HK1067802B - Electronic circuit, modulation method, information processing device, and information processing method - Google Patents

Description

Electronic circuit, modulation method, information processing apparatus, and information processing method

Technical Field

The invention relates to an electronic circuit, a modulation method, an information processing apparatus, and an information processing method. More particularly, the present invention relates to an electronic circuit in which the number of occurrences of communication failure at a receiving end is reduced when data is transmitted by an antenna including a resonance circuit in an amplitude modulation manner, a modulation method thereof, an information processing apparatus thereof, and an information processing method thereof.

Background

An IC (integrated circuit) card system employing a non-contact communication technique is constituted by a portable IC card and a device (hereinafter referred to as "R/W device") generally called a card reader/writer. The R/W device reads out information stored in the IC card in a non-contact manner and is capable of causing predetermined information to be stored in the IC card in a non-contact manner (refer to, for example, japanese unexamined patent application publication No.10-13312 corresponding to U.S. patent No.6,126,077).

More specifically, the IC card system is a very convenient system capable of reading and writing information in a non-contact manner, and has been used as an alternative system to a conventional magnetic card system typified by a commuter pass and an identification card, for example, in recent years.

Hitherto, the constitution of a transmitting section (a transmitting section is constituted by an antenna and a section for transmitting digital data in a modulator-demodulator) in an R/W device of an IC card system is, for example, as shown in fig. 1. In the following, the emission part is referred to as "emission device" by assuming that the emission part is a single device.

More specifically, as shown in fig. 1, the transmitting device 1 has a carrier output section 11 that outputs a carrier wave 21 of a predetermined frequency (e.g., 13.56MHz), a transmission data output section 12 that outputs a signal wave (rectangular wave) 22 of a predetermined frequency (e.g., 212kHz) corresponding to digital data to be transmitted (hereinafter referred to as "transmission data"), a modulation and amplification section 13 that generates an amplitude modulated wave 23 by changing and amplifying the amplitude of the carrier wave 21 in accordance with the signal waveform 22 and outputs the amplitude modulated wave 23, and an antenna section 14 having a resonance circuit constituted by a coil La and a capacitor Ca for outputting an electromagnetic wave 24 in accordance with the amplitude modulated wave 23 (e.g., transmitting the electromagnetic wave 24 to an IC card (not shown)).

The modulation and amplification section 13 also functions as a driving section (driving) of the antenna section 14 when viewed from the antenna section 14, as described later. Therefore, hereinafter, the modulation and amplification section 13 is also referred to as "antenna driving section 13".

More specifically, for example, the structure of the emitting device 1 is as shown in fig. 2.

That is, the modulation and amplification section 13 is constituted by the transistor TR1 and the transistor TR2 for modulation and amplification, the switch SW, the resistor R1 and the resistor R2 as emitter loads of the transistor TR1 and the transistor TR2, the coil L1, the coil L2, the capacitor C1, and the primary side of the transformer TR.

The carrier output section 11 is connected to the bases of the transistor TR1 and the transistor TR 2. However, the inverted signal of the carrier wave 21 input to the base of the transistor TR1 is input to the base of the transistor TR 2.

The resistor R1 has one end connected to the emitters of the transistors TR1 and TR2 and the other end connected to ground, and the resistor R2 has one end also connected to the emitters of the transistors TR1 and TR2 and the other end connected to the switch SW. The other end of the switch SW having one end connected to the resistor R2 is grounded. The switch SW performs a switching operation according to a change of the pulse signal 22 input from the transmission data output section 12.

The coil L1 has one end connected to the collector of the transistor TR1 and the other end connected to the voltage Vcc1, and a resonance circuit constituted by the capacitor C1 and the primary side coil of the transformer TR is also connected to the collector of the transistor TR 1. In the same manner, one end of the coil L2 is connected to the collector of the transistor TR2, the other end is connected to the voltage Vcc1, and a resonance circuit constituted by the capacitor C1 and the primary side coil of the transformer TR is also connected to the collector of the transistor TR 2.

The antenna portion 14 is designed as a closed circuit in which a secondary side coil La of a transformer Tr, a resistor Ra, and a capacitor Ca are connected in parallel. That is, the antenna portion 14 operates in such a manner that the coil La functions as a loop antenna and as an LCR resonance circuit constituted by the coil La, the resistor Ra, and the capacitor Ca.

Next, the operation of the emitting device of fig. 2 is described.

The carrier 21 of 13.56MHz from the carrier output section 11 is always applied to the bases of the transistor TR1 and the transistor TR 2.

In this state, when a pulse signal of 212KHz corresponding to transmission data is output from the transmission data output section 12, the switch SW performs a switching operation according to a change of the pulse signal 22. That is, when the switch SW is in the on state, since the resistor R2 is connected into the circuit, emitter loads of the transistor TR1 and the transistor TR2 become a combination of resistance values of the resistor R1 and the resistor R2. In contrast, when the switch SW is in the off state, since the resistor R2 is separated from the circuit, the emitter loads of the transistor TR1 and the transistor TR2 become the resistance value of the resistor R1.

As such, emitter loads of the transistor TR1 and the transistor TR2 vary according to the pulse signal 22 (transmission data) input from the transmission data output section 12. Then, as a result of the emitter load variation of the transistor TR1 and the transistor TR2, the emitter current varies accordingly, and the magnitude of the collector voltage Vc also varies between two levels. That is, collector voltage Vc corresponds to amplitude modulated wave 23.

The amplitude of the electromagnetic wave 24 output from the coil La of the antenna portion 14 also changes in accordance with the change in the amplitude of the collector voltage Vc (amplitude modulated wave 23).

In other words, the carrier wave 21 input to the bases of the transistor TR1 and the transistor TR2 is amplitude-modulated and amplified in accordance with the pulse signal 22 having two levels, i.e., a low level and a high level (by changes in the emitter currents of the transistor TR1 and the transistor TR2 corresponding to changes in the pulse signal 22), forming an amplitude-modulated wave 23 having two-stage amplitudes, i.e., a first stage corresponding to the high level of the pulse signal 22 and a second stage corresponding to the low level of the pulse signal 22. The amplitude modulated wave 23 is applied to the antenna portion 14 through the base electrodes of the transistor TR1 and the transistor TR 2. The antenna section 14 outputs an electromagnetic wave 24 based on the applied amplitude modulated wave 23, i.e. the electromagnetic wave 24 has two amplitude levels corresponding to the first and second levels.

However, when the electromagnetic wave 24 (digital data corresponding to the pulse signal 22 superimposed on the carrier wave 21) transmitted from the antenna portion 14 of the transmitting device 1 of fig. 2 according to the above-described operation is received and demodulated by the IC card having the limiter for limiting the input, the demodulated data is distorted within the operating range of the limiter, and as a result, a problem arises in that communication failure often occurs.

Summary of The Invention

The present invention has been made in view of the above circumstances. An object of the present invention is to reduce the number of occurrences of communication failure at a receiving end in the case of transmitting digital data through an antenna including a resonance circuit in an amplitude modulation manner.

To achieve the above object, in one aspect, the present invention provides a first electronic circuit for amplitude modulating digital data transmitted through an antenna including a resonant circuit, the electronic circuit comprising: a modulation circuit having a first transistor for amplitude-modulating a carrier wave applied to a base of the first transistor in accordance with a signal wave applied to an emitter of the first transistor to form an amplitude-modulated wave, and applying the amplitude-modulated wave to the antenna through a collector of the first transistor; and a signal wave generating circuit for inputting the first pulse signal in a rectangular waveform corresponding to the digital data, for generating a signal wave corresponding to the waveform-shaped second pulse signal so that a level at a rise time of each pulse of the first pulse signal is higher than a high level at a steady state of the first pulse signal and a level at a fall time of each pulse of the first pulse signal is lower than a low level at a steady state of the first pulse signal, and applying the generated signal wave to an emitter of the first transistor.

The signal wave generating circuit includes a load circuit as an emitter load of the first transistor; a load change circuit that changes an emitter load of the load circuit in accordance with the first pulse signal; and an extraction circuit that extracts a high-frequency component of the first pulse signal. Thus, a signal wave corresponding to the second pulse signal can be generated by applying the high-frequency component of the first pulse signal extracted by the extraction circuit to the load circuit.

The extraction circuit may be a differentiating circuit.

The signal wave generating circuit may further include a buffer connected to the input terminal of the extracting circuit.

The load change circuit includes a second transistor as a switch that is turned on and off in accordance with a first pulse signal applied to a base thereof, and a predetermined element that is a part of the emitter load may be disconnected from the load circuit when the second transistor is turned off, and the disconnected element may be connected to the load circuit when the second transistor is turned on, thereby changing the transmitter load. The signal wave generating circuit further includes an inverter circuit connected to the input terminal of the extracting circuit.

The inverter circuit may be constituted by a third transistor as a switch and a resistor.

The inverter circuit includes a set of NPN-type transistors and PNP-type transistors as the third transistor.

The inverter circuit may further include a schottky diode connected between the base and the collector of each of the NPN-type transistor and the PNP-type transistor.

There may be a plurality of first transistors, and an emitter resistance different from a resistance forming the load circuit may be connected to an emitter of one or more first predetermined transistors among the plurality of first transistors. The signal wave generating circuit may apply the signal wave of the second pulse signal corresponding to the shaped first pulse signal waveform to the emitters of the first transistors other than some of the plurality of first transistors whose emitters are connected to the emitter resistor.

In another aspect, the present invention provides a first modulation method using a modulation circuit having a transistor for amplitude-modulating digital data transmitted through an antenna including a resonance circuit, for amplitude-modulating a carrier wave applied to a base of the transistor in accordance with a signal wave applied to an emitter of the transistor to form an amplitude-modulated wave, and applying the amplitude-modulated wave to the antenna through a collector of the transistor, the modulation method comprising the steps of: inputting a first pulse signal of a rectangular waveform corresponding to digital data; generating a signal wave corresponding to the second pulse signal subjected to waveform shaping so that a level of a rise time of each pulse of the first pulse signal is higher than a high level at a steady state of the first pulse signal and a level of a fall time of each pulse of the first pulse signal is lower than a low level at a steady state of the first pulse signal; and applies the generated signal wave to the emitter of the transistor.

In the first electronic circuit and the first modulation method of the present invention, a first pulse signal of a rectangular waveform corresponding to digital data is input. Then, a signal wave corresponding to the waveform-shaped second pulse signal is generated so that the level at the rise time of each pulse of the first pulse signal is higher than the high level at the steady state of the first pulse signal, and the level at the fall time of each pulse of the first pulse signal is lower than the low level at the steady state of the first pulse signal. When the generated signal wave is applied to the emitter of the transistor, a carrier wave applied to the base of the transistor is amplitude-modulated in accordance with the signal wave corresponding to the second pulse signal applied to the emitter of the transistor, forming an amplitude-modulated wave. An amplitude-modulated wave is applied to an antenna including a resonance circuit through a collector of a transistor, and an electromagnetic wave based on the applied amplitude-modulated wave is emitted from the antenna.

The first electronic circuit of the present invention may be provided as a single device or as a part of an information processing apparatus. That is, for example, the first electronic circuit may function as a transmission section of an information processing apparatus that transmits and receives digital data, and the first electronic circuit may function as a wireless transmission section of an information processing apparatus that is capable of wired and wireless communication.

In another aspect, the invention provides a second electronic circuit for amplitude modulating digital data transmitted via an antenna including a resonant circuit, the electronic circuit comprising: a modulation circuit having a field effect transistor for amplitude-modulating a carrier wave applied to a gate of the field effect transistor in accordance with a signal wave applied to a source of the field effect transistor to form an amplitude-modulated wave, and applying the amplitude-modulated wave to an antenna through a drain of the field effect transistor; and a signal wave generating circuit for inputting the first pulse signal in a rectangular waveform corresponding to the digital data, for generating a signal wave corresponding to the waveform-shaped second pulse signal so that a level at a rise time of each pulse of the first pulse signal is higher than a high level at a steady state of the first pulse signal and a level at a fall time of each pulse of the first pulse signal is lower than a low level at a steady state of the first pulse signal, and applying the generated signal wave to a source of the field effect transistor.

In another aspect, the present invention provides a second modulation method using a modulation circuit having a field effect transistor for amplitude-modulating digital data transmitted through an antenna including a resonance circuit, for amplitude-modulating a carrier wave applied to a gate of the field effect transistor in accordance with a signal wave applied to a source of the field effect transistor to form an amplitude-modulated wave, and applying the amplitude-modulated wave to the antenna through a drain of the field effect transistor, the modulation method comprising the steps of: inputting a first pulse signal of a rectangular waveform corresponding to digital data; generating a signal wave corresponding to the second pulse signal subjected to waveform shaping so that a level of a rise time of each pulse of the first pulse signal is higher than a high level at a steady state of the first pulse signal and a level of a fall time of each pulse of the first pulse signal is lower than a low level at a steady state of the first pulse signal; and applies the generated signal wave to the source of the field effect transistor.

In the second electronic circuit and the second modulation method of the present invention, the first pulse signal of a rectangular waveform corresponding to the digital data is input. Then, a signal wave corresponding to the waveform-shaped second pulse signal is generated so that the level at the rise time of each pulse of the first pulse signal is higher than the high level at the steady state of the first pulse signal, and the level at the fall time of each pulse of the first pulse signal is lower than the low level at the steady state of the first pulse signal. When the generated signal wave is applied to the source of the field effect transistor, a carrier wave applied to the gate of the field effect transistor is amplitude-modulated in accordance with the signal wave corresponding to the second pulse signal applied to the source of the field effect transistor, forming an amplitude modulated wave. An amplitude-modulated wave is applied to an antenna including a resonance circuit through a drain of a field effect transistor, and an electromagnetic wave based on the applied amplitude-modulated wave is emitted from the antenna.

The second electronic circuit of the present invention may be provided as a single device or as a part of an information processing apparatus. That is, for example, the second electronic circuit may function as a transmission section of an information processing apparatus that transmits and receives digital data, and the second electronic circuit may function as a wireless transmission section of an information processing apparatus that is capable of wired and wireless communication.

In another aspect, the present invention provides an information processing apparatus that amplitude-modulates first digital information and transmits the information, the information processing apparatus including: a modulation device having a transistor for amplitude-modulating a carrier wave applied to a base of the transistor in accordance with a signal wave corresponding to first digital information applied to an emitter of the transistor to form an amplitude-modulated wave and outputting the amplitude-modulated wave through a collector of the transistor; a first output device for outputting a carrier wave applied to a base of the transistor; a second output device that outputs a first pulse signal of a rectangular waveform corresponding to the first digital information; signal wave generating means for generating a signal wave corresponding to the second pulse signal subjected to waveform shaping so that a level at a rise time of each pulse of the first pulse signal is higher than a high level at a steady state of the first pulse signal and a level at a fall time of each pulse of the first pulse signal is lower than a low level at a steady state of the first pulse signal, and applying the generated signal wave to an emitter of the first transistor; and an antenna device having a resonance circuit for transmitting an electromagnetic wave based on the amplitude modulated wave output from the modulation device to another information processing device.

The information processing apparatus may further include detection means for detecting a variation component of a waveform corresponding to the second digital information, which is transmitted from the other information processing apparatus and received by the antenna means; and demodulation means for demodulating a signal corresponding to the second digital information based on the variation component of the waveform detected by the detection means.

The other information processing apparatus may be an IC card capable of non-contact communication, and the information processing apparatus may be a card reader/writer apparatus that performs non-contact communication with the IC card through the antenna apparatus to write first information into the IC card and read second information from the IC card.

In another aspect, the present invention provides an information processing method for an information processing apparatus, the information processing apparatus including: a modulation circuit having a transistor for amplitude-modulating a carrier wave applied to a base of the transistor in accordance with a signal wave corresponding to digital information to be transmitted applied to an emitter of the transistor to form an amplitude-modulated wave and outputting the amplitude-modulated wave through a collector of the transistor; and an antenna having a resonance circuit for transmitting an electromagnetic wave based on the amplitude modulated wave output from the modulation circuit to another information processing apparatus, the information processing method including the steps of: outputting a carrier wave applied to the base of the transistor; outputting a first pulse signal of a rectangular waveform corresponding to digital information; a signal wave generating means for generating a signal wave corresponding to the second pulse signal subjected to waveform shaping so that a level at a rise time of each pulse of the first pulse signal is higher than a high level at a steady state of the first pulse signal and a level at a fall time of each pulse of the first pulse signal is lower than a low level at a steady state of the first pulse signal; and applies the generated signal wave to the emitter of the transistor.

In the information processing apparatus and the information processing method of the present invention, a first pulse signal of a rectangular waveform corresponding to digital data is input. Then, a signal wave corresponding to the waveform-shaped second pulse signal is generated so that the level at the rise time of each pulse of the first pulse signal is higher than the high level at the steady state of the first pulse signal, and the level at the fall time of each pulse of the first pulse signal is lower than the low level at the steady state of the first pulse signal. When the generated signal wave is applied to the emitter of the transistor, a carrier wave applied to the base of the transistor is amplitude-modulated in accordance with the signal wave corresponding to the second pulse signal applied to the emitter of the transistor, forming an amplitude-modulated wave. An amplitude-modulated wave is applied to an antenna including a resonance circuit through a collector of a transistor, and an electromagnetic wave based on the applied amplitude-modulated wave is emitted from the antenna.

The information processing apparatus may be an apparatus that transmits only digital data or an apparatus that can transmit and receive digital data. Data that can be transmitted and received by the information processing apparatus of the present invention may be only digital or analog and digital. Further, the information processing apparatus of the present invention may be an apparatus capable of wireless communication only or an apparatus capable of wired and wireless communication.

As described above, according to the present invention, digital data to be transmitted through an antenna including a resonance circuit can be amplitude-modulated. Specifically, the digital data may be amplitude-modulated in such a manner that the number of times of occurrence of communication failure at the receiving end is reduced.

Further, according to the present invention, digital data can be transmitted through an antenna including a resonance circuit using amplitude modulation. Specifically, communication in which the number of times of occurrence of communication failure at the receiving end can be reduced can be realized.

Drawings

Fig. 1 is a block diagram showing an example of the structure of a conventional transmitting apparatus;

fig. 2 is a block diagram showing a specific example of the structure of the conventional transmitting apparatus of fig. 1;

FIG. 3 is a graph of the measurement of collector voltage (amplitude modulated wave) for the emitter device of FIG. 2;

FIG. 4 is a measurement diagram of magnetic flux (electromagnetic waves) output from an antenna portion of the transmitting device of FIG. 2;

fig. 5 shows an example of waveforms when a receiving end demodulates digital data transmitted from the transmitting apparatus of fig. 2;

fig. 6 is a block diagram showing an example of the structure of a transmitting apparatus employing the present invention;

fig. 7 is a block diagram showing a detailed example of the structure of the shaped wave application section of the transmitting apparatus of fig. 6;

fig. 8 is a circuit diagram showing a specific example of the structure of the transmitting apparatus of fig. 6;

fig. 9 is a circuit diagram showing another specific example of the structure of the transmitting apparatus of fig. 6;

fig. 10 is a circuit diagram showing a specific example of the structure of an inverter of the transmitting device of fig. 9;

fig. 11 is a circuit diagram showing another specific example of the structure of an inverter of the transmitting device of fig. 9;

fig. 12 is a circuit diagram showing another specific example of the structure of an inverter of the transmitting device of fig. 9;

FIG. 13 is a graph of the measurement of collector voltage (amplitude modulated wave) for the emitter device of FIG. 9;

fig. 14 is a measurement diagram of magnetic flux (electromagnetic wave) output from an antenna portion of the transmitting apparatus of fig. 9;

fig. 15 is a circuit diagram showing another specific example of the structure of the transmitting apparatus of fig. 6;

fig. 16 is a circuit diagram showing another specific example of the structure of the transmitting apparatus of fig. 6; and

fig. 17 is a block diagram showing an example of the structure of an R/W device to which the present invention is applied.

Detailed Description

The applicant of the present application has analyzed the causes of the above-described conventional problems and devised the present invention based on the analysis results. Therefore, first, the analysis result, that is, the cause of the above-described conventional problem will be described.

By using the conventional transmitting apparatus 1 of fig. 2, the applicant of the present application measured the collector voltage Vc (amplitude modulated wave 23) and the magnetic flux (electromagnetic wave) 24 output from the antenna portion 14 in the case where the pulse signal 22 was actually input from the transmission data output portion 12. The measurement results are shown in fig. 3 and 4. That is, fig. 3 shows a measurement diagram of the pulse signal 22 and the collector voltage Vc (amplitude modulated wave 23) in the transmitting apparatus 1 of fig. 2, and fig. 4 shows the pulse signal 22 and the magnetic flux (electromagnetic wave) 24 output from the antenna portion 14.

As shown in fig. 3, the collector voltage Vc (amplitude modulated wave 23) of the driving antenna portion 14 follows the pulse signal 22. For example, as shown in the change section 23-1, at the rise time of the pulse signal 22 (when changing from the low level to the high level), the amplitude of the collector voltage Vc (amplitude modulated wave 23) also immediately changes from the low level to the high level with the change. Also, as shown in the change section 23-2, at the falling time of the pulse signal 22 (when changing from the high level to the low level), the amplitude of the collector voltage Vc (amplitude modulated wave 23) also immediately changes from the low level to the high level with the change.

However, as shown in fig. 4, the magnetic flux (electromagnetic wave) 24 output from the antenna portion 14 does not change immediately with the pulse signal 22, but has a delay with respect to the change of the pulse signal 22. For example, as shown in the changing section 24-1, at the rise time of the pulse signal 22, the magnetic flux (electromagnetic wave) 24 does not change immediately therewith, and the change in the amplitude of the magnetic flux (electromagnetic wave) 24 from the low level to the high level becomes a waveform of a first order delay manner. Also, as shown in the changing section 24-2, at the falling time of the pulse signal 22, the magnetic flux (electromagnetic wave) 24 does not change immediately therewith, and the change in the amplitude of the magnetic flux (electromagnetic wave) 24 from the high level to the low level becomes a waveform in a first order delay manner.

After the magnetic flux (electromagnetic wave) 24 is transmitted from the antenna portion 14, as shown in fig. 4, when the signal is received and detected by a receiving device (not shown) in a normal state, the waveform 25 shown in fig. 5 is detected. Although not shown, the detected waveform 25 may be demodulated in a form closer to the pulse signal 22 corresponding to the transmission data.

In contrast, when the receiving apparatus is, for example, a limiter having a limit input as described above, i.e., an IC card in a limiter operating state (not shown), the waveform 26 shown in fig. 5 is detected. As shown in fig. 5, when the detected waveform 26 is higher than a predetermined level of the comparator (broken line drawn in the waveform 26 in fig. 5), the detected waveform 26 reaches a high level (hereinafter also referred to as "H"), and when lower than the predetermined level (hereinafter also referred to as "L"), the detected waveform 26 reaches a low level, thereby demodulating the signal 27 shown in fig. 5. As shown in fig. 5, the demodulated signal 27 is greatly different from the original signal (pulse signal 22), and as a result, a communication failure occurs.

In the above manner, the above problem occurs because the magnetic flux (electromagnetic wave) 24 output from the antenna portion 14 of fig. 2 does not immediately follow the pulse signal 22 corresponding to the transmission data but has a delay.

The mechanism of generating the delay of the magnetic flux (electromagnetic wave) 24 is described below.

When the resonance circuit of the antenna part 14 is in a resonance state, the antenna part 14 stores energy therein in the form of a resonance current (hereinafter, this energy will be referred to as "resonance energy"), and unless energy is supplied by the antenna driving part 13, the resonance energy will be consumed for a limited period of time.

In other words, the antenna driving portion 13 drives the antenna portion 14 by supplying predetermined energy to the antenna portion 14 (hereinafter, the energy will be referred to as "driving energy" so as to be distinguished from resonance energy).

The higher the Q factor (quality factor) of the antenna portion 14, the longer it takes to consume the resonance energy.

Therefore, if a signal of a predetermined level is output from the transmission data output section 12 instead of the pulse signal 22, the amplitude of the collector voltage Vc becomes fixed, thereby reaching a stable state in which the loss of the resonance current of the antenna section 14 and the drive energy are equal to each other, the resonance current becomes fixed, and as a result, the amplitude of the output magnetic flux (electromagnetic wave) 24 also becomes fixed.

In contrast, in the above manner, since the pulse signal 22 is output from the transmission data output section 12, the amplitude of the collector voltage Vc (amplitude modulated wave 23) also varies. It is assumed here that the amplitude of collector voltage Vc changes in such a way that it changes immediately with pulse signal 22. In this case, for example, at the rise time of the pulse signal 22, the amplitude of the collector voltage Vc changes from low level to high level, the drive energy increases and becomes larger than the loss of the resonance circuit, and the resonance current gradually increases. Subsequently, when the increased driving energy and the loss reach a steady state equal to each other, the resonance current becomes stable. As a result, the amplitude of the magnetic flux (electromagnetic wave) 24 also becomes fixed at a predetermined level (high level) higher than the level before the change (low level).

However, since the resonance energy is Q times of the loss, a fixed time is required to reach a steady state (a state where the increased driving energy and the loss are equal to each other). As a result, the magnetic flux (electromagnetic wave) 24 output from the antenna portion 14 is delayed with respect to the pulse signal 22 corresponding to the transmission data. That is, it takes a fixed time (delay) from the rise time of the pulse signal 22 for the amplitude of the magnetic flux (electromagnetic wave) 24 to reach the high level from the low level.

For the same reason, it takes a fixed time (delay) from the falling time of the pulse signal 22 for the amplitude of the magnetic flux (electromagnetic wave) 24 to reach the low level from the high level.

Thus, as a technique for eliminating such a delay of the magnetic flux (electromagnetic wave) 24, that is, as a technique for solving the above-described conventional problem, the applicant of the present application invented a technique for reinforcing a changed portion of the driving energy (this portion corresponds to the rise and fall of the pulse signal 22) when the signal corresponding to the transmission data is a signal having a change similar to that of the pulse signal 22, and also invented a transmission apparatus according to this technique as shown in fig. 6. That is, fig. 6 shows an example of the structure of a transmitting apparatus employing the present invention.

In the transmitting apparatus 51 shown in fig. 6, components corresponding to those of the conventional transmitting apparatus (fig. 1) are denoted by the same reference numerals, and description thereof is appropriately omitted.

As shown in fig. 6, the transmitting apparatus 51 further includes a shaped wave applying section 61 between the transmission data output section 12 and the modulating and amplifying section (antenna driving section) 13 when compared with the conventional transmitting apparatus 1.

More specifically, as shown above, normally (in fig. 1), a signal wave corresponding to the pulse signal 22 itself output from the transmission data output section 12 is applied to the modulation and amplification section 13, and as a result, the amplitude modulated wave 23 is output from the modulation and amplification section 13. In this case, as described above, when the driving energy corresponding to the amplitude modulated wave 23 is applied to the antenna portion 14, a delay occurs in the magnetic flux (electromagnetic wave) 24 output from the antenna portion 14.

Therefore, in the transmitting apparatus 51 of fig. 6, the shaped wave applying section 61 inputs the first pulse signal 22 of the rectangular waveform corresponding to the transmission data output from the transmission data outputting section 12; generating a signal wave corresponding to the second pulse signal 71 which has been subjected to waveform shaping so that the level at the rise time of each pulse of the first input pulse signal 22 is higher than the high level (H) at the time when the first pulse signal 22 is in a steady state, and the level at the fall time of each pulse of the first input pulse signal 22 is lower than the low level at the time when the first pulse signal 22 is in a steady state; and applies the resulting signal wave to the modulation and amplification section 13.

As a result, the carrier wave 21 output from the carrier wave output section 11 is amplitude-modulated and amplified by the modulation and amplification section 13 in accordance with the signal wave corresponding to the second pulse signal 71, an amplitude-modulated wave 72 reinforced by an amplitude variation section is formed (in fig. 6, the actual modulated wave is omitted, only the amplitude variation section is shown), and driving energy corresponding to the amplitude-modulated wave 72 is applied to the antenna section 14. As a result, an electromagnetic wave 73 whose amplitude level changes almost immediately with the pulse signal 22 is output from the antenna portion 14 (in fig. 6, the actual modulated wave is omitted, and only the amplitude change portion is drawn).

In the above manner, in the transmitting apparatus 51 in fig. 6, since the change of the electromagnetic wave 73 output from the antenna portion 14 becomes faster, the number of times of the above-described communication failure occurring at the receiving end can be reduced. That is, the problems existing in the conventional methods can be solved.

There is no particular limitation on the structure of the shaped wave applying section 61 as long as it is possible to apply the signal wave corresponding to the second pulse signal 71 to the modulating and amplifying section 13 to thereby shape the waveform of the first pulse signal 22. In the present example, the shaping wave applying section 61 has, for example, a structure shown in fig. 7.

More specifically, as shown in fig. 7, the shaping wave applying section 61 includes a high-frequency component extracting section 81 for extracting a high-frequency component 91 of the first pulse signal 22 output from the transmission data outputting section 12; and an applying section 82 for outputting a signal wave corresponding to the second pulse signal 71, so that the high-frequency component 91 of the first pulse signal 22 extracted by the high-frequency component extracting section 81 is added to the first pulse signal 22 output from the transmission data outputting section 12.

More specifically, the transmitting device 51 of fig. 6 may be constituted as shown in fig. 8 or 9. In the transmitter 51 of fig. 8 and 9, components corresponding to those of the conventional transmitter 1 of fig. 2 are denoted by the same reference numerals, and descriptions thereof are omitted as appropriate.

In fig. 8, further, when compared with the transmission device 1 of fig. 2, in the transmission device 51, a series circuit of a capacitor C2 and a buffer 101 connected in series is connected between the emitters of the transistor TR1 and the transistor TR2 and the transmission data output section 12.

More specifically, in the example of fig. 8, the shaped wave applying section 61 is constituted by a capacitor C2, a buffer 101, a resistor R1 and a resistor R2 which are emitter loads and are also used for the conventional modulating and amplifying section 13, and a switch SW for changing the emitter loads.

A differentiating circuit formed by the capacitor C2 and the emitter load (variable load formed by the resistor R1 and the resistor R2) corresponds to the high-frequency component extracting section 81 of fig. 7.

The buffer 101 is provided for following purposes. That is, when the switch SW is, for example, a transistor, since the transmission data output section 12 as a signal source of the pulse signal 22 has a limited output impedance, if the transmission data output section 12 is directly connected to an emitter load, a problem arises that variation of the transistor as a switch is delayed. Therefore, in the example of fig. 8, in order to solve this problem, a buffer 101 is provided between the transmission data output section 12 and the capacitor C2.

The switch SW for changing the emitter load is not particularly limited, and, for example, an NPN type transistor may be used. In this case, as shown in fig. 9, one end of the resistor R1 is connected to the emitters of the transistors TR1 and TR2, the other end is grounded, one end of the resistor R2 is also connected to the emitters of the transistors TR1 and TR2, and the other end is connected to the collector of the transistor TRs. Further, the transmission data output section 12 is connected to the base of the transistor TRs, and the emitter of the transistor TRs is grounded.

However, in the case of using the NPN-type transistor TRs as a switch, the current of the transistor TR1 and the transistor TR2 of the modulation and amplification section 13 is required to be increased at the timing (at the rising time of the pulse) when the pulse signal 22 applied to the base of the transistor TRs reaches the high level (H). This corresponds to the case where a negative pulse component is added to the emitter loads of the transistor TR1 and the transistor TR 2. This can be achieved by converting the pulse signal 22 output from the transmission data output section 12 using an inverter and then passing the signal through a high-pass filter. More specifically, as shown in fig. 9, the buffer 101 of fig. 8 may be replaced with an inverter 111.

The inverter 111 may be implemented in various ways as shown in fig. 10 to 12. Of course, the inverter 111 may be constructed in a different manner from that of fig. 10 to 12.

In the example of fig. 10, the inverter 111 is formed of a transistor TRi1, a resistor Ri1, a resistor Ri2, and a resistor Ri3 as switches.

The resistor Ri1 has one end connected to the base of the transistor TRi1 and the other end connected to the emission data output section 12, and the resistor Ri2 has one end also connected to the base of the transistor TRi1 and the other end connected to ground. The emitter of transistor TRi1 is grounded. One end of the above-described capacitor C2 forming a differential circuit is connected to the collector of the transistor TR1 (the other end is connected to the emitter of the transistor TR1 and the transistor TR2, as shown in fig. 9, for example), one end of the resistor Ri3 is also connected to the collector of the transistor TR1, and the other end is applied with the voltage Vcc 2.

Thus, the inverter 111 having the structure of fig. 10 has a simple structure. On the other hand, the inverter 111 has a problem in that power is consumed when the transistor TRi1 is in an on state. Therefore, when it is necessary to solve the problem, that is, when the inverter 111 is required to consume no current, the inverter 111 may be configured, for example, as shown in fig. 11. That is, in the example of fig. 11, the inverter 111 is formed of a PNP type transistor TRi2, an NPN type transistor TRi3, and resistors Ri4 to Ri 7.

The resistor Ri4 has one end connected to the base of the transistor TRi2 and the other end connected to the emission data output section 12, and the resistor Ri5 has one end also connected to the base of the transistor TRi2 and the other end applied with the voltage Vcc 2. Voltage Vcc2 is applied to the emitter of transistor TRi 2. One end of the above-described capacitor C2 forming a differential circuit is connected to the collector of the transistor TR2 (the other end is connected to the emitters of the transistor TR1 and the transistor TR2, for example, as shown in fig. 9), and the collector of the transistor TR 3 is also connected to the collector of the transistor TR 2.

In other words, one end of the capacitor C2 is connected to the collector of the transistor TRi3, and the collector of the transistor TRi2 is also connected to the collector of the transistor TRi 3.

The resistor Ri6 has one end connected to the base of the transistor TRi3 and the other end connected to the emission data output section 12, and the resistor Ri7 has one end also connected to the base of the transistor TRi3 and the other end connected to ground. The emitter of transistor TRi3 is grounded.

Further, when the operating speed of the inverter 111 is required to be high, for example, the inverter 111 may be configured as shown in fig. 12.

That is, in the example shown in fig. 12, in comparison with the inverter 111 having the configuration of fig. 11, schottky diode Di1 is connected between the base and collector of PNP transistor TRi2, and schottky diode Di2 is connected between the base and collector of NPN transistor TRi 3.

In the above-described embodiment, since the inverter 111 is configured as shown in fig. 12, when the voltage is lower than the predetermined voltage, by causing a current to flow through the schottky diode Di1, it is possible to suppress a drop in the emitter voltage with respect to the base of the transistor TRi 2. Also, when the voltage is lower than the predetermined voltage, by causing a current to flow through the schottky diode Di2, it is possible to suppress a drop in the emitter voltage with respect to the base of the transistor TRi 3. That is, the storage time of the transistors TRi2 and TRi3 is reduced, and the switching speed of the transistors TRi2 and TRi3 is increased.

The voltage Vcc2 shown in fig. 10 through 12 may be from the same power source (not shown) as the voltage Vcc1 of fig. 9, or may be a voltage from a different power source (not shown).

Next, the operation of the transmitting device 51 will be described. The transmitting means 51 may be implemented in various ways as described above. Unless otherwise specified, the description is given assuming that the transmitting device 51 is a transmitting device having the structure shown in fig. 9.

Further, the operation of the transmitting device 51 is substantially the same as that of the conventional transmitting device 1 of fig. 2. Therefore, here, description of the operation that has been described in the conventional transmitting apparatus 1 is appropriately omitted, and in the following description, emphasis will be placed on description of operations different from those of the conventional transmitting apparatus 1.

More specifically, as shown in fig. 9, when the first pulse signal 22 is output from the transmission data output section 12, the shaping wave applying section 61 switches the transistor TRs in accordance with the first pulse signal 22 in a manner similar to the conventional case, so that the emitter load of the transistor TR1 and the transistor TR2 changes (becomes the value of the resistor R1 or the combination of the resistance values of the resistor R1 and the resistor R2), and also adds the high frequency component (the high frequency component 91 of fig. 7) of the first pulse signal 22 extracted by the differentiating circuit including the capacitor C2 through the inverter 111 to the emitter load.

The shaping wave applying section 61 operates as follows: the emitter currents corresponding to the signal waves applied to the emitters of the transistor TR1 and the transistor TR2 are made to vary corresponding to the second pulse signal 71, thereby shaping the waveform of the first pulse signal 22. In other words, the shaping wave applying section 61 applies the emitter current (signal wave) varying with the second pulse signal 71 to the emitters of the transistor TR1 and the transistor TR 2.

As a result of the above operation, when the first pulse signal 22 changes (at the rise time and the fall time of each pulse), the emitter currents (signal waves) of the transistor TR1 and the transistor TR2 greatly change immediately. As a result, collector voltage Vc (amplitude modulated wave 72) with an enhanced amplitude of variation appears as shown by variation portion 72-1 and variation portion 72-2 in fig. 13. Then, the driving energy corresponding to the generated collector voltage Vc (amplitude modulated wave 72) is applied to the antenna portion 14, and a magnetic flux (electromagnetic wave) 73 shown in fig. 14 is output from the antenna portion 14.

Accordingly, fig. 13 shows a measurement diagram of collector voltage Vc (amplitude modulated wave 72) actually output in the case where first pulse signal 22 is output from transmission data output section 12 in transmission device 51 of fig. 9. Fig. 14 shows a measurement diagram of the magnetic flux (electromagnetic wave) 73 actually output in the case where the first pulse signal 22 is output from the transmission data output section 12 in the transmission device 51 of fig. 9.

As shown in fig. 13, the amplitude of the collector voltage Vc (amplitude modulated wave 72) changes in a manner corresponding to the waveform-shaped second pulse signal 71 (fig. 6) so that the level at the rise time of each pulse of the first input pulse signal 22 is higher than the high level (H) when the first pulse signal 22 is in a steady state, and the level at the fall time of each pulse of the first input pulse signal 22 is lower than the low level when the first pulse signal 22 is in a steady state. That is, as shown in the change portion 72-1, the amplitude of the collector voltage Vc (amplitude modulated wave 72) at the rise time of each pulse of the first input pulse signal 22 is higher than the high level when the first pulse signal 22 is in the steady state. Also, as shown in the change section 72-2, the amplitude of the collector voltage Vc (amplitude modulated wave 72) at the falling time of each pulse of the first input pulse signal 22 is lower than the low level when the first pulse signal 22 is in the steady state.

As a result, as shown in fig. 14, the magnetic flux (electromagnetic wave) 73 output from the antenna portion 14 changes almost immediately with the pulse signal 22 corresponding to the transmission data, as compared with the above-described conventional magnetic flux (electromagnetic wave) 24 of fig. 4. For example, as shown in the changing section 73-1, at the rising time of each pulse of the first input pulse signal 22, the amplitude of the magnetic flux (electromagnetic wave) 73 also changes from the low level to the high level almost immediately with the rise. Also, as shown in the changing section 73-2, at the falling time of each pulse of the first input pulse signal 22, the amplitude of the magnetic flux (electromagnetic wave) 73 changes from the high level to the low level almost immediately with the fall.

In the above, although the transmitting device 51 is described in conjunction with fig. 8 and 9, the transmitting device 51 is not limited to the structure of the example in fig. 8 or 9 and may be implemented in various ways as long as the transmitting device 51 can output the collector voltage Vc (amplitude modulated wave 72) as shown in fig. 13.

For example, in the examples of fig. 8 and 9, in order to reduce the influence of in-phase noise (in-phase), the transmission device 51 is designed in such a structure: the transistor TR1 and the transistor TR2 for modulation and amplification are connected differentially. Alternatively, the transmitting device 51 may be formed of only one of the transistor TR1 and the transistor TR 2.

Further, in practice, since the transistors for modulation and amplification require a large current, instead of using a single transistor TR1 and a transistor TR2 which are differentially connected as shown in fig. 8 and 9, two groups of transistors in which a plurality of transistors are connected in parallel are often used, and the two groups are differentially connected.

More specifically, for example, the transmitter 51 is configured in the manner shown in fig. 15, with the transistor TR1 of fig. 9 being replaced by a set of two transistors TR1 and TR2 connected in parallel, and the transistor TR2 of fig. 9 being replaced by a set of two transistors TR1 and TR2 connected in parallel, the two sets of transistors being differentially connected.

In this case, the signal wave corresponding to the second pulse signal 71 (fig. 6) obtained by shaping the waveform of the first pulse signal 22 corresponding to the transmission data may be applied to all the emitters of the transistor TR1-1 and the transistor TR1-2 and the emitters of the transistor TR2-1 and the transistor TR2-2 (the emitter loads of all the transistors of each group may be changed, and the high-frequency component of the first pulse signal 22 may be applied to all the emitter loads), but the following problem arises.

That is, as shown in fig. 17 (described later), in the case where the transmission device 51 is incorporated into the R/W device 121 of the IC card system, if the IC card 122 as the communication party is too close to the R/W device 121, there is a case where the load of the transmission device 51 varies. In this case, there is a problem that when the amplitude of the amplitude modulated wave 72 of fig. 6 varies, power transmission is interrupted because the peak value is too strong (the portion corresponding to the high frequency component of the first pulse signal 22) is too strong.

Therefore, in order to solve the problem, that is, in order to secure electric power required for emission, as shown in fig. 15, a signal wave corresponding to the second pulse signal 71 (fig. 6) may be applied only to the emitters of the transistor TR1-1 and the transistor TR1-2, and one end of the emitter resistor R3 may be connected to the emitters of the transistor TR1-2 and the transistor TR2-2 (the other end is grounded), instead of the above. In other words, as shown in fig. 15, the emitter load (the emitter load formed by the resistor R1 and the resistor R2 which varies according to the switching of the transistor TRs) which varies according to the first pulse signal 22 output from the transmission data output section 12 and the high frequency component of the first pulse signal 22 output from the differential circuit including the capacitor C2 through the inverter 111 are applied only to the emitters of the transistor TR1-1 and the transistor TR2-1, and the emitter loads of the transistor TR1-2 and the transistor TR2-2 other than the above can be constant.

The transmitter 51 may be configured as shown in fig. 16, for example.

More specifically, in the example of fig. 16, when compared with the example of fig. 9, the collector of the switching transistor TRs2 is connected to one end of the resistor R1 (the other end opposite thereto is connected to the emitters of the transistor TR1 and the transistor TR 2). The emitter of the transistor TRs2 is grounded. One end of the resistor R4 is connected to the base of the transistor TRs2, and the other end is applied with the voltage Vcc 2. That is, the transistor TRs2 is always on.

The differential circuit formed by the resistor R5 and the capacitor C2, which are grounded at one end, is also connected to the base of the transistor TRs 2. That is, in the example of fig. 9, the high frequency component of the first pulse signal output from the transmission data output section 12 is directly applied to the emitters of the transistor TR1 and the transistor TR 2. However, in the example of fig. 16, a high frequency component is applied to the base of the transistor TRs 2. The transistor TRs1 is the same as the transistor TRs of fig. 9.

Further, the transmitting device 51 may be a single device as in the above-described embodiments. Alternatively, the transmitting device 51 may be incorporated into the information processing device as a part of the information processing device.

For example, as shown in fig. 17, the transmitter 51 may be a part of the R/W device of the IC card system described above. That is, fig. 17 shows an example of the structure of the R/W device to which the present invention is applied.

As shown in fig. 17, the R/W device 121 has a main control part 131 and a data storage part 132 that control the entire R/W device 121.

The main control portion 131 has a CPU (central processing unit) 141, a ROM (read only memory) 142(412), and a RAM 143. The CPU 141 performs various processes in accordance with a program stored in the ROM 142 or a program loaded from the data storage portion 132 or the like into the RAM 143. In the RAM 143, data necessary for the CPU 141 to perform various processes is appropriately stored.

The main control section 131 also has a carrier output section 11 and a transmission data output section 12, which are the same as those in fig. 6.

The R/W device 121 also has a modulation and amplification section 13, an antenna section 14, and a shaped wave application section 61, which are the same as those in fig. 6.

In other words, in the R/W device 121, as a transmitting section, the transmitting device 51 introduced has the same structure as that in fig. 6.

The R/W device 121 also has a detection section 133, a demodulation section 134, and a data input section 144 in the main control section 131, constituting a reception section with respect to the above-described transmission section (transmission device 51).

Next, the operation of the R/W device 121 will be briefly described.

When the IC card 122, which is a communication party of the R/W device 121, is placed at a predetermined distance (communication distance) facing the antenna portion 14 of the R/W device 121, the antennas of the IC card 122 catch the magnetic flux output from the antenna portion 14 and resonate with each other, thereby reaching a state in which they are capable of non-contact communication with each other.

In this state, when the first digital information (data written to the IC card 122, etc.) stored in advance in the data storage portion 132 is output as a pulse signal from the transmission data output portion 12, a signal is superimposed on the carrier wave (amplitude modulated wave) output from the carrier wave output portion 11 according to the same operation principle as the transmitting device 51, the wave is applied to the antenna portion 14, and the wave is output as an electromagnetic wave from the antenna portion 14.

The electromagnetic wave output from the antenna portion 14 is received by the antenna of the IC card 122, and the wave is detected and demodulated into the first original information by the IC of the IC card 122 in the above-described manner. When the first information is data to be stored in a memory (not shown), the first information is stored in the memory in the IC. On the other hand, when the first information is an instruction to read out information, predetermined information is read out from a memory in the IC based on the first information.

The response data reporting that the first information is recorded in the memory or the data (second digital information) read out from the memory in the IC card is superimposed on the carrier wave by the IC, and the wave is applied to the antenna part 14 of the R/W device 121 through the antenna of the IC card 122.

More specifically, in this example, in the IC card 22, after the second information is encoded, the equivalent load of the antenna of the IC card 122 is varied according to the logical value of the signal.

The load variation of the antenna of the IC card 122 appears as a load variation at the antenna end of the antenna part 14 of the R/W device 121.

Therefore, the detection section 133 detects the load variation as an amplitude variation component of the carrier wave, that is, an ASK (amplitude shift keying) modulation signal.

That is, in this example, for transmission of data from the IC card 122 to the R/W device 121, a load modulation method is adopted, and after the data to be transmitted is encoded, the radiated electromagnetic wave is ASK-modulated by changing the load as viewed from the antenna end to the inside according to the logical value of the signal.

The demodulation section 134 demodulates a pulse signal corresponding to the second digital information from the ASK modulated signal (amplitude variation component of the carrier wave) detected by the detection section 133, and applies the pulse signal to the received data input section 144.

When the second digital information corresponding to the pulse signal from the demodulation section 134 is response data, the reception data input section 144 supplies it to the CPU 141. On the other hand, when the second digital information is data to be written to the data storage portion 132, the data is written (stored) to the data storage portion 132. When the response data is obtained, the CPU 141 performs processing corresponding to the response data.

In this manner, the R/W device 121 performs non-contact communication with the IC card 122 via the antenna portion 14, writes the first digital information into the IC card 122, and reads the second digital information from the IC card 122.

In the above-described mode, in the transmitting apparatus 51 (fig. 6) of the present invention, the first pulse signal 22 of a rectangular waveform corresponding to the transmission data is input. The signal wave corresponding to the waveform-shaped second pulse signal 71 is generated so that the level at the rise time of each pulse of the first input pulse signal 22 is higher than the high level (H) when the first pulse signal 22 is in the steady state, and the level at the fall time of each pulse of the first input pulse signal 22 is lower than the low level when the first pulse signal 22 is in the steady state. The generated signal wave is applied to the emitters of the transistors (for example, the transistor TR1 and the transistor TR2 of fig. 9) of the modulation and amplification section 13. As a result, the carrier wave 22 applied to the base of the transistor is amplitude-modulated into the amplitude modulated wave 72 in accordance with the signal wave corresponding to the second pulse signal 71 applied to the emitter of the transistor. The amplitude-modulated wave 72 is applied to the antenna portion 14 through the collector of the transistor (driving power is supplied), and the amplitude-modulated wave 72 is emitted as an electromagnetic wave 73 from the antenna portion 14 including the resonance circuit.

Since the amplitude of the electromagnetic wave 73 output from the antenna portion 14 changes almost instantaneously with the first pulse signal corresponding to the above-described transmission data, the electromagnetic wave 73 received by the receiver can be demodulated almost accurately by the receiver into the first original pulse signal 22. That is, it is possible for the transmitting apparatus 51 of the present invention to reduce the number of times of communication failure at the receiving end.

Further, for example, as shown in fig. 9, the transmission apparatus 51 can be constituted by adding a simple circuit constituted by the capacitor C2 and the inverter 111 to the conventional transmission apparatus 1 (fig. 2), so the transmission apparatus 51 can be manufactured at substantially the same cost and at almost the same level of hardware resources as the conventional transmission apparatus 1.

In other words, the transmitting apparatus 51 can be constituted only by a simple work without requiring modification of cost and addition of the shaped waveform applying section 61 in the conventional transmitting apparatus 1. More specifically, for example, when the conventional transmission device 1 having the structure of fig. 2 is modified to the transmission device 51 having the structure of fig. 9, a person who performs the modification may connect the capacitor C2 and the inverter 111 as shown in fig. 9.

In the above-described embodiment of the emitting device 51, a transistor is used. Alternatively, a field effect transistor (FET transistor) may be used instead of the transistor in addition to the structure shown in fig. 12.

For example, in the transmitter device 51 having the structure of fig. 9, the transistor TR1 and the transistor TR2 may be replaced with a field effect transistor FET1 and a field effect transistor FET2 (not shown), respectively. However, in this case, the connection mode of the field effect transistor FET1 and the field effect transistor FET2 is: the gates correspond to the bases of the transistors TR1 and TR2, respectively, the sources correspond to the emitters, and the drains correspond to the collectors.

Claims (16)

1. An electronic circuit for amplitude modulating digital data transmitted through an antenna including a resonant circuit, the electronic circuit comprising:

a modulation circuit having a first transistor for amplitude-modulating a carrier wave applied to a base of the first transistor in accordance with a signal wave applied to an emitter of the first transistor to form an amplitude-modulated wave, and applying the amplitude-modulated wave to the antenna through a collector of the first transistor; and

a signal wave generating circuit to which a first pulse signal of a rectangular waveform corresponding to the digital data is input, for generating the signal wave corresponding to the waveform-shaped second pulse signal, so that: the signal wave generating circuit is configured to apply the generated signal wave to the emitter of the first transistor, and the level at the rise time of each pulse of the first pulse signal is higher than the high level at the steady state of the first pulse signal, and the level at the fall time of each pulse of the first pulse signal is lower than the low level at the steady state of the first pulse signal.

2. The electronic circuit according to claim 1, wherein the signal wave generating circuit comprises:

a load circuit as an emitter load of the first transistor;

a load change circuit that changes an emitter load of the load circuit in accordance with the first pulse signal; and

an extraction circuit that extracts a high-frequency component of the first pulse signal,

wherein the signal wave corresponding to the second pulse signal is generated by applying the high-frequency component of the first pulse signal extracted by the extraction circuit to the load circuit.

3. An electronic circuit according to claim 2, wherein the extraction circuit is a differentiating circuit.

4. The electronic circuit according to claim 2, wherein said signal wave generating circuit further comprises a buffer connected to an input terminal of said extracting circuit.

5. An electronic circuit according to claim 2, wherein said load change circuit includes a second transistor as a switch that is turned on and off in accordance with said first pulse signal applied to a base thereof, which changes an emitter load by disconnecting a predetermined element that is a part of the emitter load from said load circuit when said second transistor is turned off, and by connecting said disconnected element to said load circuit when said second transistor is turned on, and

the signal wave generating circuit further includes an inverter circuit connected to an input terminal of the extracting circuit.

6. An electronic circuit according to claim 5, wherein said inverter circuit is constituted by a third transistor as a switch and a resistor.

7. The electronic circuit according to claim 6, wherein the inverter circuit comprises a set of NPN-type transistors and PNP-type transistors as the third transistor.

8. The electronic circuit of claim 7, wherein said inverter circuit further comprises a schottky diode connected between the base and collector of each of said NPN-type transistor and said PNP-type transistor.

9. An electronic circuit according to claim 2, wherein there are a plurality of said first transistors,

an emitter resistance different from a resistance forming the load circuit is connected to an emitter of one or more first predetermined transistors among the plurality of first transistors, and

the signal wave generating circuit applies the signal wave corresponding to the second pulse signal obtained by shaping the waveform of the first pulse signal to the emitters of the first transistors other than the transistor whose emitter is connected to the emitter resistance among the plurality of first transistors.

10. A modulation method of a modulation circuit having a transistor for amplitude-modulating digital data transmitted through an antenna having a resonance circuit, for amplitude-modulating a carrier wave applied to a base of the transistor in accordance with a signal wave applied to an emitter of the transistor to form an amplitude-modulated wave, and applying the amplitude-modulated wave to the antenna through a collector of the transistor, the modulation method comprising the steps of:

inputting a first pulse signal of a rectangular waveform corresponding to the digital data;

generating the signal wave corresponding to the waveform-shaped second pulse signal so that: a level at each rise time of each pulse of the first pulse signal is higher than a high level at a steady state of the first pulse signal, and a level at each fall time of each pulse of the first pulse signal is lower than a low level at a steady state of the first pulse signal; and is

The generated signal wave is applied to an emitter of the transistor.

11. An electronic circuit for amplitude modulating digital data transmitted through an antenna including a resonant circuit, the electronic circuit comprising:

a modulation circuit having a field effect transistor for amplitude-modulating a carrier wave applied to a gate of the field effect transistor in accordance with a signal wave applied to a source of the field effect transistor to form an amplitude-modulated wave, and applying the amplitude-modulated wave to the antenna through a drain of the field effect transistor; and

a signal wave generating circuit to which a first pulse signal of a rectangular waveform corresponding to the digital data is input, for generating the signal wave corresponding to the waveform-shaped second pulse signal, so that: a level at each rise time of each pulse of the first pulse signal is higher than a high level at a steady state of the first pulse signal, and a level at each fall time of each pulse of the first pulse signal is lower than a low level at a steady state of the first pulse signal, and the generated signal wave is applied to a source of the field effect transistor.

12. A modulation method for a modulation circuit having a field effect transistor for amplitude-modulating digital data transmitted through an antenna including a resonance circuit, for amplitude-modulating a carrier wave applied to a source of the field effect transistor in accordance with a signal wave applied to the source of the field effect transistor to form an amplitude-modulated wave, and applying the amplitude-modulated wave to the antenna through a drain of the field effect transistor, the modulation method comprising the steps of:

inputting a first pulse signal of a rectangular waveform corresponding to the digital data;

generating the signal wave corresponding to the waveform-shaped second pulse signal so that: a level at each rise time of each pulse of the first pulse signal is higher than a high level at a steady state of the first pulse signal, and a level at each fall time of each pulse of the first pulse signal is lower than a low level at a steady state of the first pulse signal; and

the generated signal wave is applied to a source of the field effect transistor.

13. An information processing apparatus for amplitude modulating first digital information and transmitting the information, the information processing apparatus comprising:

a modulation device having a transistor for amplitude-modulating a carrier wave applied to a base of the transistor in accordance with a signal wave corresponding to the first digital information to form an amplitude-modulated wave, the signal wave being applied to an emitter of the transistor and the amplitude-modulated wave being output through a collector of the transistor;

a first output device for outputting the carrier wave applied to the base of the transistor;

second output means for outputting a first pulse signal of a rectangular waveform corresponding to the first digital information;

signal wave generating means for generating the signal wave corresponding to the waveform-shaped second pulse signal such that: a signal wave generating means for applying the generated signal wave to the emitter of the transistor, the signal wave generating means being higher in level at each rise time of each pulse of the first pulse signal output from the second output means than a high level at a steady state of the first pulse signal and lower in level at each fall time of each pulse of the first pulse signal than a low level at a steady state of the first pulse signal; and

an antenna device having a resonance circuit for transmitting an electromagnetic wave based on the amplitude modulated wave output from the modulation device to another information processing device.

14. The information processing apparatus according to claim 13, further comprising:

detection means for detecting a variation component of a waveform corresponding to second digital information transmitted from the other information processing means and received by the antenna means; and

and a demodulation unit for demodulating a signal corresponding to the second digital information from the variation component of the waveform detected by the detection unit.

15. The information processing apparatus according to claim 14, wherein the other information processing apparatus is an IC card capable of non-contact communication, and

the information processing apparatus is a card reader/writer apparatus that writes the first digital information into the IC card and reads the second digital information from the IC card by the antenna apparatus performing non-contact communication with the IC card.

16. An information processing method for an information processing apparatus, the information processing apparatus comprising: a modulation circuit having a transistor for amplitude-modulating a carrier wave applied to a base of the transistor in accordance with a signal wave corresponding to digital information to be transmitted to form an amplitude-modulated wave, the signal wave being applied to an emitter of the transistor and the amplitude-modulated wave being output through a collector of the transistor; and

an antenna having a resonance circuit for transmitting an electromagnetic wave based on the amplitude modulated wave output from the modulation circuit to another information processing apparatus, the information processing method comprising the steps of:

outputting said carrier wave applied to the base of said transistor;

outputting a first pulse signal of a rectangular waveform corresponding to the digital information;

generating the signal wave corresponding to the waveform-shaped second pulse signal such that: a level at each rise time of each pulse of the first pulse signal is higher than a high level at a steady state of the first pulse signal, and a level at each fall time of each pulse of the first pulse signal is lower than a low level at a steady state of the first pulse signal; and

the generated signal wave is applied to an emitter of the transistor.