JPH01266043A - Device for detecting cloudiness of window of vehicle - Google Patents

Abstract

PURPOSE:To dispense with an exclusive sensor for detecting cloudiness and automatically detect the cloudiness in a window glass in which wiring for antenna or heater is provided by detecting the change in an electrostatic capacity caused by the deposition of water between wires and judging the cloudiness of the window glass. CONSTITUTION:In a vehicle in which the antenna wire 14 of a radio receiving antenna 13 is continuously provided leaving a space, when a rear glass 12 gets cloudy and as water starts to be deposited on the periphery of the antenna wire 14, the electrostatic capacity CX of the antenna 13 rises and, in line with this, an AC detecting voltage outputted to the output node 26 of a detecting circuit 23 also starts to rise. As the electrostatic capacity CX exceeds a threshold-value electrostatic capacity, a time starting signals is outputted from a comparator 34. Thereby, a delay timer 37 starts operating and as the set time is over, a relay 38 provided on a rear-defogger feed wire 39 is excited to start electrifying heating wires 16..., to remove cloudiness.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vehicle window fogging detection device for detecting fogging that occurs on the surface of a vehicle windshield.

(Prior Art) When water vapor in the air condenses on the surface of a windshield of a vehicle due to a temperature difference between the interior and exterior of the vehicle, resulting in fogging, visibility through the windshield may deteriorate. To deal with this, for example, it is customary to incorporate a heating wire into the rear window.When the rear window becomes foggy, the heating wire is energized to generate heat, and the heat is used to remove the fog that has formed on the rear window. It is supposed to be done.

However, according to this method, the driver has to judge whether the rear window is foggy and manually turn on the heating wire each time as necessary, which is cumbersome. One idea is to use a sensor to detect fogging that has occurred, and to automate the start of energizing the heating wire based on the detection signal from the sensor. To give an example of this type of sensor, for example, as shown in FIG. 7, two sensor wires 2a are provided on the inner surface of the lower part of the rear glass 1.

2b are arranged in parallel with each other at appropriate intervals, and one end of each of the sensor wires 2a, 2b is connected to an output terminal 3.2b.
3 constitutes a fogging detection sensor 4. In this case, when the glass 1 near the sensor wires 2a and 2b becomes cloudy, the output signal of the fogging detection sensor 4 changes due to the influence of moisture adhering between both the sensor wires 2a and 2b. Heating wires 5, 5... are arranged in parallel on the inner surface of the rear glass 1.
It is used as a signal to start energizing the rear defogger 6, which is configured by the following.

On the other hand, in recent vehicles, an antenna wire for radio reception, for example, may be incorporated into the windshield (see, for example, Japanese Patent Laid-Open No. 60-7203).

(Problem to be Solved by the Invention) By the way, in order to automatically remove fogging from a windshield, it is necessary to separately prepare a dedicated sensor for detecting fogging as described above, and the sensor must be incorporated into the windshield, and it may be difficult to secure space for the sensor, especially when heating wires and antenna wires are included.

Therefore, the present invention detects fogging by utilizing the characteristic that the capacitance of a window glass with built-in antenna or electric heating wires changes when moisture adheres between the wires. An object of the present invention is to realize a fogging detection device for a vehicle window that can automatically detect fogging without providing a special sensor.

(Means for Solving the Problems) In order to achieve the above object, the present invention is characterized by the following configuration. That is, the present invention provides a capacitance detecting means for detecting the capacitance between the wires in a vehicle in which wiring for antenna or electric heating is provided on the windshield, and a capacitance detecting means that detects the capacitance exceeding a set value from the capacitance detecting means. and determining means for determining that fogging has occurred on the window glass when a signal indicating a change in is output.

(Function) According to the above configuration, for example, in a window glass provided with wiring for an antenna, a change in capacitance that occurs when moisture adheres between the wirings is detected by the capacitance detection means. When the capacitance detection means outputs a signal indicating a capacitance change greater than a set value, the determination means determines that the window glass is fogged. As a result, there is no need to prepare a separate sensor to detect the occurrence of fogging, which can reduce costs, and there is no need to secure space on the windshield to install the sensor. You can freely lay out antenna wires and heating wires.

(Example) Embodiments of the present invention will be described below based on the drawings.

As shown in FIG. 1, a rear window 12 is attached to a rear window 11 provided at the rear of a vehicle 10, and an antenna wire 14 of, for example, a radio receiving antenna 13 is attached to the upper inner surface of this rear window 12. They are arranged continuously at appropriate intervals in the horizontal direction. The antenna wire 1 is provided on the inner surface of both sides of the rear glass 12 in the vehicle width direction.
4, a strip-shaped electrode portion 15 extending in the vertical direction
a, 15b are respectively disposed, and a plurality of heating wires 16, 16...
... are arranged horizontally at appropriate intervals, and these electrode parts 15a, 15b and heating wires 16, 16...
The rear defogger 17 is constituted by...

Next, a fogging detection device for detecting fogging occurring on the rear glass 12 will be explained. As shown in FIG. 2, the antenna wire 1 provided on the upper inner surface of the rear glass 12
A flat antenna power supply section 18 is provided in the middle of the antenna power supply section 4, and a harness 22 having two signal cables 20 and 21 is connected to a connection terminal 19 of this antenna power supply section 18. . Then, one signal cable 2
0 is connected to a booster (not shown), and after the antenna input signal is amplified by the booster, it is input to a radio receiver (not shown). Further, as shown in FIG. 3, the antenna input signal transmitted to the other signal cable 21 via the harness 22 is input to the fogging detection circuit 23. In addition,
The antenna wire 14 described above is body grounded at an appropriate location other than the antenna power feeding section 18.

The above-mentioned fogging detection circuit 23 includes the above-mentioned antenna power feeding section 18.
Input node 2 to which the signal cable 21 from
4 is provided, and a fixed resistor 25 connected to this input node 24 is connected to the input side of a rectifier circuit 27 via an output node 26.

Further, the output node 26 is connected to the first .
The body is grounded via a second variable resistor 28, 29 and a standard capacitor 30. An intermediate node 3 located between the first variable resistor 28 and the second variable resistor 29
1 and the input node 24 described above are connected via an AC power supply 32.

In this case, assuming that the capacitance of the radio receiving antenna 13 is CX, the radio receiving antenna 13 having this capacitance C8, the fixed resistor 25, the first variable resistor 28, and the second variable resistor 29 and the standard capacitor 30 constitute an AC bridge 33, and the AC detection voltage Va corresponding to the change in the capacitance CX of the radio receiving antenna 13 is applied to the output node 2 of the AC bridge 33.
6 is output.

Next, one input terminal 34a of a comparator 34, which is also provided in the fogging detection circuit 23, is connected to the output side of the rectifier circuit 27. The comparator input voltage V is inputted. Further, the fogging detection circuit 23 is equipped with a potentiometer 35 having a sliding contact 35a, and the sliding contact 35a is connected to the + side input terminal 34b of the comparator 34. The + side input terminal 34 via the sliding contact 35a
A reference voltage VS is applied to b.

Note that by moving and changing the sliding contact 35a of the potentiometer 35, the + of the comparator 34 can be changed.
The value of the reference voltage vs applied to the side input terminal 3Ab can be adjusted.

On the other hand, the amplifier 3 is connected to the output terminal 34c of the comparator 34.
6 is connected to the delay timer 37, and the delay timer 37 is connected to the coil portion 38a of the default relay 38.
The output side of 7 is connected. And comparator 3
When the comparator input voltage V input to the one side input terminal 34a of 4 is higher than the reference voltage Vs applied to the + side input terminal 34b, the timer start signal is output from the output terminal 34c. There is.

Further, a normally closed switch 40 and a normally open contact 38b of the defogger relay 38 are provided connected to one electrode portion 15a of the rear defogger 17 or in the middle of the rear defogger power supply line 39. The other electrode portion 15b of the rear defogger 17 is grounded to the body.

By the way, the capacitance C8 of the radio receiving antenna 13
is known to change as shown in the characteristic curve of FIG. 4 during the process in which water vapor in the air condenses on the inner surface of the rear glass 12 and fogs up. That is, the characteristic curve showing the change in capacitance CX once rises in a parabolic curve as time passes, and after passing the peak, begins to fall, and becomes almost zero at the final stage. Therefore, a threshold capacitance C8o is set by arbitrarily selecting the value of the capacitance C, l while the above characteristic curve is rising, and a capacitance C8 that exceeds the threshold capacitance 1Lcxo is set. If the rear defogger 17 is energized when this is detected, the rear defogger 17 can be automatically operated. Therefore, the above threshold capacitance, tCXo
, so that the value of the comparator input voltage V corresponding to the first . Second
Variable resistors 28, 29 and potentiometer 35 are adjusted. Therefore, the capacitance C of the radio receiving antenna 13 is the threshold capacitance cX.

When it reaches 1. Output terminal 3 of the comparator 34
A timer operation start signal is output from 4c.

Next, the operation of this embodiment will be explained.

When the rear window 12 becomes cloudy and moisture begins to accumulate around the antenna wire 14 of the radio receiving antenna 13,
As shown in the characteristic curve of FIG. 4, the capacitance CX of the radio receiving antenna 13 rises, and correspondingly, the AC detection voltage va output to the output node 26 of the fogging detection circuit 23 also begins to rise. Therefore, the DC comparator input voltage V obtained by rectifying the AC detection voltage va also increases in accordance with the change in the capacitance C8. and,
When fogging occurs on the rear glass 12 such that the capacitance CX exceeds the threshold capacitance CXO, the comparator 3
After the timer start signal is output from the output terminal 34c of 4, and the timer start signal is amplified by the amplifier 36,
The signal is input to the delay timer 37. The delay timer 37 receives the above-mentioned timer start signal, and the rear glass 1 becomes so high that it becomes necessary to energize the rear defogger 17.
A delay time corresponding to the elapsed time until 2 becomes cloudy is set in advance. Therefore, when the delay timer 37 times up, the coil portion 38a of the defogger relay 38 provided on the rear defogger power supply line 39 becomes energized, the normally open contact 38b closes, and the heating wires 16, 16, etc.
... becomes energized and generates heat, and the fog generated on the rear glass 12 is removed by the generated heat. In this way, by detecting the change in the capacitance CX of the radio receiving antenna 13 when the rear glass 12 is fogged, there is no need to provide a special sensor to detect the fog that has occurred on the rear window 12, which reduces costs. It has the advantage of being able to lower the target. In particular, as in this embodiment, the antenna antenna wire 14 of the radio receiving antenna 13 and the heating wire 16.1 of the rear defogger 17 are attached to the rear glass 12.
6..., the antenna wire 14 and the heating wire 16 can be arranged on the rear glass 12 without any difficulty since the sensor for detecting fogging is unnecessary as described above. There is an advantage.

Furthermore, since the threshold capacitance CxO is set while the characteristic curve indicating the change in capacitance CX is rising, fogging of the rear window 12 can be detected at an early stage.

In this embodiment, when the rear defogger 17 is turned off, the opening/closing switch 4o is turned off manually, but an appropriate timer device may be installed in the rear defogger power supply line 39. For example, the 0FFli operation of the rear defogger 17 can also be performed automatically.

Furthermore, as in this embodiment, by connecting the antenna power supply section 18 and the cloudy detection circuit 23 via the signal cable 21, the change in the capacitance C of the radio receiving antenna 13 is output to the cloudy detection circuit 23. There is a practical advantage that there is no need to provide a special member on the antenna wire 14 for this purpose.

In addition, the heating wire 16.16 of the rear defogger 17...
The change in the capacitance C8 may be input to the fogging detection circuit 23 to detect the fogging that occurs on the rear glass 12.Also, any change in the characteristic curve during the rise of the capacitance C8 may be applied to the fogging detection circuit 23. The differential coefficient of may be used as the threshold value for determining the timer start signal output from the output terminal 34c of the comparator 34.

Next, another embodiment shown in FIG. 5 will be described. In this embodiment, a radio receiving antenna 1 is mounted on a windshield 41.
The present invention is applied to a front window 42 of a vehicle 1o incorporating a windshield 3', and in this embodiment,
Two antenna wires 43a, 43b are vertically arranged on the inner surface of the windshield 41 in the vehicle width direction at a distance from each other in the vertical direction. The glass 41 is bent in opposite directions near its upper edge, and the upper ends are connected to each other via an antenna feeder 18', thereby forming a radio receiving antenna 13'. A fogging detection circuit 23" having a circuit configuration similar to that shown in FIG. It is connected to the input side of 44.

The air conditioning control unit 44 outputs control signals to, for example, a mode switching valve 45 and an inside/outside air switching valve 46.

According to the configuration of this embodiment, the air conditioning control unit 44 operates as follows in a normal control mode such as heating operation. As shown in the flowchart of FIG. 6, by executing step S1, it is determined whether the windshield 41 is fogged based on the input signal from the fogging detection circuit 23'. When the determination result is NO, the normal control mode is maintained in step S2. - On the other hand, when the determination result is YES, a built-in timer (not shown) is turned ON in step S3, and an operation signal is output to the mode switching valve 45 in step S4 to set it to the differential mode, and in step S5 A switching signal is output to the inside/outside air switching valve 46 to set the outside air introduction mode. Next, in step S6, it is determined whether the built-in timer has timed up, and if the determination result is No, the process returns to step S3, and from step S3 to step S6.
Execute repeatedly. Then, when the determination result in step S becomes YES, step S2 is executed to return to the normal control mode.

As described above, also with the configuration of this embodiment, the antenna wire 4 of the radio receiving antenna 13' is attached to the windshield 41.
If only 3a and 43b are provided, the windshield 41
This eliminates the need for a special sensor to detect cloudy weather.

In addition, in a vehicle equipped with an air conditioner, the air conditioner may be turned on instead of the outside air introduction mode in step S5 in the flowchart of FIG.

(Effects of the Invention) As described above, according to the present invention, in a window glass provided with wires for antenna or electric heating, the change in capacitance that occurs when moisture adheres between the wires is detected by the capacitance detection means. When the capacitance detection means outputs a signal indicating a capacitance change greater than the set value, the 71-stage determination means determines that the window glass is fogged. This eliminates the need to separately prepare a dedicated sensor for detecting the occurrence of fogging, which reduces costs.In particular, for windshields with antenna wires or heating wires, there is no need to install an extra sensor for the fogging detection sensor. Since no space is required for the windshield, there is the practical benefit of being able to freely lay out antenna wires and heating wires.

[Brief explanation of the drawing]

1 to 6 are drawings showing embodiments of the present invention,
Figure 1 is an overall perspective view of a vehicle with a radio receiving antenna installed on the rear window, Figure 2 is an enlarged exploded perspective view of the main parts of the antenna wire of the radio receiving antenna in Figure 1 seen from inside the vehicle, and Figure 3 is a cross-sectional view of the vehicle. FIG. 4 is a characteristic diagram showing a time change in the capacitance of a radio receiving antenna on a rear windshield, and FIG. Block circuit diagram showing an embodiment in which a vehicle window fogging detection device is applied to a vehicle having a radio receiving antenna on the windshield, No. 6
The figure is a flowchart showing the operation of the air conditioning control unit, and FIG. 7 is a drawing showing a conventional back glass provided with a sensor dedicated to detecting fogging. 12...Rear glass, 14.16...Wiring (14.
... antenna wire, 16 ... heating wire), 33 ... capacity detection means (AC bridge), 34 ... determination means (comparator).

Claims (1)

[Claims] (1) In a vehicle in which antenna or electric heating wiring is provided on the windshield, a capacitance detection means for detecting the capacitance between the wirings, and a change in capacitance exceeding a set value is detected from the capacitance detection means. A fogging detection device for a vehicle window, characterized in that it has a determining means for determining that fogging has occurred on the window glass when a signal indicating the fogging has occurred on the window glass is output.