JP2002217749A - Mobile transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile transmitter that minimizes the effect of fluctuations in antenna impedance onto an oscillation circuit with a simple configuration. SOLUTION: This invention provides a mobile unit 12 provided with an oscillation circuit section 40 that applies FSK modulation to an identification ID code of a vehicle corresponding to the mobile unit and with an antenna resonance section 70 that emits a signal modulated by the oscillation circuit section 40 externally. The oscillation circuit section 40 and the antenna resonance section 70 are connected by a reference GND 47. Then a 1st connecting point A of the reference GND 47 to which a radiation element 72 of the antenna resonance section 70 is connected and a 2nd connecting point B of the reference GND 47 to which a resonator 48 of the oscillation circuit section 40 is connected are placed closely to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable transmitter, and more particularly, to a portable transmitter suitable for remotely controlling a device mounted on, for example, a vehicle.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Unexamined Patent Application Publication No.
As disclosed in Japanese Unexamined Patent Publication No. 6-206, there is known a system for remotely locking and unlocking a door of a vehicle by wireless communication between the vehicle and a portable device. The portable device of this system includes a coupling capacitor that couples a transmission control circuit including an oscillation circuit and an antenna. The coupling capacitor has a function of removing a DC component from a transmission signal output from the transmission control circuit and transmitting the signal to the antenna side. The portable device emits a radio wave from the antenna when a high-frequency current flows into the antenna according to a transmission signal output from the transmission control circuit. Also, the vehicle
When a radio wave radiated from the portable device is received, an identification ID code included in the radio wave is collated, and locking / unlocking of the door is controlled based on the collation result. Therefore, according to the above system, the occupant can lock and unlock the door of the vehicle remotely without inserting the door key into the door lock of the vehicle.

[0003]

By the way, since the antenna is a radiating element, in the transmitter, the impedance of the antenna viewed from the oscillation circuit side is reduced due to the approach of a finger or metal to the antenna. May fluctuate significantly. In the above-described conventional portable device, when the impedance of the antenna changes, the combined capacitance value including the coupling capacitor changes, so that the oscillation frequency in the oscillation circuit changes, the output intensity changes, and in some cases, the oscillation stops or abnormal oscillation occurs. May occur. As described above, in the above-mentioned conventional portable device, there is a possibility that a desired radio wave cannot be transmitted to the outside due to the impedance variation of the antenna.

Further, since the portable device is carried by a vehicle occupant, it is not appropriate to make the configuration complicated and large, and a buffer amplifier for reducing the coupling between the oscillation circuit and the antenna is inserted between the oscillation circuit and the antenna. It is difficult to do.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide a portable transmitter capable of suppressing the influence of the variation in antenna impedance on the oscillation circuit with a simple configuration. With the goal.

[0006]

The above object is achieved by the present invention.
As described in the paragraph, in a portable transmitter including an oscillation circuit, and an antenna for radiating radio waves generated by the oscillation circuit, the oscillation circuit and the antenna are connected via a predetermined reference potential line This is achieved by a portable transmitter characterized by:

According to the first aspect of the present invention, the oscillation circuit and the antenna are connected via a predetermined reference potential line. In such a configuration, since the oscillation circuit is closed with reference to the predetermined reference potential line, the influence of the fluctuation factor in the antenna on the oscillation circuit is reduced.

Further, as described in claim 2, claim 1
3. The portable transmitter according to claim 1, wherein a first connection point of the resonator of the oscillation circuit to the predetermined reference potential line and a second connection point of the antenna to the predetermined reference potential line are close to each other. The portable transmitter characterized by being disposed is effective in efficiently transmitting the oscillation vibration of the oscillation circuit to the antenna.

In the invention described in claim 2, a first connection point where the resonator of the oscillation circuit connects to a predetermined reference potential line and a second connection point where the antenna connects to the predetermined reference potential line are mutually connected. Proximity arrangement. In this case, the oscillation vibration of the resonator of the oscillation circuit is easily transmitted to the antenna.

In this case, as described in claim 3, in the portable transmitter according to claim 2, even if the pattern of the predetermined reference potential line near the first and second connection points is formed thin. Good.

According to the third aspect of the present invention, the predetermined reference potential line pattern near the first and second connection points is formed thin. In such a configuration, the resistance value is larger than the configuration in which the pattern of the reference potential line is formed thick, so that the high-frequency current from the resonator of the oscillation circuit easily flows to the antenna side. That is, the oscillation vibration of the resonator of the oscillation circuit is easily transmitted to the antenna.

Also, as described in claim 4, claim 1
The portable transmitter according to the above, further comprising a variable capacitor connected in series with the antenna, wherein the portable transmitter ensures the same output intensity at all times even if an electrical variation occurs in the antenna. Is effective in

[0013] In the fourth aspect of the present invention, a variable capacitor is connected to the antenna in series. Therefore,
Even if the L value of the antenna varies, the resonance frequency of the antenna and the capacitor can be made to match the oscillation frequency of the oscillation circuit by making the capacitance value of the variable capacitor variable. For this reason, the same output intensity is always ensured even if electrical variations occur in the antenna.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a system configuration diagram of a vehicle-mounted device remote control system including a portable transmitter according to an embodiment of the present invention. As shown in FIG. 1, the system of this embodiment includes an in-vehicle device 10 mounted on a vehicle and a portable device 12 carried by a vehicle occupant. The on-vehicle device 10 includes a door locking electronic control unit (hereinafter, referred to as a locking ECU) 1.
4 is provided. The locking ECU 14 includes an antenna 16
, Receiving section 18 and transmitting section 2 having antenna 20
2, and a door control motor 24 for locking (unlocking) and unlocking (unlocking) the door of the vehicle. The receiving unit 18 is a circuit that amplifies and demodulates a signal received by the antenna 16. The transmitting unit 22 is a circuit that performs frequency shift keying (hereinafter, referred to as FSK modulation) on a signal to be transmitted to the outside and transmits the signal from the antenna 20. The signal transmitted from the transmission unit 22 has such a strength that a predetermined communicable area is secured. Hereinafter, a signal transmitted from the transmission unit 22 of the vehicle-mounted device 10 is referred to as a request signal.

In the on-vehicle device 10, the FS
After the K-modulated request signal is transmitted, if a signal generated by the portable device 12 is received by the receiving unit 18 in response to the signal as described later, the locking ECU 14 determines the code of the received signal based on the code of the received signal. A command signal is supplied to the door control motor 24 to control locking and unlocking of the vehicle door. The locking ECU 14 has a memory that stores the identification ID code of its own vehicle.

The portable unit 12 is a transceiver for remotely locking and unlocking a vehicle door without a vehicle occupant inserting a door key into the vehicle door lock or pressing a switch or the like. is there. The portable device 12 includes a portable electronic control unit (hereinafter, referred to as a portable ECU) 30. The portable ECU 30 has a memory in which the identification ID code of the vehicle corresponding to the portable device 12 is stored.

The portable ECU 30 includes a receiving section 34 having an antenna 32 and a transmitting section 3 having an antenna 36.
8 are connected. The receiving unit 34 is a circuit that amplifies and demodulates a signal received by the antenna 32. The transmitting unit 38 is a circuit that FSK modulates a signal to be transmitted to the outside and transmits the signal from the antenna 36, as described in detail later.
The signal transmitted from the transmitting unit 38 has such a strength that a predetermined communicable area is secured. Hereinafter, portable device 1
The signal transmitted from the second transmission unit 38 is referred to as a response signal.

In the portable device 12, when the request signal from the vehicle-mounted device 10 is received by the receiving unit 34, the portable ECU 30 responds to the request signal by using a predetermined frequency centered on the oscillation frequency (for example, 300 MHz). The transmitting unit 38 transmits a response signal that is FSK-modulated (for example, 300 MHz ± 20 kHz).

In the above system, the vehicle-mounted device 10
When the door is locked while the power of the vehicle is stopped, a request signal including the identification ID code of the own vehicle which is modulated and encrypted by the transmission / reception unit 22 from the antenna 20 is transmitted at regular intervals. In this situation, when the occupant carrying the portable device 12 approaches the vehicle, specifically, the onboard device 1
When the portable device 12 enters the communicable area of “0”, the portable device 12 receives the request signal transmitted from the vehicle-mounted device 10.
In this case, the portable device 12 collates the identification ID code included in the received request signal with the identification ID code stored in its own memory, and as a result, when both match, a response including the identification ID code is performed. Send a signal.

When the on-vehicle device 10 receives the response signal from the portable device 12 after transmitting the request signal, the on-vehicle device 10 transmits the identification ID code included in the received response signal and the identification ID code stored in its own memory. Collate. As a result, if the two coincide with each other, it is determined that an occupant to be on board the vehicle is approaching, and the door control motor 24 is unlocked to unlock the door of the vehicle.
Drive.

The on-vehicle device 10 also transmits a request signal immediately after the power of the vehicle is stopped and the door is opened and closed. At this time, since the portable device 12 and the on-vehicle device 10 are within the communication range, the portable device 12 transmits a response signal in response to the request signal. Then, when the in-vehicle device 10 receives the response signal emitted by the portable device 12 after transmitting the request signal, the in-vehicle device 10 determines that the occupant in the vehicle has left the vehicle, and opens the vehicle door according to the verification result. The door control motor 24 is driven to lock.

As described above, in the system according to the present embodiment, after the vehicle-mounted device 10 transmits the request signal, the vehicle door is locked or unlocked based on the response signal emitted from the portable device 12 in response to the request signal. The door control motor 24 is controlled so as to be unlocked. Therefore, according to the system of the present embodiment, the door can be remotely locked and unlocked without contact by the vehicle occupant without inserting the door key into the door lock and without any operation by the vehicle occupant. It becomes possible.

FIG. 2 is a circuit diagram showing an electrical configuration of the transmitting section 38 and the antenna 36 provided in the portable device 12. As shown in FIG.
As shown in FIG. 2, the portable device 12 includes a code generation unit (not shown) and an oscillation circuit unit 40. Portable device 12
Supplies a signal corresponding to its own identification ID code from the code generation unit to the oscillation circuit unit 40 in a situation where a response signal is to be transmitted.

The output terminal of the code generator is connected to the oscillation circuit 4
0 input terminal 42. An input terminal 42 has, via a resistor 44, one end of a varicap diode 46 whose capacitance changes according to an applied voltage, and a resonator 4 such as a SAW vibrator that emits a waveform of an oscillation frequency.
8 is connected to one end. Varicap diode 4
The other end of 6 is grounded to reference GND 47. Also,
The other end of the resonator 48 is connected to the base terminal 50 of the transistor 50.
b. Base terminal 5 of transistor 50
Ob is grounded to a reference GND 47 via a resistor 52 and connected to a + terminal 56 of a DC power supply via a resistor 54. The + terminal 56 of the DC power supply is connected to the collector terminal 50 c of the transistor 50 via the coil load 58, and is connected to the reference G via the capacitor 60.
It is grounded to ND47. The base terminal 50b of the transistor 50 is connected to the emitter terminal 50e via the capacitor 62. The emitter terminal 50e of the transistor 50 is grounded to the reference GND 47 via the resistor 64 and the capacitor 66. In this embodiment, the reference GND 47 is a negative terminal of the DC power supply.

The portable device 12 also includes an antenna resonating unit 70
It has. The antenna resonance unit 70 includes a radiating element 72
And a resonance capacitor 74 connected in series with the radiating element 72. The resonance capacitor 74 is a variable capacitance type capacitor. The other end of the radiating element 72 and the other end of the resonance capacitor 74 are both grounded to the reference GND 47. That is, in the portable device 12, the oscillation circuit section 40 and the antenna resonance section 70 are connected via the reference GND 47.

FIG. 3 shows an example of a pattern layout of the transmitting section 38 and the antenna 36 on a printed circuit board incorporated in the portable device 12. As shown in FIG.
Reference numeral 7 denotes a solid pattern portion 47a formed by a solid pattern on a printed circuit board, and a line pattern portion 47b formed to have a smaller pattern width than the solid pattern portion 47a. The radiating element 72 of the antenna resonating unit 70 is configured by an antenna having a pattern formed on a printed circuit board.
Functions as a loop antenna.

The other end of the pattern of the radiating element 72 is a reference GN.
The other end of the resonance capacitor 74 is connected to the solid pattern portion 47a of the reference GND 47. The other end of the varicap diode 46 is connected to the line pattern portion 47b. A first connection point A where the other end of the pattern of the radiating element 72 is connected to the line pattern portion 47b, and a second connection point B where the other end of the varicap diode 46 is connected to the line pattern portion 47b, Pattern part 4
7b. The base terminal 50b of the transistor 50 is connected to an end of the line pattern portion 47b via the resistor 52. The point at which the resistor 52 is connected to the line pattern portion 47b is referred to as a third connection point C.

FIG. 4 shows a transistor 50 of this embodiment.
Of the base potential appearing at the source terminal 50b over time.
The figure is shown. In the circuit configuration of the portable device 12 described above,
The oscillation circuit section 40 is in an oscillation state due to the function of the resonator 48.
4 is connected to the base terminal 50b of the transistor 50 as shown in FIG.
As described above, the DC bias voltage V _b
Voltage that fluctuates in an alternating manner at the oscillation frequency
You.

In this embodiment, assuming that the resistance value of the resistor 52 is, for example, 10 kΩ and the impedance at the oscillation frequency of the resonator 48 is, for example, 20 Ω, the path from the base terminal 50 b side to the reference GND 47 via the resonator 48 is set. Since the resistance is small and the resistance of the path from the base terminal 50b side to the reference GND 47 via the resistor 52 is large,
A change in the base potential of the transistor 50 is not easily transmitted to the third connection point C, but is easily transmitted to the second connection point B. In this case, the resonator 48 is connected from the base terminal 50b side.
The current flowing to the reference GND 47 through the
Vibrates at the oscillation frequency of

In this embodiment, the reference GND 47
Since the solid pattern portion 47a and the line pattern portion 47b are connected by a pattern on a printed circuit board,
The resistance between them is as small as 5 mΩ, for example. In the antenna resonating section 70, the radiating element 72 and the resonance capacitor 7
In a situation where the first and second components 4 and 4 are serially resonated at a resonance frequency very close to the oscillation frequency, a path from the first connection point A of the line pattern portion 47b to the solid pattern portion 47a via the radiation element 72 and the resonance capacitor 74 ( That is, the impedance of the antenna resonating section 70) is ideally “0”.
However, actually, for example, it is 5 mΩ because of the loss. Further, as described above, the first connection point A and the second connection point B are arranged close to each other on the line pattern portion 47b.

For this reason, in this embodiment, a part of the current flowing from the base terminal 50b side to the reference GND 47 via the resonator 48 is transmitted from the first connection point A via the radiating element 72 and the resonance capacitor 74. Thus, it is distributed to the solid pattern portion 47a of the reference GND 47. Therefore, since a radio wave is radiated by the current flowing through the radiating element 72, the radiating element 72 functions as an antenna.

In the present embodiment, when a signal corresponding to the identification ID code is supplied from the code generation unit to the oscillation circuit unit 40, the capacitance of the varicap diode 46 changes according to the high level and low level of the signal. Oscillating circuit section 40
Oscillation frequency changes. For this reason, the radiation element 72
A radio wave having an oscillation frequency corresponding to the level of the identification ID code input to the oscillation circuit section 40 is emitted. That is, in the present embodiment, the portable device 12 transmits the FSK signal according to the identification ID code from the radiating element 72 as a response signal.

Next, referring to FIG. 5 together with FIG.
The features of the present embodiment will be described. FIG. 5A shows that in the present embodiment, the antenna resonating section 7 from the oscillation circuit section 40 side.
FIG. 4 is a diagram illustrating a relationship between the impedance and the oscillation frequency f when viewing the 0 side. FIG. 5B is a diagram illustrating a relationship between the impedance of the antenna resonance unit 70 itself and the oscillation frequency f. Note that in FIGS. 5A and 5B,
The frequency characteristics before the change are indicated by a solid line, and the frequency characteristics after the change are indicated by a broken line.

As described above, since the solid pattern portion 47a and the line pattern portion 47b of the reference GND 47 are connected by a pattern on a printed circuit board, the resistance therebetween has a very small value. Therefore, in this embodiment,
The oscillation circuit section 40 forms a basically closed circuit with reference to the reference GND 47 as shown in FIG. For this reason, according to the circuit configuration of the portable device 12 of the present embodiment, even if the impedance variation of the antenna resonance unit 70 occurs, the influence of the variation on the oscillation circuit unit 40 can be suppressed to a small level.

The antenna resonating section 70 is provided as shown in FIG.
As shown in the figure, the frequency characteristic has an extremely low impedance at the time of series resonance. Therefore, in a configuration in which the antenna resonance unit 70 and the oscillation circuit unit 40 are connected without passing through the reference GND 47, when a finger or a metal approaches the radiating element 72, the antenna resonance unit viewed from the oscillation circuit unit 40 side may be used. The frequency characteristic of the unit 70 changes from the state shown by the solid line in FIG. 5B to the state shown by the broken line (indicated by a white arrow in FIG. 5), and its impedance changes as shown by a black arrow in FIG. 5B. It fluctuates greatly. Therefore, in such a configuration,
Fluctuations in the oscillation frequency and abnormal oscillation in the oscillation circuit section 40 occur.

On the other hand, in this embodiment, it is assumed that the resistance between the solid pattern portion 47a and the line pattern portion 47b of the reference GND 47 is 5 mΩ, and the impedance of the antenna resonance portion 70 at the time of series resonance is 5 mΩ.
Then, as shown in FIG. 5A, the impedance of the antenna resonance unit 70 when viewed from the oscillation circuit unit 40 side becomes 2.5 mΩ at the time of series resonance, and the oscillation frequency is other than the series resonance frequency. Is between 2.5 mΩ and 5.0 mΩ. Therefore, in the circuit configuration of the present embodiment, even when a finger or metal approaches the radiating element 72, the oscillation circuit section 40
FIG. 5 shows the frequency characteristics of the antenna resonating unit 70 viewed from the side.
The state shown by the solid line in FIG. 5A changes to the state shown by the broken line (indicated by a white arrow in FIG. 5), but the impedance does not fluctuate much as shown by the black arrow in FIG. . For this reason, even if the Q value of the antenna resonating unit 70 is increased and a strong resonance state is realized, the impedance variation of the antenna resonating unit 70 is reduced by the oscillation circuit unit 40.
Has little effect on the oscillation frequency.

As described above, in the present embodiment, in order to minimize the influence of the impedance fluctuation of the antenna resonance unit 70 on the oscillation circuit unit 40, the two are connected between the oscillation circuit unit 40 and the antenna resonance unit 70. It is not necessary to insert a buffer amplifier or the like for reducing the coupling, and it suffices if both are connected via the reference GND 47. Therefore, according to the circuit configuration of the portable device 12 of the present embodiment, the impedance variation of the antenna
It is possible to suppress the influence on 0 to be small.

The resistance between the line pattern portion 47b and the solid pattern portion 47a increases as the pattern width of the line pattern portion 47b of the reference GND 47 decreases. In this case, the base terminal 50 of the transistor 50
The current flowing from the b side to the reference GND 47 via the resonator 48 hardly flows from the line pattern portion 47b directly to the solid pattern portion 47b, and easily flows to the radiating element 72 side. That is, from the base terminal 50b side, the resonator 4
Most of the high-frequency current flowing to the reference GND 47 via 8 flows to the radiating element 72 side. For this reason,
In the present embodiment, if the pattern width of the line pattern portion 47b of the reference GND 47 is reduced, the oscillation vibration of the resonator 48 of the oscillation circuit
0 efficiently, and the oscillation of the oscillation circuit section 40 can be stabilized.

FIG. 6 is a diagram showing the relationship between the output intensity of the antenna resonance unit 70 and the capacitance VC of the resonance capacitor 74. In FIG. 6, the L value of the radiating element 72 is L
Where ₀ by a solid line, the case where L ₁ by a broken line it shows it. As described above, the radiating element 72 of the antenna resonating unit 70 is configured by an antenna having a pattern formed on a printed board. In such a configuration, the thickness of the pattern on the printed circuit board changes according to the etching amount.
The L value of 2 may vary.

However, in this embodiment, the antenna resonating section 70 includes the variable capacitor type resonance capacitor 74 connected in series with the radiating element 72. In such a configuration, even if the L value of the radiation element 72 varies, the series resonance frequency can be adjusted to be equal to the oscillation frequency of the oscillation circuit unit 40 by changing the capacitance VC of the resonance capacitor 74. Thus, the output intensity of the antenna resonating unit 70 can be adjusted to the maximum intensity. Therefore, according to the configuration of the present embodiment, it is possible to always ensure the same output intensity even if the radiating element 72 has an electrical variation.

In the above embodiment, the portable device 12
Are described in the “portable transmitter” described in the claims, the oscillation circuit section 40 is described in the “oscillation circuit” described in the claims, and the antenna resonating section 70 is described in the claims. The antenna "", the reference GND 47 is described in the "predetermined reference potential line" described in the claims, and the first and second connection points A and B are the "first reference potential lines" described in the claims.
The resonance capacitor 74 corresponds to the “connection point” and the “second connection point”, respectively, and corresponds to the “variable capacitance capacitor” described in the claims.

In the above embodiment, the portable device 12 functioning as a portable transmitter is used in a vehicle-mounted device remote control system for locking and unlocking a vehicle door remotely. It is also possible to apply the present invention to various systems that use the portable device 12 as a transmitter, such as the ignition system described above and the locking and unlocking of doors other than the vehicle. In addition, the portable device 12 is used for a so-called smart entry system that locks and unlocks a vehicle door without any operation by an occupant. -It is also possible to apply to a so-called wireless system for unlocking.

In the above embodiment, the radiating element 72 of the antenna resonating section 70 is an antenna formed by a pattern formed on a printed circuit board. However, the present invention is not limited to this. The antenna element may be configured by a wire.

In the above-described embodiment, the oscillation circuit section 40 is a circuit that performs FSK modulation on the identification ID code. However, the present invention is not limited to this. It may be realized by a circuit that performs modulation or the like.

In the above embodiment, the antenna resonating section 70 includes the resonance capacitor 74 connected in series with the radiating element 72, and further includes a dump resistor inserted in parallel with the resonance capacitor 74. It may be provided. In this case, the waveform shown in FIG. 6 has a gentle slope, and the output intensity of the antenna resonating unit (that is, antenna efficiency) can be reduced.

Further, in the above-described embodiment, the oscillation circuit section 40 and the antenna resonance section 70 are connected via the reference GND 47. However, the present invention is not limited to this. The connection may be made via the + terminal 56. That is, FIG. 7 shows a main part of the pattern layout of the transmission unit on the printed circuit board incorporated in the portable device 100 according to the modification of the present invention.

In this modified example, the + terminal 56 of the DC power supply is connected to a line pattern section 102 formed on a printed circuit board as shown in FIG. The radiating element 72 of the antenna resonance unit 70 has a configuration in which one end of the pattern is connected to the reference GND 47 via the resonance capacitor 74 and the other end is connected to the line pattern unit 102. The capacitor 60 is a bypass capacitor whose impedance is reduced at the oscillation frequency.

In such a configuration, a change in the collector potential of the transistor 50 is transmitted to the line pattern portion 102 located on the collector terminal side. In this case, the radiating element 72 and the resonance capacitor 7
Since the impedance of the path leading to the reference GND 47 via the line 4 is small, the current flowing into the line pattern unit 102 flows to the radiating element 72 side. Therefore, also in such a modification, the radiation element 72 functions as an antenna. The path from the line pattern unit 102 to the reference GND 47 via the capacitor 60 is shown in FIG.
The operation is the same as that connected to the reference GND 47 at a relatively short distance as compared with the line pattern portion 47b. Therefore, the impedance on the line pattern section 102 side as viewed from the oscillation circuit 40 side is in the state shown in FIG. Therefore, also in this modified example, it is possible to obtain the same effect as the above-described embodiment.

As described above, according to the first aspect of the present invention, it is possible to reduce the influence of the impedance variation of the antenna on the oscillation circuit side with a simple configuration.

According to the second and third aspects of the invention, the oscillation vibration of the oscillation circuit can be efficiently transmitted to the antenna.

According to the fourth aspect of the present invention, the same output intensity can always be ensured even if electrical variations occur in the antenna.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a vehicle-mounted device remote control system including a portable transmitter according to an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram illustrating an electrical configuration of a transmission unit included in the portable device of the present embodiment.

FIG. 3 is a pattern layout of a transmission unit on a printed circuit board incorporated in the portable device of the present embodiment.

FIG. 4 is a diagram illustrating a temporal change of a base potential appearing at a base terminal of a transistor included in the portable device of the present embodiment.

FIG. 5A is a diagram illustrating a relationship between an impedance and an oscillation frequency when the antenna resonance section is viewed from the oscillation circuit section in the present embodiment. FIG. 5B
FIG. 4 is a diagram illustrating a relationship between the impedance of the antenna resonance unit itself and the oscillation frequency.

FIG. 6 is a diagram illustrating a relationship between an output intensity of an antenna resonance unit and a capacitance value of a resonance capacitor in the present embodiment.

FIG. 7 is a main part of a pattern layout of a transmitting unit on a printed circuit board incorporated in a portable device according to a modified example of the present invention.

[Explanation of symbols]

 12 Portable device 40 Oscillation circuit unit 47 Reference GND 70 Antenna resonating unit 72 Radiating element 74 Resonant capacitor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04Q 9/00 301 H04Q 9/00 301B // B60R 25/00 606 B60R 25/00 606 F term (reference) 2E250 AA21 BB08 CC20 DD05 DD06 FF27 FF36 HH01 JJ03 KK03 LL01 5J046 AA02 AA04 AB13 TA03 TA04 5J047 AA02 AA04 AB13 FC05 FD01 5K048 BA42 DB01 DC01 EA16 EB02 EB03 HA04 HA11 5K060 AA12 BB07

Claims (4)

[Claims] 1. A portable transmitter comprising an oscillation circuit and an antenna for radiating radio waves generated by the oscillation circuit, wherein the oscillation circuit and the antenna are connected via a predetermined reference potential line. A portable transmitter characterized by the following. 2. The portable transmitter according to claim 1, wherein a first connection point of the resonator of the oscillation circuit to the predetermined reference potential line and a first connection point of the antenna to the predetermined reference potential line are provided. 2. A portable transmitter, wherein two connection points are arranged close to each other. 3. The portable transmitter according to claim 2, wherein a pattern of the predetermined reference potential line near the first and second connection points is formed thin. 4. The portable transmitter according to claim 1, further comprising a variable capacitor connected in series with the antenna.