JP2000028311A - Surface shape recognition sensor circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a detecting accuracy of a surface shape recognition circuit by providing an amplifier circuit for amplifying a level of a signal by a signal generating means (detecting element) to produce an output to an output circuit. SOLUTION: The surface shape recognition sensor circuit recognizes a surface shape having a fine protrusion and recess pattern such as a person's fingerprint, an animal's muzzle pattern or the like. In a detecting element 10 in which an electric amount is changed according to a finger's contact with an object to be recognized, a finger's skin brought into contact with a passivation film 17 functions as an electrode, and an electrostatic capacity is formed between the electrode and a sensor electrode 16. This capacity alters according to the finger's protrusion and recess pattern for forming the fingerprint. After an output signal of the element 10 is level amplified by an amplifier 30, the signal is converted into a desired signal, and output from each sensing unit. The signal output from the each unit is a signal for reflecting the protrusion and recess pattern of the fingerprint. Accordingly, a fingerprint pattern can be detected based on the signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface shape recognition sensor circuit for recognizing a surface shape having minute irregularities such as a human fingerprint or an animal nose pattern.

[0002]

2. Description of the Related Art As a sensor for recognizing a surface shape, a sensor specifically targeting fingerprint detection has been reported. As a technology for detecting a fingerprint pattern, a capacitance detection type sensor using an LSI manufacturing technology has been proposed. This is, for example, the 'ISSCC DIGEST OF TE
CHNICAL PAPERS 'FEBRUARY1
998 pp. 284-285. The capacitance detection type sensor detects the capacitance formed between the electrodes of the small sense units two-dimensionally arranged on the LSI chip and the skin of the finger touched via the insulating film, and detects the fingerprint. This is for sensing the uneven pattern. Since the value of the capacitance formed by the unevenness of the fingerprint is different, the unevenness of the fingerprint can be sensed by detecting the difference in the capacitance.

FIG. 20 is a block diagram showing a basic configuration of a conventional sensor circuit for recognizing a surface shape using this principle. In other words, the conventional sensor circuit for surface shape recognition includes a detection element 110 composed of a capacitance formed between an electrode and the skin of a finger touched via an insulating film, and a value of the capacitance of the detection element 110. , And an output circuit 140 that converts and outputs a voltage signal from the signal generation circuit 120.

FIG. 21 is a layout diagram of a conventional sensor circuit for surface shape recognition. This sensor circuit for surface shape recognition,
The detecting element 110, the signal generating circuit 120, and the output circuit 140 each have a plurality. Of these, one set of sense units 101 is configured by each one of the detection element 110 and the signal generation circuit 120, and each of the sense units 101 is two-dimensionally arranged on an LSI chip to form a sensor array 102. Each output circuit 140 is arranged around the sensor array 102 to form the output unit 104.

Since the value of the capacitance of the detection element 110 is determined by the distance between the electrode of the sense unit 101 and the skin of the finger, the value of the capacitance of the detection element 110 differs depending on the unevenness of the fingerprint. Therefore, when a finger is pressed on the sensor array 102, a voltage signal corresponding to the unevenness of the fingerprint is output from each sense unit 101. This voltage signal is output from output unit 1
At 04, the signal is converted into a desired signal reflecting the unevenness of the fingerprint, and a fingerprint pattern is detected.

Subsequently, the configuration and operation of the sensor circuit for surface shape recognition shown in FIG. 20 will be described in more detail. FIG. 22 is a circuit diagram of the sensor circuit for surface shape recognition. In FIG. 22, Cf is the sense unit 101
Is formed between the electrode of the finger and the skin of the finger touched via the insulating film. The electrodes of the sense unit 101
It is connected to the input side of the current source 121 of the current I via the NchMOS transistor Q3. The input side of the output circuit 140 is connected to a node N1 between the electrode and the transistor Q3. The power supply voltage VDD is applied to the node N1 via the PchMOS transistor Q1. This node N1 has a parasitic capacitance Cp1. Further, the signal P is applied to the gate terminals of the transistors Q1 and Q3, respectively.
RE (bar) and RE are applied. The detection element 110 is constituted by the capacitance Cf, and the current source 121 and the transistor Q
3 constitute a signal generation circuit 120.

FIG. 23 is a timing chart for explaining the operation of the sensor circuit for surface shape recognition shown in FIG. First, Hi is connected to the gate terminal of the transistor Q1.
gh level (VDD) signal PRE (bar) is given,
A low level (GN) is applied to the gate terminal of the transistor Q3.
D) is given. Therefore, at this time, both transistors Q1 and Q3 are not conducting. In this state, the signal PRE (bar) changes from High level to Lo.
When the level changes to the w level, the transistor Q1 is turned on. At this time, since the transistor Q3 is kept off, the potential of the node N1 is precharged to VDD.

After the precharge is completed, the signal PRE
(Bar) changes to High level and the signal RE
Changes to a High level. As a result, the transistor Q1 is turned off and the transistor Q2 is turned on, and the electric charge charged to the node N1 by the current source 121 is extracted. As a result, the potential of the node N1 decreases. Assuming that the period during which the signal RE is at the High level is Δt, Δ
After a lapse of t, the potential drop ΔV at the node N1 is IΔt / (Cf +
Cp1).

Since the current I, the period Δt, and the parasitic capacitance Cp1 are each constant, the potential drop ΔV is determined by the capacitance Cf. Since the sense unit 101 is determined by the distance between the electrode of the sensor and the skin of the finger, the value of the capacitance Cf differs depending on the unevenness of the fingerprint. From this, the magnitude of the reduced potential ΔV changes reflecting the unevenness of the fingerprint. Since this potential drop ΔV is supplied to the output circuit 140 as an input signal, the output circuit 1 identifies the magnitude of ΔV, and outputs a signal reflecting the unevenness of the fingerprint.

[0010]

However, in the case of the conventional sensor circuit for recognizing a surface shape, if the parasitic capacitance Cp1 at the node N1 is large, the potential drop ΔV becomes small.
When the circuit shown in FIG. 22 is actually realized by using the LSI manufacturing technology, a parasitic capacitance Cp1 larger than the capacitance Cf is formed. The current I of the current source 121 or the signal RE is set to H
It is also possible to increase the potential decrease ΔV by increasing the period Δt during which the high level is set. However, if the current I is large, each sense unit 10
Therefore, it is desirable that the current I be rather small in order to increase the detection accuracy. Further, the period Δt cannot be made too long due to the relationship of the detection time.

As a result, ΔV as a signal input to the output circuit 140 decreases, the output result fluctuates due to noise margin, manufacturing variations, and the like, and the surface shape detection accuracy decreases. Therefore, as described above, due to the influence of the parasitic element such as the parasitic capacitance Cp1 formed in the manufacturing process, the signal change reflecting the unevenness of the fingerprint is reduced, and the detection accuracy of the surface shape recognition sensor circuit is reduced. There was a problem.

The present invention has been made to solve such a problem, and an object of the present invention is to improve the detection accuracy of a sensor circuit for recognizing a surface shape.

[0013]

In order to achieve the above object, the present invention provides a plurality of detecting means which are two-dimensionally arranged and whose electric quantity changes due to contact with a recognition object, and an electric quantity of the detecting means. First signal generating means for generating a corresponding signal;
Output means for converting and outputting a signal from the first signal generation means, wherein a surface shape recognition sensor circuit for recognizing a surface shape of a recognition target based on an output signal of the output means is provided on an input side of the output means. Amplifying means for amplifying the level of the signal by the first signal generating means and outputting the amplified signal level to the output means is provided. According to a second aspect of the present invention, in the first aspect of the present invention, each of the first signal generating means and the amplifying means is arranged near the corresponding detecting means. According to a third aspect of the present invention, in the second aspect, the output means is disposed near the corresponding amplifying means. According to a fourth aspect of the present invention, in the first aspect of the present invention, the first signal generating means is shared by a plurality of detecting means close to each other. According to a fifth aspect of the present invention, in the first aspect of the present invention, the amplifying unit is shared by a plurality of detecting units that are close to each other. According to a sixth aspect of the present invention, in the first aspect of the present invention, the output means is shared by a plurality of detection means which are close to each other. Further, the invention described in claim 7 is based on claims 1 to
3. The invention according to claim 3, wherein each of the first signal generating means, the amplifying means, and the output means is provided for each detecting means. The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the amplifying means comprises one of:
Having one input terminal and two output terminals, one output terminal connected to the detection means, the other output terminal connected to the output means, the input terminal connected to the constant voltage source, and the input terminal and one output terminal. A first element connected between the output terminals when the absolute value of the potential difference between the terminals is greater than the absolute value of the threshold value; and a first element connected to the other output terminal of the first element and connected to the first element. When the signal generating means is stopped, a voltage is applied to the other output terminal so that the absolute value of the potential difference between the input terminal of the first element and one of the output terminals is equal to or less than the absolute value of the threshold value. A first method for stopping the application of the voltage when the generating means operates;
Switch means. The invention according to claim 9 is the invention according to any one of claims 1 to 7,
Reference signal generating means connected to the input side of the amplifying means for generating a reference signal, wherein the amplifying means changes the degree of amplification based on the level of the signal by the first signal generating means and the level of the reference signal. including. According to a tenth aspect of the present invention, in the ninth aspect, the means included in the amplifying means reduces the degree of amplification when the level of the signal by the first signal generating means is smaller than the level of the reference signal. When the level of the signal by the first signal generator is higher than the level of the reference signal, the amplification is increased. The invention according to claim 11 is the invention according to claim 9 or 1
In the invention described in Item No. 0, the reference signal is a signal having the same level as a signal generated by the first signal generating means corresponding to a predetermined amount of electricity of the detecting means. According to a twelfth aspect of the present invention, in the invention of the eleventh aspect, the reference signal generating means generates a reference signal having a predetermined amount of electricity, a reference signal corresponding to the predetermined amount of electricity of the reference means, and And a second signal generating means having the same configuration as the signal generating means. According to a thirteenth aspect, in the twelfth aspect, the reference means is an element or a semiconductor element formed using a wiring. According to a fourteenth aspect of the present invention, in the twelfth aspect or the thirteenth aspect, the amplifying means comprises:
First and second output terminals having two input terminals and two output terminals, and when the absolute value of the potential difference between the input terminal and one of the output terminals is larger than the absolute value of the threshold value, the respective output terminals become conductive. The second element and the first element have one output terminal connected to the detection means and the input terminal connected to the other output terminal of the second element, and the second element has one output terminal. Is connected to the reference means, the input terminal is connected to the other output terminal of the first element, the other terminal is connected to the other output terminal of each of the first and second elements, and the first and second signal generation means are connected. When the operation is stopped, a voltage is applied to each of the first and second elements so that the absolute value of the potential difference between the input terminal and one of the output terminals is equal to or smaller than the absolute value of the threshold value. A second method for stopping application of a voltage when the second signal generating means operates. And a switch means, first and second elements and at least one output means of the respective other output terminals are connected. The invention according to claim 15 is the invention according to claim 14, wherein the output means is a differential output means connected to both the other output terminals of the first and second elements. The invention according to claim 16 is the invention according to claim 14 or 15,
The amplifying means is further connected between the other output terminals of the first and second elements and short-circuited between the other output terminals when the first and second signal generation means are stopped, and the first and second elements are short-circuited. A third switch means for opening the other output terminal when the second signal generation means operates. The invention according to claim 17 provides any one of claims 9 to 16.
In the invention described in the paragraph, the reference signal generating means is arranged near the corresponding amplifying means. Also, in the invention according to claim 18, in the invention according to any one of claims 9 to 17, the reference signal generating means is shared by a plurality of amplifying means which are close to each other. According to a nineteenth aspect of the present invention, in any one of the ninth to seventeenth aspects, the reference signal generating means is provided for each amplifying means. Further, the invention according to claim 20 provides any one of claims 1 to 20.
In the invention described in the paragraph, the detection means is a capacitor, and an input side of the amplification means is connected to a node of the detection means and the first signal generation means. According to a twenty-first aspect of the present invention, in the first aspect of the present invention, the detecting means is a variable resistance element whose resistance value changes by touching a recognition target, and the first signal generating means , Detecting means and amplifying means are connected in series in this order. According to a twenty-second aspect of the present invention, in any one of the first to twentieth aspects of the invention, the detecting means is a switch element formed by micro-machine technology and opening / closing a circuit based on a contact of a recognition target. One signal generating means, detecting means and amplifying means are connected in series in this order.

By amplifying the level of the signal corresponding to the amount of electricity of the detecting means by the amplifying means and supplying the amplified signal level to the output means, the attenuation of the input signal of the output means can be suppressed. In addition, a reference signal generating unit is provided, and a signal corresponding to the amount of electricity of the detecting unit is changed by changing an amplification degree of the amplifying unit based on a signal level of the signal corresponding to the amount of electricity of the detecting unit and a signal level of the reference signal. Level can be increased or decreased.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. (First Embodiment) FIG. 1 is a perspective view showing the whole of a first embodiment of a sensor circuit for surface shape recognition according to the present invention. This sensor circuit for surface shape recognition uses the sense unit 1 as a constituent unit. Each sense unit 1 is LS
The sensor array 2 is formed on the I-chip and spaced apart from each other in a lattice shape.

FIG. 2 is a block diagram showing a configuration of the sense unit 1 shown in FIG. That is, the sense unit 1 includes a detection element 10 whose electric quantity changes due to contact with a recognition target such as a human finger 3, a first signal generation circuit 20 that generates a signal corresponding to the electric quantity of the detection element 10, The signal generating circuit 20 includes a signal amplifying circuit 30 that amplifies and outputs a signal level, and an output circuit 40 that converts an output signal of the signal amplifying circuit 30 into a desired signal and outputs the desired signal. FIG. 2 shows a sensor circuit for surface shape recognition using a detection element 10 formed of a capacitance formed between a sensor electrode of the sense unit 1 and the skin of the finger 3, which will be described later. The input side of the signal amplification circuit 30 is connected to a node between the element 10 and the signal generation circuit 20, and the output circuit 40 is connected to the output side of the signal amplification circuit 30.

FIG. 3 is a sectional view showing the structure of the detecting element 10 in FIG. That is, a lower insulating film 12 is formed on a semiconductor substrate 11 on which an LSI or the like is formed, and a wiring 13 is formed on the lower insulating film 12. Further, an interlayer insulating film 14 is formed on the wiring 13 and the lower insulating film 12, and a sensor electrode 16 having a rectangular planar shape is formed on the interlayer insulating film 14, for example. The sensor electrode 16 is connected to the wiring 13 via a plug 15 in a through hole formed in the interlayer insulating film 14. Then, a passivation film 17 is formed on the interlayer insulating film 14 so as to cover the sensor electrode 16. Although not shown, the signal generation circuit 20 and the signal amplification circuit 30 in FIG.

In such a configuration, the finger 3 to be detected by the fingerprint is pressed by the sensor array 2 and the passivation film 1 is pressed.
7, the skin of the finger 3 touching the passivation film 17 functions as an electrode on the sensor electrode 16, and a capacitance is formed between the sensor electrode 16 and the sensor electrode 16. The fingerprint of the fingertip is formed by unevenness of the skin. Therefore, finger 3
Is in contact with the passivation film 17, the distance between the skin as an electrode and the sensor electrode 16 differs between the concave portion and the convex portion forming the fingerprint. This difference in distance appears as a difference in capacity.

In each of the sense units 1, a signal corresponding to the capacitance of the detection element 10 is output from the signal generator 20.
This signal is level-amplified by the signal amplifier circuit 30,
The signal is converted into a desired signal by the output circuit 40 and output from each sense unit 1. The signal output from each sense unit 1 is a signal reflecting the irregularities of the fingerprint. Therefore, a fingerprint pattern can be detected based on these signals.

The surface shape recognition sensor circuit shown in FIG. 1 is detected by a storage unit in which fingerprint data for collation is stored, and the fingerprint data and surface shape recognition sensor circuit prepared in the storage unit. A recognition processing unit for comparing and comparing with a fingerprint may be mounted on an LSI chip on which an integrated processing unit is integrated. In this way, by configuring the LSI on one LSI chip, it becomes difficult to falsify information at the time of data transfer, and it is possible to improve confidentiality retention performance.

Next, the sense unit 1 shown in FIG. 2 will be described in more detail. FIG. 4 is a circuit diagram of the sense unit 1. 4, Cf is the capacitance formed between the sensor electrode 16 and the skin of the finger 3 in FIG. The sensor electrode 16 forming the capacitance Cf is NchM
The drain terminal of the OS transistor Q3a is connected, and the source terminal of the transistor Q3a is connected to the input side of the current source 21a of the current I. A node N1a between the sensor electrode 16 and the transistor Q3a has Nch
The source terminal of the MOS transistor (first element) Q2a is connected. The drain terminal of the transistor Q2a is connected to the Pch with the power supply voltage VDD applied to the source terminal.
A power supply voltage VDD is applied to the drain terminal of the MOS transistor (first switch means) Q1a, and an NchM transistor whose source terminal is connected to ground via a resistor Ra.
The gate terminal of the OS transistor Q4a is connected. The inverter gate 41 is connected to the source terminal of the transistor Q4a.

Signals PRE (bar) and RE are applied to the gate terminals of the transistors Q1a and Q3a, respectively. A bias voltage VG is applied to the gate terminal of the transistor Q2a from a constant voltage source. Here, assuming that the threshold voltage between the gate and the source at which the transistor Q2a is turned off is Vth, the voltages VDD and VG are set so that VDD> VG-Vth. Also, the nodes N1a,
N2a has parasitic capacitances Cp1a and Cp2a, respectively.

The detection element 10 is constituted by the capacitance Cf,
The signal generation circuit 20 is configured by the current source 21a and the transistor Q3a, the signal amplification circuit 30 is configured by the transistors Q1a and Q2a, and the output circuit 40 is configured by the transistor Q4a, the resistor Ra, and the inverter gate 41. The surface shape recognition sensor circuit shown in FIG. 4 is different from the conventional surface shape recognition sensor circuit shown in FIG. 22 in that a transistor Q2a is added between nodes N1a and N2a.

FIG. 5 is a timing chart for explaining the operation of the sense unit 1 shown in FIG.
5A shows a potential change of a signal PRE (bar) for controlling the transistor Q1a, and FIG.
5C shows a potential change of the signal RE for controlling a, and FIG. 5C shows a potential change of each of the nodes N1a and N2a.
First, a high-level (VDD) signal PRE (bar) is applied to the gate terminal of the transistor Q1a, and a low level (GND) is applied to the gate terminal of the transistor Q3a.
Is provided. Therefore, at this time, both transistors Q1a and Q3a are not conducting.

In this state, the signal PRE (bar) becomes High.
When the level changes from the low level to the low level, the transistor Q
1a becomes conductive. At this time, the transistor Q3a remains non-conductive and the signal generation circuit 20 is in the stopped state, so that the potential of the node N2a is precharged to VDD. The node N1a is charged until the gate-source voltage of the transistor Q2a reaches the threshold voltage Vth and the transistor Q2a is turned off. As a result, the potential of the node N1a is precharged to VG-Vth.

After the precharge is completed, the signal PRE
When (bar) changes to the high level, the transistor Q1a is turned off. At the same time, the signal RE goes high.
When the level changes to the high level, the transistor Q3a becomes conductive, and the signal generation circuit 20 changes to the operating state.
When the electric charge charged to the node N1a is extracted by the current source 21a and the potential of the node N1a slightly decreases, the gate-source voltage of the transistor Q2a becomes higher than the threshold voltage Vth, and the transistor Q2a is turned on. Changes to Thereby, the electric charge of the node N2a is also extracted, and the potential of the node N2a starts to decrease.

The parasitic capacitance Cp2a mainly includes the parasitic capacitance of the drain terminal of each of the transistors Q1a and Q2a and the parasitic capacitance of the gate terminal of the transistor Q4a. The parasitic capacitance Cp2a can be considerably smaller than the parasitic capacitance Cp1 in the conventional surface shape recognition sensor circuit shown in FIG. 22 due to the actual layout. Therefore, when the potential drop starts at the node N2a as described above, the potential at the node N2a drops sharply. When the potential of the node N2a becomes the same as the potential of the node N1a, the potential of the node N2a gradually decreases thereafter.

The period during which the signal RE is kept at High level is Δ
Assuming that t, the potential drop ΔV at the node N1a after the lapse of Δt is VDD− (VG−Vth) + IΔt / (Cf + Cp1a). Here, it is assumed that the parasitic capacitance Cp2a is sufficiently smaller than the parasitic capacitance Cp1a. Therefore, in the surface shape recognition sensor circuit shown in FIG. 4, the magnitude of the potential drop ΔV is set to VDD− in comparison with the conventional surface shape recognition sensor circuit.
(VG-Vth). Thus, even if the parasitic capacitance Cp1a at the node N1a is large, the potential drop ΔV is large.

In the output circuit 40, the current flowing between the source and the drain of the transistor Q4a changes according to the potential drop ΔV as the input signal. This current change is caused by the resistance R
a is converted into a voltage change. Inverter gate 41
Converts a signal into a digital signal according to a predetermined logical threshold value. That is, if the input voltage of the inverter gate 41 is smaller than the threshold value, a signal indicating that the recess has touched the sense unit 1 is output from the inverter gate 41. Conversely, the inverter gate 41
Is larger than the threshold value, a signal indicating that the convex portion has come into contact with the sense unit 1 is output.

The potential drop ΔV at the node N2a is equal to VDD− (VG
If the threshold voltage is increased by -Vth), the range in which the threshold value of the inverter gate 41 can be set increases. Thus, the threshold value can be set so that the inverter gate 41 does not malfunction due to noise, so that the detection accuracy of the sensor circuit for surface shape recognition can be improved.

Further, in the sense unit 1 shown in FIG. 4, the detection element 10, the signal generation circuit 20 and the signal amplification circuit 3
0 and the output circuit 40 form the sense unit 1. That is, the signal generation circuit 20 and the signal amplification circuit 3
Since 0 is disposed near the corresponding detection element 10, the parasitic elements such as the parasitic capacitance Cp1a connected to the detection element 10 are reduced. Further, since the output circuit 40 is disposed near the corresponding signal amplifier circuit 30, the parasitic capacitance Cp2a between the signal amplifier circuit 30 and the output circuit 40 is reduced. Therefore, a parasitic element formed in the manufacturing process and contributing to signal attenuation can be suppressed, so that the input signal (ΔV) of the output circuit 40 can be further increased.

Incidentally, if necessary, the inverter gate 41
Alternatively, another element may be used. For example, when outputting an analog signal corresponding to the amount of electricity of the detection element 10 from the output circuit 40, an analog amplifier circuit is applied.
When a signal corresponding to the amount of electricity of the detection element 10 is converted into a digital multi-value, an A / D converter is used. Further, by sampling data by a latch circuit or the like controlled by a clock signal, the signal amount can be made to correspond to the time axis. Further, a capacitance Cf which has a pair of sensor electrodes opposed to each other with an insulating film interposed therebetween and whose value changes when the upper electrode is displaced up and down according to the unevenness of the fingerprint may be used as the detection element 10.

In place of the signal generation circuit 20 using the current source 21a, a first signal generation circuit 22 using a capacitor Cs as shown in FIG. 6 can be used. In this signal generation circuit 22, the switch SW
One of the fixed terminals is connected to the detection element 10, the other fixed terminal is connected to the ground, and the movable terminal is connected to the capacitor Cs. In the signal generation circuit 22, the switch SW1 connects the capacitor Cs to the ground when the transistor Q1a in FIG. 4 is conducting, and discharges the charge of the capacitor Cs in advance. Then, when the transistor Q1a is non-conductive, the switch SW1 connects the capacitance Cs to the detection element 10 and charges the capacitance Cs with a constant charge, whereby a signal corresponding to the amount of electricity of the detection element 10 can be generated. .

(Second Embodiment) FIG. 7 is a block diagram showing a configuration of a sense unit 1 of a surface shape recognition sensor circuit according to a second embodiment of the present invention. 7, the same parts as those in FIG. 2 are denoted by the same reference numerals, and the description thereof will be appropriately omitted. The sense unit 1 shown in FIG.
In addition to the reference signal generating circuit 50 for generating the reference signal, the signal amplifying circuit 31 includes a unit for changing the amplification degree based on the level of the signal generated by the signal generating circuit 20 and the level of the reference signal. This is different from the sense unit 1 shown in FIG.

FIG. 8 is a circuit diagram of the sense unit 1 shown in FIG. 8, the same parts as those in FIG. 4 are denoted by the same reference numerals, and the description thereof will be appropriately omitted. The sense unit 1 shown in FIG. 8 is the same as the sense unit 1 shown in FIG.
The reference element 51, the second signal generation circuit 52, and Nch
MOS transistor (second element) Q2b and PchMO
It is formed by adding an S transistor Q1b. The reference element 51 is an element that simulates the detection element 10. In the case of the sense unit 1 shown in FIG.
, The reference element 51 is composed of the capacitor Cr.

The capacitance Cr is used as a threshold value for discriminating whether a convex portion or a concave portion of the fingerprint has touched the sense unit 1. The value of the capacitance Cr is set to a value between the capacitance Cf formed when the convex portion of the fingerprint is touched and the capacitance Cf formed when the concave portion is touched. The value of the capacitance Cf formed when the concave portion of the fingerprint touches the capacitance Cr
Even if the value of is set, it functions effectively as the threshold value. The capacitor Cr is formed by an element or a semiconductor element formed using wiring. Thus, for example, MIM (me
tal-insulator-metal) capacity and PIP (polysilicon-
The capacitance Cr can be realized by a capacitance such as an insulator-polysilicon) capacitance formed by inserting an insulating film between wirings or a MOS capacitance.

The signal generation circuit 52 generates a reference signal corresponding to the capacitance Cr, and has the same circuit configuration as the signal generation circuit 20. That is, the signal generation circuit 52 is composed of the current source 21b and the NchMOS transistor Q3b, and these are the current source 21a and the NchMOS transistor Q3a forming the signal generation circuit 20, respectively.
It has the same properties as The reference signal generation circuit 50 includes the reference element 51 and the signal generation circuit 52. Therefore, the reference signal generated by the reference signal generation circuit 50 has the same level as the signal generated by the signal generation circuit 20 when the detection element 10 has the capacitance set as the threshold. .

The source terminal of the NchMOS transistor Q2b is connected to a node N1b between the reference element 51 and the signal generation circuit 52. The transistor Q2b has a drain terminal connected to a source terminal to which a power supply voltage VDD is applied.
The drain terminal of the chMOS transistor Q1b is connected. In the sense unit 1 shown in FIG. 4, the gate terminal of the transistor Q2a is connected to the constant voltage source, but in the sense unit 1 shown in FIG.
The gate terminal of 2a is connected to the drain terminal of transistor Q2b. The gate terminal of the transistor Q2b is connected to the drain terminal of the transistor Q2a. The transistors Q1b and Q2b have the same characteristics as the transistors Q1a and Q2a, respectively.

Signals PRE (bar) and RE are applied to the gate terminals of the transistors Q1b and Q3b, respectively. The nodes N1b and N2b are respectively connected to the parasitic capacitance Cp.
1b and Cp2b. Transistors Q1a, Q
1b constitutes second switch means, and the second switch means and the transistors Q2a and Q2b constitute a signal amplifier circuit 31.

FIG. 9 is a timing chart for explaining the operation of sense unit 1 shown in FIG.
(A) is a signal P for controlling the transistors Q1a and Q1b.
FIG. 8B shows a potential change of the signal RE for controlling the transistors Q3a and Q3b, and FIG. 8C shows a potential change of the node N2a.
First, the gate terminals of the transistors Q1a and Q1b
High level (VDD) signal PRE (bar) is applied, and Lo terminals are connected to the gate terminals of transistors Q3a and Q3b.
A w-level (GND) signal RE is provided. Therefore, at this time, the transistors Q1a, Q1b, Q3
Neither a nor Q3b is conducting.

In this state, the signal PRE (bar) becomes High.
When the level changes from the low level to the low level, the transistor Q
1a and Q1b become conductive. At this time, since the transistors Q3a and Q3b remain non-conductive and the signal generation circuits 20 and 52 are in the stop state, the nodes N2a and N2
The potential of b is precharged to VDD. The nodes N1a and Q1b are charged until the gate-source voltages of the transistors Q2a and Q2b reach the threshold voltage Vth and the transistors Q2a and Q2b are turned off. At this time, since the voltage VDD is applied to the gate terminals of the transistors Q2a and Q2b, the potentials of the nodes N1a and N1b are precharged to VDD-Vth.

After the precharge is completed, the signal PRE
When (bar) changes to the high level, the transistors Q1a and Q1b are turned off. At the same time, when the signal RE changes to High level, the transistor Q3
a, Q3b become conductive, and the signal generation circuits 20, 52
Changes to the operating state. Then, the current sources 21a and 21b
As a result, the charges charged in the nodes N1a and N1b are extracted, and the potentials of the nodes N1a and N1b slightly decrease.
The gate-source voltages of the transistors Q2a and Q2b become higher than the threshold voltage Vth,
a and Q2b change to the conductive state. Thereby, the node N2
The charges of a and N2b are also extracted, and the potential of the nodes N2a and N2b starts to decrease.

Here, when the capacitance Cf> the capacitance Cr, the potential of the node N1b is lower than the potential of the node N1a. Thus, the conduction resistance of transistor Q2b becomes smaller than the conduction resistance of transistor Q2a, and the potential of node N2b drops earlier than node N2a. This node N2b
Is input to the gate terminal of NchMOS transistor Q2a, so that the conduction resistance of transistor Q2a increases. For this reason, the potential drop ΔV at the node N2a is suppressed to a small value.

On the other hand, the potential at node N2a is NchMOS
Since the signal is input to the gate terminal of the transistor Q2b, the change in the conduction resistance of the transistor Q2b is small. As a result, the potential of the node N2b further decreases, so that the conduction resistance of the transistor Q2a further increases. Since the transistors Q2a and Q2b are cross-connected as described above, these operations are increased, and as a result, the potential drop ΔV of N2a is suppressed to a small value.

Conversely, when the capacitance Cf <the capacitance Cr, the potential changes at the nodes N2a and N2b are reversed. That is,
The potential of the node N2b is the initial potential VDD which has been precharged.
Does not change much. For this reason, the potential of the node N2a is greatly reduced as in the case of the sense unit 1 shown in FIG. Therefore, by setting the value of the capacitor Cr as described above, the amplification of the signal amplifier circuit 31 can be changed with this value as a boundary. As a result, a high-level signal (ΔV) is input to the output circuit 40 when the convex portion of the fingerprint touches, and a low-level signal (ΔV) is input when the concave portion of the fingerprint touches. The unevenness of the fingerprint can be clearly determined.

Further, the sense unit 1 shown in FIG.
Has the effect of preventing a malfunction caused by a leak current because a potential drop caused by the charge being extracted by the leak current at the node N2a can be offset by a potential change caused by the leak current at the node N2b. In the sense unit 1 shown in FIG.
Is connected to the node N2a, but the output circuit 40 may be connected to the node N2b. In this case, the output circuit 4
Only the polarity of the output of 0 is inverted, and the same effect as when the output circuit 40 is connected to the node N2a can be obtained.

(Third Embodiment) FIG. 10 is a circuit diagram of a sense unit 1 according to a third embodiment of the sensor circuit for surface shape recognition according to the present invention. In FIG. 10, FIG.
The same parts as those described above are denoted by the same reference numerals, and description thereof will be omitted as appropriate. The sense unit 1 shown in FIG. 10 differs from the sense unit 1 shown in FIG. 8 in that an output circuit 42 in which the potential drop ΔV at the nodes N2a and N2b is input as a complementary signal is used instead of the output circuit 40. .

The output circuit 42 can be realized by using a differential type voltage amplifier circuit. Output circuit 42 in FIG.
Is an NchMOS transistor Q4a and a resistor Ra, and an NchMOS transistor Q4b having the same characteristics as these.
And a resistor Rb, and PchMOS transistors Q4 and Q5 and NchMOS transistors Q7 and Q8 forming a current mirror type amplifier circuit. FIG.
The operation of the sense unit 1 shown in FIG. 8 is basically the same as that of the sense unit 1 shown in FIG. However, by inputting a complementary signal to the output circuit 42, a noise margin against power supply fluctuation or the like can be increased.

(Fourth Embodiment) FIG. 11 is a circuit diagram of a sense unit 1 of a surface shape recognition sensor circuit according to a fourth embodiment of the present invention. In FIG. 11, FIG.
The same parts as those described above are denoted by the same reference numerals, and description thereof will be omitted as appropriate. The sense unit 1 shown in FIG. 11 uses a signal amplifying circuit 32 including third switch means connected between the nodes N2a and N2b, instead of the signal amplifying circuit 31, as shown in FIG. Different from sense unit 1. Third
In the switching means, the source terminal and the drain terminal are connected between the nodes N2a and N2b, and the signal PR is connected to the gate terminal.
It is constituted by a PchMOS transistor Q9 to which E (bar) is applied.

In the case of the sense unit 1 shown in FIG. 8, if the characteristics of the transistors Q1a and Q1b vary,
When the nodes N2a and N2b are precharged to the power supply potential VDD, a potential difference may occur between the nodes N2a and N2b. If both the nodes N2a and N2b are not precharged to the same potential, the potential drop speed of each of the nodes N2a and N2b changes.

The operation of the sense unit 1 shown in FIG. 11 is basically the same as that of the sense unit 1 shown in FIG. However, in the case of the sense unit 1 shown in FIG.
When the signal generation circuits 20 and 52 are stopped, the transistor Q9
The short circuit between the nodes N2a and N2b at
2a and N2b can be precharged to the same potential. When a signal is detected, that is, when the signal generation circuits 20 and 52
During the operation of, the transistor Q9 is connected to the nodes N2a and N2b.
Open the gap. As a result, a change in the potential drop speed of each of the nodes N2a and N2b can be suppressed, so that a decrease in surface shape detection accuracy can be prevented.

Although the output circuit 40 is connected to the node N2a in the sense unit 1 shown in FIG. 11, the output circuit 40 may be connected to the node N2b. In this case, only the polarity of the output of the output circuit 40 is inverted, and the same effect as when the output circuit 40 is connected to the node N2a can be obtained.

(Fifth Embodiment) FIG. 12 is a circuit diagram of a sense unit 1 of a sensor circuit for surface shape recognition according to a fifth embodiment of the present invention. In FIG. 12, FIG.
11 and the same parts as those in FIG. 11 are denoted by the same reference numerals, and the description thereof will be appropriately omitted. Sense unit 1 shown in FIG.
Differs from the sense unit 1 shown in FIG. 10 in that the signal amplifying circuit 32 shown in FIG.
Is used.

In the sense unit 1 shown in FIG. 12, when the nodes N2a and N2b are precharged to the power supply potential VDD, the potential difference between the nodes N2a and N2b due to variations in the characteristics of the transistors Q1a and Q1b can be eliminated. . Therefore, as compared with the sense unit 1 shown in FIG. 10, this potential difference causes an offset voltage to be generated at the complementary input of the differential amplifier circuit, and the nodes N2a, N2
It is possible to prevent a decrease in detection accuracy due to a change in the potential drop rate of each of the electrodes 2b.

(Sixth Embodiment) FIG. 13 is a circuit diagram of a sense unit 1 according to a sixth embodiment of the surface shape recognition sensor circuit according to the present invention. In FIG. 13, FIG.
The same parts as those described above are denoted by the same reference numerals, and description thereof will be omitted as appropriate. The sense unit 1 shown in FIG. 13 is configured using transistors Q1c, Q2c, Q3c, and Q4c having different polarities from the transistors Q1a to Q4a in FIG. In FIG. 13, Q1c is NchMO
The S transistor and Q2c to Q4c are PchMOS transistors. The signals PRE (bar) and the signals PRE and RE (bar) in which the polarities of the RE are inverted are applied to the transistors Q1c and Q3c, respectively. The current source 2
The power supply voltage VDD is applied to the input side of 1a, and the source terminal of the transistor Q1c is connected to ground. N1c,
N2c is a parasitic capacitance.

FIG. 14 is a timing chart for explaining the operation of sense unit 1 shown in FIG.
The operation of the sense unit 1 is the same as that of the sense unit 1 shown in FIG. 4, except that the polarity of the signal is inverted and the direction of change of the signal (ΔV) is reversed. The same effect as that of the sense unit 1 can be obtained. Note that Δ
The potential rise ΔV at the node N2c after the elapse of t is VG + Vth +
IΔt / (Cf + Cp1c). 8 and FIG.
Similarly, the sense unit 1 shown in each of FIGS. 0 to 12 can obtain the same effect by using transistors having polarities different from those of the transistors Q1b to Q4b and Q9.

(Seventh Embodiment) FIG. 15 is a block diagram showing a configuration of a sensor circuit for surface shape recognition according to a seventh embodiment of the present invention. 15, the same parts as those in FIG. 2 are denoted by the same reference numerals, and the description thereof will be appropriately omitted. In the sensor circuit for surface shape recognition shown in FIG. 2, a signal generating circuit 20, a signal amplifying circuit 30, and an output circuit 40 are provided for each detecting element 10, and these are set as one set of a sense unit 1.
The sensor array 2 is formed by arranging the plurality of sense units 1 two-dimensionally. In this case, since the detection operations can be performed in parallel, the detection processing can be sped up.

On the other hand, at least one of the signal generating circuit 20, the signal amplifying circuit 30, and the output circuit 40 can be shared by a plurality of detecting elements 10.
When the signal generation circuit 20 is shared, as shown in FIG.
The signal generation circuits 20 are selectively connected. When the signal amplifying circuit 30 is shared, as shown in FIG. 15B, one signal amplifying circuit 30 is selectively provided between the plurality of signal generating circuits 20 and the output circuit 40 by the switches SW3 and SW4. Connect to At this time, each switch SW3, SW4
Work in conjunction. When the output circuit 40 is shared, as shown in FIG. 15C, one output circuit 40 is selectively connected to the plurality of signal amplifier circuits 30 by the switch SW5.

As described above, by sharing at least one of the signal generating circuit 20, the signal amplifying circuit 30, and the output circuit 40 with a plurality of detecting elements 10, the circuit scale and operating power can be reduced. . If the signal generation circuit 20, the signal amplification circuit 30, and the output circuit 40 are shared by the plurality of detection elements 10 arranged close to each other, the influence of the parasitic elements formed in the manufacturing process is small. Also,
Also in the sense unit 1 shown in each of FIGS. 8 and 10 to 12, the signal generation circuit 20,
At least one of the signal amplifier circuits 31 and 32 and the output circuits 40 and 42 can be shared.

(Eighth Embodiment) FIG. 16 is a block diagram showing the configuration of a sensor circuit for surface shape recognition according to an eighth embodiment of the present invention. 16, the same parts as those of FIG. 7 are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. The reference signal generating circuit 50 in FIG. 7 can be shared by a plurality of signal amplifier circuits 31. In this case, as shown in FIG. 16, one signal amplifier circuit 31 is selectively connected to the plurality of signal amplifier circuits 31 by the switches SW6 and SW7. As a result, the circuit scale and the operating power can be reduced. Also in the sense unit 1 shown in each of FIGS. 10 to 12, the reference signal generation circuit 50 can be shared by the plurality of signal amplification circuits 31 and 32.

(Ninth Embodiment) FIG. 17 is a block diagram showing the configuration of a sense unit 1 according to a ninth embodiment of the sensor circuit for surface shape recognition according to the present invention. FIG.
In FIG. 7, the same parts as those in FIG. 4 are denoted by the same reference numerals, and the description thereof will be appropriately omitted. Sense unit 1 shown in FIG.
In the above, the detection element 10 made of the capacitance Cf formed between the sensor electrode 16 and the skin of the finger 3 is used. However, instead of this, the detection element 18 made of the variable resistance element VR having elasticity is used. Can be used to configure the sense unit 1.

In this case, as shown in FIG. 17A, the first signal generation circuit 22, the detection element 18, and the signal amplification circuit 3
0 and the output circuit 40 are connected in series in this order, and the sense unit 1 is configured. Here, the signal generation circuit 22 is the signal generation circuit 22 constituted by the capacitor Cs in FIG. The signal amplification circuit 30 is the charge transfer type signal amplification circuit 30 in FIG. Variable resistance element VR
Is an element whose resistance value changes according to deformation when a recognition target such as a finger 3 comes into contact. This variable resistance element V
In accordance with the change in the resistance value of R, the speed at which the precharged charge is extracted by the capacitor Cs changes. By catching this change as a voltage signal, the unevenness of the fingerprint can be detected. Other operations are basically the same as those of the sense unit 1 shown in FIG.

As shown in FIG. 17B, a first signal generating circuit 23 including a voltage source 24 and a switch SW8 may be used instead of the signal generating circuit 22. The switch SW8 is connected to the variable resistance element VR and the voltage source 24.
Is connected between. However, the voltage V of the voltage source 24
Is set to an arbitrary value from positive to negative so that a current flows from the signal amplification circuit 30 to the signal generation circuit 23.

FIG. 18 is a block diagram showing another configuration of sense unit 1 shown in FIG. As shown in FIG. 18A, a switch element SW formed by using a micromachine technology can be used as the detection element 19. In this case, the signal generating circuit 23, the detecting element 19, the signal amplifying circuit 30, and the output circuit 40 are connected in series in this order, and the sense unit 1 is configured.

The switch element SW opens and closes the circuit based on the contact of the recognition target such as the finger 3. That is, when the switch element SW is depressed by the convex portion of the fingerprint, the connection between the signal generating circuit 23 and the signal amplifying circuit 30 is established, so that the precharged electric charge is extracted by the voltage source 24. As a result, the potential on the input side of the output circuit 40 decreases. Conversely, even if the switch element SW is pressed down by the concave portion of the fingerprint, the potential between the input side of the output circuit 40 does not decrease because the signal generating circuit 23 and the signal amplifying circuit 30 remain open. Based on this potential drop, the unevenness of the fingerprint can be detected. Other operations are basically the same as those of the sense unit 1 shown in FIG. FIG.
As shown in (b) and (c), instead of the signal generation circuit 23, the signal generation circuit 20 including the current source 21a or the capacitor Cs
May be used.

Note that the sensing elements 1 and 19 shown in FIGS. 17 and 18 are replaced by the corresponding signal generating circuits 20 and 2 in the sense unit 1 shown in FIGS. 8 and 10 to 13, respectively.
It can also be applied with 2,23. However, FIG.
In the case of the sense unit 1 shown in FIG.
It is necessary to set the signal generation circuits 20, 22, and 23 so that current flows from 0, 22, and 23 toward the signal amplification circuit 30.

(Tenth Embodiment) FIG. 19 is a circuit diagram showing another example of the signal amplifier circuit 30 shown in FIG. As shown in FIG. 19A, the signal amplification circuit 30
This can be realized by using an inverting amplifier 33 that amplifies a voltage signal. G is the voltage amplification. Further, as shown in FIG. 19B, the signal amplification circuit 30 can be realized by using a current mirror circuit 34 for amplifying a current signal. n is the current amplification factor. In FIG. 19B, Pch
Although the current mirror circuit 34 for amplifying the current using the gate width W of the MOS transistors Q10 and Q11 has been described, the present invention is not limited to this. Further, the differential signal amplifier circuit 31 in FIG. 7 can also be realized using a current mirror circuit. The sensor circuit for recognizing a surface shape according to the present invention is not limited to a human fingerprint, and is applied to recognition of a surface shape having minute irregularities such as a nose pattern of an animal.

[0068]

As described above, according to the present invention, the signal level corresponding to the quantity of electricity of the detecting means is amplified by the amplifying means and then supplied to the output means, thereby suppressing the attenuation of the input signal of the output means. can do. As a result, the influence of a noise margin, manufacturing variation, and the like can be suppressed, so that the detection accuracy of the surface shape can be improved. Therefore, if the surface shape recognition sensor circuit according to the present invention is applied to a fingerprint sensor using LSI manufacturing technology,
Since a minute signal change reflecting the irregularities of the fingerprint can be detected, there is an effect that recognition of the irregularities pattern of the fingerprint can be performed with high accuracy. This is particularly effective when the size of the two-dimensionally arranged detecting means is reduced in order to increase the resolution of the uneven pattern of the fingerprint.

According to the second aspect of the present invention, by arranging the detecting means, the first signal generating means, and the amplifying means close to each other, a parasitic element such as a parasitic capacitance connected to the detecting element can be reduced. Can be. That is, the formation of a parasitic element that contributes to signal attenuation can be suppressed.
The detection accuracy of the surface shape can be improved. Also,
According to the third aspect of the invention, the effect of the second aspect of the invention can be enhanced by further arranging the output means close to the amplification means.

In each of the fourth to sixth aspects of the present invention, the circuit scale and operating power can be reduced by sharing the first signal generating means, amplifying means or output means with a plurality of detecting means. it can. In the invention according to claim 7, the detection operation can be performed in parallel by providing the first signal generation means, the amplification means, and the output means for each detection means, so that the detection processing is speeded up. Can be. Further, according to the present invention, the first element is connected between the detecting means and the output means, and the threshold voltage of the first element is used to thereby connect the parasitic element connected to the detecting means. Even if the capacitance is large, it is possible to increase the level of the signal according to the amount of electricity of the detecting means. This allows
The same effect as that of the first aspect can be obtained.

Further, according to the ninth aspect of the present invention, the reference signal generating means is provided, and the amplification degree of the amplifying means is changed based on the signal level of the signal according to the amount of electricity of the detecting means and the signal level of each of the reference signals. For example, when the former is smaller than the latter, the amplification is reduced, and when the former is larger than the latter, the amplification is increased. This makes it possible to increase or decrease the level of the signal according to the amount of electricity of the detecting means. For example, in a fingerprint sensor, a minute signal reflecting the unevenness of a fingerprint is a detection target. However, according to the present invention, the distinction between the concave portion and the convex portion of the surface shape becomes clear, so that the detection accuracy of the surface shape can be improved.

According to the fourteenth aspect of the present invention, the first and second elements are cross-connected to constitute an amplifying means, whereby the ninth aspect of the present invention can be realized. Further, since a signal change due to a leak current can be canceled, there is an advantage that a malfunction due to the leak current can be prevented. According to the fifteenth aspect of the present invention, the use of the differential output means makes it possible to increase the noise margin against power supply fluctuations and the like. Also, in the invention according to claim 16, by using the third switching means for connecting and disconnecting the other output terminal of each of the first and second elements, the characteristic of the element constituting the second switching means can be reduced. It is possible to suppress a decrease in detection accuracy of the surface shape due to the variation.

According to the seventeenth aspect of the present invention, by arranging the reference signal generating means close to the amplifying means, a parasitic element such as a parasitic capacitance can be reduced, so that the detection accuracy of the surface shape can be improved. Can be. In the invention according to claim 18, the circuit scale and the operating power can be reduced by sharing the reference signal generating means with a plurality of amplifying means.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an entire surface shape recognition sensor circuit according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a sense unit shown in FIG.

FIG. 3 is a cross-sectional view showing a configuration of the detection element shown in FIG.

FIG. 4 is a circuit diagram of the sense unit shown in FIG. 2;

FIG. 5 is a timing chart for explaining the operation of the sense unit shown in FIG. 4;

FIG. 6 is a circuit diagram showing another configuration of the sense unit shown in FIG. 2;

FIG. 7 is a block diagram illustrating a configuration of a sense unit according to a second embodiment of the sensor circuit for surface shape recognition according to the present invention.

8 is a circuit diagram of the sense unit shown in FIG.

FIG. 9 is a timing chart for explaining an operation of the sense unit shown in FIG. 8;

FIG. 10 is a circuit diagram of a sense unit according to a third embodiment of the sensor circuit for surface shape recognition according to the present invention.

FIG. 11 is a circuit diagram of a sense unit according to a fourth embodiment of the sensor circuit for surface shape recognition according to the present invention.

FIG. 12 is a circuit diagram of a sense unit according to a fifth embodiment of the sensor circuit for surface shape recognition according to the present invention.

FIG. 13 is a circuit diagram of a sense unit according to a sixth embodiment of the sensor circuit for surface shape recognition according to the present invention.

14 is a timing chart for explaining the operation of the sense unit shown in FIG.

FIG. 15 is a block diagram showing the configuration of a surface shape recognition sensor circuit according to a seventh embodiment of the present invention.

FIG. 16 is a block diagram showing the configuration of an eighth embodiment of the sensor circuit for surface shape recognition according to the present invention.

FIG. 17 is a block diagram showing a configuration of a sense unit according to a ninth embodiment of the sensor circuit for surface shape recognition according to the present invention.

18 is a block diagram showing another configuration of the sense unit shown in FIG.

FIG. 19 is a circuit diagram showing another example of realizing the signal amplification circuit in FIG. 2;

FIG. 20 is a block diagram showing a configuration of one unit of a conventional surface shape recognition sensor circuit.

FIG. 21 is a layout diagram of the sensor circuit for surface shape recognition shown in FIG. 20;

FIG. 22 is a circuit diagram of the surface shape recognition sensor circuit shown in FIG. 20;

FIG. 23 is a timing chart for explaining the operation of the sensor circuit for surface shape recognition shown in FIG. 22;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sense unit, 2 ... Sensor array, 3 ... Finger, 1
0, 18, 19: detecting element, 11: semiconductor substrate, 12,
14 insulating film, 13 wiring, 15 plug, 16 sensor electrode, 17 passivation film, 20, 22, 23,
52: signal generation circuit, 21a: current source, 24: voltage source,
30-32 ... amplifier circuit, 33 ... voltage amplifier, 34 ...
Current mirror circuit, 40, 42 output circuit, 41 inverter gate, 50 reference signal generation circuit, 51 reference element, Cf, Cr, Cs, capacitance, Cp1a, Cp2
a, Cp1b, Cp2b, Cp1c, Cp2c: parasitic capacitance, N1a, N2a, N1b, N2b, N1c, N2c
... nodes, PRE, RE ... signals, Ra, Rb ... resistors, Q1
a to Q4a, Q1b to Q4b, Q1c to Q4c, Q5
Q11: MOS transistor, SW: switch element, S
W1 to SW9: switch, VDD, VG: voltage, VR: variable resistance element, Vth: threshold voltage, Δt: period, ΔV:
Potential drop.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsuyuki Machida, inventor 3- 19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Akihiko Hirata 3- 19-2, Nishi-Shinjuku, Shinjuku-ku, Tokyo No. Nippon Telegraph and Telephone Corporation F-term (reference) 2F063 AA43 BA29 DA02 DA05 DD07 EC00 HA04 LA11 5B047 AA25 AA30 BA02 BB04

Claims (22)

[Claims] 1. A plurality of detecting means arranged two-dimensionally and whose electric quantity changes due to contact with a recognition target; a first signal generating means for generating a signal corresponding to the electric quantity of the detecting means; Output means for converting and outputting a signal from the first signal generation means, wherein the surface shape of the recognition target is recognized based on an output signal of the output means. A sensor circuit for recognizing a surface shape, comprising: an amplifier connected to an input side and amplifying a signal level by the first signal generator and outputting the amplified signal to the output unit. 2. The sensor circuit for recognizing a surface shape according to claim 1, wherein each of the first signal generating unit and the amplifying unit is arranged near the corresponding detecting unit. 3. The surface shape recognition sensor circuit according to claim 2, wherein the output means is arranged near the corresponding amplifying means. 4. The sensor circuit for recognizing a surface shape according to claim 1, wherein the first signal generating unit is shared by the plurality of detecting units that are close to each other. 5. The sensor circuit for surface shape recognition according to claim 1, wherein the amplification unit is shared by the plurality of detection units that are close to each other. 6. The sensor circuit for surface shape recognition according to claim 1, wherein the output unit is shared by the plurality of detection units that are close to each other. 7. The surface according to claim 1, wherein each of the first signal generation unit, the amplification unit, and the output unit is provided for each of the detection units. Sensor circuit for shape recognition. 8. The amplifying unit according to claim 1, wherein the amplifying unit has one input terminal and two output terminals, and the one output terminal is connected to the detection unit and the other output terminal is connected to the detection unit. Output terminal is connected to the output means, the input terminal is connected to a constant voltage source, and the absolute value of the potential difference between the input terminal and the one output terminal is greater than the absolute value of the threshold value. A first element having a conductive state between terminals, connected to the other output terminal of the first element, and the input terminal of the first element and the one of the first element when the first signal generating means is stopped. A voltage is applied to the other output terminal so that the absolute value of the potential difference between the output terminals becomes equal to or less than the absolute value of the threshold value, and the application of the voltage is stopped when the first signal generating means operates. And a first switch means. Sensor circuit for surface shape recognition. 9. The signal processing device according to claim 1, further comprising: a reference signal generating unit connected to an input side of the amplifying unit and generating a reference signal, wherein the amplifying unit includes the first signal generating unit. A means for changing the degree of amplification based on the level of the signal and the level of the reference signal. 10. The apparatus according to claim 9, wherein the means included in the amplifying means reduces the amplification degree when the level of the signal from the first signal generating means is smaller than the level of the reference signal. The sensor circuit for recognizing a surface shape, wherein the amplification degree is increased when a signal level of the signal generating means is higher than a level of the reference signal. 11. The signal according to claim 9, wherein the reference signal is a signal having the same level as a signal generated by the first signal generating means in accordance with a predetermined amount of electricity of the detecting means. Surface shape recognition sensor circuit. 12. The reference signal generating means according to claim 11, wherein said reference signal generating means generates a reference signal corresponding to said predetermined amount of electricity of said reference means having said predetermined amount of electricity and said first signal. The second configuration having the same configuration as the generation means
A sensor circuit for recognizing a surface shape, comprising: 13. The surface shape recognition sensor circuit according to claim 12, wherein the reference means is an element or a semiconductor element formed using wiring. 14. The amplifying means according to claim 12, wherein said amplifying means has one input terminal and two output terminals, and a threshold value of an absolute value of a potential difference between said input terminal and said one output terminal. A first element and a second element that are electrically connected between the output terminals when the absolute value is greater than an absolute value of the value, wherein the first element has the one output terminal connected to the detection unit and the input element A terminal is connected to the other output terminal of the second element, and the second element has the one output terminal connected to the reference means and the input terminal connected to the other of the first element. Connected to the other output terminal of each of the first and second elements, and the first and second elements of the first and second elements are stopped when the first and second signal generation means are stopped. Input terminal and one of the outputs Applying a voltage to each of the other output terminals so that the absolute value of the potential difference between the terminals becomes equal to or less than the absolute value of the threshold value, and stopping the application of the voltage when the first and second signal generating means operate And a second switch means for connecting the first and second elements, wherein the output means is connected to at least one of the other output terminals of each of the first and second elements. 15. The surface according to claim 14, wherein the output means is a differential output means connected to both of the other output terminals of the first and second elements. Sensor circuit for shape recognition. 16. The amplifying means according to claim 14, further comprising: amplifying means connected between the other output terminals of the first and second elements, respectively. A third switch means for short-circuiting between the other output terminals when stopped and for opening the other output terminals when the first and second signal generating means operate. Sensor circuit for shape recognition. 17. The sensor circuit for recognizing a surface shape according to claim 9, wherein the reference signal generating means is arranged near the corresponding amplifying means. 18. The surface shape recognition sensor circuit according to claim 9, wherein the reference signal generating means is shared by the plurality of amplifying means which are close to each other. 19. The surface shape recognition sensor circuit according to claim 9, wherein the reference signal generating unit is provided for each of the amplifying units. 20. The apparatus according to claim 1, wherein the detection unit is a capacitor, and an input side of the amplification unit is connected to a node of the detection unit and the first signal generation unit. A sensor circuit for recognizing a surface shape. 21. The device according to claim 1, wherein the detection means is a variable resistance element whose resistance value changes by contact with a recognition target, and wherein the first signal generation means, the detection means, and the A sensor circuit for surface shape recognition, wherein amplifying means are connected in series in this order. 22. The signal processing device according to claim 1, wherein the detection means is a switch element formed by a micro-machine technology and configured to open and close a circuit based on contact of a recognition target. A sensor circuit for recognizing a surface shape, wherein the detecting means and the amplifying means are connected in series in this order.