JPS62247238A - Moisture detection sensor and manufacture thereof - Google Patents

Abstract

PURPOSE:To enable detection of fine water drops, by forming opposed electrodes with different pitches therebetween. CONSTITUTION:A window shielding glass 2 is placed into a vacuum film former and an ITO transparent conductive film 21 is deposited on the glass from above a pattern 18 of a masking agent to be attached almost evenly onto the film and then the work is withdrawn from the vacuum film former to remove the masking agent 18 together with the ITO film 21 thereon. By so doing, a comb- teeth type electrode with a coarse pitch and a power feeding electrode are completed. Thereafter, a resist film 22 is applied evenly on an area 20, a mask 23 which is formed by patterning chromium on a glass dry plate 24 at a fine pitch is placed thereon and the resist film is exposed to ultraviolet rays. Then, the work is immersed into a developer, washed with water to remove the resist film exposed and immersed into an etching liquid to remove the ITO film. Moreover, it is immersed into a sulfuric acid-hydrogen peroxide solution to remove the resist film 22. Thus, a rain drop sensor 1 combines two comb-teeth electrodes, the one coarse and the other fine in the pitch.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a rain sensor that is provided on a vehicle windshield and detects raindrops and operates a wiper, and a rain sensor that detects dew condensation and operates a defogger. The present invention relates to a moisture detection sensor, such as an activated dew condensation sensor, and a method for manufacturing the same.

[Conventional technology]

An automatic wiper that detects moisture such as raindrops adhering to the windshield of a car and activates the wiper to automatically wipe away the raindrops (for example, Japanese Patent Laid-Open No. 50-27241)
is being developed. Additionally, an auto defogger (for example, Japanese Utility Model Application No. 53-58956) has been developed that detects dew condensation on a windshield and activates the auto defogger to automatically evaporate the condensation.

There are different types of moisture detection sensors used in these devices, such as rain sensors and dew sensors, depending on the method of detecting moisture. These include resistance change detection type, capacitance change detection type, and infrared reflection detection type.

Among these, the resistance change detection type and the capacitance change detection type include
Some are equipped with comb-shaped electrodes. In the comb-shaped electrode, the comb-shaped electrodes face each other so as to be inserted into each other.

And resistance change detection type (for example, Utility Model Publication No. 55-484
No. 28), a moisture-absorbing material is provided on the electrode. The moisture-absorbing material absorbs moisture from raindrops, guides it to the electrodes, and detects changes in resistance depending on the amount of moisture.

In addition, capacitance change detection type (for example,
No. 354), an insulating film that also serves as a protective film is provided on the electrode. The device detects changes in capacitance caused by raindrops adhering to the insulating film between the comb-shaped electrodes.

All of these sensors are installed on the windshield at locations that do not obstruct the driver's view. These locations are the periphery of the windshield and are often curved parts.

By the way, the moisture detected by these sensors is in the form of particles like raindrops or condensation. The size of these particles changes from time to time. In the case of raindrops, in normal rainfall, the particle size is 0.
．． There are 5 to 51 items. In drizzle, it is 200 μm. Of course, it is also necessary to be able to detect when the entire surface of the windshield is covered with raindrops. In the case of dew condensation, it is 5 to 100 μm.

There is the following relationship between the water particle size and the detection performance of the sensor described above.

In both the resistance change detection type and the capacitance change detection type, the diameter of the detectable water droplet is determined by the distance between the opposing comb tooth electrodes, that is, the pitch. Further, in order to accurately detect the average amount of raindrops, the area of the sensor section needs to be larger than a certain level. This is to deal with variations in the distribution of water droplets adhering to the window glass.

Usually, the resistance change detection type moisture detection sensor used has a pitch of one crane and an area of 50 cd. For the capacitance change detection type, the pitch is 0.2 Tsuru and the area is 100-
It is. With this pitch, the limit of water droplets that can be detected is 1.5IIm in the former case and 0.5IIm in the latter case.
It's about 3 dragons.

Therefore, when extremely small water droplets, such as fog, adhere to the windshield, the sensor will not detect the moisture, so the auto wiper or auto defogger will not operate.

(Problems to be solved by the invention) In order to solve such problems, the inventor of this application
We considered reducing the pitch of the sensor's electrodes to improve moisture detection performance. However, there are the following manufacturing problems in forming comb-like electrodes with extremely small pitches.

There are two conventional methods for forming comb-like electrodes, depending on the pitch of the electrodes.

To form comb-shaped electrodes with a coarse pitch, see FIG. 10(a).
A lift-off method as shown in ~(d) is used.

For this purpose, first, a transparent substrate 1 such as glass, on which the electrodes are formed, is used.
01, a negative resist masking agent 102 such as polycinnamic acid is screen printed so that the teeth of the comb can be removed (as shown in FIG. 10(a)), and then ITO, etc. A transparent conductive film 103 is deposited by a vacuum film forming method (as shown in FIG. 10(b)). After vapor deposition,
After removing the masking agent 102 together with the transparent conductive film 104 thereon (as shown in FIG. 10(C)), if the sensor is of a capacitance change detection type, an insulating film 105 made of alumina or the like which also serves as a protective film is removed. is deposited using a vacuum film-forming method (see Figure 10 (
d)).

In this method, since masking is performed by screen printing, it is possible to accurately form a film even on a curved substrate.

In order to form comb-shaped electrodes with a fine pitch, the method shown in FIG. 11 (a
) to (f) are used.

In this method, a transparent conductive film 112 such as ITO is coated on a transparent substrate 111 such as glass on which the electrodes are to be formed by a vacuum film-forming method in advance, and a resist film 113 is applied thereon (Fig. 11). (shown in (a)). After coating, the resist film 113 is covered with a mask 114 made by patterning chromium on a glass plate, and ultraviolet rays are irradiated (as shown in FIG. 11(b)). After removing the mask 114 and soaking it in a developer,
The resist film 114 exposed to ultraviolet rays is removed by washing with water (as shown in FIG. 11(c)), and then the transparent conductive film 115 is removed by immersion in a corrosive solution and chemical etching (see FIG. 11(c)). d)).

Finally, the resist film 116 on the remaining transparent conductive film is removed to complete the comb tooth electrode (as shown in FIG. 11(e)). In the case of a variable capacitance type sensor, an insulating film 117 made of alumina or the like which also serves as a protective film is deposited by a vacuum deposition method (as shown in FIG. 11(f)).

In this photoetching method, when removing the resist film 113, a mask 114 made of patterned glass is used, so when using a curved substrate, as shown in FIG.
Since a gap 125 is created between the resist film 123 formed on the transparent conductive film 122 on the transparent substrate 121 and the mask 124, the resist film 123 is not removed cleanly.
The comb-shaped electrode pattern becomes blurred, making it difficult to form comb-shaped electrodes with fine pitches.

Therefore, an object of the first invention (invention related to an object) according to the present application is to enable fine water droplets to be accurately detected on average on a vehicle window glass.

A second invention (an invention relating to a method of manufacturing an object) according to the present application is to precisely form comb-shaped electrodes with coarse pitch and fine pitch on a curved substrate.

[Failure to solve the problem]

Therefore, the first invention is characterized in that it is possible to detect fine water droplets and to detect them over a wide range by using a moisture detection sensor equipped with a comb-shaped electrode in which the pitch of the comb teeth is varied.

Specifically, the moisture detection sensor according to the first invention has the following configuration.

Provided on the vehicle windshield. When installed on the outside of the windshield, it is used as a rain sensor that detects raindrops and automatically activates the wipers. When installed inside the window glass, it is used as a dew condensation sensor that detects dew condensation and automatically activates the defogger.

This is a moisture detection sensor equipped with a sensor section consisting of comb-shaped electrodes, and detects water droplets covering between the comb teeth as a change in resistance or a change in capacitance.

The comb-like electrodes of the sensor are configured with different pitches between opposing electrodes so that they can penetrate into each other.

Further, in a second invention, after forming a conductive film, a comb-shaped electrode with a coarse pitch is formed by a lift-off method.

Furthermore, a feature is that comb-shaped electrodes with a fine pitch are formed by a photoetching method.

Next, a specific configuration of the method for manufacturing a moisture detection sensor, which is the second invention, will be explained.

This is a method of manufacturing the moisture detection sensor of the first invention by forming a sensor section made of a comb-shaped electrode on a vehicle window glass. First, a masking agent is screen printed on the window glass. In screen printing, a masking agent is printed for use as a shield for forming comb-shaped electrodes with a coarse pitch and as a shield for securing a region for forming comb-shaped electrodes with a fine pitch.

A conductive film is formed over the printed mask agent using a vacuum film forming method or the like.

Then, when the masking agent is removed, the masked conductive film is exposed, forming regions for forming coarse pitch comb-shaped electrodes and fine pitch comb-shaped electrodes.

A resist film is formed over it.

The resist film is covered with a mask for comb-shaped electrodes with a fine pitch, and exposed to ultraviolet light.

The mask is removed, the exposed resist film is removed to expose the conductive film, and the conductive film is removed by immersion in a developer and etching.

Finally, the remaining resist () is removed to expose fine-pitch comb-shaped electrodes.

After that, surface treatment is performed as necessary.

[Effect]

The moisture detection sensor according to the present invention as described above is
Since comb-shaped electrodes with different pitches are formed in the sensor section, moisture is detected as follows.

In the electrode portion having a fine pitch, it is possible to detect water droplets as fine as fog. On the other hand, since the area including the rough pitch has a fairly large area, water droplets that adhere sparsely can be captured.

In addition, the method for manufacturing the moisture detection sensor as described above is as follows:
When forming electrodes with a coarse pitch using the lift-off method, a region for configuring a comb-shaped electrode with a fine pitch is formed at the same time.Thereafter, electrodes with a fine pitch are formed in a series of steps using a photoetching method. Ru. Furthermore, since the fine-pitch comb-shaped electrodes are in some narrow areas,
An area of low curvature on the windshield can be selected.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

(First Example) In this example, a rain sensor is used as a moisture detection sensor.

Here, FIG. 1 is a front view of the rain sensor according to the first embodiment of the present invention, FIG. 2 is an enlarged view of fine pitch electrodes of the rain sensor shown in the direction of the Shonin arrow in FIG. 1, and FIG. Figure 3 is a front view of the windshield glass with the rain sensor attached.

In FIG. 3, reference numeral 1 denotes a capacitance change detection type rain sensor. In the rain sensor 1, a comb-shaped electrode 5 shown in FIG. 1 is formed on a wiping part 4 of a wiper 3 above the center of the outside of a windshield glass 2 of an automobile.

The comb-shaped electrode 5 has a comb-shaped electrode formed between power feeding electrodes 6 and 7. The comb-shaped electrode has a portion 10 formed by comb teeth 8.9 with a coarse pitch of comb teeth, and a portion 11 formed with comb teeth 11.12 with a fine pitch of comb teeth, as shown in FIG. There is a part 13 that

The power supply electrode 6.7 has one end extending to the terminal 14.
．． 15 is formed. Lead wires 16.17 are fixed to the terminals 14.15 with solder. The other ends of the lead wires 16 and 17 are connected to a control circuit (not shown) to operate the wiper 3 in response to the output of the rain sensor 1.

The material and dimensions of the comb-shaped electrode 5 are as follows.

The comb-shaped electrode 5 is a film of ITO (a solid solution of indium oxide and tin oxide), and is made by a method described later.

In the part 10 with a coarse pitch, the width of the comb teeth 8.9 is 0°5,
Pitch is 0.2 fins, length is 150 inches, area is 150 cm
d. In the fine pitch portion 13, the width of the comb teeth 11.12 is 0.05 mm, the pitch is 0.02 mm, and the length is 20 fins.
The area is 4-. The film thickness of each electrode is 0.1μ
There are m.

Further, on the comb-shaped electrode 5, an insulating film made of alumina and serving as a protective film is formed with an average thickness of 0.5 μm.

A method of manufacturing this rain sensor 1 will now be described with reference to FIGS. 3 to 7.

As shown in FIG. 3, this rain sensor 1 is formed at the upper center of the windshield glass 2 of an automobile. The radius of curvature of this formed portion of the windshield glass 2 is approximately Iom. The distance between this part and the plane is 6 μm when the center of the sensor 1 touches the plane and is 10 meters away from the center to the left and right.

First, a masking agent (polycinnamic acid as a negative resist) is screen printed on the sensor forming portion of the windshield glass 2 in the pattern shown in FIG. In area 19, a pattern forming comb-shaped electrodes with a coarse pitch is drawn, and a cross section thereof is shown in FIG. 5(a). Area 2
0 has a pattern drawn on it for forming a transparent conductive film on one surface to later form fine-pitch comb-shaped electrodes, the cross section of which is shown in FIG. 6(a), and the thickness of the masking agent 18 is , approximately 20 μm.

Next, the windshield glass 2 is placed in a vacuum film forming apparatus (not shown), and an I.
A transparent conductive film 21 of TO is deposited.

As shown in FIG. 5(b) and FIG. 6(b), an ITO film 2 is placed on the windshield glass 3 and the masking agent 18.
1 adheres approximately evenly.

The windshield glass 2 is taken out from the vacuum film forming apparatus, and an alcoholic solution is sprayed onto the sensor formation portion to remove the masking agent 18 together with the ITO film 21 thereon. This completes the coarse-pitch comb-shaped electrodes and power supply electrodes (shown in FIGS. 5(C) and 6(c)).

Thereafter, by photo-etching, comb-shaped electrodes with fine pitches are formed in the area (indicated by reference numeral 20 in FIG. 4) where the ITO film was uniformly formed by the lift-off method.

A resist film 22 (a mixture of a compound having a naphthoquinonediazide structure and a phenol resin) is uniformly applied to the area 20 (as shown in FIG. 7(a)).

A mask 23 patterned with chromium at a fine pitch is placed on a glass dry plate 24 from above the resist film 22, and the resist film is exposed to ultraviolet light (as shown in FIG. 7(b)).

In this state, as described above, since the gap between the mask 23 and the resist film 22 is about 6 μm, the amount of ultraviolet light that is exposed to the pattern is small, and the pattern is not blurred.

The dry plate 24 is removed, immersed in a developer (alkaline aqueous solution), and washed with water. As a result, the exposed resist film is removed, resulting in a cross section shown in FIG. 7(c).

In this state, the ITO film is removed by immersing it in an etching solution (hydrochloric acid), resulting in the cross section shown in FIG. 7(d).

Furthermore, it is immersed in a sulfuric acid-hydrogen peroxide solution to remove the resist film 22 and is completed (as shown in FIG. 7 (+3)).

According to the rain sensor 1 according to the first embodiment of the present invention, since it has both coarse pitch and fine pitch comb-shaped electrodes, the moisture detection area can be widened as a whole, and the comb-shaped electrode 13 has a fine pitch. Can detect moisture particles. At that time, the comb-shaped electrode 13 with a fine pitch
Since it is located above, even if it is wiped by the wiper 3, water is removed more quickly than the lower, rough-pitch comb-shaped electrode IO. As a result, highly accurate moisture detection is always possible.

In addition, since the comb-shaped electrode 13 with a fine pitch is provided between the power supply electrodes 6.7, the comb-shaped electrode 13 with a coarse pitch
The power feeding electrodes 6 and 7 can be shared.

(Second Embodiment) In this embodiment, a comb-shaped electrode with a fine pitch is provided below a comb-shaped electrode with a coarse pitch.

Here, FIG. 8 is a front view of a rain sensor according to a second embodiment of the present invention.

In FIG. 8, reference numeral 31 is a rain sensor of a capacitance change detection type. The rain sensor 31 is installed in the wiping part 4 of the wiper 3 above the center of the outside of the windshield glass 2 of the automobile, as in the first embodiment.

The difference from the first embodiment is that a comb-shaped electrode 32 with a fine pitch is arranged below a comb-shaped electrode 33 with a coarse pitch.

Therefore, the power supply electrodes 34.35 extend further downward, and the power supply electrodes 36.3 of the comb-shaped electrodes 32 with fine pitches.
7 is formed.

In this embodiment, fine pitch comb-shaped electrodes 32 with good moisture detection sensitivity are provided near the center of the windshield glass, making it possible to detect raindrops similar to actual rain conditions.

(Third Example) This example is an example in which a comb-shaped electrode with a fine pitch is provided on the side of a comb-shaped electrode with a coarse pitch.

Here, FIG. 9 is a front view of a rain sensor according to a third embodiment of the present invention.

In FIG. 9, reference numeral 51 is a rain sensor of a capacitance change detection type. The rain sensor 51 is installed in the wiping part 4 of the wiper 3 above the center of the windshield glass 2 of the automobile, as in the first embodiment.

The difference from the first embodiment is that a fine-pitch comb-shaped electrode 52 is arranged on the side of a coarse-pitch comb-shaped electrode 53.

Therefore, the power supply electrodes 54 and 55 further extend laterally, and the power supply electrodes 56 and 56 of the fine-pitch comb-shaped electrodes 52.
57 is formed.

In this embodiment, since the comb-shaped electrodes 52 and 53 are arranged side by side, the view of the windshield glass 2 is not obstructed and visibility is excellent.

Although specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, but includes various embodiments within the scope of the patent.

For example, in the above-described embodiment, a fine-pitch comb-shaped electrode is provided at only one location, but a plurality of fine-pitch comb-shaped electrodes may be provided around a coarse-pitch comb-shaped electrode.

〔Effect of the invention〕

As described above, the moisture detection sensor and its manufacturing method of the present invention have the following effects.

(b) Fine water droplets such as fog can be detected.

(b) It is possible to detect sparse adhesion of water droplets with high accuracy on average.

(c) Comb-shaped electrodes with different pitches can be formed in one sensor section.

[Brief explanation of drawings]

FIG. 1 is a front view of the rain sensor according to the first embodiment of the present invention, FIG. 2 is an enlarged view of section A in FIG. 1, FIG. 3 is a front view of the windshield glass, and FIG. is the first aspect of the present invention
FIGS. 5(a) to 5(c) are front views of a rain sensor showing a method of manufacturing a rain sensor according to an example, and FIGS. )~
(C) and FIGS. 7(a) to (e) are cross-sectional views showing fine-pitch comb-shaped electrodes in the same manufacturing method, and FIG. 8 is a front view of a rain sensor according to the second embodiment of the present invention. FIG. 9 is a front view of a rain sensor according to a third embodiment of the present invention, and FIG.
FIG. 0 is a cross-sectional view of a transparent substrate for explaining a conventional masking method, and FIGS. 11 and 12 are cross-sectional views of a transparent substrate for explaining a conventional etching method. ■, 31.51-・-----Rain sensor (moisture detection sensor) 2-----Windshield glass (wind glass) 10-------Comb-shaped electrode (coarse pitch) 13---
---One comb electrode (fine pitch) Applicant: Toyota Motor Corporation Figure 1 Figure 2 Figure 3 Figure 4 Figure 10 Figure 11 Prisoner

Claims (2)

[Claims] (1) A moisture detection sensor that is installed on a vehicle windshield and has a sensor section consisting of comb-shaped electrodes, and the comb-shaped electrodes are arranged between opposing electrodes so that they fit into each other. A moisture detection sensor characterized by being configured with different pitches. (2) A method of manufacturing a moisture detection sensor by forming a sensor part consisting of comb-shaped electrodes on a vehicle windshield, the method comprising: forming a sensor part consisting of comb-shaped electrodes on a vehicle windshield, and forming a masking agent for the comb-shaped electrodes with a coarse pitch and a masking agent with a fine-pitch electrode on the windshield; A process of simultaneously screen-printing a masking agent for areas constituting the comb-shaped electrode, a process of forming a conductive film thereon, and a process of removing the masking agent and the conductive film thereon to form a comb-shaped electrode with a coarse pitch. A step of forming a region constituting a fine-pitch comb-shaped electrode, a step of forming a resist film on the region, and a step of covering the resist film with a mask for the fine-pitch comb-shaped electrode and exposing it to ultraviolet rays. , a step of removing the mask and removing the exposed resist film to expose the conductive film, a step of immersing it in a developer and etching it to remove the exposed conductive film, and a step of removing the resist film and removing the exposed conductive film. A method for manufacturing a moisture detection sensor, comprising the step of exposing pitched comb-shaped electrodes.