Personal digital assistant and stereo reproduction method

1. A personal digital assistant provided with a display section housing having a display means and an operation section housing having a key input means connected by a rotatable hinge means, wherein the display section housing rotates relative to the operation section housing with the rotatable hinge means providing a central rotational axis, comprising:

a plurality of speakers arranged surrounding the display means;

a detection means for detecting an arbitrary position of the display section housing;

a speaker identifier means for identifying a speaker situated on a leftmost side relative to a display image displayed on the display means and a speaker situated on a rightmost side relative to the display image displayed on the display means among said plural speakers based on the position of the display section housing detected by the detection means, the leftmost and rightmost sides being identified on a two-dimensional plane including the arbitrary position of the display section; and

a sound reproduction control means for reproducing stereo sound with the speaker situated on the leftmost side and the speaker situated on the rightmost side identified by the speaker identifier means;

wherein the speaker identifier means identifies the speaker situated on the leftmost side and the speaker situated on the rightmost side based on a current position of the display section and an immediately previous position of the display section detected by the detection means.

2. The personal digital assistant according to claim 1 , further comprising an audio output switching means for switching output of stereo sound left audio and right audio relative to the plurality of speakers, respectively; and

wherein the sound reproduction control means reproduces stereo sound left audio output from the speaker situated on the leftmost side and stereo sound right audio output from the speaker situated on the rightmost side by controlling a switching operation according to the audio output switching means.

3. The personal digital assistant according to claim 1 , further comprising:

a mixing means for mixing and supplying stereo sound of the left audio and right audio relative to the plurality of speakers, respectively; and

wherein the sound reproduction control means reproduces stereo sound left audio output from the speaker situated on the leftmost side and stereo sound right audio output from the speaker situated on the rightmost side by controlling a mixture ratio according to the mixing means based on the position of the display section housing detected by the detection means.

4. The personal digital assistant according to claim 1 , wherein the position comprises an angle of the display section housing relative to the operation section housing.

5. The personal digital assistant according to claim 1 , wherein the position comprises an inclination of the display section housing relative to a horizontal plane.

6. The personal digital assistant according to claim 1 , further comprising:

an image processing means for processing the display image so that the display image displayed on the display means stands upright based on the position of the display housing detected by the detection means.

7. The personal digital assistant according to claim 1 , wherein the plurality of speakers have a first speaker situated on a lower end portion left side of the display means, a second speaker situated on a lower end portion right side of the display means and a third speaker situated on an upper end middle portion of the display means.

8. The personal digital assistant according to claim 1 , wherein the plurality of speakers have a first speaker, a second speaker, a third speaker and a fourth speaker respectively situated near the four corners of the display means.

9. A stereo reproduction method in a personal digital assistant provided with a display section housing having a display means and an operation section housing having a key input means connected by a rotatable hinge means, wherein the display section housing rotates relative to the operation section housing with the rotatable hinge means providing a central rotational axis, the method comprising the steps of:

detecting an arbitrary position of the display section housing;

identifying a speaker situated on a leftmost side relative to a display image displayed on the display means and a speaker situated on the rightmost side relative to a display image displayed on the display means from among a plurality of speakers arranged surrounding the display means based on a current position of the display section and an immediately previous detected position of the display section, the leftmost and rightmost sides being identified on a two-dimensional plane including the arbitrary position of the display section; and

reproducing stereo sound with the speaker situated on the leftmost side and the speaker situated on the rightmost side.

10. The stereo reproduction method according to claim 9 , wherein stereo sound is reproduced by left audio outputted from the speaker situated on the leftmost side and by right audio output from the speaker situated on the rightmost side by switching control of an output for the stereo sound left audio and right audio relative to the plurality of speakers, respectively.

11. The stereo reproduction method according to claim 9 , wherein the stereo sound is reproduced by the speaker situated on the leftmost side and the speaker situated on the rightmost side by controlling a mixture ratio of the stereo sound left audio and right audio relative to the plurality of speakers, respectively, based on the position of the display section housing.

12. The stereo reproduction method according to claim 9 , wherein the position comprises an inclination of the display section housing relative to the operation section housing.

13. The stereo reproduction method according to claim 9 , wherein the position comprises an inclination of the display section housing relative to a horizontal plane.

14. The stereo reproduction method according to claim 9 , wherein the display image is processed so that the display image displayed on the display means stands upright based on the position of the display housing.

15. A program documentation recording medium for storing a stereo reproduction computer program on a processor, which when used on a personal digital assistant provided with a display section housing having a display means and an operation section housing having a key input means connected by a rotatable hinge means causes stereo reproduction of stereo sound, wherein the display section housing rotates relative to the operation section housing with the rotatable hinge means providing a central rotational axis, the stereo reproduction computer program comprising:

program code for detecting an arbitrary position of the display

section housing;

program code for identifying a speaker situated on a leftmost side relative to a display image displayed on the display means and a speaker situated on a rightmost side relative to the display image displayed on the display means from among a plurality of speakers arranged surrounding the display means based on a current position of the display section and an immediately previous detected position of the display section, the leftmost and rightmost sides being identified on a two-dimensional plane including the arbitrary position of the display section; and

program code for reproducing the stereo sound with the speaker situated on the leftmost side and the speaker situated on the rightmost side.

16. The program documentation recording medium according to claim 15 , wherein the stereo sound is reproduced by outputting left audio from the speaker situated on the leftmost side and outputting right audio from the speaker situated on the rightmost side by switching control of the output for the stereo sound left audio and right audio relative to the plurality of speakers, respectively.

17. The program documentation recording medium according to claim 15 , wherein the stereo sound is reproduced by the speaker situated on the leftmost side and by the speaker situated on the rightmost side by controlling a mixture ratio of the stereo sound left audio and right audio relative to the plurality of speakers, respectively, based on the position of the display section housing.