JP2000076425A - Contact type shape measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make reducible the thickness of the whole of a shape measuring instrument and to measure the recess and projection of a fingerprint as an image of high contrast. SOLUTION: This instrument consists of a sensor matrix array 1 obtained by arranging plural double gate sensors 11 on a glass substrate 10 in the state of a matrix, a contacting surface substrate 2 provided opposed to the arranging surfaces of the sensors 11 of the array 1, a gel light absorbing film 3 laminated on the substrate 2 and a back light 4 provided on a side opposite to the arranging surface of the sensor 11 of the array 1. The film 3 can easily vary its shape according to the recess/projection of the fingerprint and at the projecting part of the fingerprint, the thickness of the layer is reduced and a light absorbing quantity is reduced. At the recess part of the fingerprint, the material of the film 3 pushed out from the projection part infiltrates, thereby the thickness of the layer is increased and the absorption of light is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact-type shape measuring device suitable for measuring an uneven pattern such as a fingerprint.

[0002]

2. Description of the Related Art Fingerprints have a specific shape for each individual, and are easily used for pattern matching. Therefore, fingerprints are widely used for identifying specific individuals. Conventionally, as shown in FIG. 6, a fingerprint sensor for measuring a fingerprint pattern to be used for personal identification has been used.

The fingerprint sensor shown in FIG. 6 includes a right-angle prism 50 to which a total reflection film 50a is attached, a light source 51, a lens 52, and a CCD (Charge Cou) as a photo sensor.
pledDevice) 53. When a fingerprint pattern is measured by this fingerprint sensor, the surface of the fingerprint to be measured is brought into contact with the total reflection film 50a.
The finger FG is placed on the right-angle prism 50.

In this state, the right-angle prism 5 is
The light incident on 0 is absorbed by the convex portion of the fingerprint of the total reflection film 50a (actually, only this portion contacts the total reflection film 50), and is almost totally reflected by the concave portion of the fingerprint. An image is formed on the CCD 53 by the lens 52. Then, the CCD 53 detects the imaged light to measure the fingerprint pattern.

However, in the above-described conventional fingerprint sensor, it is necessary to change the angle of the light from the light source 51 by the right-angle prism 50, and furthermore, the CCD by the lens 52.
53 had to be imaged. For this reason, it was difficult to make the entire apparatus thin. In addition, since it is necessary to detect a difference in the amount of reflected light depending on whether or not there is contact with the total reflection film 50a, it has been difficult to measure a fingerprint pattern as an image with high contrast.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is possible to reduce the thickness of the entire apparatus and to obtain a high-contrast image with unevenness. The shape can be measured,
An object of the present invention is to provide a contact-type shape measuring device suitable for a fingerprint sensor or the like.

[0007]

In order to achieve the above object, a contact type shape measuring apparatus of the present invention measures the shape of an unevenness of a measurement object having unevenness, and emits light of a predetermined wavelength. A plurality of light detecting means for detection are arranged in a predetermined arrangement vertically and horizontally, and at least in a direction from the surface opposite to the arrangement surface of the light detection means to the arrangement surface, have light transmissivity for the light of the predetermined wavelength. A first substrate, a second substrate facing a surface of the first substrate on which the light detection means is arranged, and having a light transmitting property with respect to the light of the predetermined wavelength; A light absorber laminated on the surface opposite to the first substrate side, having a light absorbing property for the light of the predetermined wavelength, and changing a shape according to the unevenness of the mounted measurement target;
Light reading means for reading a detection result of each of the plurality of light detection means, wherein the plurality of light detection means is configured to store the first object in a state where the measurement target is placed on the light absorber. The light emitted from the opposite side of the light detection means of the substrate and reflected on the surface of the measurement target is detected.

[0008] In the above-mentioned contact type shape measuring apparatus, the light emitted from the opposite surface of the first substrate from the light detecting means enters the second substrate and the light absorber. Here, when the measurement target is placed on the light absorber, the thickness of the light absorber changes according to the unevenness of the measurement target. That is, the thickness of the light absorber is small at the convex portion to be measured, and the light absorption amount is small. On the other hand, in the concave portion, the thickness of the light absorber is large, and the light absorption amount is large. Therefore, the amount of light reflected on the surface of the object to be measured and again incident on each light detecting means through the light absorber and the second substrate is large corresponding to the convex portion and large for the concave portion. And small.

As described above, in the above-mentioned contact-type shape measuring device, the amount of light absorbed by the light absorber changes according to the uneven shape of the object to be measured. For this reason, a clear difference can be obtained between the convex and concave portions of the measurement target in the brightness of the light detected by the light detection unit, and the reading unit obtains the uneven shape of the measurement target as a high-contrast image. Can be.

The above-mentioned contact-type shape measuring apparatus may have a structure in which first and second substrates, which can be configured as a schematic planar type, are stacked. Further, when a light source that emits light for measurement is used, a structure in which planar light sources are further stacked may be used. Therefore, the entire apparatus can be configured to be thin.

In the above contact type shape measuring device, the light absorber is made of, for example, a gel-like substance whose shape changes according to the unevenness of the object to be measured.

That is, such a gel-like substance does not cause the light absorber to flow from the second substrate.
On the other hand, when the measurement object is placed, it is pressed and its shape can be easily changed. Therefore, such a gel-like substance is suitable as a substance constituting the light absorber.

In the above contact type shape measuring apparatus, the plurality of light detecting means are each formed on the first substrate side and have a first gate having a light shielding property for light emitted from the opposite surface. An electrode, a second gate electrode formed on the second substrate side and having a light-transmitting property with respect to light reflected and irradiated from the measurement object, and between the first and second gate electrodes. Each intervenes through an insulator, and generates a carrier inside according to the amount of light incident through the second gate electrode, and the carrier is applied to the carrier and the first and second gate electrodes. A semiconductor layer forming a channel in accordance with the applied voltage, a drain electrode connected to the semiconductor layer and supplied with a constant voltage, and formed separately from the drain electrode with the semiconductor layer interposed therebetween and grounded. With a source electrode A first drive circuit that selects the first gate electrode for each predetermined unit of the plurality of light detection units, and applies a voltage for forming a channel in the semiconductor layer; A second drive circuit for selecting a second gate electrode for each of the predetermined units and applying a voltage for accumulating carriers in the semiconductor layer;
A voltage supply switch for controlling supply of a constant voltage to the drain electrode, a read switch for reading the potential of the drain electrode, and control for controlling the first and second drive circuits, the voltage supply switch, and the read switch And a device.

That is, such a light detecting means may have not only a function of detecting light but also a function of selecting one of a plurality of light detecting means arranged in a predetermined arrangement in the vertical and horizontal directions. it can. Therefore, in such a light detecting means, since it is not necessary to separately provide an element for selecting the light detecting means, the light detecting means can be arranged at high density on the first substrate, and the unevenness of the measurement object can be expressed in high-resolution image data. It is possible to obtain as.

Further, the above-mentioned contact-type shape measuring device emits light of the predetermined wavelength, and the light from the surface of the first substrate opposite to the surface on which the light detecting means is arranged is provided via the first substrate. A light source for irradiating the second substrate may be further provided.

Note that a fingerprint can be applied to the above-mentioned contact type shape measuring device as a measurement target. That is,
The above-described contact-type shape measuring apparatus is preferably applied to a fingerprint sensor that measures a fingerprint pattern.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

[First Embodiment] FIG. 1 is a sectional view showing the structure of a fingerprint sensor according to this embodiment. As shown in the figure, this fingerprint sensor is arranged such that a plurality of double gate sensors 11 are arranged in a matrix on a glass substrate 10 and a sensor matrix array 1 is opposed to an arrangement surface of the double gate sensors 11 of the sensor matrix array 1. The contact surface substrate 2 provided, the gel light absorbing film 3 laminated on the contact surface substrate 2, and the backlight 4 provided on the sensor matrix array 1 on the opposite side of the arrangement surface of the double gate sensor 11. It is configured.

The sensor matrix array 1 transmits a light emitted from the backlight 4 and makes it incident on the contact surface substrate 2, and is formed on the glass substrate 10 in a matrix, and serves as a measurement target as described later. And a double gate sensor 11 for detecting light reflected on the surface of the fingerprint. In addition, a portion of the glass substrate 10 where the double gate sensor 11 is not formed is provided with ITO (Indium T
A data line, a top gate line, and a bottom gate line, which will be described later, are formed of transparent electrodes such as in Oxide. The double gate sensor 11 will be described later in more detail.

The contact surface substrate 2 is made of a transparent glass or plastic plate or the like.
Light emitted from the backlight 4 is incident through the light emitting device 0. The incident light further enters the gel light absorbing film 3. Further, as described later, when the substance constituting the gel light absorbing film 3 is pushed out by the convex portion of the fingerprint and the fingerprint comes into contact with the contact surface substrate 2, the incident light is reflected at the interface.

The gel light absorbing film 3 absorbs light emitted from the backlight 4 and incident from the contact surface substrate 2 with high efficiency.
The gel light absorbing film 3 is formed by cross-linking a polymer anion such as a polymer carboxylic acid or a polymer sulfonic acid. And a pigment that absorbs light in a wavelength range that excites the semiconductor layer of the sensor 11. In addition, examples of the monomer that generates such a polymer anion by polymerization are shown in the following chemical formulas 1 to 4.

[0022]

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[0023]

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[0024]

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[0025]

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Since the gel light absorbing film 3 is composed of the gel polymer chains as described above, when the fingerprint FP is placed on the contact surface substrate 2, the shape thereof can be easily changed according to the uneven shape of the fingerprint FP. Can be changed. Then, as shown in FIG. 2, the gel light absorbing film 3 is extruded from the convex portion cv of the fingerprint FP into the concave portion cc, and the layer thickness of the convex portion cv is reduced, and the light absorption amount is reduced. On the other hand, the concave portion c of the fingerprint
Since the gel light absorbing film 3 extruded from the convex portion cv goes around c, the layer thickness is increased, and the light absorption amount is increased.

The backlight 4 shown in FIG. 1 is composed of a flat organic EL element. The organic EL elements constituting the backlight 4 are made of MgAg, MgIn, Al-L
The organic EL layer is sandwiched between a cathode electrode made of i or the like and an anode electrode made of transparent ITO or the like. This organic EL layer has, for example, a two-layer structure of an electron transporting light emitting layer made of Bebq2 formed on the cathode electrode side and a hole transporting layer made of α-NPD formed on the anode electrode side. I have. The organic EL layer emits light in a predetermined wavelength range when a predetermined voltage is applied between an anode electrode and a cathode electrode from a driving circuit (not shown). The backlight 4 has a transparent anode electrode disposed on the glass substrate 10 side, and is provided with an organic EL.
Light emitted from the layer is incident on the contact surface substrate 2 via the electrode and the glass substrate 10.

Hereinafter, the double gate sensor 11 in the sensor matrix array 1 will be described in detail with reference to FIGS.

First, the structure of the double gate sensor 11 will be described with reference to the sectional view of FIG. The structure of the double gate sensor 11 will be described with reference to FIG. 3. First, a bottom gate electrode 113 made of a metal material having light reflectivity and blocking light from the glass substrate 10 is formed on the glass substrate 10. Further, a bottom gate insulating film 114 made of transparent silicon nitride (SiN) is formed on the glass substrate 10 so as to cover the bottom gate electrode 113.

A semiconductor layer 115 made of i-type amorphous silicon (ia-Si) is formed on the bottom gate insulating film 114 at a position facing the bottom gate electrode 113. Further, with the semiconductor layer 115 interposed, ITO
A source electrode 116 and a drain electrode 117 are formed. Source electrode 116 and drain electrode 11
Reference numeral 7 is connected to the semiconductor layer 115 via n ⁺ silicon layers 118 and 119 made of amorphous silicon (ia-Si) in which a group V element such as phosphorus (P) is diffused.

Further, the semiconductor layer 115 and the source electrode 11
A top gate insulating film 110 made of transparent silicon nitride (SiN) is formed so as to cover 6 and drain electrode 117. A top gate electrode 111 made of transparent ITO is formed on the top gate insulating film 110 at a position facing the semiconductor layer 115.

It should be noted that such a double gate sensor 11
In a position where is not formed, a bottom gate line BL connected to the bottom gate electrode 113 is formed on the glass substrate 10. Also, the bottom gate insulating film 1
14 and the top gate insulating film 110, a data line DL connected to the drain electrode 117 and the source electrode 11
6 are formed, respectively. Further, on the top gate insulating film 110, a top gate line TL connected to the top gate electrode 111 is formed.

Next, the operation of such an n-channel double gate sensor 11 will be described with reference to the schematic diagrams of FIGS.

The voltage applied to the top gate electrode (TG) 111 and the bottom gate electrode (BG) 113 is 0
In the case of (V), as shown in FIG. 4A, no channel is formed in the semiconductor layer 115, and even if a voltage of 5 (V) is applied to the drain electrode (D) 117, No current flows between the electrode (D) 117 and the source electrode (S) 116.

When the voltage applied to the top gate electrode (TG) 111 is -20 (V) and the voltage applied to the bottom gate electrode (BG) 113 is 0 (V), FIG. As shown in (b), no channel is formed in the semiconductor layer 115. However, at this time, if the top gate electrode 111 is irradiated with light, the light is incident on the semiconductor layer 115, whereby carriers (electron-hole pairs) are generated in the semiconductor layer 115, and the top gate electrode 111 is irradiated with light. (T
G) Holes are retained by the reverse bias of 111.

The voltage applied to the top gate electrode (TG) 111 is 0 (V), and the voltage applied to the bottom gate electrode (B
G) The voltage applied to 113 is a forward bias +
At 10 (V), an n-channel is formed on the bottom gate (BG) 113 side of the semiconductor layer 115 as shown in FIG. Thereby, the drain electrode (D) 1
When a voltage of 5 (V) is applied to 17, a current flows between the drain electrode (D) 117 and the source electrode (S) 116. This state is used for resetting the potential charged in the data line.

The voltage applied to the top gate electrode (TG) 111 is −20 (V), the voltage applied to the bottom gate electrode (BG) 113 is +10 (V), and the top gate electrode When light is not incident on the semiconductor layer 115 via the (TG) 111, FIG.
As shown in (d), holes are drawn toward the top gate electrode (TG) 111 and electrons are drawn toward the bottom gate electrode (BG) 113 in the semiconductor layer 115. Accordingly, the depletion layer spreads in the semiconductor layer 115, the n-channel is pinched off, and even if a voltage of 5 (V) is applied to the drain electrode (D) 117, the drain electrode (D) 117 and the source electrode ( S) No current flows between them.

The voltage applied to the top gate electrode (TG) 111 is −20 (V), the voltage applied to the bottom gate electrode (BG) 113 is +10 (V), and the top gate electrode When light is incident on the semiconductor layer 115 through the (TG) 111, FIG.
As shown in FIG. 4, a hole-electron pair is generated below the hole attracted to the top gate electrode (TG) 111 side (including the one generated in the state of FIG. 4B). The generated holes correspond to the bottom gate electrode (BG) 1 to which the negative voltage is applied.
13, and acts in a direction to reduce the influence of the negative voltage of the bottom gate electrode (BG) 113 on the inside of the semiconductor layer 115. Thereby, as shown in FIG. 4F, when a voltage of 5 (V) is applied to the drain electrode (D) 117, an n-channel is formed, and the drain electrode (D) 117 and the source electrode (S) are formed. A current flows between the current path and the current path.

In the fingerprint sensor described above, the double gate sensor 11 is driven by the drive circuit shown in the block diagram of FIG. 5 to obtain data of the image of the concave and convex pattern of the fingerprint FP. FIG.
As shown in FIG. 1, the driving circuit of the fingerprint sensor includes a sensor matrix array 1, a top gate driver 12, a bottom gate driver 13, a constant voltage generating circuit 14, a precharge switch 15, a column switch 16, a controller 17.

As described above, the sensor matrix array 1 has a plurality of double gate sensors 11 arranged in a matrix. The drain electrode 117 of each double gate sensor 11 is connected to the data line DL in units of columns (vertical direction in the figure) of the sensor matrix array 1, and the top gate electrode 11
1 is the top gate line TL in row (horizontal direction in the figure)
In addition, the bottom gate electrodes 113 are connected to the bottom gate lines BL in row units. The source electrode 116 of each double gate sensor 11 is grounded.

When the double gate sensor 11 is driven as described above and a channel is formed in the semiconductor layer 115, a current flows between the drain electrode 117 and the source electrode 116, and the double gate sensor 11 is pre-charged to the data line DL. Discharge the charged potential to ground.

The top gate driver 12 is connected to each of the top gate lines TL formed for each row of the sensor matrix array 1 and has a voltage of 0 (V) or-.
A voltage of 20 (V) is sequentially applied to the top gate line TL at a predetermined timing according to a control signal TGC from the controller 17.

The bottom gate driver 13 is connected to each of the bottom gate lines BL formed for each row of the sensor matrix array 1, and is connected to 0 (V) or +
A voltage of 10 (V) is sequentially applied to the bottom gate line BL at a predetermined timing according to a control signal BGC from the controller 17.

The constant voltage generation circuit 14 generates a constant voltage Vdd, and generates the generated constant voltage Vdd (for example, 5 Vdd).
(V)) is applied to each data line DL via the precharge switch 15 to precharge the data line DL. The precharge switch 15 is connected to the controller 17
Is turned on / off according to the control signal VC from the control voltage VC.
d to each data line DL.

The column switch 16 is connected to each of the data lines DL formed for each column of the sensor matrix array 1, and according to a control signal CSC from the controller 17, the potential level on the data line DL (the double gate sensor 11). (Corresponds to the intensity of light incident on the
Is read, and data IM of the image of the uneven pattern of the fingerprint FP is read.
G is supplied to the controller 17.

The controller 17 has a control signal TG for controlling the driving of each of the top gate driver 12, the bottom gate driver 13, and the column switch 16.
C, BGC, CSC, and precharge switch 15
A control signal VC for controlling ON / OFF of the control signal is generated and supplied to each unit. The controller 17 also outputs data IMG of the image of the concavo-convex pattern of the fingerprint FP read from the column switch 16 in accordance with the control signal CSC.
And supplies it to an external verification device (not shown).

Hereinafter, an operation for reading the concave and convex pattern of the fingerprint FP by the fingerprint sensor will be described.

First, as shown in FIG. 2, when a finger having a fingerprint FP to be measured is placed on the contact surface substrate 2, the shape of the gel light absorbing film 3 on the contact surface substrate 2 becomes uneven. The thickness of the gel light absorbing film 3 becomes thinner in the convex portion cv, and becomes thicker in the concave portion cc. In this state, the backlight 4 is driven to emit light toward the fingerprint FP to be measured.

The light emitted from the backlight 4 enters the contact surface substrate 2 via the glass substrate 10. Then, this light passes through the contact surface substrate 2 and enters the gel light absorbing film 3. The light incident on the gel light absorbing film 3 is absorbed by the action of the gel light absorbing film 3 before reaching the surface of the fingerprint FP placed thereon. cv is small, and large in the concave portion cc having a large layer thickness.

The light that reaches the surface of the fingerprint FP without being absorbed by the gel light absorbing film 3 is reflected there and proceeds in the direction of the contact surface substrate 2. This reflected light is also absorbed by the action of the gel light absorbing film 3, and the amount of light absorbed at this time is small in the convex portion cv having a small layer thickness and large in the concave portion cc having a large layer thickness. The light that has entered the contact surface substrate 2 without being absorbed by the gel light absorbing film 3
And enters the top gate electrode 111 of each of the double gate sensors 11 arranged on the glass substrate 10.

The magnitude of the amount of light incident on the top gate electrode 111 of the double gate sensor 11 as described above depends on FIG.
Are driven as follows, and are read out to the controller 17 as electric signals in row units of the matrix sensor array 1.

First, immediately before the fingerprint shape is sensed by the double gate sensor 11, a reset step of discharging the charge accumulated in the double gate sensor 11 is performed. Next, the controller 17 turns on the precharge switch 15 by the control signal VC. In the data line DL,
The constant voltage Vdd from the constant voltage generation circuit 14 is supplied.
When the potential difference between the source and the drain of the double gate sensor 11 becomes almost Vdd, the controller 1
7 by the control signal VC from the precharge switch 15.
Is turned off, and the data line DL is charged with the voltage Vdd.

In this state, the controller 17 controls the top gate driver 12 by the control signal TGC, and the double gate sensor 11 connected to the top gate line TL of the row from which an electric signal corresponding to the amount of incident light is to be read.
A voltage of 0 (V) is applied to the top gate electrode 111. Further, the bottom gate driver 13 is controlled by the control signal BGC, and a voltage of +10 (V) is applied to the bottom gate electrode 113 connected to the bottom gate line BL of the row.

By applying such a voltage,
N is added to the semiconductor layer 115 of the double gate sensor 11 in the row.
A channel is formed, a current flows between the drain electrode 117 and the source electrode 116, and the charge previously accumulated in the semiconductor layer 115 of the double gate sensor 11 is erased (reset). As a result, in the semiconductor layer 115, the charge stored immediately before the fingerprint shape sensing is lost and the semiconductor layer 115 becomes neutral, and the potential of the data line DL is discharged to ground to 0.
(V).

Next, the controller 17 outputs the control signal TG
C controls the top gate driver 12 to apply a voltage of 0 (V) to the top gate electrode 111 of the double gate sensor 11 connected to the top gate line TL of the row from which an electric signal corresponding to the amount of incident light is to be read. Is applied.
Also, the bottom gate driver 13 is controlled by the control signal BGC.
And a voltage of 0 (V) is also applied to the bottom gate electrode 113 connected to the bottom gate line BL of the row.

By applying such a voltage,
The drain electrode 117 of the double gate sensor 11 in the row
No current flows between the gate electrode and the source electrode 116. In this state, when the controller 17 turns on the precharge switch 15 with the control signal VC, the constant voltage generation circuit 14 supplies the constant voltage Vdd to the data line DL. Thus, when the data line DL is precharged and its potential becomes almost Vdd, the control signal V
The precharge switch 15 is turned off by C.

Next, the controller 17 outputs the control signal VC
To turn off the precharge switch 15 and stop supplying the constant voltage Vdd to the data line DL. Further, the controller 17 controls the top gate driver 12 by the control signal TGC, and applies a voltage of −20 (V) to the top gate electrode 111 of the double gate sensor 11 connected to the top gate line TL of the row. .
Also, the bottom gate driver 13 is controlled by the control signal BGC.
And a voltage of +10 (V) is applied to the bottom gate electrode 113 connected to the bottom gate line BL of the row.

By applying such a voltage,
Of the double gate sensors 11 in the row that have not been irradiated with sufficient light, the depletion layer spreads in the semiconductor layer 115, so that the formed n-channel is pinched off. Therefore, no current flows between the gate electrode 117 and the source electrode 116, and the potential of the data line DL remains at Vdd.

On the other hand, in the double gate sensor 11 irradiated with sufficient light, a hole-electron pair is generated in the semiconductor layer 115, and holes are held in the semiconductor layer 115 by the negative potential of the top gate electrode 111. You. The retained holes play a role in neutralizing the negative potential of the top gate electrode 111, and the n-channel is formed without being pinched off. As a result, a current flows between the drain electrode 117 and the source electrode 116, and the data line DL
Is discharged to the ground.

Next, the controller 17 outputs the control signal CS
The column switch 16 is controlled by C, and the potential on each data line DL is read. The read potential becomes low when the corresponding double gate sensor 11 is irradiated with light, and becomes high when the light is not irradiated. Data line DL read by column switch 16
The upper potential is supplied to the controller 17 as data IMG of the concavo-convex pattern for one row.

Thus, the data I of the concavo-convex pattern for one row
When the reading of the MG is completed, the controller 17 repeats the same processing as described above for the next row of the matrix sensor array 1. When the same processing as described above is completed for all the rows of the matrix sensor array 1, data IMG of an image of the entire concavo-convex pattern of the fingerprint FP placed on the contact surface substrate 2 can be obtained.

The data IMG of the image of the concavo-convex pattern of the fingerprint FP read out as an electric signal as described above is output from the controller 17 and stores the concavo-convex pattern of a plurality of fingerprints registered in advance for comparison. Supplied to the verification device. Then, the matching device matches the read unevenness pattern of the fingerprint with the unevenness pattern of the fingerprint registered in advance, and outputs a match or mismatch result.

As described above, in the fingerprint sensor according to the present embodiment, the light emitted from the backlight 4 enters the gel light absorbing film 3 via the glass substrate 10 and the contact surface substrate 2. The layer thickness of the gel light absorbing film 3 becomes thinner at the convex portion cv of the placed fingerprint FP and becomes thicker at the concave portion cc.
That is, the amount of light absorbed by the gel light absorbing film 3 is small in the convex portion cv, and the gel light absorbing film 3 is small in the concave portion cc.
The amount of light absorbed by For this reason, the amount of light reflected on the surface of the fingerprint FP and again entering the double gate sensor 11 through the gel light absorbing film 3 and the contact surface substrate 2 is apparent from the convex portion cv and the concave portion cc of the fingerprint FP. A significant difference will occur. Therefore, with the fingerprint sensor according to the present embodiment, it is possible to obtain a high-contrast image of the uneven pattern of the fingerprint FP.

The fingerprint sensor according to this embodiment has a flat glass substrate 10 and a contact surface substrate 2.
And the backlight 4 is arranged in an overlapping manner. For this reason, the entire device can be configured to be thinner than a conventional fingerprint sensor using a right-angle prism, a lens, or the like.

In the fingerprint sensor according to this embodiment, not only the function of detecting the brightness of light reflected from the surface of the fingerprint FP but also the function of selecting an optical signal for reading is double. The gate sensor 11 is used. For this reason, since it is not necessary to form an element for selection other than the photosensor on the glass substrate 10, the double gate sensor 11 can be arranged on the glass substrate 10 at high density, and the uneven pattern of the fingerprint FP can be reduced. It can be obtained as high-definition image data.

Further, since the gel light absorbing film 3 applied to the fingerprint sensor according to this embodiment uses the gel polymer chains as described above as its material, the uneven shape of the fingerprint to be measured is obtained. , The shape can be easily changed according to the above formula, and there is no flow from the contact surface substrate 2. Moreover, when the finger is placed on the contact surface substrate 2, the substance does not adhere to the finger.

In the above embodiment, in the sensor matrix array 1, the double gate sensors 11 are arranged on the substrate 10 in a matrix. That is, the double gate sensor 11 was used for measuring the reflected light. On the other hand, the present invention may use a photosensor other than the double gate sensor, for example, a CCD, a phototransistor, a photodiode, or the like.

In the above embodiment, the flat backlight 4 composed of the organic EL element was used as the light source for irradiating light from the back surface of the sensor matrix array 1 to the contact surface substrate 2. However, the light source
A side light or the like may be used, and another type of light emitting element other than the organic EL element may be used. Alternatively, natural light may be used as a light source without providing a light emitting element as a light source. As the light source, not only a light source that emits visible light but also a light source that emits non-visible light (infrared ray, ultraviolet ray, or the like) can be used. A photo sensor may be used.

In the above embodiment, the gel light absorbing film 3 is provided on the contact surface substrate 2, and the pattern of the fingerprint unevenness is measured by the change in the shape of the gel light absorbing film 3 due to the unevenness of the fingerprint. On the other hand, for example, the contact surface substrate 2 may be formed in a box shape having an open top, and a liquid having a light absorbing property such as black ink may be immersed therein.

In the above embodiment, the case where the present invention is applied to the fingerprint sensor, that is, the case where the shape to be measured is a fingerprint uneven pattern is described. However, the shape to be measured in the present invention is not limited to a fingerprint,
The present invention can be applied to measurement of a fine uneven pattern of any shape.

In the above embodiment, the uneven pattern of the fingerprint is obtained only as a two-tone image, depending on the magnitude of the light absorption by the gel light absorbing film 3. On the other hand, the gel light absorbing film 3
The amount of light absorbed by the light can vary stepwise according to the layer thickness. For this reason, if the intensity of light received by the double gate sensor 11 can be acquired as a gradation image, the present invention can be applied to measurement of a three-dimensional shape.

[0072]

As described above, according to the present invention, the entire apparatus can be made thin. Further, the shape of the unevenness can be measured with high contrast.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a fingerprint sensor according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating how the shape of a gel light absorbing film changes in the fingerprint sensor of FIG.

FIG. 3 is a cross-sectional view illustrating a structure of a double gate sensor used in the fingerprint sensor of FIG.

FIGS. 4A to 4F are diagrams for explaining the operation of the double gate sensor of FIG.

FIG. 5 is a block diagram illustrating a driving circuit of the fingerprint sensor of FIG. 1;

FIG. 6 is a cross-sectional view showing the structure of a conventional fingerprint sensor.

[Explanation of symbols]

1 ... Sensor matrix array, 2 ... Contact surface substrate, 3 ...
Gel light absorbing film, 4 backlight, 10 glass substrate, 11 double gate sensor, 12 top gate driver, 13 bottom gate driver, 14 constant voltage Generating circuit, 15: Precharge switch, 16: Column switch, 17: Controller, 110: Top gate insulating film, 111: Top gate electrode, 113 ...
Bottom gate electrode, 114 ... bottom gate insulating film, 1
15 ... semiconductor layer, 116 ... source electrode, 117 ... drain electrode, 118 ... n ⁺ silicon layer, 119 ... n ⁺ silicon layer, DL ... data line, TL ... Top gate line, BL: bottom gate line, FP: fingerprint, c
v: convex part, cc: concave part

Claims (4)

[Claims] 1. A contact-type shape measuring device for measuring the shape of an unevenness of a measurement object having unevenness, wherein a plurality of light detecting means for detecting light of a predetermined wavelength are arranged in a predetermined arrangement in a matrix. A first substrate having a light-transmitting property with respect to the light of the predetermined wavelength, at least in a direction from the surface opposite to the surface on which the light detection means is disposed to the surface on which the light detection means is provided; A second substrate facing the arrangement surface and having a light transmitting property with respect to the light of the predetermined wavelength; and a second substrate on the second substrate, the surface being opposite to the first substrate side, the predetermined wavelength being A light-absorbing body having a light-absorbing property for the light and changing the shape in accordance with the unevenness of the placed measurement object; and a light-reading unit that reads the detection results of the plurality of light-detecting units. Wherein the plurality of light detection means is configured so that the measurement target is the light absorption target. A contact-type shape measuring device for detecting light emitted from the surface of the first substrate opposite to the light detecting means and reflected by the surface of the object to be measured in a state of being placed on a body; apparatus. 2. The contact type shape measuring apparatus according to claim 1, wherein the light absorber is formed of a gel-like substance whose shape changes according to the unevenness of the object to be measured. 3. A first gate electrode formed on the first substrate side and having a light-shielding property with respect to light emitted from the opposite surface; A second gate electrode formed on the substrate side and having a property of transmitting light reflected and irradiated from the measurement object, and interposed between the first and second gate electrodes via an insulator, respectively; Then, a carrier is generated inside according to the amount of light incident through the second gate electrode, and a channel is formed according to the voltage applied to the carrier and the first and second gate electrodes. A semiconductor layer to be formed, a drain electrode connected to the semiconductor layer and supplied with a constant voltage,
A source electrode which is formed separately from the drain electrode with the semiconductor layer interposed therebetween and is grounded; and wherein the light readout means is configured to set the first gate electrode by a predetermined unit of the plurality of light detection means. A first driving circuit for selecting and applying a voltage for forming a channel in the semiconductor layer; and a second driving circuit for selecting the second gate electrode for each of the predetermined units and accumulating carriers in the semiconductor layer. A second drive circuit for applying a voltage, a voltage supply switch for controlling supply of a constant voltage to the drain electrode, a read switch for reading a potential of the drain electrode, the first and second drive circuits, 3. The power supply device according to claim 1, further comprising a voltage supply switch and a control device for controlling the read switch.
3. The contact-type shape measuring device according to 1. 4. A light source which emits light of the predetermined wavelength and irradiates the second substrate from the surface of the first substrate opposite to the surface on which the light detecting means is arranged, via the first substrate. The contact-type shape measuring apparatus according to claim 1, further comprising: