CN100562717C - Hybrid sensor - Google Patents

Abstract

A hybrid sensor comprising: a plurality of stacked flexible sheets; wherein a first sheet of the plurality of flexible sheets includes: a switch electrode pattern, and a detection electrode pattern, wherein the detection electrode pattern substantially covers the second The entire area in one sheet except for the area where the switching electrode pattern is formed, wherein the first sheet further includes: a guard electrode pattern supplied with the same potential as that supplied to the detection electrode pattern and located at the on the first chip to prevent parasitic capacitance between the detection electrode pattern and the switch electrode pattern.

Description

hybrid sensor

Priority is claimed from Japanese Patent Application No. 2004-139518 filed on May 10, 2004, and Japanese Patent Application No. 2004-291873 filed on October 4, 2004, the contents of which are incorporated herein by reference.

technical field

The present invention relates to a hybrid sensor including an electrostatic capacitance sensor that detects a nearby object using a change in electrostatic capacitance, and a contact pressure sensor that detects load pressure. More specifically, the present invention relates to a hybrid sensor manufactured by stacking a plurality of elastic or flexible sheets each provided with an electrode pattern.

Background technique

A related art hybrid sensor having an electrostatic capacitance sensor and a contact pressure sensor, and a system for detecting a human body sitting on a seat of a car using the hybrid sensor are disclosed in Japanese Unexamined Patent Application, First Publication, No. 2002 -326554, assigned to the same applicant as this application. As shown in FIG. 8, the hybrid sensor 6 is formed by stacking upper and lower flexible sheets 11 and 12 made of an insulating resin film such as a polyester film and an insulating sheet 13 therebetween. The flexible sheets 11 and 12 are respectively provided with switching electrode patterns 14 and 15 on the lower surface 11a of the sheet 11 and the upper surface 12a of the sheet 12 facing each other. The electrode patterns 14 and 15 are formed by screen printing in which a suitable conductive material such as silver paste is deposited. Each of the electrode patterns 14 and 15 includes a plurality of landing (land) portions 14a and 15a, which are used as switch contacts 16 arranged in a matrix pattern, and lead portions 14b and 15b, which connect the land portions 14a to and 15a are electrically connected to a detection circuit (not shown). The insulating sheet 13 has a plurality of openings 17 at positions corresponding to the landing portions 14a and 15a. Each of said openings 17 has a diameter sufficient to enable one of said landing portions 14a to be in contact with an associated one of said landing portions 15a. When a pressure load is applied, one or some of the landing portions 14a of the upper flexible sheet 11 contact the associated one or some of the landing portions 15a of the lower flexible sheet 12 through the opening 17 to make electrical contact. The hybrid sensor 6 performs the function of the contact pressure sensor through the structural elements described above.

The function of the capacitance sensor in the hybrid sensor 6 is realized by a pair of detection electrode patterns 7 a and 7 b formed on the surface 11 a of the upper flexible sheet 11 facing the insulating sheet 13 . The detection electrode patterns 7 a and 7 b are insulated from the switch electrode pattern 14 . The electrostatic capacitance sensor thus configured detects an adjacent object without contacting it based on a change in electrostatic capacitance obtained from the detection electrode patterns 7a and 7b.

According to the above structure, the manufacturing cost for the hybrid sensor can be reduced because the contact pressure sensor and the electrostatic capacitance sensor are formed on the same flexible sheet.

However, the hybrid sensor described above inevitably has insufficient sensitivity for detecting an adjacent object when the object is relatively far from the sensor. This is because the detection electrode pattern for the electrostatic capacity sensor is provided on a relatively small area of the flexible sheet.

Contents of the invention

The present invention has been accomplished in consideration of the above problems. Accordingly, an object of the present invention is to provide a hybrid sensor including an electrostatic capacitance sensor in which sensitivity for detecting a neighboring object is improved, and thereby realize a highly reliable hybrid sensor.

According to an exemplary embodiment of the present invention, a hybrid sensor includes a plurality of stacked flexible sheets. A first sheet of the plurality of flexible sheets includes a switching electrode pattern and a detecting electrode pattern. The detection electrode pattern covers substantially the entire area of the first sheet except the area where the switching electrode pattern is formed. The first sheet may further include a guard electrode pattern supplied with the same potential as that supplied to the detection electrode pattern. The guard electrode pattern is located on the first sheet to block parasitic capacitance between the detection electrode pattern and the switch electrode pattern.

A second sheet of the plurality of flexible sheets may be an insulating sheet having a plurality of holes therein, and a third sheet of the plurality of flexible sheets may include a ground electrode pattern. The positions of the plurality of holes in the second sheet and the ground electrode pattern of the third sheet may correspond to the positions of the switch electrodes on the first sheet. Accordingly, when pressure is applied to the first and second sheets, the switch electrode may contact the ground electrode through the hole in the second sheet.

According to an exemplary embodiment of the present invention, a hybrid sensor includes: a plurality of stacked flexible sheets; wherein a first sheet of the plurality of flexible sheets includes: a switch electrode pattern and a ground electrode pattern, which together form a plurality of landing portions , a detection electrode pattern, and a first plurality of slits surrounding the landing portion and separating the landing portion from the detection electrode pattern; wherein the detection electrode pattern substantially covers the first sheet except for forming the The detection electrode pattern and the entire area except the area of the first plurality of slits, wherein the first sheet further includes: a guard electrode pattern supplied with the same potential as that supplied to the detection electrode pattern, and positioned at The first chip is used to prevent parasitic capacitance between the detection electrode pattern and the switch electrode pattern.

According to an exemplary embodiment of the present invention, an electrostatic capacitance sensor includes a plurality of stacked flexible sheets; wherein a first sheet of the plurality of flexible sheets includes: a detection electrode pattern; a second circuit pattern; and a guard electrode pattern, which is supplied with the same potential as that supplied to the detection electrode pattern, and is located on the first sheet to block a parasitic capacitance between the detection electrode pattern and the second circuit pattern; and a detection circuit, which is connected to the detection electrode pattern, the detection circuit detects the electrostatic capacitance of the detection electrode pattern.

Description of drawings

These and other features, aspects and advantages of the present invention will be better understood with reference to the following description and drawings, which should not be construed as limiting the invention in any way, wherein:

FIG. 1 is a perspective view showing a hybrid sensor according to a first exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a hybrid sensor according to a first exemplary embodiment of the present invention.

FIG. 3 is a perspective view showing a hybrid sensor according to a second exemplary embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a hybrid sensor according to a second exemplary embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a modification of the hybrid sensor according to the second exemplary embodiment of the present invention.

FIG. 6 is a plan view showing a hybrid sensor according to a third exemplary embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a hybrid sensor according to a third exemplary embodiment of the present invention.

FIG. 8 is a perspective view showing a conventional hybrid sensor.

Detailed ways

Now, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

1 and 2 show a hybrid sensor according to a first exemplary embodiment of the present invention. The hybrid sensor 1 includes upper and lower flexible sheets 21 and 24 made of an insulating resin film such as a polyester film, and an insulating sheet 13 between the upper and lower sheets 21 and 24 . The sheets 13, 21 and 24 are stacked together to form a thin film circuit. The flexible sheet 21 is provided with switching electrode patterns 14 on the lower surface (in FIGS. 1 and 2 ) of the sheet 21 facing the insulating sheet 13 . The flexible sheet 24 is provided with a ground electrode pattern 25 on the upper surface (in FIGS. 1 and 2 ) of the sheet 24 facing the insulating sheet 13 . The switch and ground electrode patterns 14 and 25 are formed by screen printing where a suitable conductive material such as silver paste is deposited. The switching electrode pattern 14 includes a plurality of landing portions 14a configured in a matrix pattern as switching contacts 16; and wire portions 14b electrically connecting the landing portions 14a. Similarly, the ground electrode pattern 25 includes a plurality of landing portions 25 a respectively configured to face the landing portions 14 a of the switch electrode pattern 14 , and wire portions 25 b electrically connecting the landing portions 25 a. The insulating sheet 13 has a plurality of openings 17 at positions corresponding to the landing portions 14a and 25a. Each of said openings 17 has a sufficient diameter such that when a pressure load is applied to said sensor 1, one of said landing portions 14a can come into contact with an associated one of said landing portions 25a.

The upper flexible sheet 21 also has detection electrode patterns 22 formed on the lower surface (in FIGS. 1 and 2 ) of the flexible sheet 21 on which the switching electrode patterns 14 are provided. The detection electrode pattern 22 is formed to cover substantially the entire area except the area where the switching electrode pattern 14 is formed. Alternatively, the detection electrode pattern 22 may be formed on the upper surface of the flexible sheet 21 . The detection electrode pattern 22 thus formed has a large detection area, which facilitates the detection of adjacent objects.

The hybrid sensor 1 is connected to a sensor circuit 30 . The ground electrode pattern 25 is grounded through the terminal c of the sensor circuit 30 as a common ground of the contact pressure sensor and the electrostatic capacity sensor included in the hybrid sensor 1 . The switch electrode pattern 14 is connected to the terminal "a" of the sensor circuit 30 to output an ON/OFF signal, which is converted to a ground (GND) voltage when there is an electrical connection between the landing portions 14a and 25a. flat.

The detection electrode pattern 22 is connected to an input terminal b of a detection circuit 31 included in the sensor circuit 30 to detect electrostatic capacitance. The detection circuit 31 includes an oscillator that oscillates in response to a frequency or a duty cycle determined, for example, by an electrostatic capacitance between the detection electrode pattern 22 and the ground; and a low-pass filter that responds to The output of the oscillator is integrated. The resistor 32 is connected between the input terminal b and the voltage-controlled current source Vcc.

The operation of the hybrid sensor 1 will now be described as follows.

When a pressure load is applied, one or more of the landing portions 14a of the switch electrode pattern 14 on the upper flexible sheet 21 contact the ground pattern on the lower flexible sheet 25 through the opening 17 One or more of the landing portions 25a of 25 for electrical connection. Accordingly, the potential of the switch electrode pattern 14 transitions to the ground level, and the pressure load is detected. The hybrid sensor thus acts as a contact pressure sensor.

Although the electrostatic capacitance generated between those electrode patterns 22, 14 and 25 is not so high because the detection electrode pattern 22 does not overlap to the region where the switch electrode pattern 14 and the ground electrode pattern 25 are located, the parasitic capacitance Co is formed between the detection electrode pattern 22 and the switch electrode pattern 14 and the ground electrode pattern 25 . However, when an object reaches the detection electrode pattern 22, the capacitance Cx generated between the object and the detection electrode pattern 22 is increased. The object has a ground capacitance much larger than the capacitance Cx to be detected, so that the potential of the object can be regarded as the ground potential. The total capacitance C of the parasitic capacitance Co and the capacitance Cx due to the neighboring objects is also increased. The detection circuit 31 senses the change in the total capacitance C to detect the adjacent object. The hybrid sensor thus acts as an electrostatic capacitance sensor.

As described above, it is possible to add the function of the electrostatic capacity sensor to the hybrid sensor only by forming the detection electrode pattern 22 disposed to face the object to be detected on the upper flexible sheet 21. 1. The ground electrode pattern 25 may also serve as a common ground for both the detection electrode pattern 22 and the switching electrode pattern 14 . In addition, the switch electrode pattern 14 may be formed on the lower flexible sheet 24 , and the ground electrode pattern 25 may also be formed on the upper flexible sheet 21 .

3 and 4 show a second exemplary embodiment of the invention. Structural elements similar or identical to those of the first embodiment have the same reference numerals, and explanations thereof are omitted.

As shown in FIGS. 3 and 4 , the hybrid sensor 2 of the second embodiment includes a guard electrode pattern 42 in addition to the structural elements included in the hybrid sensor of the first embodiment shown in FIGS. 1 and 2 . The guard electrode pattern 42 is formed on the lower surface of the upper flexible sheet 41 (in FIGS. 3 and 4 ) so as to be located in the space or region between the switch electrode pattern 14 and the detection electrode pattern 22, and to surround all The switch electrode pattern 14 is described above. That is, considering the plane of the flexible sheet 41 , the guard electrode pattern 42 , the detection electrode pattern 22 and the switch electrode pattern 14 are not overlapped. The guard electrode pattern 42 is supplied with the same voltage as that supplied to the detection electrode pattern 22 . For this, the sensor circuit 50 supplies the output voltage from the detection electrode pattern 22 to the guard electrode pattern 42 through the buffer amplifier 51 serving as a voltage follower buffer and the terminal d connected to the guard electrode pattern 42 .

According to the above structure, the detection electrode pattern 22 and the guard electrode pattern 42 always have the same potential, and thus no electrostatic capacity is formed between them. The parasitic capacitance Co between the detection electrode pattern 22 , the switch electrode pattern 14 and the ground electrode pattern 25 is thus greatly reduced. It is thus possible to amplify the variation in the capacitance Cx generated between the adjacent object and the detection electrode pattern 22 and increase the sensitivity of the electrostatic capacitance sensor.

As shown in FIG. 5 , alternatively, another guard electrode pattern 44 may be formed on the upper surface of the lower flexible sheet 24 in addition to the guard electrode pattern 42 . In this case, the guard electrode pattern 44 is formed on the upper surface to cover substantially the entire area except the area on which the ground electrode pattern 25 is formed so as to surround the ground electrode pattern 25 . Because the guard electrode pattern 44 is also formed on the lower flexible sheet 24 opposite to the upper flexible sheet 41 facing the adjacent object to be detected. This structure makes it possible to prevent errors caused by, for example, noise generated on the lower side (in FIG. 5 ) of the electrostatic capacity sensor and from adjacent objects approaching the lower flexible sheet 24 from the lower side. detection. Similar to the first embodiment, the switch electrode pattern 14 may be formed on the lower flexible sheet 24 and the ground electrode pattern 25 may be formed on the upper flexible sheet 41 .

6 and 7 show a third exemplary embodiment of the present invention. Structural elements similar or identical to those of the first and second embodiments have the same reference numerals, and explanations thereof are omitted.

The hybrid sensor 3 according to the third embodiment includes upper and lower flexible sheets 61 and 62 and an insulating sheet 63 between the upper and lower flexible sheets 61 and 62 . The upper flexible sheet 61 is provided with an electrode pattern 64 including a switch electrode pattern 64 c , a ground electrode pattern 64 d and a guard electrode pattern 69 on its lower surface facing the insulating sheet 63 . In FIG. 6 , the electrode pattern 64 is drawn by a solid line for clarity. Similar to the first and second embodiments, the electrode pattern 64 has a landing portion 64a and a lead portion 64b. At the landing portion 64a, the switch electrode pattern 64c and the ground electrode pattern 64d are arranged with comb teeth facing each other. The guard electrode pattern 69 is disposed on the outer periphery of the switch electrode pattern 64c to surround the pattern 64c at the landing portion 64a and the lead portion 64b.

The lower flexible sheet 62 is provided with a plurality of short-circuit patterns 65 arranged in a matrix at positions corresponding to the landing patterns 64 a of the electrode patterns 64 of the upper flexible sheet 61 .

The insulating sheet 63 has a plurality of openings 67 at positions corresponding to the landing portion 64 a and the short-circuit pattern 65 . Each opening 67 has a diameter sufficient to enable one of the landing portions 64 a to contact an associated one of the short-circuit patterns 65 when a pressure load is applied to the sensor 3 .

The upper and lower flexible sheets 61 and 62 and the insulating sheet 63 are further provided with slits 68a, 68c, and 68b, respectively. A slit 68 a on the flexible sheet 61 is formed on the periphery of the guard electrode pattern 69 to surround the pattern 69 . Therefore, the slit 68 a separates the area where the electrode pattern 64 is formed from the other parts of the upper flexible sheet 61 , except for the no-slit forming part on the left side in FIG. 6 . The slits 68b and 68c are respectively formed at the opening 67 of the insulation sheet 63 and the outer periphery of the short pattern 65 on the lower flexible sheet 62 to surround them. When the upper and lower flexible sheets 61 and 62 and the insulating sheet 63 are stacked together, the slits 68a, 68b and 68c are overlapped to form through slits.

At the outer periphery of the slit 68a on the upper flexible sheet 61, a detection electrode pattern 66 is formed to surround the slit 68a. As shown in FIG. 6, the detection electrode pattern 66 is formed to cover substantially the entire area except the area where the electrode pattern 64 and the slit 68a are formed. The detection electrode pattern 66 thus formed has a large detection area that facilitates the detection of adjacent objects. When an object reaches the detection electrode pattern 66, the capacitance Cx generated between the object and the detection electrode pattern 66 is increased. The object has a ground capacitance much larger than the capacitance Cx to be detected, so the potential of the object can be regarded as the ground potential. Changes in said capacitance Cx are thus detectable.

The hybrid sensor 3 is connected to a sensor circuit similar to the sensor circuit 50 shown in FIG. 3 . That is, the switch electrode pattern 64c is connected to the terminal "a" of the sensor circuit 50, the detection electrode pattern 66 is connected to the terminal b of the sensor circuit 50, and the ground electrode pattern 64b is connected to to the terminal c of the sensor circuit 50 , and the guard electrode pattern 69 is connected to the terminal d of the sensor circuit 50 .

In this embodiment, the electrode pattern 64, which may be called a membrane switch, is separated from the region where the detection electrode pattern 66 is formed by the slit 68a. This structure prevents misoperation of the hybrid sensor 3 caused by a bending force applied to the hybrid sensor 3 when the hybrid sensor 3 is installed at a bend.

As described above, the hybrid sensor according to the present invention has the detection electrode pattern provided to cover substantially the entire area except the area on which the switching electrode pattern is formed. Therefore, the detection electrode pattern has a large detection area that contributes to detection of adjacent objects. This structure makes it possible to improve the sensitivity of the electrostatic capacity sensor.

In addition, the electrostatic capacitance sensor in the hybrid sensor according to the present invention has a guard electrode pattern arranged in a region or a space between the detection electrode pattern and other electrode patterns. The guard electrode pattern is applied with a voltage equal to that of the detection electrode pattern. Therefore, the detection electrode pattern is isolated from the other electrode patterns in consideration of electrostatic capacity. This structure makes it possible to avoid degradation of the sensitivity of the electrostatic capacity sensor even if a plurality of functions are provided on the hybrid sensor.

While exemplary embodiments of the invention have been described and illustrated above, it is to be understood that these are only exemplary of the invention and are not to be considered limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims (8)

1. A hybrid sensor comprising: multiple stacked flexible sheets; Wherein the first sheet of the plurality of flexible sheets comprises: switch electrode pattern, and detection electrode pattern, Wherein the detection electrode pattern substantially covers the entire area of the first sheet except the area where the switch electrode pattern is formed, wherein the first sheet further includes: A guard electrode pattern is supplied with the same potential as that supplied to the detection electrode pattern, and is positioned on the first sheet to prevent parasitic capacitance between the detection electrode pattern and the switching electrode pattern. 2. The hybrid sensor of claim 1, wherein: A second sheet of the plurality of flexible sheets includes an insulating sheet having a plurality of holes therein; A third sheet of the plurality of flexible sheets includes a ground electrode pattern, and The location of the hole in the second sheet and the location of the ground electrode pattern on the third sheet correspond to the location of the switching electrode pattern on the first sheet. 3. The hybrid sensor of claim 2, wherein: The switch electrode pattern is formed on a lower side of the first sheet, facing the second and third sheets; and the ground electrode pattern is formed on a top side of the third sheet, facing the first sheet. and the first sheet such that when pressure is applied to the first and third sheets, the switch electrode pattern contacts the ground electrode pattern through the hole in the second sheet. 4. A hybrid sensor comprising: multiple stacked flexible sheets; Wherein the first sheet of the plurality of flexible sheets comprises: a switch electrode pattern and a ground electrode pattern which together form a plurality of landing portions, detection electrode pattern, and a first plurality of slits surrounding the landing portion and separating the landing portion from the detection electrode pattern; wherein the detection electrode pattern substantially covers the entire area of the first sheet except the area where the detection electrode pattern and the first plurality of slits are formed, Wherein said first tablet also includes: A guard electrode pattern is supplied with the same potential as that supplied to the detection electrode pattern, and is located on the first sheet to prevent parasitic capacitance between the detection electrode pattern and the switching electrode pattern. 5. The hybrid sensor of claim 4, wherein: A second sheet of the plurality of flexible sheets includes an insulating sheet having a plurality of holes therein; A third sheet of the plurality of flexible sheets includes a conductive short pattern; and Wherein the position of the hole in the second sheet and the short circuit pattern on the third sheet correspond to the positions of the landing parts of the switch electrode pattern and the ground electrode pattern on the first sheet. 6. The hybrid sensor of claim 5, wherein: The second sheet also includes a second plurality of slits surrounding the aperture; The third sheet also includes a third plurality of apertures surrounding the shorting pattern; and The positions of the first, second, and third slits correspond such that when the first, second, and third sheets are stacked together, the first, second, and third slits Form through gaps. 7. The hybrid sensor of claim 5, wherein: The switch electrode pattern and the ground electrode pattern are formed on a lower side of the first sheet, facing the second and third sheets, and the short circuit pattern is formed on a top side of the third sheet, facing For the second and first sheets, such that when pressure is applied to the first and third sheets, the switch electrode pattern and the ground electrode pattern contact the Short pattern. 8. The hybrid sensor of claim 4, wherein: The first plurality of slits surrounds the landing portion and the guard electrode pattern, and separates the landing portion and the guard electrode pattern from the detection electrode pattern; a second sheet of the plurality of flexible sheets further comprising a second plurality of slits surrounding the aperture; A third sheet of the plurality of flexible sheets further includes a third plurality of slits surrounding the shorting pattern; and The positions of the first, second, and third slits correspond such that when the first, second, and third sheets are stacked together, the first, second, and third slits Form through gaps.

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