JP2005202694A - Detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image detecting device which can detect the contact or non-contact of an element to be detected with the detector from a detection signal in the image detecting device in which the level of the detection signal changes between the state that the element to be detected is brought into contact with the detector and the state that the element to be detected is not brought into contact with the detector. <P>SOLUTION: The image detecting device (1) in which the level of the detection signal changes between the state that the element to be detected is brought into contact with the detector (14) and the state that the element to be detected is not brought into contact with the detector (14), includes a judging means (21) for judging whether the element to be detected is brought into contact with the detector (14) or not in response to the detection signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a detection apparatus, and more particularly, to a detection apparatus in which the level of an output detection signal changes between a state in which a detection target is in contact with a detection unit and a state in which the detection target is not in contact with the detection unit.

  In recent years, in the field of information processing, fingerprints and the like tend to be used as personal identification information as security is improved. Along with this, various fingerprint sensors have been developed.

  In the fingerprint sensor, reading of the fingerprint is started by detecting that the finger is in contact with the detection unit. At this time, the contact of the finger with the detection unit is currently performed by an optical sensor arranged around the reading window in addition to the image sensor for fingerprint detection.

  However, since the conventional fingerprint sensor needs to include a sensor for determining whether or not the finger has touched the fingerprint detection portion in order to determine whether or not the finger has touched the fingerprint detection portion, the sensor is large. As a result, costs increased.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a detection device that can detect contact and non-contact of a detection target with a detection unit only from a detection signal without using a dedicated sensor or the like. And

  The present invention relates to an image detection apparatus (1) in which the level of a detection signal changes between a state in which a detection target is in contact with a detection unit (14) and a state in which the detection target is not in contact with a detection unit (14). The method further comprises determining means (21) for determining whether the detected object is in contact with the detecting portion (14) according to the detection signal.

  The determination means (21) compares the level of the detection signal with a reference level, and determines whether or not the detected object is in contact with the detection unit (14) according to the magnitude relationship. . The reference level is higher than the level of the detection signal when the detection target is not in contact with the detection unit (14) and the detection signal when the detection target is in contact with the detection unit (14). It is characterized by being set to a level smaller than the level.

  Further, the determination means (21) determines that the detected object is in contact with the detection unit (14) when the level of the detection signal is higher than the reference level, and when the level of the detection signal is lower than the reference level. It is determined that the detected object is not in contact with the detection unit (14).

  The determination means (21) is characterized by determining whether or not the detected object is in contact with the detection section (14) according to the amplitude of the detection signal.

  The determination means (21) determines that the detected object is in contact with the detection unit (14) when the amplitude is greater than the specified value, and the detected object is detected by the detection unit (14) when the amplitude is smaller than the specified value. It is determined that it is not touching.

  The determination means (21) is characterized by determining whether or not the detected object is in contact with the detection section (14) according to the displacement of the detection signal.

  The determination means (21) determines that the detected object is in contact with the detection unit (14) when there are a plurality of sets of peaks and bottoms of the detection signal.

  The reference numerals in the parentheses are given for ease of understanding and are merely examples, and the scope of claims is not limited thereby.

  According to the present invention, it is possible to determine whether or not the detected object is in contact with the detection unit by determining whether or not the detected object is in contact with the detection unit. Since it can be determined whether or not the detection object is in contact with the detection unit without providing a sensor or the like, the structure can be simplified and the apparatus can be configured at low cost.

[First embodiment]
FIG. 1 is a block diagram of a first embodiment of the present invention, and FIG. 2 is a perspective view of the first embodiment of the present invention.

  The image detection apparatus 1 according to the present embodiment is a fingerprint detection apparatus using a line sensor, and is an apparatus that detects a fingerprint by moving a finger in a direction orthogonal to the line sensor. The light emitting elements 12-1, 12-2 and 12-3, the light guide 13, the image guide 14, the light receiving device 15, and the electronic component 16 are mounted and sealed with a mold resin 17. The mold resin 17 is mixed with carbon and the like so as not to transmit light. Thus, unnecessary light that does not propagate through the image guide 14 is prevented from entering the light receiving device 15.

The light emitting elements 12-1, 12-2, 12-3 are composed of, for example, light emitting diodes (LEDs) that emit near-infrared light or red light. Are mounted at substantially equal intervals in the arrow X direction. A drive pulse signal is supplied to the light emitting elements 12-1, 12-2, and 12-3 from the control device 21 that includes the electronic component 16 mounted on the circuit board 11. The drive pulse signal is PWM (pulse) according to the detection signal detected by the light receiving device 15.
width modulation) controlled.

  Light emitted from the light emitting elements 12-1, 12-2 and 12-3 is supplied to the light guide 13. The light guide 13 transmits the central wavelength component of the light emitted from the light emitting elements 12-1, 12-2, 12-3. The light guided by the light guide 13 enters the inside of the finger from the palm side toward the finger side. The light incident on the finger is irregularly reflected by the tissue inside the finger. As a result, it appears that the fingerprint side of the finger in the vicinity of the incident light is emitting light. Light from the fingerprint side is supplied to one end surface of the image guide 14.

  The image guide 14 is composed of optical fiber bundles arranged in the arrow X direction, and is disposed adjacent to the light guide 13 and parallel to the light guide 13. The optical fiber constituting the image guide 14 has a structure in which a clad is formed around the core, and a light absorber is formed around the clad, in order to distinguish the groove portion and the crest portion of the fingerprint. Acts as an image guide.

  The image guide 14 has a configuration in which optical fibers are arranged and fixed in the direction of the arrow X, and one end face thereof is formed with an angle with respect to the central axis. The angle of one end face of the image guide 14 is such that light from the air layer (refractive index 1.0) cannot propagate through the fiber to the other end face, and light from the finger (refractive index 1.5 to 1.7). Is set to an angle at which it can propagate through the fiber to the other end face. For example, the angle is ideally set to about 9.97 ° to 31.64 ° when the refractive index of the fiber core is 1.62 and the refractive index of the cladding is 1,52.

  At this time, even if the inclination angle of the end face is larger than this due to the nonuniformity of the interface between the core and the clad of the optical fiber, it is possible to distinguish the groove portion and the peak portion of the fingerprint. For example, the angle of one end face of the image guide 14 can be detected at 30 ° to 60 °. The larger the inclination angle of the one end surface of the image guide 14, the smaller the apparatus can be made. In the present embodiment, the inclination angle of the one end face of the image guide 14 is set to about 40 ° to reduce the size. For this reason, light leakage occurs. For this reason, in this embodiment, detection is performed in consideration of the influence of light leakage.

  According to the image guide 14 having the structure described above, a gap is formed between the fingerprint groove and the end face of the image guide 14, and light enters the end face of the image guide 14 from the air. It is not propagated to the other end face. In addition, the crest portion of the fingerprint is in close contact with the end surface of the image guide 23, and light passing through the inside of the finger passes through the image guide 14 and propagates to the other end surface of the image guide 14.

  Therefore, by detecting the light emitted from the other end face of the image guide 14, it is possible to identify whether it is a fingerprint groove portion or a mountain portion. On the other end surface of the image guide 14, a light receiving device 15 for detecting whether light has propagated through the image guide 14 is disposed.

The light receiving device 15 has a configuration in which a plurality of light receiving elements 15-1 to 15-n are arranged in a line in the arrow X direction. The light receiving elements 15-1 to 15-n are, for example, CMOS (complementary metal oxide semiconductor) photoelectric sensors or CCDs (charge coupled).
device) such as a sensor that accumulates electric charge at regular intervals. The light receiving elements 11-1 to 11-n are set to be approximately equal to or larger than the pitch of the optical fibers constituting the image guide 14.

  The light receiving device 15 receives light emitted from the other end of the image guide 14 by the light receiving elements 15-1 to 15-n, and accumulates electric charges according to the amount of the received light. The electric charges accumulated in the light receiving elements 15-1 to 15-n are output as detection signals at regular intervals. The detection signal output from the light receiving device 15 is supplied to the control device 21.

  The control device 21 includes a detection unit 31 and a control unit 32.

  FIG. 3 is a block diagram of the detection unit 31.

  The detection unit 31 includes amplifiers 41 and 51, a slice level generation circuit 42, comparators 43 and 52, and a reference voltage source 53.

  Detection signals detected by the light receiving elements 15-1 to 15-n of the light receiving device 15 are sequentially supplied to the detection unit 31. A detection signal from the light receiving device 15 is supplied to the amplifiers 41 and 51 and the slice level generation circuit 42. The amplifiers 41 and 51 amplify the detection signal from the light receiving device 15 and output it. For example, the slice level generation circuit 42 generates a signal having an average value of detection signals from the light receiving elements 15-1 to 15-n.

  The signal amplified by the amplifier 41 is supplied to the non-inverting input terminal of the comparator 43. The signal generated by the slice level generation circuit 42 is supplied to the inverting input terminal of the comparator 43 as a slice level.

  The comparator 43 compares the output signal of the amplifier 41 with the slice level from the slice level generation circuit 42, and when the output signal of the amplifier 41 is larger than the slice level from the slice level generation circuit 42, the output is set to a high level and is small. Sometimes the output is low. As a result, the detection signal of the light receiving element corresponding to the groove portion of the fingerprint is set to the low level, the detection signal of the light receiving element corresponding to the peak portion of the fingerprint is set to the high level, and the fingerprint image is binarized. The output of the comparator 43 is supplied to the control unit 32.

  On the other hand, the signal amplified by the amplifier 51 is supplied to the non-inverting input terminal of the comparator 52. The reference voltage source 53 generates a reference voltage. The reference voltage is lower than the detection signal level output from the light receiving elements 15-1 to 15-n when the finger is brought into contact with the light receiving device 15, and when the finger is not touched, the light receiving elements 15-1 to 15-1 are output. The voltage is set higher than the detection signal level output from 15-n. The reference voltage generated by the reference voltage source 53 is supplied to the inverting input terminal of the comparator 52.

  The comparator 52 compares the output signal of the amplifier 51 with the reference voltage from the reference power supply 53. When the output signal of the amplifier 51 is larger than the reference voltage, the output is set to a high level, and when the output signal is small, the output is set to a low level. . When the output of the comparator 52 is at a high level, it can be determined that a finger is in contact with the light receiving device 15, and when the comparator 52 is at a low level, it is determined that no finger is in contact with the light receiving device 15. it can.

  The output of the comparator 52 is supplied to the control unit 32 as a finger contact detection signal.

The control unit 32 is, for example, an ASIC (application specific
An integrated circuit) and a one-chip CPU (central processing unit) are supplied to the light receiving device 15 and supply a clock for controlling the read timing. Further, the control unit 32 reproduces a fingerprint image based on the output of the comparator 43 of the detection device 31. The reproduced image is supplied to the host device via the interface.

  FIG. 4 shows a flowchart of the contact detection operation of the control unit 32.

  The controller 32 detects whether or not the contact detection pulse output from the comparator 52 in step S1-1 is at a high level. If the contact pulse is at the high level in step S1-1, the control unit 32 determines that the finger has touched the image guide 14, starts the fingerprint detection process in step S1-2, and performs step S1-3. The fingerprint detection process is executed based on the output pulse from the comparator 43.

  When detecting that the contact detection pulse has become low level in step S1-4, the control unit 32 determines that the finger has moved away from the light receiving device 15, ends the fingerprint detection processing in step S1-5, and operates. The state is set to the standby state.

  According to the present embodiment, it is possible to determine whether or not the finger is in contact with the light receiving device 15 by the output from the light receiving device 15 without providing a dedicated sensor or the like, so that the configuration of the device can be simplified. Therefore, it is small and can be manufactured at low cost.

[Second Embodiment]
FIG. 5 shows a block diagram of the second embodiment of the present invention. In the figure, the same components as in FIG.

  The image detection apparatus 100 according to the present embodiment is different from the first embodiment in the configuration and operation of the control device 111.

  The control device 111 according to the present embodiment includes an ADC (analog digital converter) 121 and a control unit 122.

  The ADC 121 converts the analog detection signal from the receiving device 15 into digital data. The digital data converted by the ADC 121 is supplied to the control unit 122. The control unit 122 detects the contact of the finger with the light receiving device 15 based on the digital data from the ADC 121 and activates the fingerprint detection process.

  FIG. 6 shows an operation flowchart of the control unit 122.

  The control unit 122 captures data from the ADC 121 in step S2-1, detects a peak value from the data after removing noise components and the like from the data captured in step S2-2 by a digital filter, and stores the peak value. In S2-3, the bottom value is detected and stored. Here, the peak value is data in which the data is larger than the data before and after the peak value. The bottom value is data in which the data is smaller than the data before and after the bottom value.

  Next, the control unit 122 determines whether there are a plurality of pairs of the peak value and the bottom value stored in step S2-4. When there are a plurality of pairs of peak values and bottom values in step 2-4, the control unit 122 temporarily determines that a fingerprint image has been detected. That is, the possibility of the finger being touched is determined by detecting the fingerprint pattern in step S2-4.

  Next, the control part 122 determines whether a peak value and a bottom value are more than a regulation value by step S2-5. The specified value is set to a level higher than the detection signal level output from the light receiving elements 15-1 to 15-n when the finger is not touched.

  In addition, the control unit 122 determines that the finger is imaged when there are a plurality of pairs of peak values and bottom values in step S2-4 and the peak value and bottom value are equal to or more than the specified values in step S2-5. It is determined that the user is in contact with the guide 14, and the finger contact is notified to the fingerprint detection processing program or the like in step S2-6.

  According to the present embodiment, it is detected by digital processing whether or not the peak value and the bottom value of the detection signal are equal to or greater than a specified value, and whether or not the finger is in contact with the image guide 14 is detected based on the detection result. Therefore, a sensor or the like for detecting whether or not the finger is in contact with the image guide 14 becomes unnecessary.

  In this embodiment, it is possible to reliably detect contact of the finger with the image guide 14 by determining whether or not there are a plurality of pairs of peak values and bottom values.

  In this embodiment, since the contact of the finger with the image guide 14 is detected by detecting whether or not the peak value and the bottom value are equal to or greater than the specified value, when the image guide 14 is used outdoors or the like, If the detection signal level increases due to light leakage or the like, it may be determined that the finger is in contact with the image guide 14 even though the finger is not in contact with the image guide 14.

For this reason, in step S2-4, it is detected whether or not it is a pair of a peak value and a bottom value, that is, a fingerprint pattern, so that the contact of the finger with the image guide 14 can be reliably detected.

[Modification]
FIG. 7 shows an operation flowchart of a modified example of the control unit 32. In the figure, the same processing parts as those in FIG. 6 are denoted by the same reference numerals, and the description thereof is omitted.

  In this modification, the control unit 32 calculates the difference between the peak value and the bottom value in step S3-1 when there are a plurality of pairs of the peak value and the bottom value in step S2-4. Next, the control part 32 determines whether the difference of a peak value and a bottom value is more than a regulation value by step S3-2.

  When the difference between the peak value and the bottom value is greater than or equal to the specified value in step S3-2, the control unit 32 determines that the finger has touched the image guide 14, and in step S2-6, determines that the finger touches the fingerprint. Notify the detection processing program.

  In this modification, by detecting the contact of the finger with the image guide 14 based on the difference between the peak value and the bottom value, for example, even when the brightness of the outside is different, such as outdoors and indoors, the finger is guided to the image guide 14. Can be reliably detected.

  [Others]

In addition, although the example which applied the present Example to the fingerprint detection apparatus was demonstrated, it is not limited to this, It cannot be overemphasized that it can apply generally to the image detection apparatus which has a line type light-receiving device.
In this embodiment, the fingerprint detecting device using the image guide 14 is used to detect the contact of the finger with the image guide 14. However, the present invention can be applied to a device that detects the contact of the finger such as a keyboard. .

It is a block block diagram of 1st Example of this invention. 1 is a perspective view of a first embodiment of the present invention. 3 is a block configuration diagram of a detection unit 31. FIG. 3 is an operation flowchart of a control unit 32. It is a block block diagram of 2nd Example of this invention. 6 is an operation flowchart of the control unit 122; 10 is an operation flowchart of a modified example of the control unit 122.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,100 Image detection apparatus 11 Circuit board, 12-1 to 12-3 Light emitting element, 13 Light guide 14 Image guide 15 Light receiving apparatus, 15-1 to 15-n Light receiving element, 16 Mold resin 21, 111 Control apparatus 31 Detection unit, 32 control unit 121 ACD, 122 control unit

Claims (8)

In the detection device in which the level of the detection signal changes between the state in which the detection target body is in contact with the detection unit and the state in which the detection target body is not in contact with the detection unit,
A detection apparatus comprising: determination means for determining whether or not the detected object is in contact with the detection unit according to the detection signal. The determination unit compares the level of the detection signal with a reference level, and determines whether or not the detected object is in contact with the detection unit according to the magnitude relationship. The detection device described. The reference level is greater than the level of the detection signal when the detected object is not in contact with the detection unit, and the level of the detection signal when the detected object is in contact with the detection unit The detection apparatus according to claim 2, wherein the detection apparatus is set to a lower level. The determination means determines that the detected object is in contact with the detection unit when the level of the detection signal is higher than the reference level, and when the level of the detection signal is lower than the reference level, The detection apparatus according to claim 3, wherein the detection object is determined not to be in contact with the detection unit. The detection device according to claim 1, wherein the determination unit determines whether or not the detected object is in contact with the detection unit according to an amplitude of the detection signal. The determination unit determines that the detected object is in contact with the detection unit when the amplitude is greater than a specified value, and the detected object contacts the detection unit when the amplitude is smaller than a specified value. 6. The detection apparatus according to claim 5, wherein it is determined that the detection is not performed. The said determination means determines whether the said to-be-detected object is contacting the said detection part according to the displacement of the said detection signal, The description in any one of Claim 1 thru | or 3 characterized by the above-mentioned. Detection device. The detection device according to claim 7, wherein the determination unit determines that the detected object is in contact with the detection unit when there are a plurality of sets of peaks and bottoms of the detection signal.