JP4423831B2 - Portable transmitter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a portable transmitter, and is suitable for a keyless entry system, for example.
[0002]
[Prior art]
In keyless entry systems, portable transmitters are used. In such a communication system, a single polarized wave is conventionally transmitted from a portable transmitter. In that case, depending on the inclination of the transmitter, the direction of polarization becomes inconsistent with the direction of the receiving antenna, which causes a problem in the stability of the communication system.
[0003]
On the other hand, as a means for increasing the stability of a communication system, there is a technique called reception diversity in which two types of antennas that can receive radio waves independently are used to avoid radio wave reception mismatch. One type of reception diversity is polarization diversity, which is a technique that uses two types of antennas that can receive different polarizations.
[0004]
If this polarization diversity is used in a communication system such as a keyless entry system, the communication quality becomes stable.
[0005]
[Problems to be solved by the invention]
However, in a field such as a keyless entry system in which it is important to suppress the manufacturing cost and size of the receiving antenna, it is difficult to employ reception diversity which has a problem that the apparatus becomes large.
[0006]
An object of this invention is to provide the portable transmitter which can increase the stability of communication by sending two polarized waves in the transmission side in view of the said point.
[0007]
[Means for Solving the Problems]
To achieve the above object, the invention of claim 1 wherein is possess the following characteristics.
[0011]
As a portable transmitter for transmitting different polarized waves with two types of antennas, the invention according to claim 1 uses a slot antenna (32) and a loop antenna (33), and causes them to transmit the same data frame. It is said.
[0012]
Co In yet invention 請 Motomeko 1, of the conductor pattern on the multilayer substrate (3) Specific examples of the combinations according to the slot antenna and the loop antenna, a slot antenna formed on the top and bottom surfaces of the multilayer board The end points of the U-shaped conductors are connected to each other through a through hole, and the loop antenna is formed in a U-shape on the inner layer of the multilayer substrate.
[0013]
Further, as a portable transmitter for transmitting different polarized waves with two types of antennas, the invention according to claim 2 uses a slot antenna and a (32) electric field antenna (37), and causes them to transmit the same data frame. It is characterized by that.
[0014]
In yet invention 請 Motomeko 2, using a double-sided substrate (3) shaped conductor pattern as a specific example of a combination according to the slot antenna and the electric field-type antenna, slot antenna formed on the top and bottom surfaces of the double-sided substrate The end points of the U-shaped conductors are connected through through-holes. In the electric field antenna, one end point of the linear conductor formed on the top and bottom surfaces of the double-sided board is connected through the through-holes. a linear antenna forming the connection configurations Te (37a), that are characterized in that constructed out with arranged ground plane pattern in the bottom surface of the double-sided substrate (37b). The ground plane pattern (37b) may be located between the U-shaped conductors of the slot antenna formed on the bottom surface of the double-sided board.
Incidentally, the reference numerals in parentheses of each means described above are an example showing the correspondence with the specific means described in the embodiments described later.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 2 shows an outline of the in-vehicle keyless entry system according to the first embodiment of the present invention. An in-vehicle keyless entry system means that a person has a portable transmitter 2 and communicates with a receiver 1 installed in the automobile by means of the portable transmitter 2 so that the vehicle can be used without using a mechanical key. This is a system that can lock and unlock the door. The receiver 1 includes a receiving circuit 11 and a receiving antenna 12.
[0016]
FIG. 1 shows the structure of a transmission circuit board 3 (hereinafter simply referred to as a board) housed in a portable transmitter 2. This is formed using a multilayer substrate. The power used is supplied from a battery placed outside the substrate 3. In FIG. 1, the thickness of the substrate 3 is drawn larger than the actual ratio for easy viewing. A slot antenna 32 and a loop antenna 33 are formed as conductor patterns on the substrate 3 as two types of transmission antennas arranged so that the planes of polarization to be transmitted are different. In order to increase the efficiency of transmission output, the pattern width is made as wide as possible. A portion of the antenna line perpendicular to the substrate 3 is formed by a through hole.
[0017]
The slot antenna 32 is formed by bending a skeleton slot into a U-shape along the side surface of the substrate 3. The configuration is such that the end points of the U-shaped conductors formed on the upper surface and the bottom surface of the substrate 3 are the same. The connection is made through a through hole.
[0018]
The slot antenna 32 is matched by a matching capacitor 323 and fed by feeding points 321 and 322. Of these, 322 is the ground side.
[0019]
The loop antenna 33 is formed in a U-shape on the inner layer of the substrate 3 and is fed by the end points 331 and 332. Of these, 332 is the ground side.
[0020]
A transmission circuit 31 that outputs a transmission signal is connected to a high-frequency switch 34, where the power supply point 321 or the power supply point 331 for the antenna is switched. As the high frequency switch 34, a switching circuit using a dedicated IC or a high frequency diode is used.
[0021]
Matching circuits 351 and 352 are added to the output side of the high-frequency switch 34 in order to match the impedance of each antenna. The microcomputer 36 sends a data frame to the transmission circuit 31 and controls the switching timing of the high frequency switch 34 at the same time. The data frame is a basic unit of communication data in the keyless entry system, which includes identification data unique to each vehicle and command data such as locking and unlocking.
[0022]
A block diagram of the same circuit is shown in FIG. 3, which explains the operation of this embodiment. When locking and unlocking the door of a car, a person presses a switch not shown in the figure of the portable transmitter. Then, the microcomputer 36 senses that the switch has been pressed, generates exactly the same data frames a plurality of times in succession, and sends them to the transmission circuit 31. At this time, every time transmission of one data frame is completed, the high-frequency switch 34 is controlled to switch the output destination transmission antenna. The transmission circuit 31 that has received the data frame converts it into the transmission signals of the antennas 32 and 33, and the high frequency switch 34 distributes the output to the antennas 32 and 33 as controlled by the microcomputer 36.
[0023]
In the radio wave traveling in the X-axis direction of the three-dimensional coordinate axis in FIG. 1, the slot antenna 32 generates polarization in the Z-axis direction, and the loop antenna 33 generates polarization in the Y-axis direction, which are orthogonal to each other. Therefore, by configuring the X-axis direction to be in front of the portable transmitter 2, the operator can operate the portable transmitter 2 regardless of the orientation of the receiving antenna 12. Even if transmission is performed while maintaining a simple inclination, the polarized wave emitted by one of the antennas (32, 33) is satisfactorily received by the antenna 2 of the receiver 1. As a result, it is possible to avoid reception failure due to mismatch in the polarization direction and to improve the stability of communication.
[0024]
In the present embodiment, the transmission circuit 31, the high-frequency switch 34, and the microcomputer 36 constitute means for transmitting the same data frame by alternately switching two types of transmission antennas.
[0025]
(Second Embodiment)
In the second embodiment of the present invention, the transmission antenna used on the substrate 3 in the first embodiment has a different configuration. FIG. 4 shows the structure of the substrate 3 housed in the portable transmitter 2. This is formed by using a double-sided substrate, and in FIG. 4, the thickness of the substrate 3 is drawn larger than the actual one in consideration of ease of viewing as in FIG. 3. In addition to the slot antenna 32 arranged on the substrate 3 in the same manner as in the first embodiment, an electric field antenna 37 as a conductor pattern is composed of a linear antenna 37a and a ground plane pattern 37b. In order to increase the efficiency of transmission output, the pattern width is made as wide as possible.
[0026]
The linear antenna 37a is configured such that one end points of linear conductors formed on the upper surface and the bottom surface of the substrate 3 are connected to each other through a through hole, and power is supplied at the end points 371. Since the linear antenna 37 a is connected to the ground surface pattern 37 b provided on the bottom surface of the substrate 3 on the ground side of the transmission circuit 31, the linear antenna 37 a and the ground surface pattern 37 b constitute an electric field antenna 37. The electric field antenna 37 and the slot antenna 32 are two types of antennas having different planes of polarization configured as conductor patterns on the substrate 3.
[0027]
The configuration and operation of the high-frequency switch 34 and the microcomputer 36 are the same as in the first embodiment.
[0028]
In the radio wave traveling in the X-axis direction of the three-dimensional coordinate axis in FIG. 4, the slot antenna 32 generates polarization in the Z-axis direction, and the linear antenna 37a generates polarization in the Y-axis direction. To do. Therefore, by configuring the X-axis direction to be in front of the portable transmitter 2, the operator can operate the portable transmitter 2 regardless of the orientation of the receiving antenna 12. Even if transmission is performed while maintaining a proper inclination, the polarized wave emitted by any of the antennas (32, 37) is satisfactorily received by the antenna 2 of the receiver 1. As a result, this embodiment also has the same effect as the first embodiment.
[0029]
(Third embodiment)
The configuration of the portable transmitter 2 according to the third embodiment of the present invention is shown in FIG. In this embodiment, the configuration of the substrate 3 is changed in the first embodiment, and a phase shift circuit 38 is installed instead of the high frequency switch 34. The slot antenna 32, loop antenna 33, microcomputer 36, feed points 321, 322, 331, 332, and matching capacitor 323 have the same configuration as in the first embodiment. The matching circuit 351 connected to the slot antenna 32 at the feeding point 321 is directly connected to the transmission circuit 31 on the other side. The matching circuit 352 connected to the loop antenna 33 at the feeding point 331 is connected to the transmission circuit 31 via the phase shift circuit 38 on the other side.
[0030]
FIG. 6 shows a block diagram of the same circuit, and the operation of this embodiment will be described. The data frame transmitted from the microcomputer 36 is branched as two identical transmission signals by the transmission circuit 31, and one is fed to the feeding point 321 of the slot antenna 32 via the matching circuit 351. The other is fed through the phase shift circuit 38 and the matching circuit 352 to the feed point 331 of the loop antenna 33. At this time, the phase is shifted 90 degrees by the phase shift circuit 38.
[0031]
In the radio wave traveling in the X-axis direction of the three-dimensional coordinate axis in FIG. 5, the slot antenna 32 simultaneously generates a polarization in the Z-axis direction, and the loop antenna 33 simultaneously generates a polarization in the Y-axis direction. However, since the phase of the polarization emitted from the loop antenna is delayed by 90 degrees in the phase shift circuit 38, the polarization in the Z-axis direction and the polarization in the Y-axis direction are shifted by 90 degrees. Polarized.
[0032]
By configuring the portable transmitter 2 so that the X-axis is forward, the operator can tilt the portable transmitter 2 in any orientation regardless of the orientation of the receiving antenna 12. Even if the signal is held and transmitted, any one of the rotating polarization planes is received well by the antenna 2 of the receiver 1. As a result, it is possible to avoid a reception failure due to the mismatch of the polarization direction, and the stability of communication is improved. As a result, the same effect as in the first embodiment can be obtained.
[0033]
In the present embodiment, the transmission circuit 31, the microcomputer 36, and the phase shift circuit 38 constitute means for transmitting the same data frame to two types of transmission antennas by shifting the phase of the transmission signal. Yes.
[0034]
Further, the technique of using a phase shift circuit in place of the high frequency switch performed in this embodiment can be applied to the second embodiment as it is.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a transmission circuit board according to a first embodiment.
FIG. 2 is a schematic view of a keyless entry system.
FIG. 3 is a block diagram of a transmission circuit board according to the first embodiment.
FIG. 4 is a configuration diagram of a transmission circuit board according to a second embodiment.
FIG. 5 is a configuration diagram of a transmission circuit board according to a third embodiment.
FIG. 6 is a block diagram of a transmission circuit board according to a third embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Receiver, 2 ... Portable transmitter, 11 ... Reception circuit, 12 ... Reception antenna,
3 ... Transmission circuit board, 31 ... Transmission circuit, 32 ... Slot antenna,
33 ... Loop antenna, 34 ... High frequency switch, 36 ... Microcomputer,
321, 331 ... feeding point, 322, 332 ... feeding point (ground side),
323: matching capacitor, 351, 352: matching circuit,
37 ... Electric field type antenna, 37a ... Linear antenna,
37b: Ground plane pattern, 38: Phase shift circuit.

Claims (2)

Means (31, 31) having a slot antenna (32) and a loop antenna (33) arranged so that transmission planes of polarization are different from each other, and transmitting the same data frame to both the slot antenna and the loop antenna 34, 36, 38)
The slot antenna and the loop antenna are conductor patterns on the multilayer substrate (3), and the slot antenna has end points of U-shaped conductors formed on the top and bottom surfaces of the multilayer substrate through through holes. A portable transmitter, wherein the loop antenna is formed in a U-shape in an inner layer of the multilayer substrate. Means (31) having a slot antenna (32) and an electric field antenna (37) arranged so that polarization planes to be transmitted are different from each other, and transmitting the same data frame to both the slot antenna and the electric field antenna , 34, 36, 38)
The slot antenna and the electric field type antenna are conductor patterns on the double-sided board (3), and the end points of the U-shaped conductors formed on the top and bottom surfaces of the double-sided board have through-holes. The electric field antenna is a linear antenna having a configuration in which one end points of linear conductors formed on the upper surface and the bottom surface of the double-sided substrate are connected through a through hole ( and 37a), all SANYO constructed out with the bottom surface arranged ground plane pattern of the double-sided substrate (37b),
The portable transmitter, wherein the ground plane pattern (37b) is located between U-shaped conductors of the slot antenna formed on the bottom surface of the double-sided board .

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