JP7289237B2 - touch sensor - Google Patents

Description

The present invention relates to a touch sensor used to detect contact with an obstacle.

2. Description of the Related Art Conventionally, vehicles such as automobiles are sometimes provided with an opening/closing body (for example, a slide door or a tailgate) that opens and closes an opening provided in the vehicle, and an opening/closing device that drives the opening/closing body. The opening/closing device includes an electric motor as a driving source and an operation switch for turning on/off the electric motor. An electric motor included in the opening/closing device operates based on the operation of the operation switch, and drives the opening/closing body to open or close. Further, among the opening/closing devices, there is an automatic opening/closing device that drives the opening/closing member to open or close regardless of whether or not the operation switch is operated. One conventional automatic opening/closing device includes a touch sensor that detects an obstacle sandwiched between an opening and an opening/closing body, and drives the opening/closing body based on the detection result of the touch sensor. For example, when an obstacle is detected by a touch sensor, an automatic opening/closing device opens an opening/closing body that has been driven to close until then, or stops the opening/closing body on the spot.

An example of the touch sensor as described above is described in Patent Document 1. The touch sensor described in Patent Document 1 has an elastically deformable hollow sensor section and two linear electrodes provided in the sensor section. Each linear electrode includes a conductor layer and a covering layer provided around the conductor layer. Furthermore, the two linear electrodes are spirally provided in the sensor section and normally intersect each other in a non-contact state. Also, the coating layer is made of a conductive resin. Therefore, when the sensor section receives some external force and elastically deforms, and the two linear electrodes come into contact with each other in the sensor section, the electrical resistance between the linear electrodes greatly changes (decreases).

JP 2013-228299 A

Sensors including touch sensors are required to further improve detection accuracy, detection sensitivity, etc. (hereinafter sometimes collectively referred to as "detection performance"). On the other hand, the touch sensor described in Patent Document 1 tends to be inferior in detection performance at low temperatures to detection performance at normal temperatures. The inventors of the present invention have been conducting research to improve the detection performance of the touch sensor, especially at low temperatures, and have found that the pitch of the linear electrodes provided in a spiral in the sensor unit and the line It was found that the ratio of the thickness of the coating layer to the thickness of the electrode has a great influence on the detection performance.

An object of the present invention is to further improve the detection performance of a touch sensor based on the above findings.

The touch sensor of the present invention includes a hollow sensor portion that elastically deforms when an external force is applied, and spirally provided inside the sensor portion at a predetermined pitch, and come into contact with each other as the sensor portion elastically deforms. and a plurality of linear electrodes. Each of the linear electrodes includes a conductor layer made of a plurality of twisted strands, and a coating layer made of a conductive resin that covers the conductor layer. A ratio (P/T) between the pitch (P) of each of the linear electrodes and the thickness (T) of the coating layer in the linear electrode is 12.5 or more and 13.3 or less.

In one aspect of the invention, the ratio (P/T) is 12.5.

In another aspect of the invention, the pitch (P) is 7.5 mm and the thickness (T) of the coating layer is 0.6 mm.

ADVANTAGE OF THE INVENTION According to this invention, the touch sensor with which detection performance improved conventionally is implement|achieved.

Fig. 2 is a front view showing a tailgate of a vehicle on which the touch sensor unit is mounted; FIG. 10 is a side view showing the tailgate of the vehicle on which the touch sensor unit is mounted; It is a perspective view showing a touch sensor unit. It is an enlarged drawing which shows the structure of a touch sensor. It is a cross-sectional view showing the structure of a touch sensor. FIG. 4 is a schematic diagram showing a state of arrangement of linear electrodes in a sensor section; (a) and (b) are schematic diagrams showing input states of forces to linear electrodes having different pitches when an obstacle comes into contact with the linear electrodes. It is a figure which shows the result of the performance test of a touch sensor.

An example of a touch sensor to which the present invention is applied will be described in detail below with reference to the drawings. A touch sensor according to this embodiment is mounted on a vehicle 10 shown in FIGS. The illustrated vehicle 10 is a so-called hatchback type vehicle. The rear portion of the vehicle 10 is provided with an opening 11 through which large luggage can be taken in and out of the vehicle compartment. The opening 11 is opened and closed by an opening/closing body 12 rotatably supported by a hinge (not shown) provided on the rear side of the ceiling of the vehicle 10 . The opening/closing body 12 is called a "tailgate", a "reargate", a "back door", etc., but is called a "tailgate" in this specification.

The vehicle 10 is equipped with a power tailgate device 13 that rotates (opens and closes) the tailgate 12 in the directions indicated by the solid line arrow and broken line arrow in FIG. The power tailgate device 13 includes an actuator 13a with a reduction gear that opens and closes the tailgate 12, a controller 13b that controls the actuator 13a based on the operation of a switch (not shown), and a pair of actuators for detecting an obstacle BL. and a touch sensor unit 20. The touch sensor according to this embodiment is mounted on the vehicle 10 as part of the touch sensor unit 20 . That is, the touch sensor according to the present embodiment is one component of the touch sensor unit 20 , and the touch sensor unit 20 is one component of the power tailgate device 13 .

As shown in FIG. 1 , the touch sensor unit 20 is provided on the outer peripheral surface of the tailgate 12 . Specifically, the touch sensor units 20 are provided on both side surfaces of the tailgate 12 in the vehicle width direction. More specifically, the touch sensor units 20 are provided on both curved side surfaces (edges) of the tailgate 12 along the shape of the side surfaces. Therefore, when an obstacle BL is sandwiched between the opening 11 and the tailgate 12 , the obstacle BL is detected by the touch sensor unit 20 . The touch sensor unit 20 outputs a detection signal when detecting the obstacle BL, and the detection signal output from the touch sensor unit 20 is input to the controller 13b. The controller 13b to which the detection signal is input opens the closed tailgate 12 or stops the closed tailgate 12 on the spot regardless of the operation state of the operation switch.

As shown in FIG. 3, touch sensor unit 20 includes touch sensor 30, sensor holder 31 and bracket 32, and these touch sensor 30, sensor holder 31 and bracket 32 are integrated. Specifically, the touch sensor 30 is integrated with the bracket 32 via the sensor holder 31 .

The bracket 32 is made of a resin material such as plastic, has substantially the same length as the side surface (edge) of the tailgate 12 (FIGS. 1 and 2), and has a plate-like appearance as a whole. . A part of the touch sensor 30 in the longitudinal direction is fixed to the sensor holder 31 while the remaining part is not fixed to the sensor holder 31 . A sensor holder 31 to which a part of the touch sensor 30 is fixed is joined to the bracket 32 . In the following description, the longitudinal portion of the touch sensor 30 that is not fixed to the sensor holder 31 may be referred to as a "drawer portion" to distinguish it from other portions. However, such a distinction is merely a distinction for convenience of explanation.

The touch sensor unit 20 having the basic structure as described above is attached to the vehicle 10 by fixing the bracket 32 to the side surface (edge) of the tailgate 12 (FIGS. 1 and 2). At this time, the pull-out portion of the touch sensor 30 is pulled into the tailgate 12 through a pull-in hole provided in the tailgate 12 . Further, the pull-in hole after the pull-out portion is pulled in is closed by the grommet GM attached to the pull-out portion.

The structure of the touch sensor unit 20 will be described in more detail below.

As shown in FIG. 3, the touch sensor 30, which is one of the components of the touch sensor unit 20, includes a sensor section 40, a plurality of electrodes 41 and 42 provided inside the sensor section 40, and a connector 43. , and a part of the sensor unit 40 containing the electrodes 41 and 42 is embedded in the sensor holder 31 . The sensor holder 31 is made of insulating rubber and has elasticity. That is, the sensor holder 31 deforms when an external force is applied, and returns to its original shape when the external force is removed. Also, the connector 43 is connected to another connector (not shown). By connecting the connector 43 to another connector, the touch sensor unit 20 is electrically connected to the controller 13b (FIGS. 1 and 2), and the detection signal output from the touch sensor unit 20 can be input to the controller 13b. becomes.

As shown in FIGS. 4 and 5, the sensor holder 31 has a housing portion 31a and a base portion 31b integrally formed. The accommodating portion 31a is hollow, the touch sensor 30 is accommodated inside the accommodating portion 31a, and the base portion 31b is fixed to the bracket 32 (FIG. 3). 4, illustration of the sensor portion 40 of the touch sensor 30 and the bracket 32 is omitted.

As shown in FIG. 5, the sensor portion 40 of the touch sensor 30 is hollow. Specifically, the sensor unit 40 is a tube made of insulating rubber and has elasticity. That is, the sensor section 40 deforms when an external force is applied, and returns to its original shape when the external force is removed. Also, the inner diameter of the sensor section 40 is approximately three times the outer diameter of the electrodes 41 and 42 .

As shown in FIGS. 4 and 5, each electrode 41, 42 is a linear electrode. The two linear electrodes 41 and 42 are spirally provided inside the sensor section 40 and normally intersect each other in a non-contact state. Further, the outer peripheral surfaces of the spirally wound linear electrodes 41 and 42 are fixed (welded) to the inner peripheral surface of the sensor section 40, and between the two linear electrodes 41 and 42, , there is a gap to accommodate another similar linear electrode.

As shown in FIG. 5 , each of the linear electrodes 41 and 42 includes a conductor layer 50 made up of a plurality of strands 50 a twisted together, and a coating layer 51 covering the conductor layer 50 . The wire 50a in this embodiment is a copper wire. That is, the conductor layer 50 in this embodiment is a twisted wire in which a plurality of copper wires are twisted together. Moreover, the coating layer 51 in this embodiment is made of a conductive resin and has a predetermined thickness (T). The thickness (T) of the coating layer 51 of the linear electrode 41 and the thickness (T) of the coating layer 51 of the linear electrode 42 are the same or substantially the same. In the following description, the thickness (T) of the coating layer 51 may be called "coating thickness (T)".

As shown most clearly in FIG. 4, the two linear electrodes 41, 42 are each spirally wound and normally cross without contacting each other. On the other hand, the sensor portion 40 shown in FIG. 5 is elastically deformed when an external force is applied, and the sensor holder 31 (accommodating portion 31a) in which the sensor portion 40 is accommodated is also elastically deformed when an external force is applied. Therefore, when the accommodation portion 31a of the sensor holder 31 receives an external force exceeding a certain level and is elastically deformed (collapsed), an external force is applied to the sensor portion 40 accordingly. Then, the sensor part 40 is elastically deformed, and along with this, the two linear electrodes 41 and 42 come close to each other and come into contact with each other. Specifically, the covering layer 51 of one linear electrode 41 and the covering layer 51 of the other linear electrode 42 are in contact with each other. That is, the two linear electrodes 41 and 42 are electrically connected (short-circuited).

As shown in FIG. 3 , a mold portion 45 is provided at the tip of the touch sensor 30 . As shown in FIG. 4, the molded portion 45 is composed of a separator SP made of an insulator, a resistor R, two connecting members SW1 and SW2, and a molding resin MR covering them. An end of the linear electrode 41 is connected to one end of the resistor R via a connecting member SW1, and an end of the linear electrode 42 is connected to the other end of the resistor R via a connecting member SW2. . That is, the two linear electrodes 41 and 42 are connected in series via the resistor R inside the mold portion 45 . Therefore, when the linear electrodes 41 and 42 are not short-circuited, the resistance value of the resistor R is input to the controller 13b (FIG. 1). On the other hand, when the linear electrodes 41 and 42 are short-circuited, the resistance value not passed through the resistor R is input to the controller 13b (FIG. 1). That is, when the linear electrodes 41 and 42 are short-circuited, the resistance value input to the controller 13b is greatly reduced. When the input resistance value becomes smaller than a predetermined threshold value, the controller 13b shown in FIG. to stop the tailgate 12 on the spot. Here, the short circuit of the linear electrodes 41 and 42 is caused by the obstacle BL sandwiched between the opening 11 and the tailgate 12. FIG. Specifically, when the accommodation portion 31a of the sensor holder 31 contacts the obstacle BL sandwiched between the opening 11 and the tailgate 12, the accommodation portion 31a receives an external force and is elastically deformed. Then, as described above, the sensor section 40 accommodated in the accommodation section 31a is elastically deformed, and the linear electrodes 41 and 42 accommodated in the sensor section 40 come close to each other and come into contact with each other. In this way, when the obstacle BL contacts the touch sensor unit 20 (sensor holder 31) attached to the tailgate 12, the touch sensor unit 20 outputs a lower resistance value as a detection signal, and the controller 13b is entered in However, in some embodiments, when the obstacle BL contacts the touch sensor unit 20 (sensor holder 31), a predetermined electrical signal is output as a detection signal from the touch sensor unit 20 and input to the controller 13b.

Please refer to FIG. On the spirally wound linear electrodes 41 and 42, crests 61 and troughs 62 appear alternately along the longitudinal direction (horizontal direction of the paper surface of FIG. 6). In FIG. 6, only the linear electrodes 42 are hatched (dot pattern) so that the linear electrodes 41 and 42 can be easily distinguished from each other.

The pitch (P) of the linear electrodes 41 is the interval between two adjacent peaks 61 and 61 or the interval between two adjacent valleys 62 and 62 in the linear electrodes 41 . The pitch (P) of the linear electrode 42 is the interval between two adjacent peaks 61 and 61 or the interval between two adjacent valleys 62 and 62 in the linear electrode 42 . The pitch (P) of the linear electrodes 41 and the pitch (P) of the linear electrodes 42 are the same or substantially the same.

In this embodiment, the ratio (P/T) between the pitch (P) of the linear electrodes 41 and 42 and the coating thickness (T) of the linear electrodes 41 and 42 shown in FIG. 5 is 12.5 or more and 13.3. It is below. More specifically, the pitch (P) of the linear electrodes 41 and 42 shown in FIG. 6 is 7.5 mm, and the coating thickness (T) of the linear electrodes 41 and 42 shown in FIG. 5 is 0.6 mm. is. That is, the ratio (P/T) in this embodiment is 12.5.

In the touch sensor 30 of the present embodiment, the ratio (P/T) between the pitch (P) of the linear electrodes 41 and 42 and the thickness (T) of the coating layer 51 of the linear electrodes 41 and 42 is within the above range. High detection performance, especially at low temperatures. The reason for this will be explained below.

Please refer to FIG. The linear electrodes 41 and 42 are more likely to collapse as the pitch (P) increases (wider). Specifically, as the pitch (P) of the linear electrodes 41 and 42 increases, the height of the ridges 61 of the linear electrodes 41 and 42 becomes lower and the gradient becomes gentler. Similarly, the greater the pitch (P) of the linear electrodes 41 and 42, the shallower the valleys 62 of the linear electrodes 41 and 42 and the gentler the gradient. In other words, the greater the pitch (P) of the linear electrodes 41 and 42, the smaller the force required to push down the peaks 61 of the linear electrodes 41 and 42 and push up the valleys 62 thereof. Therefore, the linear electrodes 41, 42 can contact each other with a smaller force. In other words, the smaller the pitch (P) of the linear electrodes 41 and 42, the greater the force required to bring the linear electrodes 41 and 42 into contact with each other.

Please refer to FIG. The linear electrodes 41 and 42 are more easily crushed as the coating thickness (T) is smaller (thinner). Specifically, the smaller the coating thickness (T) of the linear electrodes 41 and 42 is, the weaker the elastic restoring force of the linear electrodes 41 and 42 is. In other words, the smaller the coating thickness (T) of the linear electrodes 41 and 42, the more the coating required to push down the peaks 61 (FIG. 6) of the linear electrodes 41 and 42 and push up the valleys 62 (FIG. 6). force becomes smaller. Therefore, the linear electrodes 41, 42 can contact each other with a smaller force. In other words, the greater the coating thickness (T) of the linear electrodes 41, 42, the greater the force required to bring the linear electrodes 41, 42 into contact with each other.

As described above, in order to bring the linear electrodes 41 and 42 into contact with each other with as little force as possible, the pitch (P) shown in FIG. 6 should be increased and the coating thickness (T) shown in FIG. 5 should be decreased. is preferred. That is, it is preferable to increase the ratio (P/T). In particular, when the temperature is low, not only the coating layer 51 but also the resin members such as the sensor section 40 and the sensor holder 31 (accommodating section 31a) become hard. Therefore, even if the same external force is applied to the sensor holder 31 (receiving portion 31a), the force acting on the linear electrodes 41 and 42 at low temperature is smaller than the force acting on the linear electrodes 41 and 42 at room temperature ( weaker). Therefore, increasing the ratio (P/T) leads to improved detection performance of the touch sensor 30 at low temperatures.

However, if the pitch (P) of the linear electrodes 41 and 42 is made too large (wide), the detection performance of the touch sensor 30 may rather deteriorate. FIGS. 7A and 7B are schematic diagrams showing how forces are input to the linear electrodes 41 and 42 when an obstacle BL of the same size comes into contact with the linear electrodes 41 and 42 with different pitches (P). is. In the actual touch sensor 30, the sensor section 40 exists around the linear electrodes 41 and 42, and the obstacle BL does not directly contact the linear electrodes 41 and 42. FIG.

As shown in FIGS. 7(a) and 7(b), when the pitch (P) is large (FIG. 7(b)), compared to when the pitch (P) is small (FIG. 7(a)), The distance from the point of contact (input point) between the object BL and the linear electrodes 41 and 42 to the apex of the nearest peak portion 61 increases. As the pitch (P) becomes larger, the distance from the input point to the apex of the nearest peak 61 becomes longer.

On the other hand, in order to more efficiently crush the ridges 61 of the linear electrodes 41 and 42 (to push them down), it is desirable that the input point and the apex of the ridges 61 coincide. In other words, it is desirable to apply a downward force to the apex of the peak portion 61 . For this reason, if the pitch (P) of the linear electrodes 41 and 42 is made too large (wide), the input efficiency of the force to the linear electrodes 41 and 42 may decrease, and the detection performance of the touch sensor 30 may deteriorate. It is understandable that there is

Also, if the coating thickness (T) of the linear electrodes 41 and 42 shown in FIG. There is a possibility that it may take a long time to

As described above, at first glance, if the ratio (P/T) between the pitch (P) of the linear electrodes 41 and 42 and the coating thickness (T) of the linear electrodes 41 and 42 is increased, the touch sensor 30 can be operated at a low temperature. Although it seems that the detection performance of In order to improve the detection performance of the touch sensor 30, especially at low temperatures, it is necessary to set the ratio (P/T) in consideration of various technical factors. In this regard, the touch sensor 30 of the present embodiment, in which the ratio (P/T) is in the range of 12.5 or more and 13.3 or less, achieves improved detection performance, especially at low temperatures.

Next, the results of tests conducted by the inventors to confirm the effects of the present invention will be described. In this test, two types of touch sensors to which the present invention is applied and two types of touch sensors as comparative examples were prepared. The specifications of each touch sensor are as listed in the table shown in FIG. In the table shown in FIG. 8, the two types of touch sensors to which the present invention is applied are denoted as Example 1 and Example 2, respectively, and the two types of touch sensors prepared as comparative examples are labeled as comparative examples. 1 and Comparative Example 2.

Furthermore, in this test, an external force was applied to each of the prepared touch sensors in a low-temperature environment, and the resistance value was measured. More specifically, the resistance value between the linear electrodes of each touch sensor was measured with a force of 20 N applied to the outer peripheral surface of each touch sensor in an environment of -30°C. The application of an external force to the touch sensor was realized by pressing a round bar-shaped pusher with a diameter of 40 mm against the outer peripheral surface of the sensor holder.

According to this test, the touch sensors (Examples 1 and 2) to which the present invention was applied showed that the resistance value when the same external force was applied at a low temperature was higher than that of the touch sensors (Comparative Examples 1 and 2) as comparative examples. It was confirmed that it was significantly smaller than the That is, it was confirmed that the touch sensors to which the present invention was applied (Examples 1 and 2) had higher detection performance at low temperatures than the touch sensors serving as comparative examples (Comparative Examples 1 and 2).

The present invention is not limited to the above embodiments, and can be modified in various ways without departing from the scope of the invention.

10 vehicle 11 opening 12 opening and closing body (tailgate)
13 Power tailgate device 13a Actuator 13b Controller 20 Touch sensor unit 30 Touch sensor 31 Sensor holder 31a Housing part 31b Base part 32 Bracket 40 Sensor part 41, 42 Electrode (linear electrode)
43 Connector 45 Molded portion 50 Conductor layer 50a Wire 51 Covering layer 61 Peak 62 Valley BL Obstacle GM Grommet MR Molding resin P Pitch R Resistance SP Separator SW1, SW2 Connection member T Thickness (coating thickness)

Claims (1)

a hollow sensor section that elastically deforms when an external force is applied;
A touch sensor having a plurality of linear electrodes provided spirally at a predetermined pitch inside the sensor unit and coming into contact with each other as the sensor unit elastically deforms,
Each of the linear electrodes includes a conductor layer made of a plurality of twisted strands, and a coating layer made of a conductive resin that covers the conductor layer,
a ratio (P/T) between the pitch (P) of each linear electrode and the thickness (T) of the coating layer in the linear electrode is 12.5;
The touch sensor , wherein the pitch (P) is 7.5 mm and the thickness (T) of the coating layer is 0.6 mm .

Images