JPH0623053Y2 - Car window glass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a window glass for an automobile, and is particularly preferably applied to a window glass of an automobile that uses a heating conductor as an antenna or a part of an antenna element. Is.

[Outline of device]

A heating current connection terminal is fixed on the window glass surface of an automobile equipped with an anti-fog heating conductor, and a receptacle containing a decoupling choke coil is detachably connected to this connection terminal, and the heating conductor and choke are connected. By eliminating the power supply line between the coil and the stray capacitance to the ground, the power receiving efficiency is improved when the heating conductor is used as the antenna conductor, and the variation of the antenna characteristic due to the stray capacitance is eliminated. It is a window glass.

[Conventional technology]

A heater conductor for defrosting is attached to a window glass of an automobile (particularly a rear window glass) by printing or embedding. It is well known to use this heater conductor as a part of an antenna or an antenna element for AM or FM broadcasting band, for example.

FIG. 8 is a conductor pattern diagram of such a window glass antenna, showing a large number of heater wires 2 in the defrosted area of the rear window glass 1.
Is additionally provided, and the bus bars 3 and 4 connected to one end of the heater wire 2 divided into upper and lower groups are passed through and the electric power is fed back through the bus bar 5 at the other end. In order to use the heater wire 2 as a receiving antenna for AM / FM broadcasting, a feeder 7a such as a coaxial wire is connected to a feeding point 6 provided on the heater wire 2,
The received signal is supplied to the preamplifier 9 through the DC cut capacitor 8, and the amplifier output is led to the tuner through the coaxial feeder cable 7b. The heating current flows through the lead wires 12 and 13 via the choke coils 11a and 11b magnetically coupled to each other, and is passed through the bus bars 3 and 4. The choke coil 11a connected to the main power source + B via the power supply line 17 and the choke coil 11b connected to the ground point via the power supply line 18 are uncoupled, and the magnetic flux due to each heating current cancels out in the core. The small volume core can be operated non-saturated. For high frequencies received, the choke coils 11a and 11b exhibit high impedance,
Since the received signal induced in the heater wire 2 does not escape to the low impedance power source or ground, the power receiving efficiency is improved. A decoupling capacitor 14 is coupled to the power supply line 17 connected to the main power supply + B so that the power supply noise does not get on the received signal.

FIG. 9 is an equivalent circuit of the antenna of FIG. 8, where e ₀ is the induced electromotive force of the heater wire 2, C ₁ is the effective capacitance of the antenna,
C ₂ is the reactive capacitance of the antenna, C _L is the lead wires 12, 13
Stray capacitance, L _x is the equivalent inductance of the choke coils 11a and 11b (1 of the inductance of each coil).
Equivalent to / 2), C _c is the capacity of the DC cut capacitor 8,
C _k is the stray capacitance of the feeder cable 7b.

[Problems to be solved by the invention]

Since the stray capacitance C _L of the lead wires 12 and 13 connecting the heater wire 2 and the choke coils 11a and 11b becomes an ineffective capacity with respect to the grounding point, if the heater wire 2 is used as an antenna conductor, reception in the AM radio broadcasting band will occur. Large signal loss and poor power reception efficiency. The stray capacitance C
The size of _L changes accordingly. When the size of the stray capacitance C _L changes, the reception gain fluctuates. Therefore, when the heater wire 2 is used as an antenna conductor, the reception sensitivity as designed cannot be obtained in both AM and FM radio broadcasting bands. .

In addition, the impedance changes as the length of the lead wires 12 and 13 changes depending on the vehicle type. As a result, the tuning point of the heater wire 2 is deviated, so that tuning must be performed every time the vehicle type changes in order to obtain the optimum frequency characteristic.

In view of the above problems, the present invention improves the power receiving efficiency when the heating conductor is used as the antenna conductor, and
The purpose is to stabilize the characteristics as an antenna.

[Means for solving problems]

In the glass antenna of the present invention, a heating conductor 2 for anti-fogging attached to a window glass 1 of an automobile and power supply electrodes (bus bars 20, 21) connected to both ends of the heating conductor 2 are extended to be arranged close to each other on a glass surface. Terminal portions 20a, 21a, a pair of connecting terminals 36, 37 soldered and fixed to the terminal portions 20a, 21a, a pair of terminal pieces 32, 33 detachably coupled to the pair of connecting terminals, and a power source portion. Receptacle 27 having connector members 34 and 35 for connecting to the connecting electric wires 17 and 18, and the pair of terminal pieces 32 and 33 and the connector member 3 which are built in the receptacle 27.
4 and 35, and a choke coil 11a, 11b which allows a heating current to be supplied to the heating conductor 2 and which has a high impedance in the reception frequency band.

[Action]

Since the receptacle 27 having the choke coils 11a and 11b built therein is detachably coupled to the terminals 36 and 37 on the glass surface, a power supply line between the choke coils 11a and 11b and the heating conductor 2 is unnecessary. Signal loss due to the stray capacitance is reduced, and power reception efficiency is improved. Since the heating current is supplied to the heating conductor 2 via the choke coils 11a and 11b, the heating conductor 2 and the feeding system for the heating current can be insulated in a high frequency manner, and the antenna characteristic of the heating conductor 2 changes in the feeding mode. Can be prevented from changing.

〔Example〕

FIG. 1 shows an embodiment of the present invention and is a front view and a wiring diagram of a rear window glass.

A plurality of anti-fogging heater wires 2 are attached along the width direction of the rear window glass 1, and bus bars 20 and 21 are provided as power supply electrodes at both left and right ends of these heater wires 2. Each of the bus bars 20, 21 extends downward and then extends along the lower edge portion 1a of the rear window glass 1 to the central portion, and one terminal portion 20a, 21 of each bus bar 20, 21 is provided.
a is made to oppose in the center of the lower part of the rear window glass 1. The heater wire 2 and the bus bars 20 and 21 are
It can be formed by screen-printing a conductive paste made of fine silver particles and low-melting-point glass powder on the surface of the rear window glass 1 and then firing it.

A power supply terminal 15 for extracting a reception current induced in the heater wire 2 is provided in the center of the uppermost heater wire 2. The reception current extracted from the power supply terminal 15 is sent to the preamplifier 9 via the feeder line 7a, amplified here, and then supplied to the vehicle-mounted AM / FM receiver via the feeder line 7b. A DC cut capacitor 8 is inserted in the feeder line 7a.

Choke coils 11a and 11b are directly attached to the respective terminal portions 20a and 21a of the bus bars 20 and 21, and a heating current is supplied to the heater wire 2 via these choke coils 11a and 11b. The choke coils 11a and 11b are the third
As shown in the drawing, coil wires 24, 25 are attached to the ring-shaped core 23.
Are formed in a toroidal shape in which they are wound in opposite directions, and are housed in a flat box-shaped receptacle 27.

The bottom plate 27a of the receptacle 27 has a pair of terminal insertion openings 3
0, 31 are formed, and these terminal insertion ports 30,
Female terminals 32 and 33 are provided along the line 31, respectively. The terminal 24a of the coil wire 24 is connected to the female terminal 32, and the terminal 25a of the coil wire 25 is connected to the female terminal 33.
Are connected. Also, the side wall 27b of the receptacle 27
A male connector 34 and a female connector 35 are provided so as to protrude from the male connector 34, the terminal 24b on the other side of the coil wire 24 is connected to the male connector 34, and the terminal 25b on the other side of the coil wire 25 is connected to the female connector 35. Are connected. Decoupling capacitor 1 between terminals 24b and 25b of each coil wire
4 has been inserted.

As shown in FIG. 2, male terminals 36 and 37 are attached to the terminal portions 20a and 21a of the bus bars 20 and 21 facing each other at the center of the lower edge portion 1a of the rear window glass 1 by soldering or the like. ing. These male terminals 3
6 and 37 are inserted into the terminal insertion ports 30 and 31 provided on the bottom plate 27a of the receptacle 27 to mount the receptacle 27 on the rear window glass 1. When attached in this manner, the female terminal 3 provided in the receptacle 27
2, 33 and the male terminals 36, 37 are in contact with each other and electrically connected to each other, so that the choke coils 11a, 11b can be directly connected to the bus bars 20, 21. A lock mechanism is provided to maintain this contact state.

In this embodiment, the terminal insertion ports 30 and 31 are formed in an arc shape,
A wide portion and a narrow portion are formed respectively, and the tip ends of the male terminals 36 and 37 are bent at a substantially right angle to form a lock mechanism. At the time of mounting, as shown by an arrow 39 in FIG. 2, the front ends of the male terminals 36 and 37 are inserted into the receptacle 27 through the wide portions of the terminal insertion openings 30 and 31, and then the receptacle 27 is inserted.
Is rotated in the direction of arrow 40. When attached in this manner, the tip ends of the male terminals 36 and 37 are bent with the female terminals 32 and 33 and the male terminals 36 and 37 in contact with each other as shown in FIG.
Since it hangs on a, the receptacle 27 can be prevented from falling off.

After attaching the receptacle 27 to the bus bars 20 and 21,
The power supply line 1 is connected to the male connector 34 and the female connector 35.
Connect 7 and 18. This connection is made by connecting the female connector 17a and the male connector 18 to each end of the power supply lines 17 and 18.
A is provided and the connector is connected. By this connection, the choke coil 11a can be connected to the plus B power source side, the choke coil 11b can be connected to the ground point, and the heating current can be supplied to the heater wire 2 by closing the switch 28. .

Since the choke coils 11a and 11b are directly connected to the bus bars 20 and 21, no lead wire is required to connect them. Therefore, it is possible to eliminate the loss of the reception current due to the stray capacitance of the lead wire to the ground and improve the reception gain. That is, when the connection is made through the lead wire as in the conventional case, the reception gain of the AM radio broadcast is reduced by about 0.02 dB / PF due to the stray capacitance of the lead wire. Since the lead wire usually has a stray capacitance of about 50 PF, the conventional glass antenna had a gain loss of about 1 dB, but this can be eliminated. Further, by eliminating the lead wire, an unstable element of receiving sensitivity due to power feeding is eliminated, so that the antenna characteristic when the heater wire 2 is used as an antenna conductor can be stabilized.

Further, since it is possible to eliminate the variation of the tuning point due to the lead wire, it is not necessary to retune the tuning every time the vehicle type changes.

As shown in FIG. 1, the frequency characteristics of sensitivity in the FM radio broadcasting band (76 to 90 MHz) when the choke coils 11a and 11b are connected with the horizontal lengths of the bus bars 20 and 21 being equal to each other are the fifth. As shown in FIG. In this case, an overall flat frequency characteristic can be obtained, but the reception gain decreases with a gentle slope as the frequency increases.

Value of l in FIG. 1, that is, plus B for supplying heating current
By changing the length 1 of the bus bar 20 connected to the power source as shown in FIGS. 4A and 4B, the frequency characteristic in the FM radio broadcasting band can be changed. That is, as shown in FIG. 4A, when the horizontal portion of the bus bar 20 is eliminated, the characteristic shown in FIG. 5A is obtained. In this case, the reception gain can be improved as the frequency becomes higher.

As shown in FIG. 4B, when the horizontal portion of the bus bar 21 (ground side) is eliminated and the horizontal portion of the bus bar 20 is lengthened, the characteristic shown in FIG. 5B is obtained. In this case, as the frequency becomes higher, the reception gain improves with a gentle slope, and a frequency characteristic is obtained in which the reception gain starts to decrease near 90 MHz.

As shown in FIG. 6, when the upper and lower heater wires are short-circuited by the bus bar 41 to form a U-shaped pattern, for example, the bus bar 40 provided on the upper heater wire 2 is provided near the lower edge portion 1a of the rear window glass 1. The terminal portion of the bus bar 40 and the end portion of the bus bar 42 can be arranged close to each other in the lower portion of the rear window glass 1. Therefore, even when such a pattern shape is adopted, the choke coils 11a and 11b can be directly connected to the bus bars 40 and 42 without the lead wire.

When the choke coils 11a and 11b are directly connected to the bus bar, it is desirable to reduce the size. For miniaturization, use a presettable electronic tuner that includes a capacitance variable element such as a variable capacitance diode in the tuning circuit instead of the conventional μ tute that has an LC tank circuit in the front end (antenna input stage). Good. The value of the equivalent inductance L _x of the choke coils 11a and 11b when the electronic tuner is used is 60 to 500 μH, and the equivalent inductance 1 when the conventional μ tuner is used 1
Compared with ~ 2mH, it is possible to reduce the size significantly.

In the case of a small car having a small window glass, it is difficult to attach an antenna conductor for FM radio separately. If the choke coils 11a and 11b are directly connected to the bus bar as shown in this embodiment, a high-gain and stable reception signal can be obtained from the heater wire, so that FM radio broadcasting can be favorably received even in a small car.

Also, as shown in FIG. 7, when the received power is guided to the antenna wire group 43 provided above the heater wire 2, the same effect as when the heater wire 2 is directly used as the antenna conductor is obtained. To be

A transparent conductive film may be used as the heating conductor instead of the heater wire 2.

[Effect of device]

As described above, the present invention extends the power supply electrodes connected to both ends of the anti-fogging heating conductor attached to the window glass of the automobile to the respective terminal portions arranged close to each other to pass the heating current to the heating conductor and receive the reception frequency. In order to connect a choke coil that has a high impedance in the band, a built-in choke coil and a receptacle that can be detachably attached directly to the connection terminal provided on the above-mentioned terminal part (on the glass surface), By eliminating the power supply line between the choke coil and the power supply electrode, the stray capacitance to ground can be eliminated. Therefore, the loss of the receiving current induced in the heating conductor can be reduced, and the receiving gain when the heating conductor is used as all or part of the antenna conductor can be improved. Further, the heating conductor and the feeding system for the heating current can be almost completely insulated from each other in terms of high frequency, and stable antenna characteristics that are not affected by changes in the feeding mode from the glass surface to the feeding section can be obtained.

[Brief description of drawings]

FIG. 1 is a front view and wiring diagram of a rear window glass showing an embodiment of the present invention, FIG. 2 is a perspective view showing attachment of a choke coil, and FIG. 3 is a sectional view showing a state in which the choke coil is connected, 4A and 4B are front views of a rear window glass showing another embodiment different from that of FIG. 1, and FIGS. 5A, 5B and C are FM broadcast bands of the glass antennas of FIGS. 4A, 4B and 1. FIG. 6 is a front view of a rear window glass showing an example in which a heater wire is provided in a U-shaped pattern, and FIG. 7 is a graph showing the reception current induced in the heater wire to an antenna conductor. Fig. 8 is a front view of a rear window glass showing an example of Fig. 9 and Fig. 8 is a front view and a wiring diagram of a rear window glass showing a conventional glass antenna.
The figure is an equivalent circuit diagram of the glass antenna of FIG. In the reference numerals used in the drawings, 1 ... rear window glass 2 ... heater wire 11a, 11b ... choke coil 20, 21 ... bus bar 20a, 21b ... terminal portion 27 ... receptacle 32, 33 ... terminal 34 , 35 ... connectors 36, 37 ... terminals.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Iijima 4-8 Doshomachi, Higashi-ku, Osaka City, Osaka Prefecture Nihon Sheet Glass Co., Ltd. (56) References JP-A-60-210005 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A heating conductor for anti-fogging attached to a window glass of an automobile, a terminal portion in which a feeding electrode connected to both ends of the heating conductor is extended and arranged in proximity to a glass surface, and soldering is fixed to the terminal portion. With a pair of connection terminals, a pair of terminal pieces removably coupled to the pair of connection terminals, and a connector member for connecting to a power supply line from a power supply unit, and a built-in receptacle. A window glass for an automobile, comprising: a choke coil having a high impedance in a reception frequency band while passing a heating current supplied to the heating conductor between the pair of terminal pieces and the connector member.