for example, when an information processing device is mounted and used on knees in the seated state, radiated waves to a vertically downward direction of the information processing device need to be restricted.

In a notebook PC on which an antenna is mounted near a chassis of a display unit, even when it is mounted and used on user's knees, the antenna may be sufficiently separated from the user's knees or thighs so as to satisfy a standard of the SAR. Suppose further that a so-called convertible PC is mounted on user's knees, which is used as both of a notebook PC mode and a tablet PC mode. Even in this case, when a PC main body or display unit has a certain degree of thickness, an antenna in the tablet PC mode may be separated from the user's knees or thighs.

However, since thinning of a convertible PC advances recently, an antenna fails to be sufficiently separated from user's knees or thighs, and as a result a standard of the SAR is not satisfied. In this respect, much the same is true on a slate information processing device. Although not limited to the above devices, the thinning is demanded in various information processing devices. In a thinned information processing device, even if mounted in an internal portion or on a top side of the device, an antenna fails to be sufficiently separated from user's knees or thighs located in a vertically downward side.

SUMMARY

According to one aspect of the present invention, there is provided an information processing apparatus having radio communication function. This information processing apparatus includes a tilt detector configured to detect a tilt of the information processing apparatus; an output changer configured to change an output of radio waves from an antenna for radio communication; and an output controller configured to reduce an output of radio waves from the antenna to a predetermined value or less with respect to the output changer when it is determined based on a detection result obtained by the tilt detector that a tilt of a predetermined external surface of a chassis of the information processing apparatus to a horizontal surface is a predetermined angle or less.

DESCRIPTION OF EMBODIMENTS

Preferred embodiments of the present invention will now be described in detail below with reference to the accompanying drawings, wherein like reference numerals refer to like elements throughout.

First Embodiment

FIG. 1illustrates a configuration example of an information processing apparatus according to a first embodiment.

The information processing apparatus1illustrated inFIG. 1has radio communication function. In an internal part or on an external surface of a chassis of the information processing apparatus1, an antenna11which transmits and receives radio signals at the time of radio communication is provided. The information processing apparatus1further includes a tilt detection unit12, an output changing unit13, and an output controller14.

The tilt detection unit12detects a tilt of the information processing apparatus1. The tilt detection unit12detects at least an angle between a predetermined surface of the chassis of the information processing apparatus1and a horizontal surface.

The output changing unit13changes intensity of radio waves radiated from the antenna11under the control of the output controller14. The output controller14controls operations of the output changing unit13based on detection results from the tilt detection unit12. In the case where a tilt of the above-described reference plane to the horizontal surface is a predetermined angle θth or less, for example, the output controller14controls the output changing unit13to reduce the intensity of radio waves radiated from the antenna11to a predetermined intensity or less. “A tilt of the reference plane to the horizontal surface is θth or less” is that an absolute value of an angle between the reference plane and the horizontal surface is equal to or smaller than θth.

On the top side ofFIG. 1, one example of a cross-sectional surface of the chassis of the information processing apparatus1is here illustrated. In an example ofFIG. 1, the chassis10of the information processing apparatus1has an approximately flat plate-shaped contour. InFIG. 1, two main surfaces (surfaces perpendicular to a thickness direction) of the approximately flat plate-shaped chassis10are supposed to be referred to as a top surface10aand a bottom surface10bfor descriptive purposes. The top surface10ais approximately parallel to the bottom surface10b. A cross-sectional diagram illustrated inFIG. 1indicates a cross-sectional surface of the chassis10viewed from a direction parallel to the top surface10aand the bottom surface10bof the chassis10. Suppose further that the reference plane P is parallel to the bottom surface10b.

On the top surface10a, for example, a mechanism faced to a face side of a user at the time of normally using the information processing apparatus1such as a display unit of images and an input unit which receives an input operation through the user is provided. In the above-described case, the information processing apparatus1detects that a tilt of the reference plane P to the horizontal surface H is θth or less (namely, an absolute value of the angle θ between the reference plane P and the horizontal surface H is equal to or smaller than θth), thus estimating that its own apparatus is mounted on knees or thighs in a state where the user is seated. When the information processing apparatus1is mounted and used on the user's knees or thighs, the bottom surface10bof the information processing apparatus1contacts with the user's knees or thighs, and as a result the antenna11comes close to the user's knees or thighs.

As compared with the above, when a tilt of the reference plane P to the horizontal surface H is θth or less, the output controller14controls the output changing unit13to reduce intensity of radio waves radiated from the antenna11. Through the above processing, the output controller14controls the output changing unit13to reduce the intensity of radio waves radiated to a user's body close to the antenna11in a vertically downward direction. Particularly, when the information processing apparatus1is mounted on the user's knees or thighs, as a thickness of the chassis10is thinner, a distance between the antenna11and user's knees or thighs is shorter. As can be seen from the above discussion, also in the case where the chassis10is thinned, the intensity of radio waves radiated to the user's knees or thighs is reduced under the control of the output controller14and, for example, a local SAR with respect to the user's knees or thighs is equal to or smaller than a reference value.

Note that in the chassis10, the reference plane P is preferably parallel to a surface (inFIG. 1, the bottom surface10b) facing to a surface on which the display unit and the input unit are provided. The first embodiment makes it possible to correctly estimate a distance between the information processing apparatus1and user's knees or thighs.

When absolute values of angles between straight lines in all directions along the reference plane P and the horizontal surface H are equal to or smaller than θth, the output controller14preferably controls the intensity of radio waves radiated from the antenna11to predetermined intensity or less. As one example where the above-described control is possible, both of absolute values of angles between two straight lines perpendicular to each other along the reference plane P and the horizontal surface H are supposed to be equal to or smaller than θth. In this case, the output controller14may control the intensity of radio waves radiated from the antenna11to the predetermined intensity or less.

The chassis10illustrated inFIG. 1may be further a part of a configuration of the information processing apparatus1. For example, a notebook PC generally has a configuration in which a first chassis including a keyboard and a second chassis including a display unit are connected via a hinge. In the above-described case, the chassis10illustrated inFIG. 1may be set as the first chassis including a keyboard. Accordingly, in the case where the antenna11is provided in the first chassis or on an external surface thereof, the first embodiment makes it possible to reduce the intensity of radio waves radiated to user's knees or thighs close to this antenna11.

Second Embodiment

As an example of the information processing apparatus, a slate information processing apparatus will be described below.FIG. 2illustrates an example of a contour of the information processing apparatus according to a second embodiment.

Examples of the information processing apparatus100illustrated inFIG. 2include a portable PC for a user. The information processing apparatus100is driven by a power supply from a built-in battery. A chassis of the information processing apparatus100has an approximately flat plate shape, and a touch panel display101is provided on one surface of the chassis. A cradle connection jack102is further provided on one of side surfaces contacted with a mounting surface of the display101of the chassis. Into the cradle connection jack102, a connector provided on the after-mentioned cradle is inserted.

The information processing apparatus100further has radio communication function. The information processing apparatus100performs radio communication, for example, via a wide area radio communication line network of 3G (3rd Generation) mobile phone. The information processing apparatus100includes an antenna103for performing radio communication in an internal part or on an external surface of a chassis. In an example ofFIG. 2, the antenna103is provided in a position close to an outer edge part of an approximately flat plate-shaped chassis.

FIG. 3illustrates an example of a contour of the cradle. InFIG. 3, along with the cradle, the information processing apparatus connected to this cradle is also illustrated.FIG. 4further illustrates a state where the information processing apparatus is connected to the cradle.

On the cradle200, the connector201for connecting to the information processing apparatus100is provided. When the connector201of the cradle200is inserted into the cradle connection jack102provided on the information processing apparatus100, the information processing apparatus100is connected to the cradle200in a state where its own apparatus stands erect, as illustrated inFIG. 4. In addition, to the cradle200, for example, an AC (Alternating Current) adapter is connected. The information processing apparatus100connected to the cradle200receives direct-current power AC/DC (Direct Current) converted by an AC adapter from the cradle200via the connector201, thereby driving its own apparatus by using the power.

FIG. 5illustrates a hardware configuration example of the information processing apparatus.

The whole information processing apparatus100is controlled by a CPU (Central Processing Unit)111. To the CPU111, a RAM (Random Access Memory)112and a plurality of peripheral devices are connected via a bus119.

The RAM112is used as a main storage device of the information processing apparatus100. In the RAM112, at least a part of an OS (Operating System) program or application program executed by the CPU111is temporarily stored. In addition, in the RAM112, various data necessary for a processing executed by the CPU111is stored.

Examples of the peripheral devices connected to the bus119include a flash memory113, a graphics processing circuit114, an input I/F (Interface)115, a memory card interface116, a radio communication circuit117, and an I/O (In/Out) processing circuit118.

The flash memory113is used as a secondary storage device of the information processing apparatus100. In the flash memory113, an OS program, application program, and various data are stored. As the secondary storage device, other types of nonvolatile memory devices such as an HDD (Hard Disk Drive) may be used.

To the graphics processing circuit114, the display101is connected. The graphics processing circuit114displays an image on the display101according to a command from the CPU111.

To the input I/F115, a touch panel101aprovided on a display surface of the display101is connected as an input device. The input I/F115supplies an output signal from the touch panel101ato the CPU111.

To the memory card interface116, a memory card116abeing a portable storage device using a flash memory as a storage device is connected. The memory card interface116supplies data read out from the memory card116ato the CPU111. In the memory card116a, the memory card interface116further writes data, writing of which is requested from the CPU111.

The radio communication circuit117performs radio communication via the wide area radio communication line network of the 3G mobile phone. To the radio communication circuit117, the antenna103is connected via the output adjustment unit121, and the radio communication circuit117transmits and receives radio waves by using the antenna103. The output adjustment unit121controls a voltage produced from the radio communication circuit117to the antenna103, thus changing the intensity of radio waves radiated from the antenna103. Note that the radio communication circuit117may be a circuit for performing radio communication via the wide area radio communication line network by using other methods such as WiMAX (Worldwide Interoperability for Microwave Access).

The I/O processing circuit118is a circuit so as to transmit and receive information between the CPU111and the other devices. To the I/O processing circuit118, the output adjustment unit121, a gravity sensor122, and a cradle detection unit123are connected.

The I/O processing circuit118controls the output adjustment unit121to change the intensity of radio waves radiated from the antenna103according to a request from the CPU111.

The gravity sensor122is a sensor which detects a tilt of the information processing apparatus100, and has, for example, a sensor which detects gravity acceleration with respect to two or more axial directions. The I/O processing circuit118supplies tilt detection results through the gravity sensor122to the CPU111. Examples of the sensor which detects a tilt of the information processing apparatus100include various sensors such as a combination of a gravity sensor and other acceleration sensors.

The cradle detection unit123detects whether the connector201of the cradle200is connected to the cradle connection jack102. The I/O processing circuit118supplies to the CPU111a detection result of connection to the connector201via the cradle connection jack102.

Here,FIG. 6illustrates a configuration example of the output adjustment unit.

The output adjustment unit121has, for example, switches121aand121b, and an attenuator121c. On the other hand, the radio communication circuit117has antenna connection terminals117aand117bto be connected to connection terminals103aand103bof the antenna103through connection lines, respectively. InFIG. 6, connection lines between the antenna103and the radio communication circuit117are illustrated with thick lines.

The output adjustment unit121is inserted, for example, between the connection terminal103aof the antenna103and the antenna connection terminal117aof the radio communication circuit117. According to a control signal from the I/O processing circuit118, the switches121aand121bswitch a route of the connection line between the connection terminal103aand the antenna connection terminal117abetween a route to go through the attenuator121cand a route to bypass the attenuator121c. In the case where the switches121aand121bswitch to the route to go through the attenuator121c, the intensity of radio waves radiated from the antenna103is reduced as compared with a case of switching to the route to bypass the attenuator121c. When the bottom surface of the information processing apparatus100contacts with a user's body, a resistance value of the attenuator121cis set so that an influence exerted on the user's body by radio waves radiated from the antenna103may satisfy a standard of the SAR.

Suppose that the switches121aand121bselect the route to go through the attenuator121cin an initial state (steady state). As a result, for example, in the case where the control of the output adjustment unit121is not performed by abnormality generated in the execution of an application program by the CPU111, the intensity of radio waves radiated from the antenna103is reduced by the attenuator121c.

As a method for changing the intensity of radio waves radiated from the antenna103, it is not limited to an example of using an attenuator as inFIG. 6and, for example, a structure in which the intensity of radio waves is changed under the control of the CPU111may be provided within the radio communication circuit117.

Next,FIG. 7is a block diagram illustrating an example of processing function included in the information processing apparatus.

The information processing apparatus100includes a display direction controller141and an output controller142. Each process of the display direction controller141and the output controller142is performed, for example, by executing a predetermined program through the CPU111. For example, the process of the display direction controller141may be performed by executing the application program, and on the other hand, the process of the output controller142may be performed by executing a BIOS (Basic Input/Output System) program. At least a part of each process of the display direction controller141and the output controller142may be further performed by using an exclusive processing circuit. For example, a part of the process of the display direction controller141may be performed by the graphics processing circuit114.

The display direction controller141changes a display direction of images of the display101according to tilt detection results of the information processing apparatus100from the gravity sensor122.

The output controller142controls a radio wave intensity adjustment operation through the output adjustment unit121based on tilt detection results from the gravity sensor122, a state of the display direction controlled by the display direction controller141, and detection results of connection to the cradle200through the cradle detection unit123.

Control processing of the display direction through the display direction controller141will be here described. First,FIG. 8illustrates a definition of a direction of the information processing apparatus.

FIG. 8is a diagram obtained by viewing the information processing apparatus100from a direction perpendicular to a surface on which the display101is mounted. In the following description, among surfaces of the chassis of the information processing apparatus100, a surface on which the display101is mounted is supposed to be called a “display surface”, and on the other hand a surface facing to this display surface is supposed to be called a “bottom surface”. In the present embodiment, the display surface and the bottom surface are parallel to each other.

Four side surfaces SD1to SD4connected to four sides of the display surface are further defined as follows. The side surface SD1is a side surface on which the cradle connection jack102is provided, and the side surface SD2is a surface facing to the side surface SD1. Accordingly, in a state where the information processing apparatus100is connected to the cradle200, the side surface SD1is located on the bottom side, and the side surface SD2is located on the top side as inFIG. 8. In the case where the side surface SD1is located on the bottom side, the side surface SD3is located on the left side, and the side surface SD4is located on the right side. Suppose in the present embodiment that as an example, the antenna103for radio communication is located in a position close to the side surface SD2.

Reference axes A1and A2for representing a tilt of the information processing apparatus100are further defined as follows. Both of the reference axes A1and A2are parallel to the display surface and the bottom surface, and perpendicular to each other. When the side surface SD1is located on the bottom side and the side surface SD2is located on the top side, the reference axis A1indicates a vertical direction. When the side surface SD3is located on the left side and the side surface SD4is located on the right side, the reference axis A2indicates a horizontal direction.

When setting as a reference a state where the display surface is directed to the top side, and the display surface and the bottom surface are horizontal, an angle indicating a tilt of the information processing apparatus100is defined as follows. In the case where the display surface is directed to the top side, and the display surface and the bottom surface are horizontal, an angle between the reference axis A1and a horizontal surface is equal to zero degree, and also an angle between the reference axis A2and a horizontal surface is equal to zero degree.

When the information processing apparatus100is turned so that the side surface SD2may be located on the top side from a state where an angle between the reference axis A1and the horizontal surface is zero degree, an angle between the reference axis A1and the horizontal surface changes to a plus direction. On the other hand, when the information processing apparatus100is turned so that the side surface SD1may be located on the top side from a state where an angle between the reference axis A1and the horizontal surface is zero degree, an angle between the reference axis A1and the horizontal surface changes to a minus direction.

When the information processing apparatus100is turned so that the side surface SD4may be located on the top side from a state where an angle between the reference axis A2and the horizontal surface is zero degree, an angle between the reference axis A2and the horizontal surface changes to a plus direction. On the other hand, when the information processing apparatus100is turned so that the side surface SD3may be located on the top side from a state where an angle between the reference axis A2and the horizontal surface is zero degree, an angle between the reference axis A2and the horizontal surface changes to a minus direction.

FIG. 9illustrates a transition example of the display direction of an image in the display.

The display direction controller141controls the display direction of an image in the display101to correspond to four states C1to C4illustrated inFIG. 9. Based on the tilt detection result through the gravity sensor122, the display direction controller141transits the display direction of an image from each of the four states C1to C4to any one of the other three states.

The state C1indicates a most typical operating state of the information processing apparatus100. In the state C1, an image is displayed on the display101so that the side surface SD1may be located on the bottom side of the image, the side surface SD2may be located on the top side of the image, the side surface SD3may be located on the left side of the image, and the side surface SD4may be located on the right side of the image.

The state C2is a state where an image displayed on the display101is turned by 180 degrees from the state C1and displayed. In the state C2, the image is displayed on the display101so that the side surface SD2may be located on the bottom side of the image, the side surface SD1may be located on the top side of the image, the side surface SD4may be located on the left side of the image, and the side surface SD3may be located on the right side of the image.

Suppose, for example, that when an image is displayed as in the state C1, the side surface SD1side is taken up and an angle between the reference axis A1and the horizontal surface changes from more than −θth1to −θth1or less. In this case, the display direction controller141changes the display direction of the image as in the state C2. Suppose, for example, that when an image is displayed as in the state C2, the side surface SD2side is taken up and an angle between the reference axis A1and the horizontal surface changes to θth1or more. In this case, the display direction controller141changes the display direction of the image as in the state C1.

The state C3is a state where an image displayed on the display101is turned by 90 degrees from the state C1in a clockwise direction and displayed. In the state C3, the image is displayed on the display101so that the side surface SD3may be located on the bottom side of the image, the side surface SD4may be located on the top side of the image, the side surface SD2may be located on the left side of the image, and the side surface SD1may be located on the right side of the image.

The state C4is a state where an image displayed on the display101is turned by 90 degrees from the state C1in a counterclockwise direction and displayed. In the state C4, the image is displayed on the display101so that the side surface SD4may be located on the bottom side of the image, the side surface SD3may be located on the top side of the image, the side surface SD1may be located on the left side of the image, and the side surface SD2may be located on the right side of the image.

Suppose, for example, that when an image is displayed as in the state C3, the side surface SD3side is taken up and an angle between the reference axis A2and the horizontal surface changes to −θth1or less. In this case, the display direction controller141turns the display direction of the image by 180 degrees as in the state C4. Suppose, for example, that when an image is displayed as in the state C4, the side surface SD4side is taken up and an angle between the reference axis A2and the horizontal surface changes to θth1or more. In this case, the display direction controller141turns the display direction of the image by 180 degrees as in the state C3.

Even in any state of the states C1to C4, a user's body (particularly, a part near an abdomen or groin) is more likely to be located in the vertically downward direction of the image displayed on the display101. Here, in the state C2, the side surface SD2is directed to the side of the user's body. In the present embodiment, since the antenna103is mounted in a position close to the side surface SD2, the antenna103comes close to the user's body in the state C2. To solve the above problem, from the display direction controller141, the output controller142acquires information indicating that the display direction of the image corresponds to any state. When recognizing that the display direction of the image transits to the state C2, the output controller142controls the output adjustment unit121to reduce the intensity of radio waves radiated from the antenna103.

Next, a process of the output controller142will be described.FIG. 10illustrates an example of the operating state of the case where the information processing apparatus is used on user's legs.

The information processing apparatus100may be used on seated user300's knees or thighs (hereinafter, referred to simply as “on legs”). As illustrated in a central diagram ofFIG. 10, when the information processing apparatus100is used on the user300's legs, the display surface is directed upward and the bottom surface is horizontal. As can be seen from the above discussion, suppose that the information processing apparatus100is used on the user300's legs. In this case, the antenna103mounted on the information processing apparatus100comes close to the user300's legs (knees or thighs) located in the vertically downward direction of the antenna103. Particularly, as the information processing apparatus100is more thinned, the antenna103comes closer to the user300's legs. As a result, the antenna103radiates radio waves of higher intensity to the user300's legs.

To solve the above problem, based on tilt detection results through the gravity sensor122, the output controller142of the information processing apparatus100determines that the bottom surface of its own apparatus is horizontal. In this case, the output controller142controls the output adjustment unit121to reduce the intensity of radio waves radiated from the antenna103. As a result, even when the information processing apparatus100is mounted and used on the user300's legs, a standard of the SAR is satisfied.

Note that when the information processing apparatus100is used on the user300's legs, the tilt of its own apparatus is not stabilized, and the bottom surface is not necessarily completely horizontal. As illustrated in a left diagram ofFIG. 10, for example, the bottom surface may be tilted by certain angles to the horizontal surface H. Among the edges of the information processing apparatus100, the edge of the front side may be higher than the edge of the near side as viewed from the user300.

Alternatively, as illustrated in a right diagram ofFIG. 10, the bottom surface of the information processing apparatus100may be tilted by certain angles to the horizontal surface H. Among the edges of the information processing apparatus100, the edge of the near side may be higher than the edge of the front side as viewed from the user300. Note that a reference axis A ofFIG. 10is parallel to the bottom surface, and indicates an axis directed to an anteroposterior direction as viewed from the user300. For example, when the display direction of the display101is set in the state C1or C2ofFIG. 9, the reference axis A ofFIG. 10corresponds to the reference axis A1ofFIG. 9. Further, when the display direction of the display101is set in the state C3or C4ofFIG. 9, the reference axis A ofFIG. 10corresponds to the reference axis A2ofFIG. 9. Although not illustrated in the figure, among the edges of the information processing apparatus100, the edge of the left side or right side may be higher than the other edge as viewed from the user300.

To solve the above problem, when the tilt of the bottom surface of the information processing apparatus100is a predetermined angle θth2or less, the output controller142determines that the information processing apparatus100is used on the user300's legs, and reduces the intensity of radio waves radiated from the antenna103. Suppose, for example, that an absolute value of an angle between the reference axis A1illustrated inFIG. 9and the horizontal surface H is θth2or less and an absolute value of an angle between the reference axis A2and the horizontal surface H is θth2or less. In this case, the output controller142reduces the intensity of radio waves radiated from the antenna103. Note, for example, that the θth2is 15 degrees.

FIG. 11is a flowchart illustrating an example of a process procedure of the output controller. The output controller142repeatedly performs a process ofFIG. 11at regular time intervals.

(Step S11) The output controller142acquires detection results from the cradle detection unit123, and determines whether the cradle200is connected to the information processing apparatus100. If so, the output controller142performs a process of step S15. On the other hand, if not, the output controller142performs a process of step S12.

(Step S12) The output controller142acquires a control state of the image display direction from the display direction controller141. If the control state corresponds to the state C2, the output controller142performs a process of step S14. On the other hand, if the control state corresponds to any one of the states C1, C3, and C4, the output controller142performs a process of step S13.

(Step S13) From the gravity sensor122, the output controller142acquires an angle θ1between the reference axis A1and the horizontal surface H, and an angle θ2between the reference axis A2and the horizontal surface H. If an absolute value of the angle θ1is θth2or less and an absolute value of the angle θ2is θth2or less, the output controller142performs a process of step S14. On the other hand, if at least one of the absolute values of the angles θ1and θ2exceeds the θth2, the output controller142performs a process of step S15.

(Step S14) The output controller142controls the output adjustment unit121to reduce the intensity of radio waves radiated from the antenna103. Specifically, the output controller142switches the switches121aand121bof the output adjustment unit121to a route to go through the attenuator121c.

(Step S15) The output controller142controls the output adjustment unit121to increase the intensity of radio waves radiated from the antenna103. Specifically, the output controller142switches the switches121aand121bof the output adjustment unit121to a route to bypass the attenuator121c.

According to the above-described process ofFIG. 11, when the information processing apparatus100is connected to the cradle200, the output controller142controls the output adjustment unit121to increase the intensity of radio waves radiated from the antenna103. When the information processing apparatus100is connected to the cradle200, the display surface of its own apparatus is brought into an erected state. In this state, even if the intensity of radio waves radiated from the antenna103is not reduced, the antenna103is separated from the user's body so as to sufficiently satisfy a standard of the SAR. Therefore, the output controller142controls the output adjustment unit121not to reduce the intensity of radio waves radiated from the antenna103through the attenuator121c.

When the information processing apparatus100is not connected to the cradle200and the control state of the display direction of an image corresponds to the state C2, the output controller142controls the output adjustment unit121to reduce the intensity of radio waves radiated from the antenna103. As illustrated inFIG. 9, in the state C2, the side surface SD2of the chassis of the information processing apparatus100is normally directed to a direction of the user's body (particularly, a part near an abdomen or groin). The antenna103is disposed in a portion close to the side surface SD2, and therefore comes close to a part near a user's abdomen or groin in the state C2. Consequently, in the case where the control state of the display direction of an image corresponds to the state C2, regardless of whether the bottom surface of the information processing apparatus100is approximately horizontal, the intensity of radio waves radiated from the antenna103is reduced so as to satisfy a standard of the SAR.

Suppose further that the output controller142determines that the information processing apparatus100is not connected to the cradle200and the control state of the display direction of an image fails to correspond to the state C2. In this case, the output controller142performs a process of step S13and determines whether the bottom surface of the information processing apparatus100is approximately horizontal. When determining, based on the process of step S13, that the bottom surface is approximately horizontal, the output controller142controls the output adjustment unit121to reduce the intensity of radio waves radiated from the antenna103.

As a result, the output controller142controls the output adjustment unit121to reduce the intensity of radio waves radiated to the user's body located in the vertically downward direction of the information processing apparatus100. Accordingly, even when the information processing apparatus100is mounted and used on the seated user's legs, the output controller142controls the output adjustment unit121to suppress an influence exerted on the user's legs by radiated waves so as to satisfy a standard of the SAR. While satisfying the standard of the SAR, the present embodiment further thins the chassis of the information processing apparatus100. The present embodiment further improves a degree of freedom in a position of the antenna103of the chassis of the information processing apparatus100.

When the information processing apparatus has change function of the display direction of an image as illustrated inFIG. 9, most of them have a mechanism for detecting a tilt. The above-described information processing apparatus100uses the tilt detection mechanism in both of the determination processing of the image display direction and the determination processing of whether the bottom surface is approximately horizontal. Accordingly, the manufacturing cost is prevented from increasing.

Examples of other methods for detecting that a user's body comes close to the bottom surface of the information processing apparatus100include a method for using an electrostatic sensor, a method for using an illumination sensor, and a method for using a light emitting unit and illumination sensor of infrared rays.

An electrostatic sensor detects, based on a change in electrostatic capacity, that a user's body comes close to the bottom surface of the information processing apparatus. In the case of using an electrostatic sensor, when the user's body contacts with or comes close to the bottom surface before turning on power, the output controller142fails to determine, after turning on power, whether the user's body contacts with or comes close to the bottom surface. As compared with the above, as in the present embodiment, the user's body is supposed to contact with or come close to the bottom surface before turning on power by using a method for detecting, based on tilt detection results of the bottom surface, that the user's body comes close to the bottom surface in the vertically downward direction of the information processing apparatus100. Also in this case, the output controller142correctly determines, after turning on power, that the user's body comes close to the bottom surface.

In the case of a method for using an illumination sensor, when an intake of light is provided on a bottom surface of the information processing apparatus and intensity of light thrown from the intake is detected by the illumination sensor, the information processing apparatus detects that the user's body contacts with or comes close to the bottom surface. In this method, when the environment is dark, the detection fails to be correctly performed. As compared with the above, based on tilt detection results of the bottom surface, these features of the present embodiment permit the information processing apparatus100to detect that the user's body comes close to the bottom surface in the vertically downward direction of its own apparatus, and determine that the user's body comes close to the bottom surface irrespective of peripheral brightness.

In the case of a method for using a light emitting unit and an illumination sensor, when light is irradiated outward from a bottom surface to detect its reflected light by the illumination sensor, the information processing apparatus detects that a user's body contacts with or comes close to the bottom surface. In this method, the information processing apparatus may fail to detect that the user's body contacts with the bottom surface for the reason of failing to acquire a light path, or the user's body comes close to the bottom surface depending on a color of the surface on which light is irradiated. As compared with the above, based on tilt detection results of the bottom surface, these features of the present embodiment permit the information processing apparatus100to detect that the user's body comes close to the bottom surface in the vertically downward direction of its own apparatus, and as a result, the above-described problem is not caused.

Next,FIGS. 12 to 15illustrate a relationship among the tilt of the information processing apparatus, the display direction of an image, and the intensity of radio waves.

FIGS. 12 to 15illustrate operation examples of the case where the user uses the information processing apparatus100so that the display101may be horizontally long (specifically, so that the control state of the image display direction may correspond to the state C1or C2). Suppose, for example, that inFIGS. 12 to 15, the information processing apparatus100is mounted and used on the seated user's legs. Further, inFIGS. 12 to 15, the information processing apparatus100is supposed to be held so that the reference axis A2may be approximately horizontal, and the information processing apparatus100is supposed to be turned at the center of the reference axis A2. In this case, the angle θ1between the reference axis A1and the horizontal surface H varies.

FIGS. 12 and 13illustrate an example of the case where a threshold θth1of the tilt for determining whether the display direction of an image is changed is larger than a threshold θth2of the tilt for determining whether the bottom surface is approximately horizontal. Here, suppose, as one example, that the θth1is 30 degrees and the θth2is 15 degrees.

FIG. 12illustrates an example of the case where the tilt of the information processing apparatus100changes based on an operating state that the control state of the image display direction corresponds to the state C1. In this case, when the side surface SD2of the front side viewed from the user is turned upward among the side surfaces of the information processing apparatus100, the θ1detected by the gravity sensor122changes in a plus direction.

Even if the θ1changes from zero degree in the plus direction, the control state of the image display direction will not change from the state C1. When the θ1changes from zero degree to 15 degrees, since the conditions of step S13ofFIG. 11are satisfied, the intensity of radio waves radiated from the antenna103remains to be a weak state. When the θ1exceeds 15 degrees, the conditions of step S13are not satisfied. Therefore, the output controller142determines that the bottom surface is not horizontal, and controls the output adjustment unit121to increase the intensity of radio waves radiated from the antenna103.

On the other hand, when the side surface SD1of the near side viewed from the user is turned upward among the side surfaces of the information processing apparatus100, the θ1detected by the gravity sensor122changes in a minus direction. Even if the θ1changes from zero degree to −15 degrees, the control state of the image display direction will not change from the state C1. Since the conditions of step S13ofFIG. 11are satisfied, the intensity of radio waves radiated from the antenna103remains to be a weak state. When the θ1becomes lower than −15 degrees, the conditions of step S13are not satisfied. Therefore, the output controller142determines that the bottom surface is not horizontal, and controls the output adjustment unit121to increase the intensity of radio waves radiated from the antenna103. However, when the θ1becomes lower than −30 degrees, the control state of the image display direction changes into the state C2. At this time, the output controller142controls the output adjustment unit121to reduce the intensity of radio waves radiated from the antenna103again. Even when the user comes close to the side surface SD2, strong radio waves are prevented from being radiated to this user.

FIG. 13illustrates an example of the case where the tilt of the information processing apparatus100changes based on an operating state that the control state of the image display direction corresponds to the state C2. In this case, when the side surface SD1of the front side viewed from the user is turned upward among the side surfaces of the information processing apparatus100, the θ1detected by the gravity sensor122changes in a minus direction. Even if the θ1changes from zero degree in the minus direction, the control state of the image display direction will not change from the state C2. In the user's body, particularly, a groin part is estimated to remain to come close to the antenna103. Therefore, even if the θ1becomes from zero degree to lower than −30 degrees, the intensity of radio waves radiated from the antenna103remains to be a weak state irrespective of the determination result of step S13.

On the other hand, when the side surface SD2of the near side viewed from the user is turned upward among the side surfaces of the information processing apparatus100, the θ1detected by the gravity sensor122changes in a plus direction. When the θ1changes from zero degree to 30 degrees, the control state of the image display direction will not change from the state C2. Therefore, the intensity of radio waves radiated from the antenna103remains to be a weak state irrespective of the determination result of step S13. However, when the θ1exceeds 30 degrees, the control state of the image display direction changes into the state C1. At this time, since the user's groin part is estimated to be separated from the antenna103, the output controller142controls the output adjustment unit121to increase the intensity of radio waves radiated from the antenna103.

FIGS. 14 and 15illustrate an example of the case where a threshold θth1of the tilt for determining whether the display direction of an image is changed is equal to or smaller than a threshold θth2of the tilt for determining whether the bottom surface is approximately horizontal. Here, suppose, as one example, that both of the θth1and the θth2are 15 degrees.

FIG. 14illustrates an example of the case where the tilt of the information processing apparatus100changes based on an operating state that the control state of the image display direction corresponds to the state C1. In this case, when the side surface SD2of the front side viewed from the user is turned upward among the side surfaces of the information processing apparatus100, the θ1detected by the gravity sensor122changes in a plus direction. Even if the θ1changes from zero degree in the plus direction, the control state of the image display direction will not change from the state C1. When the θ1changes from zero degree to 15 degrees, the conditions of step S13are not satisfied. Therefore, the output controller142determines that the bottom surface is not horizontal, and controls the output adjustment unit121to increase the intensity of radio waves radiated from the antenna103.

On the other hand, when the side surface SD1of the near side viewed from the user is turned upward among the side surfaces of the information processing apparatus100, the θ1detected by the gravity sensor122changes in a minus direction. Even if the θ1changes from zero degree to −15 degrees, the control state of the image display direction will not change from the state C1. Since the conditions of step S13ofFIG. 11are satisfied, the intensity of radio waves radiated from the antenna103remains to be a weak state. When the θ1becomes lower than −15 degrees, the control state of the image display direction changes into the state C2, and at the same time, the conditions of step S13are not satisfied. Therefore, the output controller142controls the output adjustment unit121to increase the intensity of radio waves radiated from the antenna103.

FIG. 15illustrates an example of the case where the tilt of the information processing apparatus100changes based on an operating state that the control state of the image display direction corresponds to the state C2. In this case, when the side surface SD1of the front side viewed from the user is turned upward among the side surfaces of the information processing apparatus100, the θ1detected by the gravity sensor122changes in a minus direction. Even if the θ1changes from zero degree in the minus direction, the control state of the image display direction will not change from the state C2. The user's groin part is estimated to remain to come close to the antenna103. Therefore, even if the θ1becomes from zero degree to lower than −30 degrees, the intensity of radio waves radiated from the antenna103remains to be a weak state irrespective of the determination result of step S13.

On the other hand, when the side surface SD2of the near side viewed from the user is turned upward among the side surfaces of the information processing apparatus100, the θ1detected by the gravity sensor122changes in a plus direction. When the θ1changes from zero degree to 15 degrees, the control state of the image display direction will not change from the state C2. Since the conditions of step S13are satisfied, the intensity of radio waves radiated from the antenna103remains to be a weak state. When the θ1exceeds 15 degrees, the control state of the image display direction changes into the state C1, and at the same time the conditions of step S13are not satisfied. Therefore, the output controller142controls the output adjustment unit121to increase the intensity of radio waves radiated from the antenna103. Suppose that the control state of the image display direction corresponds to the state C2, and the θth1is equal to or smaller than the θth2. In this case, if the θ1is equal to or higher than zero degree, the output controller142controls the intensity of radio waves based on only a change in the display direction irrespective of the determination result of step S13.

Note that each of the θth1and the θth2changes according to a setting operation of the user.

Processing function of the above-described information processing apparatus1and100according to the present embodiments can be performed by a computer. In that case, there is provided a program having described therein processing contents of function with which each of the apparatus should be provided. When the program is executed by a computer, the above-described processing function is performed by a computer. The program having described therein the processing contents is recorded in a computer-readable recording medium. Examples of the computer-readable recording medium include a magnetic recording system, an optical disk, a magneto-optical recording medium, and a semiconductor memory. Examples of the magnetic recording system include an HDD (Hard Disk Drive), an FD (Floppy Disk), and a magnetic tape. Examples of the optical disk include a DVD (Digital Versatile Disk), a DVD-RAM, a CD-ROM (Compact Disk Read Only Memory), and a CD-R (Recordable)/RW (ReWritable). Examples of the magneto-optical recording medium include an MO (Magneto-Optical disk).

In the case of distribution of programs, portable recording media, such as DVD and CD-ROM with the recorded programs are sold. Also, programs are stored in a storage device of a server computer, and the programs are transferred to other computers from the server computer via a network.

The computer which executes the program stores, for example, a program recorded in a portable recording medium or a program transferred from the server computer in the storage device of the computer. The computer then reads out the program from the storage device of the computer, and executes processings according to the program. The computer may directly read out the program from the portable recording medium to execute the processings according to the program. The computer may also sequentially execute processings according to a received program every time the program is transferred from the server computer connected via a network.

As can be seen from various embodiments discussed above, the proposed information processing apparatus and radio wave intensity control method reduce a radiant quantity of radio waves to a human body coming close to a vertically downward direction of its own apparatus.

Further, the proposed program reduces a radiant quantity of radio waves to a human body coming close to a vertically downward direction of a computer.