1. A tire inflation pressure determining apparatus, comprising:
an antenna for converting variations in a supplied electromagnetic field applied from the exterior, and generating electromagnetic field fluctuations toward the exterior;
an inflation pressure sensor whose electric capacitance varies in accordance with air pressure inside a tire;
a sensor resonance circuit for producing electrical resonance in accordance with the electric capacitance;
a data generation circuit for generating transmission data that includes information of the air pressure on the basis of intensity of the electrical resonance; and
a response circuit for varying electric current that flows to the antenna in accordance with bit values of the transmission data represented by digital data, and generating the electromagnetic field fluctuations, wherein
the transmission data is transmitted to the exterior with the aid of the electromagnetic field fluctuations.
2. The tire inflation pressure determining apparatus of claim 1, wherein:
a clock generation circuit for generating a clock having a frequency that corresponds to the receiving frequency on the basis of the AC signals having a predefined receiving frequency outputted from the antenna, and
an excitation coil to which the clock is inputted, wherein
the sensor resonance circuit has a resonance coil that constitutes an LC resonance circuit together with the electric capacitance and is electromagnetically coupled to the excitation coil.
3. The tire inflation pressure determining apparatus of claim 2, wherein the antenna has a coil and a capacitor that constitute a parallel LC resonance circuit for resonating at the receiving frequency.
4. The tire inflation pressure determining apparatus of claim 1, wherein:
the apparatus is used under conditions that the supplied electromagnetic field varies at a supply frequency that is selectively switched between a first frequency and a second frequency in a time sharing fashion;
the antenna resonates at the first transmission frequency and increases the output of the drive power; and
the sensor resonance circuit has a resonance coil that constitutes an LC resonance circuit together with the electric capacitance and that is excited by the transmission electromagnetic field, and has a resonance frequency that corresponds to the second transmission frequency.
5. The tire inflation pressure determining apparatus of claim 4, wherein the antenna has a coil and a capacitor that constitute a parallel LC resonance circuit for resonating at the first frequency.
6. The tire inflation pressure determining apparatus of claim 1, wherein the response circuit is a switching circuit for switching impedance of the antenna in accordance with the bit value.
7. The tire inflation pressure determining apparatus of claim 1, wherein a power circuit for rectifying and accumulating AC drive power generated in the antenna.
8. The tire inflation pressure determining apparatus of claim 1, wherein a temperature sensor for determining temperature inside a tire, wherein the data generation circuit includes information about the temperature in the transmission data.
9. The tire inflation pressure determining apparatus of claim 1, wherein a memory in which associated information related to the tire on which the sensor unit is mounted is stored in advance, wherein the data generation circuit includes the associated information in the transmission data.
10. The tire inflation pressure determining apparatus of claim 1, wherein:
a level-sensing circuit for sensing a strong connection state in which amplitude of an AC signal outputted from the antenna in accordance with the variations in the transmission electromagnetic field is at a predefined level or higher; and
a response circuit for varying electric current that flows to the antenna in accordance with bit values of the transmission data represented by digital data, and generating the electromagnetic field fluctuations when the strong connection state has been sensed.
11. The tire inflation pressure determining apparatus of claim 10, wherein:
the data generation circuit generates the transmission data, which includes information of the strong connection state in addition to information of the air pressure; and
the rotational speed of a tire can be measured by allowing information of the strong connection state included in the transmission data to be periodically received in the exterior.
12. The tire inflation pressure determining apparatus of claim 10, wherein the antenna has a coil and a capacitor that constitute a parallel LC resonance circuit for resonating at a fluctuation frequency of the supplied electromagnetic field.
13. The tire inflation pressure determining apparatus of claim 10, wherein:
a clock generation circuit for generating, based the AC signal, a clock having a frequency that corresponds to a fluctuation frequency of the supplied electromagnetic field, and an excitation coil to which the clock is inputted; and wherein
the sensor resonance circuit has a resonance coil that constitutes an LC resonance circuit together with the electric capacitance and is electromagnetically coupled to the excitation coil.
14. A tire inflation pressure determining apparatus, comprising:
an antenna for converting variations in a supplied electromagnetic field applied from the exterior, and generating electromagnetic field fluctuations toward the exterior;
a level-sensing circuit for sensing a strong connection state in which amplitude of an AC signal outputted from the antenna in accordance with the variations in the supplied electromagnetic field is at a predefined level or higher;
an inflation pressure sensor for determining air pressure inside a tire;
a data generation circuit for generating transmission data that includes information of the air pressure; and
a response circuit for varying electric current that flows to the antenna in accordance with bit values of the transmission data represented by digital data, and generating the electromagnetic field fluctuations when the strong connection state has been sensed, wherein the transmission data is transmitted to the exterior with the aid of the electromagnetic field fluctuations.
15. The tire inflation pressure determining apparatus of claim 14, wherein the antenna has a coil and a capacitor that constitute a parallel LC resonance circuit for resonating at a fluctuation frequency of the supplied electromagnetic field.
16. The tire inflation pressure determining apparatus of claim 14, wherein:
the inflation pressure sensor has an electric capacitance that varies in accordance with the air pressure;
the tire inflation pressure determining apparatus furthermore has a sensor resonance circuit for generating electrical resonance in accordance with the electric capacitance; and
the data generation circuit generates transmission data that includes information of the air pressure on the basis of intensity of the electrical resonance.
17. The tire inflation pressure determining apparatus of claim 16, wherein:
a clock generation circuit for generating a clock having a frequency that corresponds to a fluctuation frequency of the supplied electromagnetic field on the basis of the AC signal, and an excitation coil to which the clock is inputted; and
the sensor resonance circuit has a resonance coil that constitutes an LC resonance circuit together with the electric capacitance and is electromagnetically coupled to the excitation coil.
18. The tire inflation pressure determining apparatus of claim 14, wherein the response circuit is a switching circuit for switching impedance of the antenna in accordance with the bit value.
19. The tire inflation pressure determining apparatus of claim 14, wherein a power circuit for rectifying and accumulating AC drive power generated in the antenna.
20. A tire inflation pressure determining apparatus, comprising:
an antenna for converting variations in a supplied electromagnetic field applied from the exterior, and generating electromagnetic field fluctuations toward the exterior,
a level-sensing circuit for sensing a strong connection state in which amplitude of an AC signal outputted from the antenna in accordance with the variations in the supplied electromagnetic field is at a predefined level or higher;
an inflation pressure sensor for determining air pressure inside a tire;
a data generation circuit for generating transmission data that includes information of the air pressure and information of the strong connection state; and
a response circuit for varying electric current that flows to the antenna in accordance with bit values of the transmission data represented by digital data, and generating the electromagnetic field fluctuations when the strong connection state has been sensed; and wherein
the transmission data is transmitted to the exterior with the aid of the electromagnetic field fluctuations, and the rotational speed of a tire can be measured by allowing information of the strong connection state to be periodically received at the exterior.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. An apparatus for producing spatially distributed sound into a set of headphones having left and right ear-cups, said apparatus comprising:
an input for receiving a sound signal including a left channel signal, a right channel signal, and a front channel signal;
dividing means for dividing the front channel signal into two secondary front channel signals;
left output means for outputting the left channel signal and one of the secondary front channel signals into the left ear-cup; and
right output means for outputting the right channel signal and another one of the secondary front channel signals into the right ear-cup.
2. An apparatus according to claim 1, wherein:
the left output means include a first and a second left transducer for respectively outputting the left channel signal and the one of the secondary front channel signals; and
the right output means include a first and a second right transducer for respectively outputting the right channel signal and the other one of the secondary front channel signals.
3. An apparatus according to claim 2, wherein:
the left output means include a third left transducer for outputting a copy of the right channel signal; and
the right output means include a third right transducer for outputting a copy of the left channel signal.
4. An apparatus according to claim 1, wherein the sound signal includes a rear channel signal, the dividing means being adapted to divide said rear channel signal into two secondary rear channel signals, the left output means being adapted to output one of said secondary rear channel signals into the left ear-cup, and the right output means being adapted to output another one of said secondary rear channel signals into the right ear-cup.
5. An apparatus according to claim 4, wherein:
the left output means include a first, second and third left transducer for respectively outputting the left channel signals and each one of the secondary front and rear channel signals; and
the right output means include a first, second and third right transducer for respectively outputting the right channel signal and each of the other ones of the secondary front and rear channel signals.
6. An apparatus according to claim 4, further comprising a stereophonic to surround sound decoding circuit for receiving a stereophonic signal and decoding said stereophonic signal to produce the sound signal supplied into the input.
7. An apparatus according to claim 6, wherein said stereophonic to surround sound decoding circuit comprises a 3D processor.
8. An apparatus according to claim 4, further comprising phase adjusting means for adjusting the phase of each of the front and rear channel signals.
9. An apparatus according to claim 4, wherein the left and right output means each include an acoustic delay line for introducing a delay of an order of a millisecond to the secondary rear channel signal with respect to the secondary front channel signal.
10. A set of headphones, comprising a left ear-cup, a right ear-cup and an apparatus according to claim 4.
11. A set of headphones according to claim 10, wherein the first left and right transducers are disposed towards a front portion of a corresponding one of the left and right ear-cups, the second left and right transducers being disposed in a central portion of said corresponding ear-cup, and the third left and right transducers being disposed towards a rear portion of said corresponding ear-cup.
12. A method for producing spatially distributed sound into a set of headphones having left and right ear-cups, said method comprising the steps of:
a) receiving a sound signal including a left channel signal, a right channel signal, and a front channel signal;
b) dividing the front channel signal into two secondary front channel signals;
c) outputting the left channel signal and one of the secondary front channel signals into the left ear-cup; and
d) outputting the right channel signal and another one of the secondary front channel signals into the right ear-cup.
13. A method according to claim 12, wherein the sound signal received in step a) includes a rear channel signal, and said method further comprises:
in step b), dividing said rear channel signal into two secondary rear channel signals,
in step c), outputting one of said secondary rear channel signals into the left ear-cup; and
in step d), outputting another one of said secondary rear channel signals into the right ear-cup.