JPH0654269B2 - Pressure sensitive plate for detecting uneven pressure distribution - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pressure-sensitive plate for detecting uneven surface pressure distribution, in which minute uneven surfaces are brought into contact with each other to detect the distribution of the uneven surfaces.

(Prior Art) Conventionally, in order to measure a two-dimensional pressure distribution, a method is known in which pressure transducers such as a load cell and a flexible surface pressure sensor are arranged in a matrix and the output of the pressure transducer is scanned. (For example, JP-A-62-71828). In addition, a large number of electrode pairs are arranged facing each other in a matrix, and the pressure is detected by detecting the change in the space between the electrode pairs in the portion where the pressure is applied and the change in the capacitance formed by the electrode pair. An apparatus for measuring distribution is also known (for example, Japanese Patent Laid-Open No. 62-226030).

However, in any of these surface pressure distribution measurements, the resolution, that is, the minimum surface pressure distribution interval is about several mm, and pressure distributions below that cannot be measured. Therefore, in the conventionally known technology, for example, 200
Since it is impossible to measure the pressure distribution on a fine uneven surface of about ~ 300 μm due to the interference of the pressure-sensitive member, it is possible to measure 100 μm from the conventional method.
An apparatus for measuring the pressure distribution on a fine uneven surface of about m or less has been desired for a long time.

(Object and Structure of the Invention) The present invention has been made in view of the above points, and an object thereof is to measure a fine uneven surface pressure distribution of about 100 μm or less by utilizing contact pressure, and to achieve this object. Therefore, a structure is proposed in which the pressure sensitive portion is independently separated, and the sensing is separated into a pressure receiving sheet having a plurality of protrusions arranged at fine intervals and a position corresponding to at least the protrusion of the pressure receiving sheet. A pressure sensitive sheet with holes for
By stacking an electrode base having a pair of electrodes formed so as to be separated and intersect at a position corresponding to the hole of the pressure-sensitive sheet, and when the uneven surface is brought into contact with the pressure-sensitive sheet, the force applied to the pressure-sensitive sheet is applied. The pressure sensitive plate was configured to measure changes in the physical properties inside the holes of the pressure sensitive sheet from a set of electrodes on the electrode base. With this structure, the surface pressure sensor can be separated, and the pressure distribution on a fine uneven surface can be measured.

(Example) The present invention will be described below with reference to the drawings.

1 to 4 show an embodiment of a pressure-sensitive plate for detecting pressure distribution on an uneven surface according to the present invention.

FIG. 1 shows the appearance of the pressure sensitive plate. The thickness of the pressure sensitive plate 1 is about 100 μm, and the size depends on the application, but for fingerprint detection, for example, 150 mm × sufficient to hold one fingertip ×
It is about 150 mm.

FIG. 2 is an exploded perspective view of the pressure sensitive plate.

The pressure sensitive plate 1 includes a pressure receiving sheet 1a as shown in FIG.
A pressure-sensitive sheet 1b as shown in (b) and an electrode base 1c as shown in (c) are laminated together.

The pressure receiving sheet 1a is a sheet made of an elastic member such as silicon rubber or raw rubber having a thickness of about 50 μm by a mold or the like, and the surface has a matrix of protrusions 11 having a pitch of about 50 μm, a diameter of about 30 μm and a height of about 30 μm. It is formed in a large number. The number of the protrusions 11 may be determined depending on the use,
For fingerprint detection, for example, the above 150 mm x 150
About 300 × 300 pieces are preferable in mm. It is preferable to form a protective film 11P on the surface of the protrusion 11 with resin or the like. (See FIG. 4) The pressure-sensitive sheet 1b has a thickness of about 20 μm to 50 μm, such as polyimide or polyester resin film or ceramic or polymer insulating sheet 20, which is etched, laser, or physically (for example, by a pin). The holes 21 having the same pitch and the same number as the protrusions 11 of the pressure receiving sheet 1a are formed in a matrix shape by (drilling) or the like. The diameter of the hole 21 is about 30 μm. Pressure sensitive conductive material 22 in each hole 21
Embed. Toshiba Siltouch 100, 200, 300 (trade name) is used as an example of the pressure-sensitive conductive material.
The pressure-sensitive conductive material 22 may be liquid or particles, and may be applied and embedded in the form of paint.

The electrode base 1c is longitudinally formed on one surface (the back surface in FIG. 2C) of a relatively hard plate member 30 such as glass or ceramics by a method such as etching at an interval equal to the pitch of the projections 11 of the pressure embedding sheet 1a. A large number of X electrodes 31 are formed in parallel, and a large number of Y electrodes are arranged in parallel in the lateral direction by a method such as etching on the other surface (the surface in FIG. 2C) at intervals equal to the pitch of the protrusions 11 of the pressure receiving sheet 1a. The electrodes 32 are formed, and the plate member 3 is formed from each Y electrode 32.
0 through the electrode pieces 32a, 32 as shown in FIG.
a ′, 32b, 32b ′, 32c, 32 ′, ... Are exposed on the surface of the plate member 30. The exposed position of these electrode pieces is a position in contact with the pressure-sensitive conductive material 22 of the pressure-sensitive sheet 1b together with the X-ray electrode 31 formed on the surface.
The X electrode 31 on the surface is focused on one side 30a of the plate member phase 30, and the Y electrode 32 on the surface is focused on the other side 30b of the plate member 30. These two sides 30a and 30b of the plate member 30
A connector for connection with an external circuit is coupled to the external circuit, and the external circuit is electrically connected to the X electrode 31 and the Y electrode 32.

As shown in FIG. 4, the pressure receiving sheet 1a, the pressure sensitive sheet 1b, and the electrode base 1C correspond to the protrusion 11, the pressure sensitive conductive material 22, the X electrode 31, and the electrode pieces 32a, 32a ',. The pressure sensitive plate 1 is formed by being joined in such a positional relationship.

FIG. 5 shows a basic circuit configuration of a detection circuit for detecting the pressure distribution on the uneven surface using the pressure sensitive plate having the above configuration.

A detection circuit using this type of matrix scanning is already known and is not the subject matter of the present invention, so a brief description will be given.

Reference numeral 100 denotes a reference signal generator, and the controller 101 divides the reference signal generated from the reference signal generator 100 and applies an X-direction scanning signal S _x applied to the X electrodes and a Y-direction scanning signal S _y applied to the Y electrodes. To occur. 102 is an X-direction scanning control circuit that outputs an X-direction switching signal that turns on the X-direction analog switch 104 at a predetermined timing based on the scanning signal S _x from the controller 101, and 103 is based on the scanning signal S _y from the controller 101. The Y-direction analog switch 105 is turned on at a predetermined timing to output a Y-direction switching signal, and 106 is an X-direction scanning control circuit.
An amplifier for amplifying a signal obtained from the sensing plate 1 via a directional analog switch 104, 107 is a signal processing circuit including a noise processing, 108 compares the reference voltage V _R obtained a surface distribution signals the signal processing from the resistor R Is a comparator that outputs a surface distribution signal.

Next, a case of detecting a fingerprint will be described as an example of the fine uneven surface pressure distribution.

When a fingertip is placed on the pressure sensitive plate 1 and lightly pressed, the protrusions 11 of the pressure receiving sheet 1a are pressed by the ridges of fingerprints. Fingerprint P
Assuming that is located with respect to the pressure receiving plate 1a as shown by the chain line in FIG. 4, the protrusions 11a, 11b, 11c, 11d.
Is strongly pushed down, and as a result, the pressure-sensitive conductive material 22a, 22b, 22c, 22 of the pressure-sensitive sheet 1b immediately below is pushed down.
d is pressurized and has conductivity. As a result, the X electrode 31a and the Y electrode pieces 32a, 31b and 32b directly below the
Since 31c and 32c respectively conduct, therefore, from the comparator 108 of the detection circuit shown in FIG. 5, "1" is obtained with respect to the coordinates of the position corresponding to the mountain P of the fingerprint, and "0" is obtained with respect to the coordinates of other positions. A fingerprint pattern signal consisting of is output. In this way, information on the fingerprint pattern can be detected.

In each of the above-mentioned embodiments, the protrusions of the pressure-sensitive sheet 1a, the portions of the pressure-sensitive conductive material of the pressure-sensitive sheet 1b, and the intersections of the X electrodes and the Y electrodes of the electrode base 1c are all arranged in a matrix. Although the pressure-sensitive sheet 1a and the electrode base 1c are arranged in a matrix, the pressure-sensitive conductive material portions of the pressure-sensitive sheet 1b are spaced apart from each other by a distance smaller than the pitch of the protrusions 11 of the pressure-sensitive sheet 1a. (For example, 10
Moreover, if the diameter of each part is smaller than the diameter of the protrusion 11 (for example, 15 to 20 μm), they may be arranged randomly rather than in a matrix.

FIG. 6 is a sectional view showing another embodiment of the pressure sensitive plate according to the present invention.

This embodiment is a pressure sensitive plate utilizing magnetic action, and the pressure sensitive plate 1 is a pressure receiving sheet 1 having the same structure as shown in FIG.
a, a pressure-sensitive sheet 1b that senses irregularities using a magnetic action, and an electrode base 1c having the same structure as that shown in FIG.

A description of the pressure receiving sheet 1a and the electrode base 1c is omitted, and the pressure sensitive sheet 1b will be described.

The pressure-sensitive sheet 1b is a non-magnetic sheet 40 such as a resin film or ceramics, in which holes 41 having the same pitch and number as the protrusions 11 of the pressure-sensitive sheet 1a are formed in a matrix by etching, laser, physical means or the like. is there. The diameter of the hole 41 is about 30 μm. Each hole 41 is filled with magnetizable fine particles 42 such as iron powder. The particles 42 are then magnetized. The particles 42 may be a single particle, a plurality of particles, or may be magnetized such as a magnet.

An elastic film 43 such as silicon rubber is arranged under the non-magnetic sheet 40, and a ferromagnetic magnetoresistive element 44 is arranged at a position corresponding to the hole 41 of the elastic film 43.

In the electrode base 1c, the electrode pair of the X electrode 31 and the Y electrode piece 32a is connected to the magnetoresistive element 44.

The pressure-sensitive plate 1 of this embodiment has a ferromagnetic magnetoresistive effect, that is, when a current is passed through the magnetoresistive element 44 through the X electrode 31 and the Y electrode 32, if a magnetic field is applied to the resistive element 44, the resistive element 44 is applied. This utilizes the effect that the resistance value of changes with the direction and magnitude of the magnetic field.

The detection circuit for the pressure distribution on the uneven surface using the pressure sensitive plate 1 is the fifth
It is the same as shown in the figure.

For example, in order to detect a fingerprint pattern, a finger tip is placed on the pressure sensitive plate 1 and lightly pressed, and a voltage is applied to the X electrode 31 and the Y electrode 32 by the controller 101 at a predetermined timing to scan, and the fingerprint is pressed. Pressure receiving sheet 1a
Of the particles 4 of the pressure-sensitive sheet 1b under the protrusions 11 of the
2 is pushed downward, and the magnetic field applied to the magnetoresistive element 44 increases. As a result, a current flows between the X electrode 31 and the Y electrode 32, and the peaks of the fingerprint, that is, the unevenness can be detected.

As a modified example of this embodiment, as shown in FIG. 7, the pressure-sensitive sheet 1b has a hole 41 formed in the insulating sheet 40, and iron powder particles 42 are simply put in the hole 41. A pressure sensitive plate may be configured by attaching a magnetizing piece 45 to the lower surface of the pressure receiving sheet 1a at a position corresponding to the protrusion 11 and disposing the magnetoresistive element 44 on the electrode pair of the electrode base 1c.

The detection principle of the uneven surface pressure distribution according to this embodiment is the same as that of the embodiment shown in FIG. 6, but when the protrusion 11 is pressed, the magnetization state of the magnetizing piece 45 is changed by the magnetoresistive element 4 via the iron powder particles 42.
Since the number is 4, the sensitization effect can be obtained and the unevenness can be surely detected.

Instead of the elastic film 43 of the embodiment shown in FIG. 6, an elastic piece may be put in the bottom of each hole 41 of the non-magnetic sheet 40.

FIG. 8 is a sectional view showing still another embodiment of the pressure sensitive plate according to the present invention.

This example is a pressure sensitive plate that utilizes the change in capacitance,
The pressure-sensitive plate 1 includes a pressure-sensitive sheet 1a having the same structure as shown in FIG. 2 (a) and a sensing sheet 1b that forms an electrostatic capacitance and changes the electrostatic capacitance according to the unevenness to sense the unevenness. Composed.

In the pressure sensitive sheet 1b, holes 51 are formed in the metal thin film 50 by etching or a physical method at the same pitch and number as the projections 11 of the pressure receiving sheet 1a, and elastic films 52 and 53 are arranged above and below the metal thin film 50. Holes 51 in elastic membranes 52 and 53
Electrodes 54 and 55 made of a metal material are formed at the positions corresponding to, and shield films 56 and 57 made of a metal foil are arranged further outside the elastic films 52 and 53.

The electrode 54 formed on the upper elastic film 52 constitutes a parallel Y electrode, the electrode 55 formed on the lower elastic film 53 constitutes a parallel X electrode, and at the position of the hole 51 of the metal thin film 50. X
The electrode 53 and the Y electrode 54 are arranged to intersect with each other.

A detection circuit for detecting the pressure distribution on the uneven surface using the pressure sensitive plate of this embodiment is not particularly shown, but like the pressure sensitive plate using the pressure sensitive conductive material described above, the Y electrode 54 is sequentially switched to a high frequency. A signal is applied, the X electrodes 55 are sequentially switched and scanned, and the pressure receiving plate 1a is formed by a convex portion such as a ridge of a fingerprint.
When the projection 11 of the
The gap between the electrode 55 and the electrode 55 on the lower elastic film 53 becomes small, the electrostatic capacitance between both electrodes changes, and the electric field strength inputted from the Y electrode becomes large, so that unevenness can be detected. In this case, since each intersection of the matrix is shielded by the metal thin film 50 and the upper and lower shield films 56 and 57, it is possible to prevent the radiation of radio waves and the wraparound, and it is possible to detect an accurate pattern without being affected by others. .

Various embodiments of the pressure sensitive plate according to the present invention have been described above.
In each case, the multiple protrusions of the pressure receiving sheet are separated and independent, so when the convex and concave portions of the pressure receiving sheet contact the surface of the pressure receiving sheet, only the protrusion that hits the convex portion is pressed and the influence on the adjacent protrusions is affected. Since it is completely cut off, the convex pattern can be accurately detected.

Although the unevenness is detected in a matrix in the above embodiment, the arrangement of the protrusions and the electrodes of the pressure-receiving sheet may not be arranged in a matrix, but may be a combination of concentric circles and radial circles, for example.

(Effects of the Invention) As described above, in the present invention, a pressure-sensitive sheet having a plurality of protrusions arranged at fine intervals, and a pressure-sensitive sheet having holes at least at positions corresponding to the protrusions of the pressure-sensitive sheet. And an electrode base having a pair of electrodes formed so as to be spaced apart and intersect at a position corresponding to the hole of the pressure-sensitive sheet, and when the uneven surface is brought into contact with the pressure-sensitive sheet, the pressure-sensitive sheet is formed. Since the physical properties inside the holes of the pressure-sensitive sheet are changed by the applied force, and the current value flowing through the pair of electrodes of the electrode base is changed accordingly, the fine uneven surface pressure of 100 μm or less is obtained. The distribution can be accurately detected, which is suitable for detecting a fine uneven surface pressure distribution such as a fingerprint pattern.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of a pressure-sensitive plate for detecting pressure distribution on an uneven surface according to the present invention, and FIG. 2 is an exploded perspective view of the pressure-sensitive plate shown in FIG. 1. (B) is a pressure sensitive sheet, and (c) is an electrode base. Figure 3 is Figure 2 (c)
FIG. 4 is a partial enlarged perspective view of the electrode base shown in FIG. 4, FIG. 4 is a partial cross-sectional view of the pressure sensitive plate shown in FIG. 1, and FIG. 5 is a pressure sensitive plate shown in FIG. The basic circuit configuration of the detection circuit, FIG. 6 is a partial sectional view of another embodiment of the pressure-sensitive plate for detecting uneven pressure distribution according to the present invention, and FIG. 7 is a modification of the pressure-sensitive sheet of the pressure-sensitive plate shown in FIG. Sectional view showing an example, No. 8
FIG. 7 is a partial cross-sectional view of still another embodiment of the pressure sensitive plate for detecting the uneven pressure distribution according to the present invention. 1 ... Pressure-sensitive plate, 1a ... Pressure-sensitive sheet, 1b ... Pressure-sensitive sheet, 1c ... Electrode base, 11 ... Projection, 20 ... Insulation sheet, 21 ... Hole, 22 ... Pressure-sensitive conductive material, 30 ......
Plate member, 31 ... X electrode, 32 ... Y electrode

Claims (4)

[Claims] 1. A pressure receiving sheet having a plurality of protrusions arranged at fine intervals, a pressure sensitive sheet having holes at positions corresponding to at least the protrusions of the pressure receiving sheet, and corresponding to the holes of the pressure sensitive sheet. Formed by laminating an electrode base having a pair of electrodes formed so as to be spaced apart and intersect at a position where the pressure-sensitive sheet is formed by a force applied to the pressure-sensitive sheet when the uneven surface is brought into contact with the pressure-sensitive sheet. A pressure-sensitive plate for detecting uneven pressure distribution, characterized in that a physical property inside the hole is changed so that a current or a voltage detected through the set of electrodes of the electrode base is changed. 2. The pressure-sensitive sheet has a pressure-sensitive conductive material in the holes, and a pair of electrodes of the electrode base are electrically connected to each of the holes via the pressure-sensitive conductive material. The pressure-sensitive plate for detecting the pressure distribution on the uneven surface described in. 3. The pressure-sensitive sheet according to claim 1, wherein the pressure-sensitive sheet has magnetic particles in the holes, and a pair of electrodes of the electrode base is electrically connected to each hole via the magnetoresistive element. Pressure sensitive plate for detecting uneven pressure distribution. 4. The concavo-convex surface according to claim 1, wherein a pair of electrode pieces face each other across a hole of the pressure-sensitive sheet and are arranged such that a distance between both electrode pieces is changed by a force applied to the pressure-receiving sheet. Pressure sensitive plate for pressure distribution detection.